impressions of the champlain bridge with photos, by delcan

625 Cochrane Drive, Suite 500, Markham, ON Canada L3R 9R9 Tel: 905.943.0500 ● Fax: 905.943.0400

www.delcan.com

DRAFT CONFIDENTIAL

December 15, 2010 OUR REF: BO 2198 JCCBI Ref: Contract 61445 Mr.Glen Carlin Directeur General Les Ponts Jacques Cartier et Champlain Incorporée 1111 rue St. Charles O, bureau 600 Tour Ouest Longueuil, Quebec J4K 5G4 Dear Sir

Re: REPORT – IMPRESSIONS OF THE CHAMPLAIN BRIDGE We are pleased to submit our draft Report on our Impressions of the Champlain Bridge. We look forward to reviewing this report with you and to completing it to your entire satisfaction. Yours truly, W. Victor Anderson, P.Eng. Executive Vice President WVA:fdk J:\tor\bo2198\bt\docs\report 1 cover letter.doc Enc. Report - Impressions of the Champlain Bridge

The Jacques Cartier and DRAFT Champlain Bridges Incorporated

IMPRESSIONS OF THE CHAMPLAIN BRIDGE

Page i December 15, 2010

TABLE OF CONTENTS

EXECUTIVE SUMMARY .............................................................................................. 1

1. INTRODUCTION ............................................................................................... 3

Section 5 ......................................................................................................... 4

Section 6 ......................................................................................................... 4

Section 7 ......................................................................................................... 5

2. BACKGROUND .................................................................................................. 7

3. THE ST. LAWRENCE RIVER AND THE ST. LAWRENCE SEAWAY ................................. 7

4. BEDROCK ........................................................................................................ 7

5. DESCRIPTION OF THE CROSSING ....................................................................... 8

Section 5 ......................................................................................................... 8

Section 6 ......................................................................................................... 9

Section 7 ......................................................................................................... 9

Sections 5, 6 and 7 ......................................................................................... 10

6. CONSTRUCTION OF THE BRIDGE ...................................................................... 10

7. HISTORY OF REPAIRS AND MODIFICATIONS ...................................................... 11

8. CURRENT REHABILITATION PROGRAMME ........................................................... 14

9. CURRENT PROGRAMME OF DE-ICING THE BRIDGE .............................................. 21

10. CURRENT BRIDGE DESCRIPTION AND CONDITION .............................................. 21

Abutments ..................................................................................................... 21

Pier Foundations on Approach Spans ................................................................. 21

Pier Stems on Approach Spans ......................................................................... 22

Pier Caps on Approach Spans ........................................................................... 23

Bearings on Approach Spans ............................................................................ 24

Concrete Girders on Approach Spans ................................................................. 24

Concrete Deck Panels on Approach Spans .......................................................... 24

Concrete Diaphragms on Approach Spans .......................................................... 24

Transverse Post-Tensioning on Approach Spans .................................................. 24

Barriers on Approach Spans ............................................................................. 25

Paving and Waterproofing on Approach Spans .................................................... 26

Wearing Surface on Approach Spans ................................................................. 26

Structural Steel Deck Truss Approach Spans ....................................................... 26

Main Pier Foundations ..................................................................................... 26

Main Piers ..................................................................................................... 27

Structural Steel Through Truss Main Spans ........................................................ 27

Orthotropic Steel Deck and Wearing Surface ....................................................... 28

Painting of Structural Steel .............................................................................. 28

11. STRUCTURAL HEALTH MONITORING .................................................................. 29



Page ii December 15, 2010

12. SUMMARY ...................................................................................................... 29

13. CONCLUSION ................................................................................................. 30



Page 1 December 15, 2010

EXECUTIVE SUMMARY Delcan was retained in August 2010 by The Jacques Cartier and Champlain Bridges Incorporated to carry out a Structural Health Assessment Study of the Champlain Bridge. The objective of this contract was the undertaking of a study in order to provide the Corporation with an expert assessment of the current structural health of the Champlain Bridge. This Report – Impressions of the Champlain Bridge, records Delcan’s impressions of the bridge based on work carried out by Delcan in 2010. The work covered the deck, superstructure and substructure of the main sections of the bridge, namely, Sections 5, 6 and 7 which include: • Section 5, the section extending from Île des Soeurs to the steel structure of the bridge

and comprising prestressed concrete girders integrated with deck infill sections and diaphragms which are transversely post-tensioned to the girders.

• Section 6, the bridge section spanning the St. Lawrence Seaway and including the main span which consists of a cantilever-type through truss steel structure and the flanking deck-truss approach (transition) spans, and

• Section 7, located between the steel structure of Section 6 and the abutment on the

South Shore and including prestressed concrete girders integrated with deck infill sections and diaphragms which are transversely post-tensioned to the girders in a fashion similar to that incorporated in Section 5.

This report is based upon works carried out by Delcan which include a review of the bridge in the field, and a review of extensive records, reports and studies provided by the Corporation as to the history of the various interventions on the bridge since its construction. Overall, our impression of the bridge is that it is in a condition which requires extreme vigilance in order to maintain it safely in service over even a relatively short term. Some of the deterioration which has been observed is very severe. Deterioration such as this tends to progress exponentially, the rate of increase of deterioration increasing itself with time, hence increasing concern with regard to this bridge. A number of repairs have been carried out to the prestressed concrete girders with a view to compensating for known loss or increasing the load-carrying capacity of the bridge both in bending and in shear. These, however, must be considered to be measures which are not appropriate for long-term service. Rather, they are intended to help secure the bridge in the short term until something more substantive can be implemented. It has been recognized that there is a risk of partial collapse of the bridge, or even the collapse of a span, given the structural configuration of the prestressed concrete girder and diaphragm grillage which comprises the superstructures in Section 5 and Section 7. This is combined with concerns with regard to the condition and load-carrying capacity of the pier caps and the poor condition of some of the pier stems as well as concerns with regard to the condition of the foundations. The possibility that there will be a partial or complete collapse of one span given all of these negative aspects of the bridge, cannot altogether be ruled out. It is a risk which is being borne and managed at this time.




The Champlain Bridge is considered to be a lifeline bridge from the perspective of seismic loading. This means that the bridge should be capable of resisting the 475 year design seismic event without being taken out of service, and of resisting the 1000 year large earthquake event and being open immediately to emergency vehicles. However, the bridge has not been designed to sustain significant seismic loading and we understand that analyses have shown that it has no capacity to do so. In its current condition, this bridge can be expected to collapse partially or altogether in a significant seismic event. In summary, this bridge is not in a condition which is compatible with it continuing to serve for an extended period of time as a major crossing of the St. Lawrence River under the substantial vehicular, truck and bus loads which it must sustain, without some risk, which cannot altogether be quantified.




1. INTRODUCTION The Champlain Bridge is one of the major crossings of the St. Lawrence River in Montreal. It opened to traffic on June 28, 1962, to provide a six-lane, 60 mile-per-hour highway crossing of the St. Lawrence River and the St. Lawrence Seaway between Montreal and the South Shore. Starting from Montreal, the bridge includes the following sections: Section 1: Montreal approaches west of Wellington Street. Section 2: Approaches between Wellington Street and the west bank of the St. Lawrence

River. Section 3: Crossing of secondary river channel to Île des Soeurs. Section 4: Roadway and plaza on Île des Soeurs. Section 5; Main river crossing between Île des Soeurs and the St. Lawrence Seaway. Section 6: Crossing of the St. Lawrence Seaway. Section 7: East approach structure. Section 8: Approach roadways on the South Shore. This report deals with Sections 5, 6 and 7.

Figure 1 - Aerial View of Champlain Bridge Delcan was retained in August 2010 in accordance with a Request for Proposals issued by The Jacques Cartier and Champlain Bridges Incorporated to carry out the Structural Health Assessment Study of the Champlain Bridge, Contract Number 61445. The objective of this contract is the undertaking of a study in order to provide the Corporation with an expert assessment of the current structural health of the Champlain Bridge. This assessment is to include a review of the known and potential modes of material and structural degradation, an overview of the measures implemented and planned by the Corporation to mitigate structural aging of the bridge, and a qualitative assessment as to the technical feasibility and inherent risks on a structural basis associated with the operation of this bridge for an extended period of time. As a part of this study, Delcan was also to examine the Corporation’s 10-year $212 Million bridge rehabilitation programme




which was initiated in 2009 and determine if the bridge can continue to be sustained in this interval and beyond, knowing that the structure and its components are likely to deteriorate in a non-linear fashion over time. The study is to cover the deck, superstructure and substructure of the main sections of the bridge, namely Sections 5, 6 and 7 as noted above. They are described briefly hereafter. Section 5 This section extends from Île des Soeurs to the main steel structure of the bridge. This is the longest section of the bridge; it measures 2,050.4 m (7,053 feet 4 inches) and includes 40 spans measuring 53.7 m (176 feet 4 inches) each.

Figure 2 - Prestressed Concrete Girders in Section 5 The spans comprise prestressed concrete girders integrated with deck infill sections and diaphragms which are transversely post-tensioned to the girders, hence forming a highly-connected grillage whereby the top flanges of the girders and the deck infill sections comprise the bridge deck. Section 6 This section includes the bridge spanning the St. Lawrence Seaway.

Figure 3 – Cantilever-Type Through Truss Steel Structure of Section 6




Clearance of 36.6m (120 feet) is maintained over the full width of the channel. This section includes the main span which consists of a cantilever type through-truss steel structure measuring 450.5 m (1,477 feet 9 inches) composed of three spans, including the central one measuring 215 m (706 feet 9 inches) and comprised of cantilever arms and a suspended central span. Section 6 also includes flanking deck-truss approach (transition) spans. Both the cantilever through truss and deck truss which make up this section of the bridge have steel orthotropic decks. Section 7 Located between the steel structure of Section 6 and the abutment on the South Shore, Section 7 includes ten spans, with four spans measuring 53.7 m (176 feet 4 inches), two measuring 51.4 m (168 feet 8 inches), three measuring 52.5 m (172 feet 4 inches) and one span measuring 52.7 m (172 feet 10 inches), for a total length of 528.4 m (1,733 feet 1 inch). Section 7 contains subsection 7A and 7B which are slightly different in design. Like Section 5, the top flanges of the post-tensioned girders in sections 7A and 7B also form part of the bridge deck.

Figure 4 - Prestressed Concrete Girders in Section 7 The description of professional services in this study is included in the Request for Proposal as follows: The study shall examine the structural health of the bridge on the basis of the data and documentation that is currently available as well as the Consultant’s own expertise in matters relating to deterioration and rehabilitation of infrastructure, taking into account without limitation, the following aspects and information concerning the bridge and its condition: • The structural configuration of the bridge, in particular, the unusual configuration of the

deck slab, a portion of which consists of the top flanges of the prestressed girder, and the balance of which is comprised of a cast-in-place section sandwiched between the top flanges and which relies entirely on transversal post-tensioning to support dead and live loads.




• The Owner’s historical records of major repairs to most if not all of the concrete (prestressed/cast-in-place) components of the bridge which include repairs to expansion joints (several repair cycles), barriers, bearings, prestressed beams (several cycles of repairs to flanges, web, and post-tensioning anchor ends), pier caps, pier shafts, underwater repairs, main span pier columns and more recently, localized repair to deck slab and observed structural damage to the diaphragms.

• The structural reinforcement undertaken and currently ongoing to pier caps, edge

girders (for example, the incorporation of a queen post system), to compensate for the limited structural capacity of these important bridge components.

• Numerous reports (some of which are listed in Appendix 5A) pertaining to the annual

inspection and underwater inspection of the bridge.

• Reports and special studies (some of which are listed under Appendix 5A) regarding the structural rating of the bridge under dead and highway live loads, special rating reports concerning edge girders and pier caps, and structural rating of substructure components under wind load.

• Reports and special studies (some of which are listed under Appendix 5A) regarding life

cycle costs, risk assessment and risk mitigation measures (stand-by emergency above deck girder and modular support truss for example), remaining fatigue life of orthotropic deck-sections, and special non-destructive test methods (magnetic survey of deck, ultrasonic inspection of pins, half-cell potential survey of girders, concrete coring programs and other).

• The Owner’s recent implementation of some form of structural-health monitoring

technology on a limited number of the beams of the Champlain Bridge.

• Limitations in current technology and knowledge in respect to the ability to accurately diagnose and to predict future trends in regards to material degradation and structural capacity of main load carrying components of the substructure, superstructure, deck and accessory bridge devices and equipment.

• The high traffic demands, the limited available time to undertake works without

impacting negatively upon service to the users of the bridge and the capacity to intervene in a timely manner given the size of the bridge and the available expertise and capacity of contractors within the Greater Montreal construction market.

• Complications originating from the operation of the reserved bus line (contraflow traffic

with no divider) which makes rerouting of heavy trucks to interior lanes impractical and/or problematic from a risk management perspective.

• Degree of uncertainty related to the level of performance of certain key components.

• Issues relating to seismic response and/or rehabilitation for seismic loading.

• Volume of traffic and percentage of heavy trucks that the bridge currently handles

annually and is likely to handle in the future.




• The integrated nature of the superstructure system within the approach spans due to longitudinal and transversal post-tensioning which makes replacement of the deck and girder components either very difficult if not impossible.

In addition to the works identified in Article 5.01.1 – Scope as well as the services and considerations listed above, the Consultant shall review the Owner’s past and current rehabilitation strategies and provide a qualitative statement in its report as to the risks associated with this strategy, including an identification of the real and/or potential risks and their manageability, considering the importance of the bridge and knowing that the turnaround time to replace the structure may be on the order of ten (10) years. 2. BACKGROUND A list of reports, reference drawings and other documents to be consulted was included in Appendix 5A of the Request for Proposal. Aerial photos of the Champlain Bridge were provided in Appendix 5B of the Request for Proposal. The overall layout of the Champlain Bridge was described in Appendix 5C of the Request for Proposal. The number of traffic lanes to be kept open was provided in Appendix 5D of the Request for Proposal. Additional information was made available comprising a number of reports and other documentation. The story of the construction of the bridge is well-described in a document entitled “The Champlain Bridge – a Photographic Story” by Hans van der Aa, which was published in 1962. Reference is made to this and other documents in describing the construction of the bridge in subsequent sections of this report. 3. THE ST. LAWRENCE RIVER AND THE ST. LAWRENCE SEAWAY The bridge crosses the main channel of the St. Lawrence River though Section 5 and rises to cross the St. Lawrence Seaway through Section 6, descending through Section 7 to the connecting roads on the South Shore. The bridge spans the St. Lawrence River where its widening forms the Laprairie Basin. The bridge is located in flat, open country and both riverbanks are low. The bridge rises to provide a 120 foot clearance above the St. Lawrence Seaway which skirts the bank of the river on the east side. Because the Laprairie Basin is quite wide at this location, the river is relatively shallow. 4. BEDROCK The bedrock is regular, nearly-horizontal shale strata. Some intrusions of igneous rocks and very thin beds of clay were responsible for the depth of pier foundations varying from 2 to 10 feet under the surface of the rock in Sections 5 and 7A. Below the level of these foundations, the rock is sound and the need for consolidation by injection was insignificant. The rock, in its natural state, was generally covered with overburden 0 to 12 feet thick, of alluvia of glacial origin.




5. DESCRIPTION OF THE CROSSING Section 5 Section 5 is the main river crossing between Île des Soeurs and the St. Lawrence Seaway. It comprises a length of 7103 feet. This section of the bridge includes 40 prestressed concrete spans of approximately 176 feet each supported on T-shaped piers founded on the shale bedrock. The original contract to construct this section represented the largest application of prestressed concrete in Canada both in individual span length and quantity of work up to that time. The contracting strategy involved consideration of prestressed concrete, steel and reinforced concrete superstructure options, and the successful bid was the lowest of 28 received. It came at a time when prestressed concrete was still a relatively new construction method in Canada. Each span consists of seven precast beams, at 12 foot 2 ½ inch centres with two intermediate diaphragms and a transversely stressed slab. The stressing of the beams, diaphragms and deck was performed with 12 wire Freyssinet cables. The circular pier footings were poured in the dry inside sheet pile cofferdams and slip forms were used for the shaft construction. The pier cap beams were poured in formwork supported by steel trusses sitting on the tops of the pier shafts. In the design of this bridge, extensive efforts were made to reduce ice forces on the piers and foundations. Hence the piers and foundations are relatively small and the cantilevers associated with supporting the roadway on the piers are relatively large. This was found at the time to be the optimum solution in the context of a prestressed concrete superstructure capable of carrying a 76 foot roadway and two 1 foot 6 inch curbs to accommodate the six lanes of traffic required on the bridge. A key feature of the design of this bridge section is that the superstructure comprises: • Seven prestressed post-tensioned concrete girders.

• Six post-tensioned concrete deck infill sections. • Post-tensioned concrete diaphragms interconnecting the girders and the deck. • Deck post-tensioning running through the top flanges of the girders transversely to the

girders, across the full width of the deck. • Simple spans, that is spans not connected to adjoining spans at the piers. • Very long reinforced cantilevers supporting the superstructure on the stems of the piers. • Pier stems shaped to reduce ice forces. • Relatively compact circular foundations supported on the bedrock, with minimal

anchorages to the bedrock around the perimeters. The six longitudinal spaces that separate the beams are approximately the same width as the upper flanges of these beams. They are concreted at the same level and with the same thickness as the flanges. The slab thus formed is prestressed transversely by means of cables anchored on the two outside girders. No mild reinforcement was used to help connect the infill strip sections to the girder flanges. Because of its unusual configuration, the superstructure is highly integrated.




The cofferdams for the piers were made by driving steel sheet piles around a cylindrical template. It was noted during construction that some time was wasted on account of numerous water blowouts which made it necessary to re-drive the sheet piles and to repeat the pumping operation. It was also necessary at times to drive a second concentric sheet pile ring into the interior of the cofferdam in order to reduce the hydrostatic pressure on the ground at the bottom of the sheet piles by draining half-way up the space between the two sheets. The pier cantilever sections supporting the superstructure were heavily reinforced as a consequence of efficiencies gained by reducing the size of the pier stem to minimize ice loads, and of the requirement to support a fairly heavy concrete superstructure. Section 6 Section 6 is the crossing of the St. Lawrence Seaway. From Île des Soeurs the bridge climbs up on a 0.85% grade for the long crossing of Laprairie Basin (Section 5) bringing the bridge to a sufficient height in Section 6 to provide the 120 foot vertical clearance over the Seaway channel which runs close to the east bank of the river. The 120 foot clearance is maintained to the underside of the steel main span for the full 300 foot width of the Seaway channel. Section 7 comes down to the South Shore on a 3% grade. Section 6 was originally built with a steel superstructure and reinforced concrete roadway slab. The main steel superstructure is a three span cantilever unit crossing the Seaway channel. This is flanked by four 250 foot long simple truss spans, giving a total length of 2504 feet 9 inches. The 252 foot flanking spans are deck trusses with four trusses spaced at 23 foot 4 inch centres in each span. The cantilever unit is a three truss design to provide minimum depth of construction below road level over the Seaway and consists of three trusses spaced at 43 foot 6 inch centres. The anchor arms have a 385 foot 6 inch span and a central clear span of 706 feet 9 inches is made up of two cantilever arms of 160 feet 7.5 inches and a suspended span of 385 feet 6 inches. The trusses are fixed at the two main piers and the 9 inch temperature movement for the central span is all taken up with an expansion joint (originally a finger-type but later replaced by a strip-seal joint) at the east end of the suspended span. The maximum truss depth of 104 feet occurs over the main piers reducing to 35 feet at the ends of the suspended span. Extensive use was made of high-strength low-alloy steel where there were heavily-loaded truss members. The three truss layout for the main span is an unusual one. The structural steel is supported on reinforced concrete substructures which are founded on bedrock. Section 7 Section 7 carries the bridge from Section 6 down to the South Shore abutment. It comprises the six spans of Section 7A which were constructed in the same contract and using the same methodology as in Section 5 (described in detail above) and four spans constructed in a separate contract. The four spans which are at the southernmost end of Section 7 were constructed in Contract 7B where alternative prestressing methods were allowed in bidding on the 172 foot beams, and the contractor elected to use GTM stranded cables instead of the Freyssinet parallel wire cables shown on the tender drawings. This is the only contract on the bridge where Freyssinet cables were not used. These girders, like those in Section 5 and 7A, include intermediate diaphragms in greater number and a slab designed to be transversely stressed




to form a highly-integrated superstructure supported on reinforced concrete foundations founded on bedrock. Sections 5, 6 and 7 In summary, the segment of the bridge under consideration includes three sections built under three separate contracts and including a total length of 11,340 feet 2 inches from abutment to abutment. 6. CONSTRUCTION OF THE BRIDGE Studies for the bridge began in 1955. Borings were made in the river in 1956. The proposed location lines, profiles and clearances were approved in 1957, enabling final designs and drawings to proceed. The full six-lane scheme was adopted in 1958. Construction of Section 6 substructure components began before confirmation if the bridge would comprise a four-lane or six-lane carriageway. The basic bridge width comprises two 37 foot roadways in each direction separated by a median divider.

Figure 5 - Champlain Bridge Under Construction The first of many contracts for construction of the bridge was let in 1957. The major structural contracts were all let in the summer of 1959. These included the contract for construction of Sections 5 and 7A, and the contract for Section 6 steel superstructure and reinforced concrete roadway slab. The contract for Section 7B was awarded in 1960. There were many other contracts awarded as a part of the construction of the overall Champlain Bridge crossing. The works were entirely completed and the bridge open to service on June 28, 1962, the sections of the bridge under consideration here (Sections 5, 6 and 7) having been completed between June 1959 and the opening of the bridge some three years later. It can be fairly said that the bridge was designed rapidly and constructed with a view to efficiency, economy and speed of construction and included some innovative works such as




the prestressed concrete spans in Sections 5 and 7, and more traditional works such as the cantilevered steel construction in Section 6. 7. HISTORY OF REPAIRS AND MODIFICATIONS Significant rehabilitation measures carried out in the 1990s are described in detail in two technical papers published in the Canadian Journal of Civil Engineering. These papers are as follows: • Rehabilitation measures for Champlain Bridge, Montreal, Canada by G.P. Carlin, M.S.

Mirza, and M. Gaudreault, Canadian Journal of Civil Engineering, Volume 23, 1996. • Replacement of Reinforced Concrete Deck of Champlain Bridge, Montreal, by Orthotropic

Steel Deck, by G.P. Carlin and M.S. Mirza, Canadian Journal of Civil Engineering, Volume 23, 1996.

These papers note that The Jacques Cartier and Champlain Bridges Incorporated was established by the Federal Government in 1978 and that it had a clear mandate as custodians of the bridges to establish an appropriate maintenance policy. Activities are prioritized through in-depth condition surveys of various components of the bridge and the entire programme is renewed globally on an annual basis with priorities established most importantly depending upon the severity and location of deterioration as it pertains to the integrity of the bridge. Urgent temporary repairs are performed to protect severely deteriorated members such as localized failure of the deck, and failed expansion joints, for example. Detailed inspection reports are prepared. The detailed inspection reports provide recommendations based on the bridge condition for its regular inspection and maintenance, special inspections and investigations and a rehabilitation programme. A ten year major maintenance and capital plan including cost estimates for the entire bridge, and including all rehabilitation projects recommended in order of priority, timing and the estimated budget for each project, was proposed. As part of the major maintenance and capital plan, a programme to repair the concrete piers including the submerged segments was initiated in 1990. Also undertaken in 1990 and completed in 1993 was the replacement of the reinforced concrete slab at the cantilever steel superstructure over the St. Lawrence Seaway and its immediate approaches, with a lighter closed rib orthotropic steel deck. The paper entitled Rehabilitation Measures for Champlain Bridge, Montreal, Canada (Carlin, Mirza and Gaudreault) 1996 includes detailed descriptions of many aspects of the bridge including the following: • The unusual system used for construction of the bridge segments in Sections 5 and 7

whereby the top flanges of the precast prestressed beams do not support an independent deck but rather there are infill, cast-in-place slabs between the precast beam flanges, and the assembly of the precast flanges and the cast-in-place slabs at each of the spans is transversely post-tensioned, hence constituting the deck.

• The use of de-icing salts over the past decades which had rendered susceptible to corrosion the post-tensioned and prestressed cables of Sections 5 and 7 of the bridge.




• The further undermining of Sections 5 and 7 as a result of the deck drainage system in place at the time, permitting salt-laden snow melt to run onto the exterior prestressed beams. This has since been rectified with the installation of solid barriers incorporating new galvanized steel drains.

• The nature of the original expansion joints which consists of an open sliding tooth design

which permitted salt water to drain onto the tops of the piers, attacking also the ends of the prestressed beams. These were later retrofitted to strip-seal type joints.

• The condition survey and inspection of the bridge noting that detailed inspections were

carried out since the inception of The Jacques Cartier and Champlain Bridges Incorporated in 1978. In 1985, a four-year cycle detailed inspection programme was initiated. The inspection manuals and guidelines developed specifically for the bridge were also noted in this document. These inspections included many features such as

o Hammer sounding of deteriorated concrete o Scraping of corroded materials o Hammering suspect rivet heads o Measures to verify expansion bearing performance under extreme weather

conditions o Monitoring of structurally significant cracks o Hands-on inspection o Hammer sounding of structural concrete components which were not easily

accessible and areas where serious defects were suspected o Chipping and hands-on inspection of deteriorated concrete in distressed

prestressed concrete beams o Coring and testing of concrete o Measurement of steel cross-sectional area to detect any significant loss of metal o Ultrasonic and dye-penetrant testing of pin connections o Ultrasonic testing of significant cracks in the substructure o Surveying of structures when abrupt structural movements were suspected o Deck condition surveys including visual survey and coring and testing

deteriorated deck components for chloride content and compression strength An underwater inspection of all bridge piers carried out in 1988 revealed that the surface of each pier had a typical network of horizontal and vertical cracks which were characterized as narrow (0-5 mm wide), and wide (larger than 5mm in width). Underwater repair works were carried out. In 1990 an annual programme to inject cracks and repair concrete surfaces in the submerged sections in tidal zones of selected piers was initiated. The work was performed in the area extending from the river and up to a height of 0.5 to 1m above the water level. Repairs included drilling of cracks, injection of cracks, repair of honeycombing and spalling, and repair of porous concrete. Importantly, it is noted that inadequate quality control during original construction is believed to be responsible for some of the major horizontal cracking in the substructures. Most of the cracks were believed to be resulting from the alkali reactive aggregates present in the concrete mix, and it was noted that early test results supported this hypothesis, while some of the cracking was considered to be related to thermal effects. Repairs were carried out to the piers and beam ends as the bridge piers are susceptible to continuous accumulation of salt-bearing water dripping from open drains (since replaced)




which resulted in considerable deterioration of the concrete and corrosion of the steel reinforcement. Similar deterioration was noted at the beam ends as well as at the underside of the deck where spalling of concrete had occurred exposing reinforcing steel. Initiated in 1988, the repairs performed in 1990 involved rehabilitating concrete in many areas to effect rehabilitation of the piers at that time. The underside of the deck, diaphragms located on top of the piers, the underside of the beams, the beam ends were also repaired in various locations at that time (1990). Repairs were also carried out to the prestressed beams at that time. Importantly, it was noted that the exterior post-tensioned girders of the bridge had been subjected to severe chloride attack. Tests in the concrete from these exterior girders showed that the chloride ions had contaminated the exterior surface of the concrete, although the chloride ion content was found to decrease significantly with depth. Longitudinal cracking in the lower web and bottom flange of these exterior beams results in open passageway for the salt water to attack the prestressing cables. To alleviate this, a 1.5mm thick impervious membrane coat was applied to the lower regions of the girders, which helped reduce the rate of deterioration of the girders until an adequate drainage system could be installed and other protection measures considered. Cathodic testing was also tested at that time. Alternate cathodic protection systems (zinc, zinc-aluminium sprayed anode) were also explored in the late 90’s. A new active drainage system was installed in 1995. The effects of vehicular splashing onto the exterior beams were handled by installing a new parapet containment barrier wall which replaced the previously corroded steel railing. A wire mesh cathodic protection system was planned and pilot-tested. Consideration was given to the possibility of replacing exterior beams but, because the top flanges of the prestressed girders form part of the deck, and all of the beams are integral with the cast-in-place filler sections between the flanges and with the diaphragms as a result of transverse post-tensioning, this is a very difficult, if not impossible, thing to do. It was noted that the deterioration of the exterior girders, if taken to excess, makes the entire deck vulnerable and jeopardizes the integrity of the spans. The following general repairs were also carried out: • Repairs to the underside of the beam.

• Repairs to the diaphragms. • Application of protective water-proofing membrane to the bottom part and along the

cracks of the outside face of both upstream and downstream beams in Section 7 and of all beams in Section 5.

• Addition of external prestressing to the exterior beams of the Champlain Bridge. The paper published in 1996, noted then that typically the severe corrosion in some areas of the prestressed beams had resulted in spalling of the concrete, exposing of the reinforcing steel and exposing of the prestressing stands. On some exterior girders, several strands were found to have ruptured and many were close to failure. Additional external prestressing was used to remedy this situation. At that time, typical damage to the Champlain Bridge exterior girders was limited to the central portion to strands that had little curvature, with anchors in the lower part of the beams. Therefore, at that time, loss of shear capacity was slight and only bending capacities were investigated and




restored (later, shear capacity became an issue as deterioration progressed, and it was necessary to take steps to restore shear capacity in some instances).

• An impressed current type cathodic protection system was tested in 1989, and a second

test initiated in 1991, but it is understood that extensive similar protection has not been implemented on the bridge. The testing of the cathodic protection system raised some questions as to its performance and consideration was also given to zinc anode spray to examine its feasibility.

The issue of hydrogen embrittlement of prestressing tendons caused by hydrogen produced from the impressed currents used for cathodic protection, was also investigated. A corrosion protection strategy was developed in the context of a Value Engineering Study for Sections 5 and 7 of the Champlain Bridge. Section 6 was excluded as it was then undergoing deck replacement. This Value Engineering study was very extensive and was carried out by a committee of many experts from all disciplines directly related to the proposed technical solutions. It resulted in a range of recommendations on a priority basis for protecting the bridge from corrosion. External post-tensioning ducts made of PVC had to be replaced by HDPE (high density polyethylene) ducts. In some cases, the external post-tensioning had to be replaced altogether. Also at this time, the molded elastomer expansion bearings of the bridge were replaced by new molded rubber and steel expansion bearings. The above discussion is derived from the 1996 paper, Rehabilitation Measures for Champlain Bridge, Montreal, Canada by Carlin, Mirza and Gaudreault. In addition to all of the works noted therein, the replacement of the reinforcement of the concrete deck of the Champlain Bridge by an orthotropic steel deck was also implemented. This is described in the paper by Carlin and Mirza entitled “Replacement of Reinforced Concrete Deck of Champlain Bridge, Montreal, by Orthotropic Steel Deck” noted previously. This paper noted that Section 6 of the bridge includes a three span steel span superstructure supported on concrete piers which, at that time, supported the original reinforced concrete deck. The deck was replaced by a new orthotropic steel deck which had the effect of greatly extending the service life of the deck, reducing the dead load on the steel superstructure, improve the rigidity of the bridge, and increasing the live load carrying capability of the steel superstructure. Field erection work commenced in the Fall of 1990 and the works were completed in the Fall of 1993. This was a major programme of bridge strengthening and rehabilitation which resolved the issues then existing as to the original reinforced concrete deck of the main span. The programme of inspection, investigation, testing, repair and rehabilitation has continued to the present day, at ever-increasing effort and expenditure. 8. CURRENT REHABILITATION PROGRAMME A 10-year major maintenance and capital plan including cost estimates for the entire bridge, and including all rehabilitation projects in order of priority and timing, and the estimated budget, is now in place for 2009-2019.




Some of the key elements of this current rehabilitation programme include the following: • An on-going programme of local/partial waterproofing and paving the bridge.

• Repairs to the pier shafts, caps and cross-beams, generally by full encapsulation. • Repairs to the prestressed beams, diaphragms and the concrete deck. • A recent strengthening of the prestressed girders by the addition of external vertical

shear reinforcement.

Figure 6 – Repairs to Prestressed Concrete Girders including External Posttensioning • Strengthening of the prestressed concrete girders by the addition of external post-

tensioning below the soffits of the prestressed concrete girders, a methodology effected by queen posts and anchorage of this new additional external post-tensioning to the girders.

Figure 7 - External Post-tensioning including the use of Queen Posts on Prestressed Concrete Girders Figure 7 – External Posttensioning of Prestressed Concrete Girders using Queen Posts




• The addition of prestressing to the pier caps which were considered to be a high risk as there was not enough development length in the reinforcing steel in these caps in accordance with modern codes, and hence the conventional reinforcement, although very heavy, is not capable of developing its full strength under load.

• Repairs to the piers of the main span (in Section 6). • There is in place a pre-purchased modular truss which has been stored nearby to the

bridge and which would be intended to support an exterior girder in the case of an emergency; i.e., significant loss of load-carrying capacity and/or deformation of such an exterior girder. In addition, a pre-purchased plate girder is available which can be installed from above the deck in order to add additional security if a girder shows signs of failing.

These are major rehabilitation efforts and they are being carried out on a programmed basis. In this context, in January 2009 a budget of $212 Million was announced in the Federal Government budget to enable the Champlain Bridge to be maintained in service as to its function and security over a 10-year period to 2019. This, we understand, was in accordance with the programme prepared by The Jacques Cartier and Champlain Bridges Incorporated to best assure the safety and security of the bridge under traffic operations for a 10-year period. This major investment was based on internal estimates prepared in 2008 and supported by inspections reported in 2007 and earlier. The 10-year programme was also developed to account for results stemming from structural evaluations and live load ratings carried out in the period 2000-2007. The programme of inspection, investigation, repair and rehabilitation has continued in conjunction with the maintenance programme until the present day, and it is ongoing. The most recent annual inspection was carried out in 2010 by AECOM and it is reported in for volumes entitled “Volume S-1 Sommaire des inspections et recommandations”, “Volume S-2 Notes d’inspections, tableaux de cotation et mesures de dilatation”, “Volume S-3 Photographies des inspections générales”, and “Volume S-4A Inspections détaillés”. These are very detailed reports on what is clearly a substantial inspection and consideration of appropriate recommendations, and it is one step in the programme of annual inspections carried out by AECOM. The 2010 report has resulted in 10 prioritized recommendations. Very briefly, the 2010 Annual Inspection Report finds that the general state of the structures of the Champlain Bridge and its approaches are variable depending upon the sections, the works and the elements considered. In general the structures are deemed to be in a passable state but certain elements are in a condition which ranges from mediocre to deficient. Of the 10 recommendations judged to be the highest priority amongst the ensemble of recommendations presented in the 2010 report, the following apply to Sections 5, 6 and 7.




These recommendations are reproduced following: PRIORITÉ SECTION ACTION A1 5 Effectuer les travaux d’inspection détaillée du platelage à

l’intrados, incluant expertise de dalle et une étude de capacité résiduelle de la dalle.

A2 7 Effectuer les travaux d’inspection détaillée du platelage à l’intrados, incluant expertise de dalle et une étude de capacité résiduelle de la dalle.

A3 5 Supporter les zones de béton endommagé exposant des fils de précontrainte transversale à l’intrados de la dalle.

A4 7 Supporter les zones de béton endommagé exposant des fils de précontrainte transversale à l’intrados de la dalle.

A8 5 Remplacer les joints de tablier qui montrent de délaminage et de l’éclatement très important au platelage (partie sous le joint entre les diaphragmes d’extrémités) ou autres déficiences majeures au niveau des profilés et épaulements. Inclure l’ajout d’une membrane d’étanchéité de part et d’autre des joints.

A9 7 Remplacer les joints de tablier qui montrent de délaminage et de l’éclatement très important au platelage (partie sous le joint entre les diaphragmes d’extrémités) ou autres déficiences majeures au niveau des profilés et épaulements. Inclure l’ajout d’une membrane d’étanchéité de part et d’autre des joints.

A10 6 Réparer les zones de béton endommagé sur les semelles, les fûts, les chevêtres et les assises ayant un CMI de 12.5 % et plus.

We reproduce here as well the comments which AECOM has made in their Executive Summary as to Sections 5, 6 and 7 as these give a good sense of their perspective of these sections, having inspected them in detail very recently (in April to August 2010). Sections 5 et 7 Les section 5 et 7 sont l’objet d’un programme de réfection majeur depuis 1987 dont plusieurs éléments principaux (piles, chevêtres, poutres et joints) sont réparés, remplacés et renforcis. La continuité de ce programme est essentielle pour conserver l’intégrité de la structure et en améliorer son état général en attendant son éventuel remplacement complet. Dans cet esprit, plusieurs recommandations prioritaires concernent ces deux sections. On observe la progression de la détérioration des câbles de précontrainte transversale au niveau de l’intrados du tablier où des zones de délaminage, d’éclatement de béton avec câbles corrodés accompagnés parfois de fils coupés, sont observés en 2010 dans presque toutes les travées des sections 5 et 7. Considérant la progression exponentielle de ces défauts dans le platelage qui a une épaisseur de 225 mm, un programme de réfection de la précontrainte transversale doit être mis de l’avant dès 2011 afin d’éviter la perte de compression nécessaire à la bonne tenue de l’élément de dalle situé entre les semelles supérieures de poutre. Également, des réparations devront être prévues pour éviter tout problème de poinçonnement local du tablier après perte des matériaux (recommandation prioritaire).




Section 6 La superstructure d’acier de la section 6 est dans un bon état général. L’entretien régulier (peinturage) semble avoir permis de conserver l’intégrité structurale malgré quelques défauts localisés de matériaux. Les joints d’expansion modulaires montrent cependant des signes d’usure et de comportement déficient sous l’effet des impacts et des charges cycliques (vibration des pièces métalliques). Une recommandation prioritaire est attribuée aux éléments de fondation de la section 6, qui se composent de huit piles de béton. Peu de travaux et d’études ont été réalisés sur ces piles aux cours des dernières années, ce qui augmente la nécessité de procéder à des études supplémentaires et de poursuivre le programme majeur de réfection. In their conclusion in the Executive Summary, AECOM notes, amongst other things, that the damage has a tendency to increase year-over-year in an exponential fashion, something which we bear in mind given the long history of repairs and rehabilitation to this bridge, the continuing rehabilitation and repair programme and the observations which AECOM has reported in their 2010 Annual Inspection. The serious concerns which AECOM has as a result of their annual inspection works, including the most recent inspection, are evident in the cases of Sections 5 and 7. Some of the key observations with regard to the current condition of the bridge include the following: • Prestressed concrete girders split at post-tensioning.

• Web concrete split away from one side of concrete girders. • Significant rehabilitation works underway on the pier caps including removal of

deteriorated concrete and the addition of post-tensioning together with the restoration of the pier cap concrete.

• Paving works being carried out on the bridge. • Installation of queen posts and external post-tensioning anchored to the prestressed

concrete girders. • Removal of concrete repairs and restoration of the main piers for the main span of the

bridge in Section 6. • Loss of transverse post-tensioning in the deck.

• Variable condition in the precast prestressed concrete girders. • Some patches on the bridge deck. There have been some repairs carried out to the

underside of the bridge deck. Generally it is considered that the deck is in relatively good condition compared to the other concrete in the bridge, probably as a result of there being transverse post-tensioning in the deck on the concrete girders.

• The Jacques Cartier and Champlain Bridges Incorporated would have replaced the edge

beams but they really cannot because of the prestress in the deck and diaphragms




which makes the replacement of the edge beams difficult if not really impossible, particularly in the context of maintaining traffic on the bridge.

• There have been efforts to restore the shear capacity of the girders including the

introduction of inclined external post-tensioning and vertical external reinforcement. There has been significant corrosion inside the prestressed concrete girders which has resulted in the partial or complete loss of some of the prestressing. There is a degree of uncertainty with regard to what these losses have been, but in at least one case 9 out of 24 post-tensioning parallel wire cables or stranded cables have been lost, leaving a severe deficiency in the capacity of the girders compared to the original design intent.

• Impressed current type cathodic protection of the bridge girder has not been

implemented, taking into consideration the results of pilot testing carried out several years ago, and the findings of international experts mandated by the Corporation to study the feasibility and risks of using cathodic protection on prestressed concrete. Bid results in the late nineties when cathodic protection was attempted, resulted in costs of about $350,000 to protect just one beam. Hence cathodic protection was far too expensive particularly when, in protecting the prestressing, its effectiveness could not be assured.

• Sacrificial zinc anodes have been put in place on pier caps. • The records of chloride ion penetration to the concrete demonstrate that this penetration

is very significant compared to typical benchmark levels. • Expansion joints in the bridge are leaking. • It was not possible to remove all of the deteriorated concrete from the pier caps without

compromising the integrity of the bridge altogether so some deteriorated concrete remains encased within the pier caps even after repairs.

• Chloride extraction is not possible at this site as the chlorides have penetrated to such a

depth and to such an extent and intensity that it is not practical. • Chloride extraction applied to the girders implies current densities so high that hydrogen

embrittlement of prestressing would most certainly occur

• It is believed that water has reached into the ducts and the grouting in the tendons is considered to have been deficient based on review of the history of the bridge and observations as to current performance. It is possible that the grout may have frozen as a result of the original contractor having used too much water in the grout.

• The concrete in the concrete beams has been recorded as being 70-80 MPa in strength

on recent testing, which is a very high strength. • Theoretically, it is considered, based on investigations carried out by others, that some

of the beams should have failed, but the fact is they are not yet apparently failing. They may, however, be quite close to failing and, indeed, might have failed if restorative measures had not been applied previously. Earlier investigations have shown that in order to prevent a failure in flexure, 16 of the original 24 longitudinal post-tensioning tendons are necessary to be in service in order for the concrete girders to survive (whereas, it is noted above that in at least one case only 15 of the 24 cables have




survived). The integrated nature of the bridge has likely prevented a complete failure, so far. However, this is a very serious concern.

• More recent investigations have pointed to a potential failure in shear if restoration

measures are not undertaken. In this latter case, the precise location of a damaged cable can have an important impact on the residual strength of a beam.

• In situ measurements of precompression in the concrete girders have been carried out

by means of coring and testing in order to attempt to assess how much prestress has been lost in individual girders. The precompression which exists in the exterior girders based on this testing turned out to be less than it was expected to be, particularly for the edge girders.

• There are spalls in the webs of the prestressed concrete beams and in at least one case

a girder has developed a hole. Local repairs and local external post-tensioning to account for the major loss of the web concrete and of the loss of prestressing as a result of corrosion, have been carried out in some cases.

• The shear forces in the girders are high and there are concrete material losses in the

webs in some cases which clearly compromise the shear carrying capacity of the girders. This has been dealt with by means of repairs to some extent and the addition of external shear reinforcement, and by the addition of inclined stressed cables. The shear capacity is considered by analysis to be provided approximately 1/3 by the concrete, 1/3 by the stirrups (which are quite sparse), and 1/3 by the inclined stressed cables at the critical location. The relative contribution of each component varies along the length of the beam.

• There have been issues with the asphalt in the orthotropic steel deck on Section 6, but

we understand that they are not currently a concern. • The orthotropic steel deck in Section 6 is considered to be in good condition. There have

been concerns with regard to the fatigue life of the orthotropic steel, partly as a result of traffic having run on the bridge by necessity prior to the bridge being completely paved, and this has been considered by calculation to understand the residual life of the orthotropic steel deck. A range of estimated fatigue lives was provided by the analysis depending on whether the confidence was, for example, 95 % or 50% in terms of the prediction of when fatigue cracks would appear or cause problems. There is a certain amount of judgment involved in such calculations. The orthotropic deck is, however, 5/8” (16mm) thick generally, and up to 3/4” (20mm) in the truck lanes. This is considered compatible with reasonable performance of an orthotropic steel deck (whereas a thinner steel plate would almost certainly create premature problems).

In summary, a rehabilitation programme is currently being carried out in the context of a continuing methodical programme of inspections, investigations, testing, repairs, rehabilitation and maintenance, and also in conjunction with many specialist studies to report at length on the nature and condition of the bridge and its deficiencies, as well as on ways of rectifying them so that the bridge can continue, for the moment, in service with an appropriate degree of safety and security as well as comfort, although not without some unknown level of risk.




9. CURRENT PROGRAMME OF DE-ICING THE BRIDGE A very considerable amount of the damage caused to the bridge has clearly been caused by the application of salt to the bridge with a view to making the bridge safe for traffic during the wintertime. In this, it has a common issue with many bridges in Canada and the United States. It is this single fact more than any other which causes deterioration to most highway/roadway bridges in Canada. It is understood that the original design took no account of the possibility of salt being applied to the bridge as it was a part of the design criteria that salt would not be applied to the bridge. After only a few years of operation, however, salt began to be applied to the structure and the deterioration is now evident. One of the Value Engineering Study recommendations was that consideration be given to eliminating the use of salt on the bridge. However, this has proved not to be possible as the issue of safety of vehicular traffic is paramount and the decision has been made to continue with the salting of the bridge1. The deterioration of the bridge, therefore, continues unabated and, in fact, as noted in the recent 2010 AECOM Annual Inspection Reports, it is increasing at an exponential rate, as is common with deterioration of this type. 10. CURRENT BRIDGE DESCRIPTION AND CONDITION The current condition of the bridge is described in detail in the recent 2010 Annual Inspections Reports produced by AECOM, as is the condition of the bridge based on their most recent inspection in 2010 and as illuminated by their previous experience on previous annual inspections. We have visited the bridge and discussed its history and current condition with The Jacques Cartier and Champlain Bridges Incorporated staff and have observed repairs being carried out to the bridge on site on Sections 5, 6 and 7. Brief summary observations as to the condition of the bridge derived from all of these inputs is as follows: Abutments The abutments are substantial reinforced concrete structures founded on the bedrock. They have suffered some deterioration. Tieback anchors were installed as a retrofit measure to mitigate against apparent movement of the abutment wall.

Figure 8 - Bridge Abutment Pier Foundations on Approach Spans The pier foundations on the approach spans are in some case below grade, and in other cases below water. The pier foundations are cylindrical concrete structures anchored into

1 The importance of being able to deliver a high traction road surface in both summer and winter months is dictated in part by the high traffic volumes, the operation of contraflow bus lane with no divider and a rather steep East approach with high truck volumes.




the bedrock by means of steel rock anchors around their preimeters and also generally keyed into the bedrock. With regard to the foundations that are below grade and the sections of underwater foundations which are below grade, the condition is unknown.

Figure 9 - Bridge Pier in Water The underwater portions of the foundations are known to have suffered from cracking and other deterioration. This cracking has been attributed to possible issues which arose during construction. Repairs have been carried out to these underwater foundations in the 1990s. Observations made recently at the pier base of Pier 39W show a considerable amount of deterioration at this pier. The deterioration includes mostly large spalls and significant loss of concrete, splitting, cracking and delaminations. It is not possible to reasonably extrapolate the observations made very recently at Pier 39W to all of the underwater piers on the bridge but based on that report and observations made 20 years ago, it appears reasonable to assume that the foundations in the water may have sustained further damage. Underwater inspections are made on a periodical basis. Pier Stems on Approach Spans The pier stems on the approach spans are variable in condition. Such defects as cracking, splitting, concrete deterioration, delaminations and degradation of concrete, as well as concrete erosion have been observed on many of the pier stems despite extensive repairs and crack sealing in the past. A new programme of rehabilitation for these pier stems was initiated in 2010. Some of the deterioration on the pier stems is very deep, reaching to and into the areas enclosed by reinforcing steel. The possibility that there is concrete in the pier stems which is subject to alkali aggregate reaction cannot be discounted at this time, although test results carried out to date have been somewhat inconclusive in this regard generally on this bridge as to the degree to which the bridge is affected by this phenomenon. The pier stems require a considerable amount of significant rehabilitation involving the removal of concrete, cleaning the reinforcing steel and encasement of the pier stems, for example, in order to restore them to reasonable condition.




Figure 10 - Bridge Piers and Pier Stems Pier Caps on Approach Spans The pier caps on the approach spans have similarly suffered considerable damage. A great deal of this damage is attributable to the flow of water through expansion joints which are located above each of the pier caps. This flow of water was made worse by the fact that the bridge has been for many years subject to the application of salt on the bridge deck and this has led, together with the original finger joint design and subsequent leakage of the joints, to the accumulation of significant damage to the pier caps as well as the ends of the girders which are supported by the pier caps and the diaphragms at these locations. This damage and contaminated concrete is reported to be so deep in some instances that it is not possible to remove all of the degraded / chloride contaminated concrete which exists in some of the pier caps without the risk of compromising to an unacceptable degree the interim load carrying capacity of the pier caps as they are being repaired. This means that in a repair which involves encasement, some degraded or substandard concrete (chloride contaminated) is being encased within the new concrete, something which, short of temporarily supporting the bridge spans, cannot be avoided. It has also been noted that the pier caps are a concern from the perspective of structural design in that the reinforcing steel which supports the loads in cantilever (beyond the pier stems) is not capable of developing itself entirely given the length of concrete embedment available, and in the context of the current condition of the concrete or possible simple concrete material repair. Also, the structural effectiveness of conventional repair to delaminated concrete was also of concern. Therefore, structural repairs have been carried out which involved adding post-tensioning to the pier caps to increase the load-carrying capacity of these structures in cantilever and hence to support the bridge superstructure.

Figure 11 - Bridge Pier with External Post-Tensioning




Post-tensioning and encasement works are being carried out in conjunction with careful removal of as much deteriorated concrete as is reasonably possible, to improve the load-carrying capacity and durability of these pier caps. Bearings on Approach Spans We understand that the bearings on the approach spans are being replaced in conjunction with the repairs being carried out on the pier caps. Concrete Girders on Approach Spans Concrete Deck Panels on Approach Spans Concrete Diaphragms on Approach Spans Transverse Post-Tensioning on Approach Spans The concrete girders are longitudinally prestressed. Following their erection they were integrated with cast-in-place diaphragms and cast-in-place infill panels, both of which were transversely post-tensioned to integrate them with the longitudinal girders. This is an unusual configuration which results in a highly-integrated structural behaviour where loads on any one element of the bridge superstructure affect loads everywhere else on that superstructure panel. The exterior girders have suffered some severe deterioration including significant spalling of concrete, concrete degradation, chloride ion intrusion, deterioration of the grout which originally secured the tendons in place, and corrosion and loss of prestressing tendons. To this deterioration can be added deterioration at the ends of the girders and deterioration of the end diaphragms as well as some deterioration of the deck which has suffered some spalling, for example. More recently, some deterioration of the interior diaphragms has also been noted.

Figure 12 - Cracks in Prestressed Concrete Girder

Figure 13 - Deck Soffit Deterioration




Because of the highly integrated nature of these deck superstructures, we have found it virtually impossible to envisage a scheme whereby the more deteriorated elements of the bridge could be replaced. We gather that significant efforts have been made in this regard by others and that it has been decided that it is more practical instead to strengthen the deteriorated members where this is possible, by adopting such measures as augmenting the prestressing in the girders by post-tensioning them with new steel, and by adding additional shear reinforcement where the shear capacity of the girders has been degraded. Concrete repairs have also been undertaken with a view to restoring the protection of the steel reinforcement and ducts within the girders to some extent. Because there are so many girders in the bridge which have been adversely affected to a greater or lesser extent by the types of deterioration noted here, it is not possible to effect comprehensive strengthening measures to all these girders at the same time and hence a staged programme is being carried out on a priority basis. This means that some risk is being borne as some of the girders which are in service have suffered severe deterioration, and the extent to which the addition of external post-tensioning has altogether replaced the lost prestressing, for example, must be a matter of judgment and, to some extent, guesswork. The Corporation has made significant efforts to estimate and calculate the loss of prestress but all the uncertainties associated with this issue cannot be eliminated without effectively dismantling the entire bridge. Experimental post-tensioned and prestressed cable investigation was carried out in 2009 using the Post-Tech Cable Break Detection System which uses remanent magnetism to identify broken, damaged or unsafe high-strength individual or bundled strands. This is a magnetic non-destructive testing method. Later in 2009, a remanent magnetization test was carried out on the deck of the Champlain Bridge to determine the condition of the transverse post-tensions laterally reinforcing the bridge deck. These test results gave some indication of cable breaks, some of which were verified by observation of the actual cable breaks themselves. Nevertheless, doubt necessarily remains as to the extent of cable breaks and wire breaks in the post-tensioning systems in the bridge. Analyses carried out by others have suggested that, if there were to be a failure of one of the external girders, it could cause a progressive collapse of an entire span. This would not necessarily be the case with a conventional bridge where the deck is more typically supported on top of the girders and the deck does not necessarily rely for its integrity altogether upon transverse post-tensioning. The fact that the original superstructure is relatively heavy with a high dead to live load ratio contributes to this risk (i.e., it would be difficult for an interior beam to carry its own weight and that of a failed edge girder for example). It is clear that this is one of the serious situations confronting this bridge and efforts to maintain it safely in service. Barriers on Approach Spans The barriers on the approach spans have replaced the original open steel barriers with a view to containing water spray from the deck and hence to minimize in particular the deterioration of the external prestressed concrete girders which is of such significant concern on this bridge. In conjunction with that, the drainage system on the bridge has been improved for the same reason. Nevertheless, deterioration of the type which has been observed some 20 years ago, for example, on the edge girders of this bridge, once initiated, tends to proceed at an increasing rate with time. It can be reasonably assumed that the




improved drainage and the barriers have slowed the progression of deterioration to some extent but, nevertheless, the deterioration is clearly more severe than it was 20 years ago. Although the barriers have been helpful, they have not altogether been a solution to the problems which arose at the edge girders. Paving and Waterproofing on Approach Spans The bridge was paved in about 2000 and parts in 2010 with a polymer modified asphalt and polymer modified tack coat providing some waterproofing. We understand that some local waterproofing membrane has been applied to some of the approach spans and this can only be helpful to them. We understand, too, that the top surface of the deck on the approach spans is in relatively good condition. This may be attributed in part to the transverse post-tensioning which causes many issues when it is wished to replace a part of the deck, for example, but which, in and of itself provides pre-compression in the concrete, hence tending to inhibit cracking, chloride ion penetration and deterioration. Wearing Surface on Approach Spans There is an asphalt wearing surface on the approach spans and it is currently the subject of a paving programme to replace it, we understand. Structural Steel Deck Truss Approach Spans We are not aware of any significant issues which have arisen to the structural steel deck truss approach spans which form a part of Section 6.

Figure 14 - Steel Trusses and Orthotropic Steel Deck Main Pier Foundations The main pier footings are variously in water and underground. AECOM comment on these foundations in their 2010 Inspection Report to the effect that these structures require further study and a major programme of repair. There are four main piers in Section 6 which support the main span. Three of these are in water and one is on land. Based on the observations of which we are aware, it is believed that the foundations for the main piers in the water may have some deterioration. The condition of the main pier foundation below grade is not known.




Figure 15 - Foundation of Main Pier Main Piers The main piers are massive reinforced concrete structures which support the main suspended span cantilever arms and the anchor arms which comprise the main structural steel bridge crossing the St. Lawrence Seaway in Section 6. These structures have suffered some significant deterioration including cracking, spalling, concrete degradation, erosion and corrosion of reinforcing steel. It is possible that the concrete in these structures is subject to alkali aggregate reaction, although this seems to be uncertain based on the investigations of which we are aware. Repairs are currently ongoing in respect of these main piers. As part of the 10 year programme, a special inspection of the piers in Section 6 was just recently completed.

Figure 16 - Main Pier Structural Steel Through Truss Main Spans The documentation which we have reviewed suggests that the structural steel main truss spans are in good condition and that there are no serious concerns with regard to the basic integrity of these structures. Tests have been carried out over a period of time to verify the




integrity of the pins which connect certain truss members and heavy steel assemblies which support the bridge on the piers. Our understanding is that these tests have resulted in no unresolved serious concerns with these elements of the bridge. A factor which can curtail the expected lifetime of a major bridge such as this is structural steel fatigue. We are not aware of any evidence to the effect that this is an issue on this bridge. Similar riveted structures have lasted for many decades more than this bridge has been in service. Orthotropic Steel Deck and Wearing Surface An important feature in the consideration of the integrity and durability of the structural steel main span structure in Section 6 is the replacement of the original reinforced concrete deck by a new orthotropic closed rib steel deck in the 1990s. This had several positive effects on the bridge including reducing the dead-load on the bridge, increasing the live-load capacity of the bridge, increasing the rigidity of the bridge, and extending the overall lifetime of the bridge. Orthotropic steel decks have been known to be prone to fatigue cracking and this has been the subject of study on this structure, a study which has taken into account the actual service condition which the bridge has experienced (in terms of whether or not a wearing surface was on the bridge during period when traffic was riding on the deck). The wearing surface on an orthotropic steel deck tends to act compositely with the deck and reduce stresses and hence increase fatigue life and it distributes wheel loads as well. This bridge has a substantial structural steel deck plate thickness and a similarly substantial and conventional 40mm thick wearing surface, two factors which suggest that the fatigue life of the orthotropic steel plate system will be reasonable. Buckland & Taylor has reported on this at considerable length noting uncertainties associated with the fatigue behaviour and expected service life of orthotropic steel decks. There were issues with the adherence of the wearing surface to the orthotropic steel deck in hot weather. It seems clear that with the wearing surface being “pushed” along the deck at that time, composite behaviour between the deck and the wearing surface was very limited, if it existed at all under those conditions, but we understand that these issues have been resolved and that the wearing surface on the orthotropic steel plate is currently performing well. Furthermore, all heavy trucks are routed to the exterior lanes. This has the effect of increasing the number of heavy load cycles to deck components supporting the outer lanes. Painting of Structural Steel The corrosion protection system on the main span structural steel and on the structural steel deck trusses has generally been successful in protecting the structural steel from severe corrosion. We understand that the bridge trusses and bracing systems have been completely painted in the period 1994 to 2005.




11. STRUCTURAL HEALTH MONITORING Some Structural Health Monitoring has been applied to the bridge with a view to obtaining some early warning as to incipient problems with the structural integrity of the bridge. Because the Structural Health Monitoring is localized, at this time the system can currently monitor specific areas of the bridge only. While it is a helpful additional diagnostic tool and is able to monitor specific areas of the bridge on a continuous round-the-clock basis, incorporating an alert system and intervention protocol we understand, it is not developed or implemented to the point where it could be used to predict remaining bridge life. 12. SUMMARY Based on the review of the available data and a visit to the bridge site, our impression of the bridge is that it includes some serious deficiencies in the context of short term and long term service. Section 5 The prestressed concrete spans of Section 5, including the substructures, piers and foundations, include many deficiencies, some of them serious. They are, in fact, serious enough that The Jacques Cartier and Champlain Bridges Incorporated has caused emergency support standby structures to be fabricated and to be in place near the bridge site in the event of the anticipated loss of an edge girder, for example. This is a very unusual step and speaks to a lack of confidence in these edge girders. The loss of prestressing in some of the girders is a serious concern. The deterioration of these edge girders is extreme. Analysis by others has suggested that, if an edge girder were to fail, it could cause the loss of an entire span as the grillage of girders, diaphragms, in-fill deck panels, longitudinal prestressing, and transverse post-tensioning is so integrated that the loss of one edge girder could provoke the progressive collapse of a span, particularly when one considers the relatively high dead load of the superstructure. At the same time, many elements of the substructures including the pier caps, the pier stems, and the foundations include very considerable deterioration, spalling, cracking, concrete degradation and erosion. It has been suggested that alkali aggregate reaction may be taking place in some of this concrete. Similarly, the lack of capability of the reinforcing in the pier caps to fully develop their tensile strength is another concern, particularly in the context of the degradation of concrete quality in the areas at the pier caps. Section 6 The structural steel which comprises Section 6 is in better overall condition than the prestressed concrete superstructure in Section 5. The replacement of the reinforced concrete deck in the 1990s by the orthotropic steel deck reduced the dead load on the bridge and increased the load-carrying capacity of the structural steel main cantilevered truss section of the bridge to a considerable degree. With the triple truss configuration, there is a degree of redundancy in the bridge and there are multiple load paths available to carry loads should local difficulties develop. However, there is no indication that there are any such local difficulties which have not been resolved, and testing has confirmed the integrity of some of the elements of the bridge including the main pins. There do not appear to be any causes for immediate concern with regard to the structural steel which comprises Section 6 of the bridge. The substructures in Section 6 are undergoing repair as they have sustained a considerable amount of damage and display cracking, spalling, degradation of concrete, possible alkali aggregate reaction, corrosion of reinforcing steel,




and local loss of concrete to spalling. The foundations of the bridge are partly underground and their condition is unknown. The substructures for Section 6 are considered to be in fair condition but require a considerable amount of work to restore them to a condition appropriate to carrying a massive steel superstructure such as is in place at this bridge. AECOM has suggested further study and rehabilitation works for the foundations of Section 6. Section 7 Section 7 displays all of the deterioration which has been noted in Section 5, although the substructures are in even worse condition than are the substructures of Section 5. The foundations in Section 7 are partly below grade and their condition is unknown. 13. CONCLUSION In summary, our impression of the bridge is that it is in a condition which requires extreme vigilance in order to maintain it safely in service over even a relatively short term. Some of the deterioration which has been observed is very severe. Deterioration such as this tends to progress exponentially, the rate of increase of deterioration increasing itself with time, hence increasing concern with regard to this bridge. A number of repairs have been carried out to the prestressed concrete girders with a view to compensating for known loss or increasing the load-carrying capacity of the bridge both in bending and in shear. These, however, must be considered to be measures which are not appropriate for long-term service. Rather, they are intended to help secure the bridge in the short term until something more substantive can be implemented. It has been recognized that there is a risk of partial collapse of the bridge, or even the collapse of a span, given the structural configuration of the prestressed concrete girder and diaphragm grillage which comprises the superstructures in Section 5 and Section 7. This is combined with concerns with regard to the condition and load-carrying capacity of the pier caps and the poor condition of some of the pier stems as well as concerns with regard to the condition of the foundations. The possibility that there will be a partial or complete collapse of one span given all of these negative aspects of the bridge, cannot altogether be ruled out. It is a risk which is being borne and managed at this time. This is considered to be a lifeline bridge from the perspective of seismic loading. This means that the bridge should be capable of resisting the 475 year design seismic event without being taken out of service, and of resisting the 1000 year large earthquake event and being open immediately to emergency vehicles. However, the bridge was not designed to sustain significant seismic loading and we understand that analyses have shown that it has no capacity to do so. In its current condition, this bridge can be expected to collapse partially or altogether in a significant seismic event. In summary, this bridge is not in a condition which is compatible with it continuing to serve as a major crossing of the St. Lawrence River under the substantial vehicular, truck and bus loads which it must sustain, without some risk, which cannot altogether be quantified.

impressions of the champlain bridge with photos, by delcan

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