Safety News

18th EDITION / ISSN 1793-1665 MAR 2011

Featured Articles02 Safety Measures for the Double Wall Cofferdam Construction in the Sea

04 Tunnel Safety

07 Thematic Exercise on “Safe Lifting Operations” at LTA Worksite

09 Achieving the Watermark Award and Beyond

11 Safety Features of Downtown Line Trains

13 Road Safety Reviewer Accreditation Course

SAFETY INEXCAVATION

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IntrOduCtIOn

The Marina Coastal Expressway (MCE) Contract 485 involves the construction of a 700m dual 5-lanes expressway of which 420m of the tunnel is built 20m under the mean sea level at the Marina Channel.

The temporary earth retaining structure system consists of two rows of tubular pipe piles for the undersea tunnel construction. This double wall cofferdam retains the earth and prevents the sea water entry into the work site which provides a dry area for the execution of ground improvement work, foundation work, excavation work and tunnel structure work.

This article will explain how the installation of temporary works is carried out and the safety measures implemented for the double wall cofferdam construction in the sea.

StAgEd COnStruCtIOn

The undersea tunnel is constructed in two stages to avoid causing disruption to the water discharge from Marina Barrage into the sea and to allow small crafts and vessels to access into Marina Bay. Stage 1 cofferdam construction in the sea began in June 2009 and was completed in December 2009. Stage 2 cofferdam construction would commence after the Stage 1 tunnel is completed.

MEthOdOlOgy FOr dOublE WAll COFFErdAM COnStruCtIOn

Tubular pipe piles were driven into hard ground to create a robust temporary earth retaining structure. Installation work commenced from the land side at Marina East using the guide frame and vibro-hammer. It then progressively advances towards the sea section. Crane mats which are made of structural steel members were placed on top of the double wall cofferdam to serve as a working platform for machinery used to install the tubular pipe piles in the sea. Material barge storing the tubular pipe piles and crane barge were also mobilised for the work.

Figure 4: Earth Retaining or Stabilizing Structures (ERSS) layout for Stage 1 cofferdam

Figure 1: Aerial view of MCE Contract 485 taken in April 2010

Figure 2: Artist impression for Stage 1 cofferdam

Figure 5: Cross-section view of double wall cofferdam

Figure 6: Stage 1 double wall cofferdam construction in progress

Figure 7: Stage 1 double wall cofferdam completed in December 2009

Figure 3: Artist impression for Stage 2 cofferdam with completed Stage 1 tunnel

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AFETY MEASURES FOR THE DOUBLE WALL COFFERDAM CONSTRUCTION IN THE SEA

Safety and RiSk Mitigation MeaSuReS foR double Wall CoffeRdaM ConStRuCtion

The major risks involved in the cofferdam construction include lifting work, installation of tubular pipe piles and working in the sea.

Some safety provisions are illustrated below –

All working personnel were required to put on life vest when the double wall cofferdam was still under construction. A safety boat is always on standby for any emergency rescue operation.

Safety provisions for heavy lifting work include ensuring that sufficient capacity for the lifting shoe, lifting angles are provided and lifting points are strengthened.

For the installation of pipe piles, vibro-hammer clamps are checked daily by a competent person. Workers are also educated on the use of life vest while working at the sea section.

Some safety provisions for works in the sea include the provision of proper working platform and fixing of blinking lights on barges to warn nearby vessels at night.

Tan Wee Thong Project Engineer

MCE C485

Figure 8: Installation of tubular pipe pile in the sea

Figure 12: Ensure sufficient lifting shoe capacity is provided

Figure 15: Daily check on the vibro-hammer clamps by the competent person before operation

Figure 17: Provision of working platform for hot works in the sea

Figure 18: Provision of blinking lights on perimeter of barges to warn nearby vessels at night

Figure 16: Training on the use of life vest

Figure 13: Reinforce the top of pipe pile by welding of additional stiffener plates at lifting points

Figure 9: Lifting and shifting of crane mat as pipe pile installation progresses

Figure 14: Ensure sufficient lifting angles are provided

Figure 10: Deck beams and panels replaced the crane mats to serve as a working platform for next stage of work

Figure 11: Safety provisions on the crane mat include life buoy, guard rail and blinking light

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Lifting shoe capacity: 68 tonMax. weight of pipe pile: 39.5 ton

Lifting shoe

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The LTA’s contractors are required to engage adequate numbers and suitable levels of competent staff with relevant tunnelling experience to provide the required level of expertise to complete the tunnelling works in a safe and professional manner.

For every 25 or more workers working underground at any one time, the occupier has to ensure that at least 5 of the workers are trained in rescue, resuscitation, use and maintenance of breathing apparatus and fire fighting equipment.

ContRol of aCCeSS and egReSS

During any emergency it is important to ensure all underground workers are safely evacuated to surface. In the event that someone is trapped underground, it is important to be able to locate the worker. To account for every site personnel, a tally board at each entrance to the underground work place is displayed and updated with the names of persons working in the tunnel and their work locations.

intRoduCtion

Tunnel construction is generally considered to be more hazardous than other construction works carried out above ground. The confined working environment, absence of natural light and ventilation, with use of heavy machinery create additional occupational safety and health hazards for site personnel.

Any person undertaking underground construction works on Land Transport Authority’s (LTA’s) projects must be familiar with the following documents –

1. LTA General Specification Appendix A: Safety, Health & Environment

2. LTA General Specification Appendix O & P: Tunnelling and Tunnelling Machines

3. LTA General Specification Appendix H: Requirements for Site Electrical Installations

4. Workplace Safety and Health (WSH) Regulations – all aspects applicable to tunnelling works

5. British Standard BS 6164: Safety in Tunnelling in the Construction Industry

6. HSE 1996 & 2001 Recommendations for Working in Compressed Air

This article will touch on some of the safe practices adopted in LTA worksites for tunnelling work.

tRaining

The confined working conditions and engagement of mechanized tunnelling requires a well-experienced team with trained supervision and support from the management. All workers employed in tunnelling works must attend the Construction Safety Orientation Course (Tunnelling) conducted by the Ministry of Manpower (MOM) and shall be trained in the operation of equipment and the safe working procedures.

CoMMuniCationS

To assist daily operations and in the event of an emergency accident or incident, an effective and reliable means of communications such as a telephone network needs to be installed and maintained at all times at the following locations:

• Guardpost;• Working chamber at the face of an excavation;• At intervals of 100 metres along the tunnel;• Working chamber side of the manlock near the door; • Interior of each chamber of the manlock; • Lock attendant’s station;• Compressor plant;• First aid station; and• Outside the portal or at the top of the shaft.

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Figure 1: Tunnel construction in process

Figure 2: Tally board at entrance to tunnel

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lighting

All lighting levels in tunnels shall be adequately illuminated at not less than 100 lux. Emergency generators shall be provided to ensure adequate illumination of the tunnels and work areas in the event of a failure in the normal power supply.

In addition, battery-powered emergency exit lights are necessary for emergencies which shall have sufficient capacity to provide power for the emergency exit lights for at least 2 hours in the event of power failure.

Ventilation & aiRboRne ContaMinantS

The sensitivity and susceptibility of individuals to airborne contaminants varies, therefore it should not be assumed that conditions safe for some individuals will be safe for others. The best practice is to maintain concentrations of all atmospheric contaminants to as low as reasonably practicable and below the Permissible Limit Level (PEL) as stipulated in the WSH (General Provisions) Regulations. The exhaust fumes of petrol engines can contain up to 10% carbon monoxide and should never be used underground. Diesel engines can only be used if no fumes or sparks are emitted and no air enters the engine without first being cleaned. Gasoline, liquefied petroleum gases and other highly flammable substances shall not be stored or used underground.

To prevent asphyxiation due to inadequate supply of air, the air in all work areas underground must contain at least 19.5% oxygen by volume. Tests for oxygen deficiency must be conducted before the commencement of works and thereafter at 4-hourly intervals. Oxygen-enriched atmospheres are as hazardous and can cause combustible materials to burn more freely, therefore oxygen levels should not exceed 23.5% by volume.

fiRe Safety

In a confined area such as a tunnel, the importance of fire prevention is of greater significance. The amount of combustible materials and gases present underground should be kept to the minimum and suitable fire-fighting equipment should be conspicuously located nearby.

Welding and cutting can generate sufficient heat to ignite combustible materials. Gases such as methane can also seep into the tunnels, creating fire and explosion hazard. Therefore, a permit to work system is essential for any hot work in tunnels.

A fire emergency procedure approved by the Singapore Civil Defence Force (SCDF) must be displayed at prominent positions inside and outside each tunnel.

Fire fighting facilities inside tunnels must include a fire alarm system that is connected to the ground level. There should be sufficient number of dry chemical fire extinguishers and water supplies allocated with adequate maintenance and checks.

CleaRanCeS, WalkWayS and Refuge aReaS

The use of heavy machinery and rolling stock in a confined space creates a potential hazard of serious injury. LTA specifies that there should be fitted an elevated walkway maintaining a separation between workers and by locomotives or other mobile equipment in a tunnel.

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Figure 3: Telephone network communicationFigure 4: Fire point in tunnel

Figure 5: Fire fighting facility in tunnel

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Risk management to address crushing and entrapment should be carefully evaluated. Warnings, refuges and procedures shall be established; complemented by thorough training to prevent such occurrence.

Rail oPeRationS

Tunnel tracks typically follow a gradient. If the brakes of a locomotive fail, the train will start to move uncontrollably unless the train’s motion has been effectively halted by the deployment of wheel chocks/stops. The train will gather speed and unless the loco driver can get the train back under control, or there is a device such as a Manchester gate at the portal to bring the train to a halt and prevent further travel, it will continue all the way down along the temporary track and this could potentially cause derailment and cause impact to workers and machinery.

Emergency plans need to be thoroughly disseminated to all workers through safety induction and familiarization tours on site. A culture of safety can be enhanced by in-house training, communication through toolbox meetings and display of procedures and escape plans on notice boards.

All stakeholders should be involved to develop an open safety culture. Accountability for safety performance must be appropriately allocated through the entire safety management process, in particular to the emergency plans. As a minimum, table top exercise and regular drills shall be conducted once every six months.

SuMMaRy

Tunnel construction may present many hazards. However, with the implementation of safe working procedures, and with additional precautionary measures in place, one can be sure that the risk can be reduced to its minimum and work can be accomplished safely.

Blaise PearceSenior Project Manager

DTL1 905

eMeRgenCy Planning & Mitigation of RiSk

Emergency planning and mitigation of risk through a systematic risk management process is essential to ensure safety of tunnel workers and other stakeholders of the tunnel project.

Figure 6: Elevated walkway Figure 8: Monitor site conditions from site office through CCTVs

Figure 7: Manchester gate installed to prevent overrun of train.

Figure 9: Emergency drill conducted with SCDF

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hEmATic ExErciSE “SAFE LiFTiNg OpErATiONS” AT LTA WOrkSiTEST

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intRoduCtion

In 2001, LTA introduced a new initiative known as “Thematic Exercise” aimed at improving its safety performance. The exercise focuses on a specific theme with thorough evaluation. Potential weaknesses identified would be brought to the prompt attention of all of our contractors for their immediate rectification, thereby eliminating the likely occurrence of an accident. Such pro-active exercise complements the regular site inspection regimes carried out by the various levels of the project team and enabling LTA to seek continuous improvement to its safety performance.

• The contractors had appointed sufficient numbers of competent Lifting Engineers who coordinated all lifting operations that are supervised by the lifting supervisors. The Lifting Engineers also formulated and prepared lifting plans to ensure that the cranes’ accesses and ground conditions (footing) are taken care of with due considerations for the stability and siting of the cranes. • The contractors had also assessed the competency and qualifications of the lifting team, i.e. crane operator, rigger, signaller, lifting supervisors etc. to ensure that they possessed the necessary safety knowledge and skills to perform the intended tasks safely before appointing them in writing to be in the lifting team. These key personnel were easily recognizable as they wore identification vests on site.

• Appropriate communication system between the crane operator and the lifting teams via walkie-talkie were in placed. In situation where communication system was not available, the signaller would position himself in a safe manner to maintain visual contact with the crane operator.

• The auxiliary load-lines were tested by Approved Examiners (AE) and the results reflected in the LM Certificates.

• All LMs operated within the Safe Working Load (SWL) as specified in the LM Certificates.

• There was no visible structural damage of the LMs used on sites and their safety switches were generally found to be acceptable and in good conditions.

• Monthly colour coding system for all lifting gears were in placed to ensure that the LG are regularly checked and paint- marked monthly before they are being used on sites.

Figure 1: Thematic exercise scheduled against construction phase

Figure 2: Lifting team wore identification vests on site

Figure 1 above is an example of the approach in the scheduling of the themes for the respective exercises. The theme-based exercises are pegged to the various phases of construction works on site. Through focusing on specific risks identified at each phase, these exercises zoomed in to ensure that risk control and mitigating measures are in place and complacency does not set in. It also helped to increase the safety awareness of contractors and their workers for their full compliance to the legal requirements and our General Specifications (GS).

During the last quarter of 2010, Safety Division conducted thematic exercise at Downtown Line 2 (DTL2) project. The theme, “Safe Lifting Operations” was chosen as the project was still largely in its excavation phase, with extensive usage of Lifting Machines (LM). This article aims to share some of the salient findings of the thematic exercise carried out.

key findingS

Good Practices/Compliances

About 30 LM were randomly picked but thoroughly checked for compliance to the legislation and our GS requirements. Safety Division noted that many of our contractors are now more aware of our stringent requirements and have put in concerted efforts to comply with the legal and contractual requirements. In this exercise, some of the notable findings were as follows:-

• All the LMs being checked were found to be less than 15 years old and inspected by an Approved Examiner within the 6-month inspection frequency, as stipulated contractually;

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• All lifting zones were clearly demarcated and cordoned off, with warning signs prominently displayed to prevent unauthorized entry.

• Proper foothold and access to crane cabin are provided for crane operator. • All LM had an additional audible alarm fitted externally to raise attention to nearby workers of its presence and to keep away from the demarcated zone.

Areas for improvement

Two areas of concern were indentified as follows:

• Some LMs still have their load charts displayed inside the crane cabin not translated into languages easily understood by the crane operators; and

• One LM was spotted with its boom length different from the readings shown in the Load Radius Indicator (LRI). All LRI are to re-calibrated whenever there is a change in the LM configurations.

These areas of concern were promptly highlighted to our contractors for their corrective actions.

In addition, Safety Division conducted a series of briefings to all lifting supervisors, project teams as well as our Qualified Persons’ (Supervision) teams of DTL2 project in Dec 2010 / Jan 2011. About 300 personnel attended the sharing sessions on the findings of the thematic exercise.

ConCluSion

Our continuous efforts in conducting such thematic exercise are well received by project teams as well as contractors. LTA is confident that such exercises and sharing sessions would help to achieve greater level of safety for the construction industry.

Tan Jway KweeSafety & Health (Enforcement) Manager

Safety Division

Figure 3: Monthly checks on LG and colour-coding by contractors

Figure 6: One of the sharing sessions held on site

Figure 5: Externally fitted visual/audible alarm

Figure 4: Demarcated lifting zone with warning signs in placed.

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This was made possible through the concerted efforts of various Groups within LTA and support from our contractors.

The high visibility of our projects and as one of the largest public developers in Singapore, LTA is well positioned to influence the construction industry and the public to do their part in protecting and conserving water. As a recipient of the Watermark Award, we have an added responsibility to be a role model for other organisations in Singapore. We can achieve this by:

• Upholding our high standards in managing and protecting our water resources

• Promoting good water conservation practices through active participation in seminars, conferences, workshops and sharing sessions

• Encouraging an innovative culture and collaborating with other agencies

This article aims to share with readers LTA’s measures in managing and protecting our water resources on our construction sites, in our journey towards achieving the Watermark Award.

PRoteCting ouR WateR ReSouRCeS on ConStRuCtion SiteS

LTA has a sound environmental management system to effectively manage impacts arising from our construction activities. In general, LTA adopts the following approach to manage our water resources at construction sites:

• Good Planning• Implementation of Good Practices• Monitoring• Education While a set of good erosion control measures is the first line of

defence against silt discharge, sediment controls aim to capture and retain silt within the site for treatment so that only clean water (of TSS, Total Suspended Solids < 50mg/L) is allowed to be discharged.

Figure 1: Proud recipients of the Watermark Award posing for a group photo with the Guest-of-Honour: Dr Yaacob Ibrahim, Minister for the Environment and Water Resources

Figure 2: Implementation of the “Brown to Clear” bio-ball filtration system on site and treating silty water with a treatment system at the final discharge point

intRoduCtion

On 30th September 2010, LTA joined a list of distinguished organisations and individuals who have made significant contributions towards Singapore’s water cause by clinching the prestigious Watermark Award from the Public Utilities Board (PUB).

chiEviNg ThE WATErmArk AWArd ANd bEYONdA good Planning

All activities and sequence of works are planned in advance, giving due considerations to the impact they may have on the environment. Wherever feasible, land clearance is carried out in stages. This minimises the amount of bare earth surfaces that are left vulnerable to the effects of rain.

Contractors also engage Qualified Erosion Control Professional (QECP) to advise them on the necessary earth control measures (ECM) that must be implemented before any earthwork can commence. This is to ensure that all works to be carried out in the immediate phase have been considered and that the controls put in place can adequately cater to the amount of silt generated. The QECP shall review his initial ECM plan at least once a month (recommended) or when the works move into a different phase.

iMPleMentation of good PRaCtiCeS

Effective Erosion and Sediment Control

All vehicular access routes in LTA sites are concrete-paved where possible. This immediately reduces the surface area of bare earth and limits the effects of erosion. Concreting also has a lot of other environmental benefits such as eliminating ground depressions which can breed mosquitoes. Dust generation can also be considerably controlled with reduced bare earth.

For exposed work areas, erosion control blankets or canvas sheet are used to cover these areas at the end of each work day and before a rainfall.

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Water Pollution Control

LTA enforces the use of spill trays for diesel-operated equipment and at each diesel transfer point. Additionally, all machinery on sites have to be inspected and serviced on a regular basis to ensure that they are in good working conditions.

A diesel storage tank on site has to be placed within a concrete bund wall with a capacity that is at least 110% that of the largest tank stored within it. This is to ensure that the concrete bund wall can adequately contain any leakages if a rupture occurs.

Recycling of Water

The treatment units at the final discharge point produce treated water that is clean and can be recycled for other uses. Besides being able to conserve water, this approach also provides contractors with some cost savings.

LTA strongly encourages the reusing and recycling of water on site. Most contractors will reuse treated water at vehicular wash bays or for wetting the ground before work commences. Treated water from the membrane treatment units can even be used to water plants.

Mataias Chew Boon Bwan Environmental Manager

Safety Division

Figure 4: Storage of treated water on site for future use

Figure 3: A diesel storage tank is contained within a bund wall to prevent spillages or leakages into our waterways

MonitoRing

To ensure that the above measures and good practices are strictly adhered to, LTA carries out a monthly environmental assessment on the contractors using the Environmental Safety and Security (ESS) Annex of Environmental form. This gives an indication of the site’s performance for that particular month and identifies areas for improvement. The quality of the treated water is also monitored at every final discharge point using a TSS probe and a CCTV. This allows the contractor to immediately stop the discharge of water into public drains if the allowable limit of 50mg/L is breached.

eduCation

Educating the Workforce

LTA believes in educating and raising awareness amongst the workforce as the foremost approach in managing the environment.

A proactive supervisor can influence the behaviour of his workers under his supervision. A worker’s simple act of choosing not to litter but to bin his packet drink properly can go a long way in maintaining the cleanliness of our waterways.

To reach out to the workforce, LTA has produced several environmental guidebooks and posters which are prominently displayed on site. Through daily toolbox meetings, environmental campaigns and even rewards for exemplary workers, environmental messages are constantly communicated across to all site personnel. Safety Division also conduct the environmental awareness training course twice a year to train site staff to supervise environmental matters on site.

ConCluSion

Singapore’s water demand is expected to double in the next 50 years. Even though two-thirds of Singapore will become water catchment by the end of this year, it is still not sufficient. The NEWater capacity needs to be tripled while the desalination capacity will have to increase by almost 10 times.

This growth in water demand is expected to come from non-domestic users, hence it is imperative that organisations emphasize on the protection and conservation of water resources in their daily operations.

The achievement of the Watermark Award is an affirmation and recognition of the commitment LTA has towards Singapore’s water resources. It is now LTA’s role to act in its capacity to influence and inspire other organisations to do their best in protecting and conserving our precious water resources and likewise, become the next Watermark Award recipient.

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intRoduCtion

The first two trains for Downtown Line (DTL) will shortly commence testing for a period of 18 months in Changchun, China. The trains are designed in Hennigsdorf, Germany, and built in Changchun, China, by Changchun-Bombardier Railway Vehicles Co. Ltd. In total, 73 driverless automatic trains will be built for the 40km underground line.

Being a driverless system, like North-East Line and Circle Line, DTL is designed to the highest safety and reliability levels. This article aims to highlight some key safety design features included in the DTL trains.

CRaShWoRthineSS deSign and SiMulation

Although the train is fitted with train-borne Automatic Train Protection (ATP) signaling equipment to prevent train collisions, its car body is designed to withstand crash scenarios in accordance with EN15227, the European standard for railway vehicle crashworthiness.

All car ends have anticlimbers installed. In case of a collision, the anticlimber corrugations of the colliding train cars are designed to interlock and prevent the train cars from mounting one another. Additionally, at the ends of every train, an energy absorbing device is installed behind the anticlimbers.

A “metal knife” type technology will be used on the crash absorber of the DTL trains. This technology deforms the crash absorber by cutting through material, thus absorbing energy impacted on the train. The crash absorber performance was verified in an impact test with a 80 tonne concrete-filled wagon, and the overall crashworthiness design validated by Bombardier using state of the art LS-Dyna crash simulation software.

bRake ContRol SySteM

DTL trains utilize EP2002, a mechatronic braking system that integrates brake electronics with pneumatic valves to provide service braking, emergency braking, and wheel slide protection within a single compact unit.

The EP2002 valve units are connected in a network throughout the train and communicate with each other so that in case of a faulty unit, braking effort is redistributed through the remaining bogies.

The pneumatics of the train brakes are configured to provide safe braking and continued running in the event of an air leak. Trains

Figure 1: Anticlimber and Crash Absorber after Crash Test

Figure 2: Brake Control Unit

with defects will still be able to move and stop at the next station where passengers will be able to exit with minimal disruption.

Emergency braking is triggered when the emergency braking electrical loop is de-energized. This occurs during critical operational situations such as obstacle detection on the track and train car separation. Brakes will be applied at emergency brake pressure, which is higher than the usual service braking pressure. This allows the train to stop as fast as possible.

fiRe & SMoke PRoteCtion

To prevent the occurrence of a fire on the train, strict fire requirements in line with internationally recognized standards are put in place. Materials used to build the train are chosen carefully to ensure that in the event of a fire, they have low toxicity, low flammability and generate minimal smoke.

Smoke detectors are installed within the air circulation ducts of the saloon. Heat detectors, also known as fire wires, are run throughout the equipment cubicles. Once exposed to heat, the alarm signal will be triggered.

When a fire develops within the saloon, emergency ventilation flaps open, allowing smoke to be expelled out of the train. Should smoke be detected in the fresh air inlet, the fresh air flaps are closed and interior air is re-circulated to prevent smoke accumulating in the saloon. An analysis of smoke emission during an interior fire was carried out to determine the optimum flap position using computational fluid dynamics software.

The train is also designed to withstand an underfloor fire for at least 45 minutes, which is duration sufficient for passengers to evacuate the train safely. Under the car body floor, a sandwich of stainless steel and insulating material is installed to function as a fire barrier. Intumescent coatings and sealants are used at all joints, openings, and exposed aluminium surfaces not covered by the fire barrier. The intumescent coating swells at high temperatures to create a thermally resistant foam coating, enhancing the fire protection provided by the fire barrier.

AFETY FEATUrES OF dOWNTOWN LiNE TrAiNSS

Anticlimber – corrugations engage in a collision to prevent mounting

Crash Absorber – deformed after impact

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PoWeR loSS

In case of power loss from the third rail, the trains have batteries on board that provide backup power to the lighting, communication, and ventilation systems for up to 60 minutes, allowing the Operations Control Centre (OCC) to assess the situation on board before determining an appropriate response.

dooRS

DTL trains use electrically operated sliding bi-parting doors to allow passenger boarding and alighting.

The doors have a ‘push-back device’ that allows the doors to spring back to their original position when pulled back (by up to 50mm per door leaf). For large objects, there will be a difference detected in the driving motor current and this will cause the doors to reopen momentarily. This reopening allows for the withdrawing of any obstacle.

If any train door is damaged, it is possible to mechanically lock the door set to prevent accidental door opening during service. One doorway per car allows for crew access from the train exterior in case of emergency.

At the bottom of the door sill, a platform gap filler rubber pad is installed. This pad serves to reduce the gap between the train and the platform to reduce the risk of feet or legs falling into the gap, and its size can be adjusted to achieve an optimal compromise between gap minimization and the filler pad impacting against the platform screen doors as a train enters the station.

detRainMent dooR

The DTL detrainment door is deployed during endurance testing, simulating worst case tilt due to curved track. The endurance test has been specified by LTA to ensure that the detrainment door has high reliability and can be depended upon in an emergency.

The detrainment door provides an avenue for passengers to escape onto the tracks during emergency. The door is locked under supervision of ATP. Before it is deployed, ATP ensures safe conditions are met for detrainment. After deployment, the door can be re-stowed by one person in under 10 minutes to allow quick resumption of services.

Figure 4: Door sill gap filler assembly

Figure 3: Fire barrier and intumescent coating after fire test

Figure 5: Detrainment Door Assembly

tRain CoMMuniCation SySteM

As operational staff will not be stationed on every train, an intercom system is installed in the Passenger Emergency Communication (PEC) unit for passengers to communicate with OCC staff when needed. There are four PEC units per car, one at each pair of doorways.

There is also an on board Public Address system to allow OCC to broadcast important audio messages. CCTV cameras are installed in each car to record images within the train at regular intervals. Video recording is activated upon certain safety critical alarms or actions.

tRain integRated ManageMent SySteM (tiMS)

TIMS comprises train-borne software and equipment that monitor the overall health status of train equipment. It sends alarms to the OCC when events and equipment faults occur.

Most importantly, TIMS coordinates the activation and deactivation of train equipment in response to events. For example, when a fire is detected, TIMS sends an alarm to OCC and switches the CCTV in the affected area to high speed video recording. OCC will then be able to view the camera feed to determine an appropriate course of action.

ConCluSion

The concerns faced in planning for the safe operation of DTL trains are neither new nor unique, for they are faced by every railway system around the world and many solutions exist.

With the safety provisions mentioned in this article, trains can operate even more safely and reliably under driverless conditions.

These safety features will operate in tandem with those of trackside signaling and station platform facilities to ensure the safe operation of the Downtown Line metro system.

Ong Wah WeiEngineer

Rolling Stock

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As the participants were from different disciplines and background, they were able to gain great insights of various road safety aspects through extensive interaction with each other during the course.

CouRSe StRuCtuRe

The course was conducted in the form of:

• Lectures

There were a total of 12 topics taught during the course. The lectures focused mainly on common road safety issues associated with general alignment and cross section details, junctions and interchanges, roadside hazard management and temporary traffic control. Photos of good and poor examples were shown to allow participants to have a better understanding of the safety issues discussed

• Case studies

Participants were able to gain comprehensive understanding of how road safety reviews were conducted through extensive discussions on the case studies. It also helped prepare participants for the hands-on activities, which are the site visits.

• Hands-on activities

The hands-on activities allow participants to apply what they have learned into practice. During the exercise, participants took up the role as road safety reviewers, undertook the safety review and prepared the formal Safety Review Report.

diSCuSSion

Before the actual site inspection, participants discussed about the possible safety concerns they could identify based on the drawing plans provided.

aCtual Site inSPeCtionS

The site inspections were performed one during the day and another in the eveing. It allows participants to identify potential safety hazards that they could not pick up when reading the drawings. For instance, participants could check whether the site was adequately illuminated during the night inspection. It also enabled participants to gauge if the recommendations proposed to their findings were practical taking into consideration the actual traffic conditions observed on site.

intRoduCtion

The Road Safety Reviewer Accreditation Course was first introduced in Land Transport Authority (LTA) in 1999. A total number of 174 students have obtained accreditation so far.

The primary objective of this course is to raise the knowledge and understanding of road safety engineering principles in Singapore. The course also aims to train staff and external consultants to be Accredited Road Safety Reviewers so that they will be able to perform safety reviews for road projects undertaken by LTA.

CouRSeS ConduCted in 2010

The course conducted in March and October 2010 saw a total of 39 participants from various disciplines in LTA, i.e. Design Development (Road), Traffic Management, Safety, Rails, Road Projects and Road Infrastructure Management. The course was also attended by external consultants who are involved in road works.

OAd SAFETY rEviEWEr AccrEdiTATiON cOUrSEr

Figure 1: Course participants and trainers

Figure 2: An example of clear zone concept discussed during the course

Figure 3: Course participants discussing on possible safety concerns based on the drawing plans

Figure 4: Course participants inspecting and observing the site to identify major safety concerns

No rigid structure at the central median

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“The course is very relevant to my job scope back in Abu Dhabi. I can now make comparisons between the practices in Singapore and Abu Dhabi. Weighing the pros and cons between the different practices, I can have a better judgment of what is the better approach now.”

Mohamed Ahmed Al AlawiTraffic Service Centre Engineer from Abu Dhabi Municipality

“The course participants were a good mix of consultants, site staff, designers and contractors. This serves as a good platform to exchange valuable information.”

Kevin Nicholson Traffic Consultant from Traffic Consult

“From this course, I learned about what road safety review is all about. One thing I like about the course is being able to interact with other participants who are from different disciplines.”

Lukman LimExecutive Project Engineer from Marina Coastal Expressway Subgroup, LTA

“This course helps to strengthen and reinforce my knowledge on road safety. Now, I have a better understanding of why certain safety issues are critical which I don’t understand in the past.”

Lim Hwee MinSenior Engineering Officer from Traffic Management, LTA

“I like the hands-on activity where we get to go to site for day and night inspection. I get to apply what I’ve learned into practice.”

Ong Wee Sheng Engineer from Ang & Ong Consultants

“The issues discussed allow me to have a deeper understanding on road safety. I hope that the accidents on our road will reduce significantly and I believe this can be achieved.”

Tan Peng ChuanSenior Engineer from AY Consultants

“The topics taught in this course were very informative and constructive. It helps to increase my awareness on road safety. I will be more careful in road design now so that the road system can be safer for motorists and pedestrians to use.”

Angela Yeo Principal Engineer from AY Consultants

“I have a clearer understanding on issues relating to Vehicle Impact Guardrail (VIG) now which I was unsure of in the past. I would recommend this course to others.”

Yeo Bee SeeHigher Principal Engineering Officer from Design Development (Road), LTA

“As a safety engineer, I find this course particularly beneficial to me. I would recommend this course to others, especially those working in the road safety discipline.”

Manea Salem Mohamed Al-Seari Road Safety Engineer from Abu Dhabi Municipality

External participantsfrom Abu Dhabi

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ConCluSion

Staff and external consultants who attended the course and obtained accreditation can conduct Road Safety Reviews for all the road and rail projects undertaken by LTA. With more upcoming road and rail projects, it is important to provide training to raise the knowledge and understanding of road safety engineering principles. This will ensure that the roads in Singapore are safe to use.

Chua Saw SengEngineer, Road System Safety

Safety Division

ACCIDENT STATISTICS2010

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* Based on Singapore Workplace Safety and Health Act Requirements

AFETY MEASURES FOR THE DOUBLE WALL COFFERDAM CONSTRUCTION IN THE SEA

Safety Phoa says…All lifting machines, lifting appliances and lifting gears used on site must be suitable for the task, used within their rated safe load capacity and must be in good working conditions.

Behaviour Based Safety (BBS) Training

As part of the BBS consultancy services, consultant Tsinghua University conducted four sessions of BBS training for selected staff from LTA project teams and contractors in January 2011.

It covered understanding of conducting safety culture surveys, BBS observation and intervention techniques, use of the BBS software as well as setting targets to improve safe behavior.

The training was well-received by the participants with clear understanding of implementing BBS. Knowledge gained by the contractors will allow them to train their staff and implement BBS on site.

Road Safety Reviewer Accreditation Course (March 2011)

The next Road Safety Reviewer Accreditation Course is scheduled for late March 2011. The 4-day course is targeted for interested parties who wish to become Accredited Road Safety Reviewer in Singapore. With the accreditation, they can undertake safety reviews for LTA road projects. Participants will also get to learn more about road safety engineering principles and understand more about the road safety situation in Singapore.

As the course requires participants to read drawing plans consisting mainly of traffic layout plans, site plans, longitudinal and cross sectional details, it is recommended for people with at least 1 year experience in road or traffic engineering.

Interested LTA staff can apply through the Learning Roadmap via HR Links. External consultants interested in this course can obtain a copy of the application form from LTA Academy.

Editorial Committee

AdvisorCorporate Safety Committee

EditorJoanne Teo Yu Jing

Circulation OfficerZaidani Bte Ramli

Contributions or Feedback to:

Land Transport AuthoritySafety Division251 North Bridge Road, Singapore 179102Tel: (65) 6332 6150 Fax: (65) 6332 6129Email address: joanne_teo@lta.gov.sgSafety News is also available online athttp://www.lta.gov.sg/projects/index_proj_safety.htm

PAGEEDITORIAL

Participants from last session of the BBS training

Updated List of Approved Codes of Practices

The WSH Council has recently approved an updated list of Approved Codes of Practices (ACOPs). These include the newly developed CP on WSH Risk Management and CP for Working Safely at Height.

Please visit www.wshc.gov.sg to download the list of revised ACOPs.

Interested parties can purchase the ACOPs from SPRING’s appointed sales vendor.