Code of Practice for Traffic Control at Work Zone, Exams of Traffic Control and Regulation

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Code of Practice for

Traffic Control at Work Zone

July 2019 Edition

Code of Practice for Traffic Control at Work Zone

July 2019 Edition

The Code of Practice (COP) for Traffic Control at Work Zone was published by Land Transport Authority

(LTA), Singapore, to provide those involved in construction activities within the public street a comprehensive

guide to temporary traffic control. The COP explains the fundamental principles for the provision of good

traffic control and also gives a detailed guide on planning and designing the traffic control plan for the safety

of road users.

This July 2019 Edition comes into effect on 1 July 2019 and supersedes all previous editions.

Clarifications on any aspect of this COP may be made with the Road Asset Regulation & Licensing Division

of LTA, Singapore.

Origin and Development of Code of Practice for Traffic Control at Work Zone

Conflicts between traffic and works on or next to the road are inevitable. It is important to reduce such conflicts

to optimise work efficiency and traffic safety, and to minimise traffic congestion, delay and inconvenience to

road users.

The first COP for Temporary Traffic Control was published in June 1998 and dealt with the specific work

area in the carriageway and its corresponding traffic control arrangement. This proved to be useful in providing

contractors with typical temporary traffic control arrangement but inadequate when major temporary traffic

schemes are involved. In June 2001, the COP for Traffic Control at Work Zone was published to provide

those involved in all forms of construction activities within the road reserve with a comprehensive guide to

temporary traffic control. In June 2006, general improvements were made to COP for Traffic Control at

Work Zone to enhance its user-friendliness. Following that, periodically updates were also made to reflect

any change in requirements such as new traffic control devices that have been introduced into the industry.

Given the increase in construction activities within the road reserve due to rapid developments and more

demands for bigger capacity utility services in recent years, a comprehensive review of the COP was necessary

to ensure that it continues to remain user-friendly and relevant from the planning to operations of temporary

traffic control in a work zone.

Under this July 2019 Edition, the content had been condensed from 5 Chapters into 4 Chapters with more

pictorials for users to better appreciate the requirements of temporary traffic control at work zone to enhance

overall safety of working on public streets. Other revisions include a flowchart to guide users on the necessary

checks to be carried out and physical improvements to ensure safe deployment of Truck Mounted Attenuator

(TMA) at work zones.

Contents

• Chapter 1 Introduction
• 1‐1 Scope..........................................................................................................................................
• 1‐2 Objectives
• 1‐3 Application
• 1‐4 Improvement Process
• 1‐5 Definitions
  • Chapter 2 Fundamental Principles of Traffic Control
• 2‐1 General.......................................................................................................................................
• 2‐2 Safe Road Environment
• 2‐3 Minimum Risk
• 2‐4 Planning Ahead
• 2‐5 Good Traffic Control Plan............................................................................................................
• 2‐6 Effective Traffic Control Devices
• 2‐7 Trained Personnel.......................................................................................................................
• 2‐8 Workers Safety
• 2‐9 Safety of Pedestrian Cyclist and Personal Mobility Device (PMD) Users
• 2‐10 Vehicles and Equipment Safety
• 2‐11 Road Surface Condition
  • Chapter 3 Planning, Design and Implementation of Traffic Control Plan
• 3‐1 General.....................................................................................................................................
• 3‐2 Phases of Traffic Control
• 3‐3 Planning for Traffic Control
• 3‐4 Design Considerations
• 3‐5 Design Traffic Control Plan........................................................................................................
• 3‐6 Drawings
• 3‐7 Implementation, Operation & Maintenance and Close‐out
• 3‐8 Implementation Procedure
• 3‐9 Operation Procedure
• 3‐10 Closing out Procedure
• 3‐11 Safe Operation Procedure for Truck Mounted Attenuator (TMA)
  • Chapter 4 Design and Application of Traffic Control Devices............................
• 4‐1 General.....................................................................................................................................
• 4‐2 Temporary Advance Warning Signs...........................................................................................
• 4‐3 Information Signs
• 4‐4 Lateral Shift Markers (LSM)
• 4‐5 Pavement (road) Marking
• 4‐6 Sign Mounting & Covering
• 4‐7 Delineation and Channelling Devices
• 4‐8 Traffic Cones
• 4‐9 Temporary Kerbs
• 4‐10 Water‐Filled Barricades
• 4‐11 Traffic Cylinders/Vertical Panels
• 4‐12 Road Safety Barriers
• 4‐13 Water‐filled Safety Barriers
• 4‐14 Barricades
• 4‐15 Plastic Mesh Fencing.................................................................................................................
• 4‐16 Plastic Barricades......................................................................................................................
• 4‐17 Impact Attenuator (Stationary & Truck Mounted)
• 4‐18 Visibility Enhancing Devices
• 4‐19 Retro‐reflective Disc
• 4‐20 Flashing Beacons
• 4‐21 Portable Amber Rotating Lamps
• 4‐22 High Visibility Warning Cloth
• 4‐23 Use of Other Devices
• 4‐24 Portable Traffic Light System
• 4‐25 Flashing Arrow
• 4‐26 Variable Message Sign
• 4‐27 Half‐Height Hoarding
• 4‐28 New Devices
  • APPENDIX I – Temporary Signs for Cycling Path
  • APPENDIX II – Examples of TCPs
  • APPENDIX III ‐ Truck Mounted Attenuator
  • APPENDIX IV – Good and Poor Temporary Traffic Control at Work Sites
  • APPENDIX V – Sign Dimensions
    • of Way APPENDIX VI ‐ Guidelines for the Deployment of Portable Traffic Light System for Shared Right

1-4 Improvement Process

1-4.1 The standard of traffic control and road safety shall be improved continually to meet the rising expectations of road users. The process involves a continuous cycle of activities shown in the following diagram and further explained below:

Improvement process- a continuous cycle

1. Set New Standards : Set standards against international practices by drawing from the experiences of developed countries.
2. Education: Ensure that all personnel involved in traffic control and road safety has knowledge that is equal to their responsibility. Educate road users on traffic control and road safety measures.
3. Implementation : Making the Code contractually binding by developer/contractor’s client would ensure successful implementation.
4. Auditing : Appoint an independent and qualified person to review the design and execution of the traffic control scheme. This is to ensure correct and consistent practice at different sites.
5. Evaluation and Review : Evaluate and review current practices continually to correct mistakes and improve standards.

1-5 Definitions

For the purposes of this COP, the following definitions apply unless the context otherwise requires:

“Authority” means the Land Transport Authority of Singapore established under the Land Transport Authority of Singapore Act 1995.

“carriageway” means the running surface which includes all traffic lanes and shoulders constructed for use by vehicular traffic.

“Peak hours” means the traffic peak hours specified by the Authority under Clause 6.10.1 of COP for Works on Public Streets, which include the hours from Monday to Saturday, 6.00am to 9.30am and from 5.00pm to 8.00pm. A listing of roads with different traffic peak hours is available on LTA.PROMPT system via URL – https://prompt.lta.gov.sg and will be updated from time to time.

“Professional Engineer” means a person who is a registered as a civil or structural engineer under the Professional Engineers Act and possesses a valid practicing certificate issued under that Act.

“qualified supervisor” means a full-time site personnel who possesses at least a Certificate in Pavement Construction and Maintenance issued by the Building and Construction Authority, or equivalent.

“competent person” means a person who has, through a combination of training, qualification and experience, acquired knowledge and skills enabling that person to correctly perform a specified task. To be conversant with the latest LTA’s Civil Design Criteria, Standard Details of Road Elements, Road Safety Guidebook and Code of Practice for Traffic Control at Work Zone.

“road” means public street as defined in the Street Works Act 1995 or any part thereof as implied by the context.

“traffic control” means the process required to regulate, warn and guide road users and advise them to traverse a section of a road in the proper manner.

“traffic control devices” means the signs, cones, barriers, flashing lamps or other devices placed temporarily on or adjacent to a road to regulate, warn, or guide road users.

“work zone” means the entire section of the road over which temporary traffic control related to the work activity is exercised.

“work area" means the area occupied physically by the works, which includes the space required for workers, equipment and materials.

“Work duration” refers to characteristic of work. The three categories of work duration are defined below:

1. Long term means stationary works which occupy lane(s) for extended period continuously.
2. Short term means stationary works which occupy lane(s) temporarily and can be removed quickly.
3. Mobile means continuously moving works with intermittent stops.

“detour” means traffic is directed to another road to bypass the closed area.

“diversion” means traffic is directed to a temporary road or lane placed in or next to the carriageway.

“road related facility” includes any traffic sign, directional sign, street name sign, traffic light, bus shelter, railing, lighting apparatus and any optical, electronic, communication, monitoring or computerised equipment necessary for the control and management of traffic, and any other road related structure and facility maintained by the Authority.

2-4 Planning Ahead

2-4.1 Traffic control requirements at work zones shall be planned in advance in the following phases:

1. Planning and Design Phase — To identify and incorporate traffic control requirements into contract specification.
2. Start of Construction Phase — To integrate traffic control into the construction planning processes.
3. Start of Every Major Phase — To re-examine and adjust traffic control scheme to suit prevailing site condition.

2-5 Good Traffic Control Plan

2-5.1 Traffic Control Plan (TCP) can be designed effectively by:

1. Designing traffic control plan in advance — To develop the TCP in detail at the beginning of each of the phases stated in 2-.
2. Complying with basic design principles of permanent roads — The road provided in the work zone should be similar to that of a normal road.
3. Exercising sound engineering judgement — To take into consideration the unique characteristics of each work site.

2-6 Effective Traffic Control Devices

2-6.1 Traffic Control Devices (TCD) should be designed, placed, operated and maintained effectively to meet the basic requirements of:

1. Warning, informing and guiding road users;
2. Commanding the attention of road users to the devices;
3. Conveying a clear and simple message;
4. Commanding the respect of road users so that they will obey instructions; and
5. Allowing adequate time for road users to respond in an orderly and predictable manner.

2-7 Trained Personnel

2-7.1 By ensuring that only competent persons are involved in traffic control. (1) Appointment of a person with authority to control the progress and to be overall in-charge; (2) Training of site supervisors who are already conversant with safe methods of work in traffic control. Site supervisors should be appointed to supervise the selection, placement, operation, maintenance and removal of the traffic control devices; and (3) Training of workers to be fully conversant with safe methods of placing, operating, maintaining and removing devices on the road.

2-8 Workers Safety

2-8.1 Workers are to be protected from the hazards of working in the work zone. This can be achieved by: (1) Training all workers on the basics of road safety; (2) Informing motorists of the workers’ presence through traffic signs; (3) Placing continuous barricades along workspace to separate workers from traffic. This will also prevent workers from straying into traffic space during work; (4) Providing appropriate means for workers access when entering or leaving the work zone especially along high-speed roads; (5) Placing temporary safety barriers to protect workers from vehicular traffic; (6) Reducing vehicular speed if necessary for the safety of workers and road users; (7) Providing proper lighting for night work so that the work site is visible at night for the safety of workers and road users. However, the lights used shall not be blinding to motorists; (8) Providing a lead vehicle to warn oncoming traffic and to shield workers. To shield workers and divert traffic with a shadow vehicle; and (9) Providing workers with high visibility clothing so as to be more conspicuous and visible during both day and night.

2-9 Safety of Pedestrian Cyclist and Personal Mobility Device (PMD) Users

2-9.1 The following provisions shall be made to separate the pedestrians, cyclists and PMD users from work- site activities and adjacent traffic: (1) Advance information signs to direct pedestrians, cyclists and PMD users to a safe road crossing; (2) In the event that existing footpath/cycling/shared path is affected by the works, an alternative smooth and clearly delineated path with temporary signs shall be provided accordingly. Examples for temporary signs for cycling path are provided in Appendix I. (3) In the event that the existing covered walkway is affected by the works, an alternative well-lit covered walkway shall be provided for to protect pedestrians, cyclists and PMD users, especially during long term work; (4) Continuous barricades to keep pedestrians, cyclists and PMD users from interference with the work activity/traffic, thereby preventing accidents; and (5) Watchmen, temporary traffic control devices and/or audible warning devices to control the movement of works vehicles and equipment across pedestrians, cyclists and PMD users’ way. (6) Provision of barrier-free access along a footpath/walkway/cycling path/shared path affected by the works. The contractor shall ensure that the same provisions are made along the temporary footpath/walkway/cycling path/shared path affected. The footpath/walkway should never be less than 1m wide, and whenever possible should be at least 1.5m. The cycling path should never be less than 1.8m wide, and whenever possible should be at least 2.0m. The shared path should be at least 2.0m wide, and whenever possible at least 2.5m.

2-10 Vehicles and Equipment Safety

2-10.1 All vehicle and equipment used on site shall not be a safety hazard to both road users and workers. Safety can be enhanced by: (1) Controlling work traffic for shared right of way by providing portable traffic signals; (2) Controlling parking by providing safe designated parking space for work vehicles, plants and equipment within work site to prevent them from causing obstruction to others; (3) Improving conspicuous of the vehicles/equipment and to alert road users by displaying revolving amber lights whenever vehicles or equipment are in operation; (4) Inspecting TCDs regularly by using a Safety Inspection Vehicle loaded with additional devices to replace damaged devices; (5) Fitting all protective vehicles with Truck Mounted Attenuators (TMA) and large arrow panel with amber lights; (6) Providing recovery/service vehicle to remove stalled vehicles immediately; and (7) Installing independent surveillance cameras where necessary to monitor traffic conditions effectively and provide real-time information on the effects of roadwork on traffic.

2-11 Road Surface Condition

2-11.1 As part of a traffic control layout, there will be occasions when areas of carriageway are brought into operation that would not normally be used. The adequacy of these temporary surfaces should be considered before use. In particular, the effect on traffic of the following should be borne in mind: (1) Cross falls on chevron areas; (2) Drain covers in hard shoulders and in central medium at crossovers; (3) Clearances if traffic runs on edge strengthening; (4) The need to sweep the surface of steel decking or road to remove any construction debris and maintain a skid resistance of not less than 65BPN and 55BPN respectively at all time.

2-11.2 The effect on carriageways of carrying unexpected traffic loads also needs to be considered (e.g. drain covers on the hard shoulder may need to be strengthened). There is also a need to provide a regular maintenance regime to reduce incidents during wet weather periods.

Flowchart 3.1 Planning Flowchart

STEP 1

Assemble Data

STEP 2

Study Road Way Occupancy

STEP 3

Identify Feasible Alternatives

STEP 4

Analyse Volume/Capacity Relation & traffic Impact

STEP 5

Analyse other Improvement Techniques

STEP 6

Evaluate Traffic Control Scheme

STEP 7

Modify Procedure

STEP 8

Select Preferred Alternatives

NOT ACCEPTABLE

ACCEPTABLE

NO

YES

Refer to Summary of Planning Process on page 19 for more details.

Is there a capacity deficiency ?

3-4 Design Considerations

3-4.1 Design shall start after preferred temporary traffic control scheme has been selected for each stage of the work. Important design consideration shall include the following: (1) Work Duration (2) Road Speed (3) Road Type (4) Road Location (5) Work Location (6) Traffic Condition (7) Type of Work (8) Mode of Operation Refer to Summary of Design Considerations on page 20 for more details.

3-5 Design Traffic Control Plan

3-5.1 Work Zone is typically subdivided into four zones as shown below: - (1) ACTIVITY ZONE (2) TRANSITION ZONE (3) ADVANCE WARNING ZONE (4) TERMINATION ZONE

3-5.2 Designing the Activity Zone

The Activity Zone comprises the following components (shown in Figure 3.1 ): (1) Work Area – Area occupied physically by the works, which includes the space required for workers equipment and material. (2) Traffic Space — Area where traffic is routed through the activity area. Traffic space must be properly delineated and channelled to guide traffic through safely. Road capacity and traffic demand will determine the width of the traffic space. (3) Safety Buffer — Space separating traffic space from workspace. No storage of equipment and material, parking of vehicles, or presence of worker (except maintenance activity) is allowed for the safety of the workers and road users. It allows an errant vehicle to stop in time before hitting the workspace. The two types of safety buffers are the longitudinal safety buffer and the lateral safety buffer. (a) Longitudinal safety buffer is a space upstream of a work area. The recommended dimensions are as shown in the Table 3- 1. (b) Lateral safety buffer is to separate work area from traffic space. The recommended dimensions are as shown in Table 3- 2.

Table 3- 1 : Longitudinal Safety Buffer Speed (km/h) Length (m) => 80 60 70 30 60 20 50 10 40 10 Table 3- 2 : Lateral Safety Buffer Speed (km/h) Minimum Width (m) Desirable Absolute => 80 1.2 0. 70 0.9 0. 60 0.5 0. 50 0.5 0. 40 0.5 0.

3-5.3 Designing the Transition Zone

A transition would be required when traffic is redirected from a normal path to a new path. A suitable taper length and geometry should be provided to meet the requirements of the design speed. The recommended lengths of various types of taper are shown in the Table 3- 3.

3-5.4 The definitions of the tapers (shown in Figure 3.2) referred to in the below paragraph are: — (1) A Merging Taper — used where two lanes merge into one lane. It needs a longer distance for the drivers to adjust their speed to merge with an adjacent lane before the end of transition. (2) A Shifting Taper — used when a lateral shift is needed without merging. (3) A Shoulder Taper — used on an expressway when work is in progress on a shoulder lane.

3-5.5 The following factors shall be considered when designing a taper. They are: — (1) The start of the taper should be located such that its full length is visible at 60m to 100m ahead. The start of the taper should be located at the upstream of a bend so that it is clearly visible on the approach. (2) Transition area is also a safety zone. Nothing other than traffic control devices are allowed in the transition zone. (3) Devices should be spaced such that the taper would appear uniform and continuous to approaching motorists, and traffic cannot weave around them easily.

Figure 3.2: Types of Tapers

3-5.6 Designing the Advance Warning Zone

The function of the advance warning zone is to give advance warning to the approaching traffic of the activity area and transition area ahead. Drivers shall be able to see the warning signs, understand the conditions ahead and know what is expected of them.

Table 3- 3 : Recommended Length for Taper (m) Speed (km/h)

Merging 200 150 120 80 40 20 Shifting 100 80 60 40 20 10 Shoulder 20 20 NA NA NA NA

Shoulder Taper

Shifting Taper

Merging Taper

3-5.7 Typically, two temporary advanced warning signs shall be provided for at every approach to work site along expressway and major road as shown in Table 3- 4. Signs warning motorists of the nature of road restriction ahead will follow this. Examples of such signs are given in Table 3- 5.

Table 3- 4 : Compulsory Advanced Warning Signs

1st sign To alert and command road user’s attention. A caution sign is normally used to alert and command driver’s attention to the work zone. Typical visibility of 1st sign = Minimum Stopping Sight distance.

2nd sign To notify road users of the general nature of the work ahead. Logo identifies the organisation carrying out the work.

Table 3- 5 : Example of Temporary Signs showing lane changes 3rd sign To guide road users of the action to be taken e.g. merge to middle lane, slow, do not over-take, workmen present.etc.

3-5.8 Posting of temporary advance warning signs shall comply with the following requirements: — (1) Provide temporary warning signs at every approach to work zone along the expressway and major road. (2) The placing of the advanced warning signs shall be in compliance with Table 3-. (3) The number of signs and spacing shall be adjusted to suit the site condition e.g. poor geometry, adverse sight distance and obstruction etc. (4) Temporary warning signs shall only be duplicated on the right side of the carriageway if signs on the left-hand side are likely to be obscured or overlooked. The typical distances of temporary warning signs upstream of the taper are as shown in the Table 3-.

Table 3- 6 : Minimum Distances of Temporary Signs Distance from taper starts

km/h

70 km/h 60 km/h 50 km/h 40 km/h and below

3rd sign 240 m 200 m 160 m 120 m 60 m 2nd sign 360 m 300 m 240 m 180 m 90 m 1st sign 480 m 400 m 320 m 240 m 120 m

3-5.9 Designing the Termination Zone

The termination zone is used to channel traffic back to its normal traffic path and also to inform motorists that they have passed the work zone.

Agency Logo

Summary of Planning Process

Planning Process of Traffic Control

Step Description Detail 1 Assemble Data  Scope of works, Method of construction, Road data, Traffic data, etc. should be required 2 Study roadway occupancy

 Duration of the works  Carriageway space occupied by the work  Road occupied at any one time or day  The hours by which the road will be affected each day 3 Identify feasible alternatives

 Lane constriction  Lane closure  Shared right-of-way  Median crossover  Detour  Temporary by-pass/diversion  Intermittent closure  Use of road shoulder or median 4 Analyse volume/capacity relation & traffic impact

 Traffic impact study  Ability to cope with the traffic demand 5 Analyse other improvement techniques

 Off-peak works  Night works  Remove parking  Reschedule works  Weekend works  Reversible lane  Restrict turning  Modify signal time 6 Evaluate traffic control schemes

 Vehicle delays and stops  Safety and accidents  Project and traffic controls’ costs  Air pollution and business losses  Etc 7 Modify procedure (^)  Review designs

 Work procedure  Alternative construction methods  Other procedure 8 Select preferred traffic control scheme

 Identify preferred traffic control scheme for each stage of the works

Summary of Design Considerations

S/No Type Differentiation Characteristic

1. Work Duration

Long Term  Long term means stationary works which occupy lane(s) for extended period continuously  Require to change the alignment of the road and/or maintain the same number of the existing lane  Require use of portable and elaborate devices e.g. use of high containment road safety barrier for the safety of road users and workers  Require relocation of traffic signals and/or traffic furniture  Detailed TCP/traffic diversion plan and comply with the LTA Civil Design criteria, Road Safety Guidebook and approved by LTA  Examples include but are not limited to:  Tunnel shaft construction  Deep excavation  Rigid Pavement Construction  Road Widening

1. Short term^ ^ Short term means stationary works which occupy lane(s) temporarily and can be removed quickly  Required use of portable devices  Examples include but are not limited to:  Connection works for utility supply  Trial trench  Trenching for utility laying  Manhole maintenance
2. Mobile^ ^ Continuously moving works with intermittent stops  Portable device  Examples include but are not limited to:  Signs washing  Road marking
3. Road Speed

Design speed for diversion shall not fall below more than 10 km/h of the existing permanent gazette speed limit

 Horizontal alignment  Vertical profile  Cross-section  Sight distance  Taper length  Safety buffer  Sign spacing

Road Geometry for diversion shall comply with LTA Civil Design Criteria

1. Road Type

Expressway Arterial Primary Access Local Access

 Legal speed  Access control  Junction type  Shoulder  Stopping/waiting  Parking/driveway

1. Road Location

Rural area Urban area Public housing Private housing CBD Industrial area

 Local traffic  Pedestrian  Local business  Bus stop  Parking  Driveway