Barry Ayotte

10056 Tayman Dr.

Union, Kentucky

(859) 372-4161

Mr. Anil Agrawal

1801 Alexander Bell Drive

Reston, VA 20191

Dear Mr. Agrawal:

Noted as one of the most functionally obsolete bridges by the ASCE, the Brent Spence Bridge case study compares the Brent Spence to other functionally obsolete bridges. The Brent Spence Bridge has not only concerned the people in the area that use the bridge but has also been noticed to be a major problem for the transportation departments working on this project for decades. Thus this report was made based on the concern of the Brent Spence Bridge’s safety and its purpose is to compare the necessity to renovate due to its overall lack in safety.

This report contains information on relevant to the Bridge Engineering journal concluding the link between bridges different levels of being functionally obsolete. I hope you find the relevancy of the case study to match the setting of your journal and decide to include it.

Sincerely,

Barry Ayotte

The Brent Spence Bridge Case Study

Prepared for Brandy Scalise

November 16, 2016

ii

Table of Contents

Introduction: Page 1

Problem: Page 3

Bridge Used for Comparison: Page 3

SR 520: Page 4

Brent Spence Bridge Problems Concerning Safety and Cost: Page 5

The Number of Commuters Effect on Safety: Page 6

Sight Distances and the Implications of Safety: Page 8

Lane Width and the Effect on Bridge Safety: Page 10

Cost of Renovations: Page 12

Conclusion: Page 13

References: Page 16

iii

Executive Summary

Purpose:

The purpose of this report is to identify and compare the necessity of

renovating the safety hazards on the Brent Spence Bridge to the cost it will

take to properly renovate these hazards. The safety hazards of the Brent

Spence must be assessed to prevent harm to the bridge’s users and the

costs it will encounter.

Research:

This report was mainly based off of research from the state’s department of

transportation for each bridge researched, scholarly articles about bridges

being functionally obsolete, and plans made for each renovation describing

the current state of each bridge and their current goals.

Key Findings:

There is sufficient evidence that the Brent Spence Bridge has unsafe

features (some that violate the FHWA for bridges) leading to the increased

chance of crashing while using the bridge. Also bridges defined as

functionally obsolete need to be identified further due to the lack of

information reported making it hard to categorize the levels at which being

functionally obsolete is dangerous.

Conclusion and Recommendation:

iv

The Brent Spence has been deemed to need renovations to improve safety,

there is a lack of information on bridges published, and the term

“functionally obsolete” needs to be further defined due to the large number

of bridges under this broad description.

1

Introduction

The case study of the Brent Spence Bridge plans to outline the details

of the bridge that undermine its safety and compare the details to the worth

in cost. Both the departments of transportation in charge of the bridge and

the citizens that know about the bridge, have known the existing functional

problems of the bridge for decades. Currently the Brent Spence Bridge is

not operating efficiently and costing lots of the bridges users’ lots of money

and time. Although many people are aware about the functionality of the

Brent Spence Bridge, there are misconceptions about what is truly the

problem. Therefore the Brent Spence Bridge was researched in depth to

find what the bridge is lacking in safety and can be fixed. The information

has been researched from various departments of transportation and online

documents listing the evidence of problems and their solutions. Thus this

information has been listed to address the safety attributes of the Brent

Spence Bridge.

To properly address the Brent Spence Bridges safety attributes the

area of discussion will be specific to the bridge’s state of functionality. The

functionality of the bridge has been chosen since the bridge has been

deemed structurally stable by the Ohio Department of Transportation.

Additional information also shows that the average bridge life is 50 to 100

years and the Brent Spence is just reaching the age gap, being built in

1963. Thus the issues with a functionally obsolete bridge are different than

2

those in a structural deficit bridge and need to be addressed separately. “A

‘functionally obsolete bridge’ has older design features and, while it is not

unsafe for all vehicles, it cannot safely accommodate current traffic

volumes, and vehicle sizes and weights, according to the American Society

of Civil Engineers” (McCarthy, 2007). Mostly the Brent Spence Bridge is

functionally obsolete due to the outdated design of the bridge. Currently it

has trouble accommodating the traffic on it and fails to meet other safety

regulations. In comparison, research sources show there are many other

bridges with the same title of being functionally obsolete. “More than three-

quarters of the 239 heavily used bridges in the nation’s capital are rated

structurally deficient or obsolete, the American Society of Civil Engineers

estimates” (Johnston, 2013). Because there are so many functionally

obsolete bridges, the Brent Spence is able to compare its features to other

bridges to evaluate its safety. But some bridges cannot be in direct relation

just because they are both labeled functionally obsolete since “[being

functionally obsolete] doesn't always mean they're unsafe, but neither does

it mean they're perfectly sound, and the amount of money needed to change

that is estimated in the hundreds of billions of dollars” (Eric, 2013). Thus to

decide whether the bridge can be compared, the same issues in safety and

cost have been taken into consideration for each comparison.

One of the main topics to discuss is comparing the safety is related to

cost. “The core problem still boils down to transportation funding. Just

before the I-5 bridge fell, the Seattle section of the American Society of Civil

3

Engineers estimated that Washington state had a $28.1 billion backlog of

bridge replacements and repairs” (Eric, 2013). Although the instance of the

I-5 bridge collapsing is not likely to happen to the Brent Spence this

example shows that the costs played a tremendous role in the upkeep of

safety. Thus the case study is also trying to evaluate what the cost has been

to replace safety hazards in relation to their importance. In an interview

with Dr. Erhardt he said that it all comes down to asking whether or not “is

it a good transportation system that will save money and promote the

welfare of the people who need it” (Dr. G, Erhardt, personal interview,

October 21, 2016). Thus safety and cost have been evaluated to answer this

exact question to determine whether renovations should be done on the

Brent Spence Bridge.

Problem

Currently the 3 major reasons that the Brent Spence Bridge is listed

as functionally obsolete. The current reasons are the number of vehicles

moving across the bridge has been over twice the amount it was designed

for, the lane width on the bridge is unsafe for the drivers, and the sight

distance are too short. As part of the case study of the Brent Spence Bridge,

these safety attributes will be in direct comparison to the other bridges that

are functionally obsolete. Also the cost for renovations based on projections

or actual costs will be included for evaluation. With this information one can

4

conclude whether the renovation on the Brent Spence Bridge promotes the

welfare for the people for a reasonable cost.

Bridge Used for Comparison

The bridge used below is used to study the effects of safety based on

the factors that make them functionally obsolete. The bridge is a river

bridge and has a speed of 50 mph when crossing. It is important to note

these conditions are most like the Brent Spence and can be compared

efficiently. Not all the bridges will have the same factors contributing to

their lack in functionality due to the information published has no checklist

to compare bridges functionality. Since not all bridges have been listed with

the same functionality problems and there is a lack of data on bridges, one

was selected based on its similarity to the Brent Spence Bridge. Although

they are different they are able to show why they are functionally obsolete

and can explain the reasons as to answer the question whether the

renovations are worth improving the safety for the cost.

SR 520 Bridge

The SR 520 Bridge has been developed to accommodate traffic across

Lake Washington. The bridge is a floating bridge and has been renovated

due to its design properties being functionally obsolete. The safety reasons

5

that have made this bridge functionally obsolete and in need of repair have

been due to the size of traffic reaching limits higher than the bridge was

designed for and little to no stretch of emergency lanes on the bridge

making it unsafe for drivers.

Research on the SR 520 Bridge has shown that most of its title of

being functionally obsolete comes from the abundance of traffic. “Originally

designed to carry 65,000 vehicles per day, the bridge currently serves an

average of approximately 100,000 vehicles per day” (Washington State

Department of Transportation). Operating at almost twice its design

capacity the average can be expected to be exceeded during peak hours and

can be imagined to be near failure in efficiency at these times. It has been

mentioned that there has been waiting on the bridge from an article on

World Access News which could mean that the level of service is very low

and could be ranked as either E or F. In the scenario that the SR 520 Bridge

operated at E or F levels of service, the bridge would be obsolete and near

failure or at failure in functionality. Thus the safety and lack of efficiency on

the bridge have proven to be major reasons in consideration for the

renovations on the bridge.

Secondly, the lack of emergency lanes was mentioned to be another

main source for renovations. The lack of safety lanes has been noted as a

violation of the FHWA for not having a total of 20 feet in emergency lanes.

The violation of the FHWA and implications of safety hazards were also

taken into consideration in the renovation plans. The importance in lane

6

width has shown its relevance while the importance and comparison is

further discussed when mentioned on the Brent Spence Bridge.

Currently, the research shows that the abundance of traffic and

insufficient lane width were the major reasons for renovations that costed

up to 4.56 billion dollars. Under this legislation budget they approved a new

floating bridge that included six lanes, emergency lanes, and a planned bike

lane. The research performed in the documents planning to build another

bridge to fix these safety issues only mentions these issues as there

reasoning for renovating. The Washington State Department of

Transportation’s website only goes in depth to include these reasons for the

functionality and not further describe their implications. Thus there is a lack

of information in correlating the effects of these safety hazards to the

potential improvement in welfare when the project finishes.

As an example of the lack of information, there is no mention of sight

distances to factor of safety when entering, on the bridge, and exiting. It is

only assumed that pictures of the bridge show that the surrounding area is

safe and open making sight distances optimal. Thus the exact data of the

bridge and the standards to compare are only evident when there is a

problem. Still, this shows the importance that the transportation

department values the efficiency of the bridge only based on the two safety

hazards it has mentioned.

7

Brent Spence Bridge Problems Concerning Safety and Cost

In this section the current information available on the functionality of

the Brent Spence Bridge will be described. Such topics include the

commuters of cars effect on safety, the lane widths effect on safety and the

stopping sight distances effect on safety. These are all measures of safety

that are related to other bridges and can be assessed. It its own category is

the cost of replacing the bridge. The cost of replacing the bridge can be

compared to other bridges choices to overcome their safety issues. Thus the

methods used by other bridges for renovations show the value of safety to

consider in what action would be best for the Brent Spence Bridge. By

discussing the safety factors and the comparable factor of cost to other

bridges that are functionally obsolete, a recommendation can be made as to

whether the safety is at such a great importance it is necessary to proceed

with renovations.

The Number of Commuters Effect on Safety

The Brent Spence Bridge has one of its largest safety problems routed

in the amount of traffic the bridge accommodates daily. Although other

components of the bridge also need to be improved to increase safety, the

sheer numbers and importance of the bridge cannot be reallocated due to

its very useful location. The current amount of vehicles used by the bridge

are 160,000 daily. This count of traffic for both direction exceeds the 80,000

8

vehicles that were designed to cross it daily. It has even been predicted that

the vehicles crossing the Brent Spence Bridge would reach 250,000 by

2040. From the data given the trend in the graph below projects rapid

growth from the time of the study (2013) till 2040.

Figure #1: Traffic Volume Predictions for the Brent Spence Bridge

It is important to address these statistics of traffic flow first in Figure

#1 because the public believe the amount of vehicles crossing the bridge

daily are making the bridge structurally unsafe. This belief can also be seen

from media sources portraying the bridge as structurally unsafe on several

accounts. There were only two main instances reported. One instance

happened when a concrete block fell from the bridge onto a car. Another

instance was when a truck became involved in a crash it broke through the

guard rail and fell off the bridge. Both incidents were addressed and the

Ohio Department of Transportation has reported that the bridge is still

1950 1960 1970 1980 1990 2000 2010 2020 2030 2040 20500

50

100

150

200

250

300

Traffic Volume Predictions for the Brent Spence Bridge

Year

Vehi

cles

Cro

ssin

g th

e Br

idge

(in th

ousa

nds o

f veh

icle

s dai

ly)

9

structurally sound after both accounts. Although the concrete slab falling

onto a car cannot be deemed as a result of the bridge being functionally

obsolete, the truck falling off the side of the bridge can. The reason it

occurred were the amounts of traffic left no room for the truck to stop so

instinctively the driver felt it necessary to avoid hitting the people in front

of them when unfortunately the guard rail failed. “Due to this increased

traffic flow, motorists are three to five times more likely to have a wreck

along this corridor than on any other portion of the interstate systems in

Ohio or Kentucky” (ODOT and KYTC, 2013). Most of the crashes reported

have been for the same reason of high traffic with no time to stop. Thus this

issue with safety on the Brent Spence Bridge has been linked to this factor

as a result in failure of bridge’s design.

In the Bridges design, the implementation of traffic the bridge is not

capable of handling makes the drivers more likely to crash. The statistic for

the likeliness to crash does pose a threat to daily commuters but it becomes

a greater risk considering the amount of trucks using the bridge. “It is also

one of the busiest trucking routes in the U.S., with freight equaling three

percent of the nation's gross domestic product (GDP) crossing the bridge

each year, according to a 2009 study from the Texas Transportation

Institute” (ODOT and KYTC, 2013).

10

Figure #2: Projected GDP That Crosses the Brent Spence Bridge

2009 2030

417

830

Projected GDP That Crosses the Brent Spence Bridge

Year of GDP

Gros

s Dom

estic

Pro

duct

(GDP

in b

illio

ns o

f dol

lars

)

Figure #2 above resembles the importance in the freight that crosses

the bridge years. The equivalent of the percentage of freight is about $419

billion. It has been predicted to almost double by 2030 according to the

study done in 2009. This statistic shows that the best method of travel for

businesses has been this bridge. The Brent Spence Bridge has been a

crucial route due to the roadways it is connected to. The shear amount of

trucks currently and prediction for that number trucks to increase make the

bridge become even more dangerous to use. In the past the safety due to

11

trucks was considered and a plan was attempted to make the bridge safer.

The attempt to make the bridge safer was ban so no truck could use the

bridge. The results of the ban showed that the trucks ended up taking

longer routes and only made other corridors susceptible to crashes. So to

make the bridge safer would require a change in the design. Therefore

renovations will be necessary for the bridge to accommodate the traffic it

has been receiving.

Sight Distances and the Implications of Safety

Currently one of the safety risks on the Brent Spence Bridge has been

the unsafe sight distances while crossing the bridge. The sight distances

that are unsafe include the traffic entering the bridge, the on-bridge traffic,

and the exiting traffic. Although there is no explicit explanation of where

there are violations of what the sight distances should be, there is evidence

linking the sight distances as a problem for drivers. In the research

performed no technical designs were found with the proper calculations

that would reveal what the sight distances should be to assure a drivers

safety. Thus without the information, more time would be needed to do the

in depth research needed. Although information was scarce, sight distances

are still a very important topic to discuss.

Considering the information on sight distances given in reports, the

entrance of a bridge proposes a bottleneck where traffic has to enter the

12

bridge. The sight distance was mentioned to be poor going up the entrance

ramp. On the bridge not only traffic, but the geometry of the bridge doesn’t

allow drivers to see the signs for exiting. Therefore if the drivers cannot see

what lane to be in to reach their exit, not enough time is given in making a

decision, which can lead to crashes. Sight distance is a factor in

determining sign placement given a formula with enough time to react.

Since not enough information is given as to the distance and time used in

the equation to determine the distances the signs were placed at, there is

no quantitative check. Sight distances were only mentioned as unsafe and a

concern mentioned in the documents considering a new bridge. Assuming

they did this calculation (as it would be necessary to place signs correctly)

they have proven it unsafe, otherwise the information is based on the

current experience and knowledge people have by crossing the bridge.

Using the calculation or making a new calculation, the current

method to move or fix the sight distances for exits couldn’t have been

performed. In an attempt to fix the sight distances, the ground on the

bridge has paved road signs in each lane as to where they lead to so people

can exit. These signs on the roadway have been noted to only help the

problem when the signs are still required for people to be able to see. Still,

when people exit the crowded bridge they frantically change lanes adding

to the increase in safety hazards. Overall the sight on the bridge is limited

and is one major concern considered in the process for renovating the Brent

Spence Bridge.

13

Lane Width and the Effect on Bridge Safety

Another factor of the road geometry that has been making the Brent

Spence Bridge unsafe is the lane widths. When the bridge was built it had 3

lanes of traffic for each tier of the double decker bridge. The increase in

traffic on the bridge soon demanded renovations. To accommodate the

demand the safety shoulders and 12 foot lanes were renovated. The

renovations made the lane widths 11 feet wide and completely removed the

shoulders so there would be 4 lanes on each tier of the bridge.

Currently these renovations make the bridge very unsafe and violate

FHWA standards. “Federal Highway Administration regulations require a

minimum of 12 feet in travel lanes and emergency lanes of at least 10 feet

on both sides of the travel lanes” (Strategic Advertisers LLC, 2013). The

purpose of lane width is for people driving at high speeds, such as the 55

mph speed of the bridge, would have more room in their lane to correct

themselves if they were close to leaving their lane. “On high-speed

roadways with narrow lanes that also have narrow shoulders, the risk of

severe lane-departure crashes increases” (FHWA, 2014). As of now the

smaller lanes and lack of an emergency lane show that the risk of lane

departure is at a maximum. The purpose of the emergency lane is for people

who need to stop or can be used in other ways if a crash occurs the high

density of traffic needs to be cleared for ambulances to reach the crash.

14

Both of the renovations to the width of the roadway and their implications

have demonstrated a lack of safety caused due to the increased risk driver

have in crashing.

To fix the current violations in safety the renovations recommended

by the Department of Transportation for both Kentucky and Ohio show how

lane widths and emergency shoulders have been an important role in

designing a new bridge. The consideration of building a new bridge is

proposed due to the renovations requiring more room for car on the bridge

that the structure currently cannot support. Since a new bridge has been

proposed, more lanes, lane widths, and sight distances can be address and

fixed properly. Two new bridge designs are shown below:

(“Designs I and I-A”, ODOT and KYTC, 2013)

The left image is the original design (I) while the right image show the

changes on the first proposal to save money (I-A). “On the proposed [I-A]

Brent Spence Bridge, outside shoulders were reduced from 14’ to 12’ and

inside shoulders were reduced from 14’ to 8’” (ODOT and KYTC, 2013). The

15

consideration of lane width and emergency lanes show increased

importance in lane width that currently proposed major issues on the Brent

Spence Bridge. But due to cost the bridge on the left, the right bridge was

recommended to still meet standards, but at a minimum. This shows that

with 6 lanes for each direction of traffic is the actual approximation needed

to handle the traffic the bridge accommodate today and traffic predicted

into the next 50 -100 years of the bridges life. Thus an increase of 4 lanes

total with the widths of the shoulder show an increase safety and the room

traffic on the bridge needs to function properly.

Cost of Renovations

Figure #3: Base Construction Costs

16

(“Initial base constructions”, ODOT and KYTC, 2013)

Since the I-A proposal is most likely to be accepted due to its qualifications

and lower price point it will be used in discussion to justify the cost. The

cost of the new Brent Spence Bridge in the figure below includes the price

including the amount it would take to install toll booths. This was included

to compare the price of the SR520 which has toll booths. There are many

variables that go into the price making it hard to compare where the exact

cost is going to in each bridge. The purpose of the cost is to show the

importance of functionally obsolete bridges. The main reasons the SR 520

required

Figure #4: Comparison of Bridges Costs

another bridge to be built was because of the current bridge couldn’t be

renovated to meet the current demands. The number associated with the

costs is to show the amount willing to be spend on a project to make these

fixes. Since the cost to renovate the Brent Spence Bridge falls under that

17

range and has a relatively normal cost for replacement compared to other

bridges, it is easily justified that the cost is reasonable for the safety issues

currently making the bridge unsafe. The increased welfare for the drivers

and the money saved in efficiency proves that the investment in a

renovations outweigh the cost it will be today.

Conclusion

During the research for the case study two conclusions were found.

The two conclusions were that the need to fix the Brent Spence Bridge is

apparent and outweighs the cost. The second conclusion is that there needs

to be more research or public information available to consider a better

ranking for functionally obsolete bridges. Using the information

provided in the report there is a clear importance to consider the levels at

which a bridge can be functionally obsolete. There is currently no standard

in defining the relativity in importance for functionally obsolete bridges.

Since an obsolete bridge can just mean a bridge isn’t operating as well as it

could there is an importance to make categories defining the significance

level while being functionally obsolete. Without this level of categorization,

research becomes difficult in finding bridges that are not only functionally

obsolete, but those that have safety issues and require attention to fix an

important problem. The Brent Spence Bridge happens to fall into a category

of bridges that require attention and would benefit greatly from

18

renovations. Not only is the evidence apparent that it would fall into a more

important category but there are many sources related to the need

providing methods to solve the problem.

Another issue that is relate to the need for categorization is the lack

of technical information to make a substantial comparison between the

different needs of bridges. Thus a second conclusion to be made is that

there must be a better system to obtain technical information on bridges

and a way to categorize their importance in pursuing renovations solely

based on the features that make them functionally obsolete. Two other

bridges considered in mentioning in the document were the Skagit Bridge

and the Frederik Douglass Memorial Bridge. Each bridge was listed as

functionally obsolete and had significant need for replacement, but lacked

enough data to mention in the report. Even on each bridge’s respective

department of transportation website, limited data was provided and was

less than the data mentioned in the Brent Spence Bridge and SR 520

documents. Even both Brent Spence and the SR 520 were still lacking in

sufficient data. To further analyze the safety in the functionality in bridges

would require more the exact plans for the bridge justifying their

measurements in safety based on traffic flow, roadway geometry, and other

safety factors. The information provided by the FHWA has been sufficient to

measure the bridges effective safety, yet the information about the bridges

themselves lacked the data to be compared. For example, the FHWA

mentioned the standards and levels of guard rails on a bridge yet no data

19

published for the Brent Spence Bridge mentions the type of guard rail used

on the bridge. Elements such as these have been left out and need to be

mentioned.

Overall the need for renovation is apparent on the Bren Spence

Bridge, but more information on the safety should be acquired to make

exact justifications for the relations between the specifications of the

problem and more detail about what can be done. Thus more data from the

actual design plans needs to either be published or sought out for a further

conclusion and a method to distinguish levels of functional obsolescence

should be developed to easily distinguish the vast amount of bridges safety

needs from others that fall under the too vastly described category of being

functionally obsolete.

20

References

Dr. Erhardt, G. (2016, October 21). Personal Interview.

FHWA. "Mitigation Strategies For Design Exceptions - Safety | Federal

Highway Administration." Mitigation Strategies For Design

Exceptions - Safety | Federal Highway Administration. FHWA, 15 Oct.

2104. Web. 06 Nov. 2016.

Jaffe, Eric. "Why America's Bridges Are in Such Dangerously Bad Shape."

Atlantic Cities (USA) 18 Jun. 2013, News. NewsBank. Web. 30 Oct.

2016.

Johnston, David Cay. "Pay to Fix America’s Crumbling Infrastructure Now,

or Pay More Later - The I-5 disaster in Seattle reflects the dire state of

our bridges and highways. But it may never be cheaper to replace

these aging arteries than it is now. By David Cay Johnston.." Daily

Beast, The 25 May 2013, News. NewsBank. Web. 30 Oct. 2016.

ODOT, and KYTC. "Options Analysis - Brent Spence Bridge Corridor." Brent

Spence Bridge Corridor. N.p., Sept. 2013. Web. 2 Nov. 2016.

McCarthy, Bill. "Could it happen here? - 3,025 - Total number of Wyoming

bridges 381 or 12.6 percent - Total structurally deficient bridges in

the state 230 or 7.6 percent - Total functionally obsolete bridges in

Wyoming 611 or 20.2 percent - Total deficient bridges in Wyoming

Source: U.S. Department of Transportation's National Bridge

21

Inventory database, December 2006." Wyoming Tribune-Eagle

(Cheyenne, WY) 3 Aug. 2007, Local News - Main: A1. NewsBank. Web.

30 Oct. 2016.

MoDOT. "I-70 Missouri River Bridge (Blanchette Bridge) Connecting St.

Charles and St. Louis Counties." Blanchette Bridge Renovations.

MoDOT, 2013. Web. 02 Nov. 2016.

"Safety." Build Our New Bridge Now. Strategic Advertisers LLC, 2013. Web.

06 Nov. 2016.

Washington State Department of Transportation. "SR 520 Bridge

Investment Grade Traffic and Revenue Study." Floating Bridge and

Eastside Project. Washington Department of Transportation, n.d. Web.

2 Nov. 2016.

Washington State Department of Transportation. "WSDOT - SR 520 Bridge

Replacement and HOV Program - Budget and Performance." WSDOT -

SR 520 Bridge Replacement and HOV Program - Budget and

Performance. Washington State Department of Transportation, 2016.

Web. 08 Nov. 2016.