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2006 Edition (23 rd^ July 2010) – Revision R

June 2016 Edition

Code of Practice for Traffic Control at Work Zone

June 2016 Edition

This edition of the Code of Practice was prepared by the Committee for Traffic Control at Work Zone, and acted upon by the Deputy Director, Road Asset Regulation & Licensing Department. It comes into effect in June 2006 and supersedes all previous editions.

Clarifications on any aspect of this Code of Practice may be made with the Land Transport Authority, 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 Code of Practice for Temporary

Traffic Control , published in June 1998 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 Code of Practice 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. The Code not only explains the

fundamental principles for the provision of good traffic control but also gives a detailed guide

on planning and designing the traffic control plan.

After more than 4 years since publication, the Committee had been tasked to review the Code

of Practice with the main objective of making the Code more user friendly and also to make

general improvement. The revised Code of Practice for Traffic Control at Work Zone is

now contained in one book with 5 Chapters covering topics from planning to operations of

temporary traffic control in a work zone.

The revised edition includes worked examples of a temporary traffic control plan and

examples of approved traffic control plans that have been used. New traffic control devices

that have been introduced into the industry are also included in the revised Code. The

sections and appendices have also been rearranged for ease of use.

Contents Chapter 1 Introduction 1-1 Scope 2 1-2 Objectives 2 1-3 Application 2 1-4 Improvement Process 3 1-5 Definitions 3

Chapter 2 Fundamental Principles of Traffic Control 2-1 General 5 2-2 Safe Road Environment 5 2-3 Minimum Risk 5 2-4 Planning Ahead 5 2-5 Good Traffic Control Plan 5 2-6 Effective Traffic Control Device 5 2-7 Trained Personnel 6 2-8 Workers Safety 6 2-9 Pedestrian Safety 6 2-10 Vehicle and Equipment Safety 7 2-11 Road Surface Condition 7 Chapter 3 Planning and Design of the Traffic Control Plan 3-1 General 8 3-2 Phases of Traffic Control 8 3-3 Planning for Traffic Control 8 3-4 Design Considerations 10 3-5 Design Process 14 3-6 Drawings 28

Chapter 4 Design and Application of Traffic Control Devices 4-1 General 36 4-2 Traffic Signs 36 4-3 Regulatory Signs 36 4-4 Temporary Warning Signs 39 4-5 Information Sign 40 4-6 Lateral Shift Markers 42 4-7 Removable Pavement (Road) Marking Tape 42 4-8 Sign Mounting & Covering 43 4-9 Delineation and Channelling Devices 45 4-10 Traffic Cones 45 4-11 Temporary Kerbs 46 4-12 Water-Filled Barricades 46 4-13 Traffic Cylinders/Vertical Panels 47 4-14 Barricades 49 4-15 Plastic Mesh Fencing 49

4-16 Plastic Barricades 49 4-17 Temporary Safety Device 52 4-18 Water-filled Safety Barriers 54 4-19 Impact Attenuator (Stationary & Truck Mounted) 55 4-20 Visibility Enhancing Devices 56 4-21 Retro-reflective Discs 56 4-22 Flashing Beacons 56 4-23 Portable Amber Rotating Lamps 57 4-24 High Visibility Warning Cloth 57 4-25 Use of Other Devices 58 4-26 Fixed or Portable Traffic Signal 58 4-27 Flashing Arrow 59 4-28 Variable Message Sign 59 4-29 Solar powered flashing Arrow 59 4-30 New Devices 59

Chapter 5 Implementation, Operation & Maintenance and Closeout 5-1 General 60 5-2 Implementation Procedure 60 5-3 Operation Procedure 62 5-4 Closing-Out Procedure 63 5-5 Inspection Procedure 63 5-6 Maintenance Procedure 64 5-7 Installation Procedure for Long-Term Work 64 5-8 Installation Procedure for Short Duration Work 64 5-9 Mobile Operation 64 5-10 Removal Procedure 65 5-11 Safe Operation Procedure for Truck Mounted Attenuator 66 5-12 Road Safety Precautions 66 5-13 Method Statement Format 66 5-14 Co-ordination with Relevant Authorities 67

Appendices Appendix I - Regulations Appendix II - Specifications Appendix III - Guidelines Appendix IV - Sign Dimensions Appendix V - Examples of TCPs

Chapter 1 Introduction

1-1 Scope

1-1.1 This Code of Practice sets out the standards and procedures for Temporary Traffic Control when carrying out works on public streets. It gives practical guidance to users of the code when implementing temporary traffic control needed to do work on public streets and road related facilities. Work activities include but are not limited to bore-hole exploration, excavation, construction, maintenance, utility works and stationing associated construction vehicles and equipment.

1-1.2 This code is not intended to prohibit the use of new method or devices. Provided, sufficient technical data is submitted to the Authority to demonstrate that the new method or device is equivalent in quality, effectiveness, durability, and safety to that specified in this code.

1-2 Objectives

1-2.1 The primary objective of temporary traffic control is to manage the traffic as efficiently and safely as possible under all work conditions.

1-2.2 Traffic control aims to give adequate warning and clear information to motorists about the nature of works on site. This will translate into correct actions required in order to pass the work site safely. Traffic control shall also include measures to safeguard pedestrians when necessary. Proper traffic control also protects those who are directly involved in carrying out the works.

1-2.3 The provision of proper traffic control ensures compliance with legal obligations. Some of which are:

1. BOWEC Regulation 4 (1999 Ed) — Employer’s and contractor’s safety obligations.

2. Road Traffic Act Section 119 — Power to place traffic signs on public streets.

3. Road Traffic Act Section 115 (Chapter 276) Part VI — Provisions as to the use of highways.

4. Road Traffic (TRAFFIC SIGNS) Rules (1990) — Prescribed traffic signs placed on or near any roads.

5. Street Works Act 1995 Section 17 — Power to control works on public streets.

6. Street Works (Works on Public Streets) Regulations 1996 — Application and approval to work on public streets for any person other than the Authority.

Full texts of the relevant Act & Regulations are listed in Appendix I.

1-3 Application

1-3.1 This Code of Practice applies to the Land Transport Authority, all utility agencies/departments, contractors and other service providers who are involved in work on public roads and road related facilities.

1-3.2 Works on public streets within the Mass Rapid Transit (MRT) Railway Protection and Railway Safety Zones shall not be carried out without clearance from Development & Building Control Department of the Authority at 251 North Bridge Road, Singapore 179102.

1-3.3 It is obligatory to apply for approval to work in the Central Expressway (CTE), Kallang Paya-Lebar Expressway (KPE) and Marina Coastal Expressway (MCE), Fort Canning and Woodsville tunnels or on roads or expressways installed with the Expressway Monitoring and Advisory Systems (EMAS), TrafficScan, Junction Eyes or GLIDE system. Application forms are available from the Integrated Transport Systems Control Centre at 181 River Valley Road, Singapore 179034.

1-3.4 Approval shall be obtained from the various departments in LTA for carrying out road opening works on public

“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.

“worksite” means the space where the work is taking place and where the workers, equipment and material storage are confined.

“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.

Chapter 2 Fundamental Principles of Traffic Control

2-1 General.

2-1.1 This Chapter elaborates on the fundamental principles in ensuring that a good and proper traffic control system is provided in a work zone. It is not possible to provide standards and applications to cover all conditions. Therefore a good understanding of the 9 fundamental principles stated in sections 2-2 to 2-10 is essential. Complying with the fundamental principles shall take precedence over standard details and typical applications.

2-2 Safe Road Environment

2-2.1 Safe passages should be provided for both motorists and pedestrians going through the work zone. This can be achieved by: (1) Warning road users in advance of changing road environment; (2) Informing road users of the condition to be encountered; (3) Guiding road users through unusual sections of road; (4) Controlling road users at conflict point ; and (5) Forgiving road users’ mistakes when accidents happen.

2-3 Minimum Risk

2-3.1 Risks for road users going through the work zone can be mitigated by ensuring: (1) No surprises; (2) No hidden traps; (3) Free of unforgiving hazards; (4) Controlled release of information; (5) Consistent messages and repeats if necessary to reinforce; and (6) Good visibility under all road conditions.

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;

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 assured by:

(1) Controlling work traffic 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 Video or Sky 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 and provide good skidding resistance.

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.

Chapter 3 Planning and Design of Traffic Control Plan

3-1 General.

3-1.1 Traffic control at work zone starts from the first advance warning sign and ends at the last traffic device where traffic returns to normal. This Section provides guidelines for the traffic engineer to plan and design the Traffic Control Plan (TCP).

3-1.2 TCP ranges from being very detailed and customised (An example is given in Appendix IV ), to a mere reference to a typical drawing(s) in this Code or specified drawings contained in contract documents.

3-1.3 Traffic control requires forethought and provision shall be included in the contract specification for the contractor to develop the TCP.

3-2 Phases of Traffic Control

3-2.1 There are five phases of traffic control for major project and complicated work on roads.

(1) PLANNING PHASE — To identify and include traffic control requirements in the contract specification, works program & method of construction. (2) DESIGN PHASE — To design the TCP in detail, with regards to types, location and layout of traffic control devices for submission to the authority for approval. (3) IMPLEMENTATION PHASE — To install the temporary traffic control devices safely in accordance with the approved TCP. (4) OPERATION AND MAINTENANCE PHASE — To inspect the TCP and devices regularly by day and night to ensure that they are effective and absolutely safe. (5) CLOSE OUT PHASE — To remove all the traffic control devices safely and reinstate the permanent traffic scheme.

3-3 Planning for traffic Control

3-3.1 The purpose of planning is to: — (1) Select an appropriate traffic control scheme at planning and design stage for incorporation in the contract specifications. (2) Integrate the works program, the method of construction and the traffic control scheme, as they are closely interrelated. (3) Enable the contractor to integrate traffic control into the planning process before work starts. (4) Enable the contractor to review the plan before the start of each major phase of work.

3-3.2 Planning normally involves the 8 following steps (see flowchart 3.1): - (1) Assemble data — A detailed understanding of the scope of works, method of construction and road/traffic data, shall be required. (2) Study roadway occupancy - The following information are needed when assessing traffic control requirements:- (a) Duration of works affecting the road. (b) Carriageway space occupied by the work. (c) The area occupied by the work at any one time or day. (d) The numbers of hours that work affect the road. (3) Identify feasible alternatives — Choose the traffic control scheme appropriate for the work zone. There are 8 typical traffic control schemes for work on existing road as shown below: - (a) Lane Constriction — To reduce the lane width to 3.3m (min) for expressway and 3.0m (min) for other roads temporarily. Consideration should be given to providing a wider lane width at tight bends and horizontal curve.

2006 Edition (23 rd^ July 2010) – Revision R

(b) Lane closures — To reduce the number of lanes temporarily. (c) Share right-of-way — To operate with the same lane as two-way traffic with “stop and go” traffic control on a single carriageway road. (d) Median crossover — To divert traffic from one carriageway to the other of a divided road via a paved median or emergency gate etc. (e) Detour — To divert traffic to other existing road. (f) Temporary by-pass/diversion — To divert traffic to a temporary road. (g) Intermittent Closure — To stop traffic passing through the road intermittently. (h) Use of Shoulder or Median — To divert traffic to the road shoulder of expressway or paved median. (4) Analyse volume/capacity relation & traffic impact — The ability to cope with the traffic demand is a basic requirement of a feasible traffic control scheme. (5) Analyse other improvement techniques — Propose other measures that can be used to overcome traffic problem. Such as:

(a) Off-peak works — allow work only at off-peak hours. (b) Night works — allow work only at night when the traffic is lighter. (c) Remove parking — prohibit roadside parking temporarily. (d) Reschedule works — defer work to a suitable time later. (e) Weekend work — allow work on weekends only, when traffic is lighter. (f) Reversible lane — provide tidal flow of traffic lanes to increase road capacity at peak hour demand. (g) Restrict turning — prohibit certain turning movements at a road junction.

(h) Modify signal time — change the phasing time of a traffic signal. (6) Evaluate traffic control schemes — Compare the impact of the alternatives in terms of: - (a) Vehicle delay and stop — increase in operation cost and delay to road users. (b) Safety and accidents — increase medical and social costs due to higher risk to workers and road users. (c) Project and traffic control cost — increase contract period and contract sum on employers/client. (d) Air pollution and business losses — environmental pollution and losses in business due to work etc. (7) Modify Procedure — Review design and work procedure to determine the need for alternative construction methods or procedure to reduce the impact. (8) Select preferred alternatives (traffic control schemes) — Identify the preferred traffic control schemes for each stage of the work.

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 Locations (5) Work Location (6) Traffic Condition (7) Type of Work (8) Type of Operation (9) Position of the construction site access.

3-4.2 Work duration refers to how long the work takes to complete. It is important because risk is proportional to the exposure time and the degree of injury, and hence influences the choice of devices. Simplified TCP and portable devices shall be used for shorter duration work to minimise the time motorists are exposed to road works and workers exposed to the traffic. Detailed TCP with better and elaborate devices shall be used for longer duration work (long-term and short-term) as there is ample time to install them. And benefits can be derived from the use of full range of devices. Duration is divided into : (1) Long Term > 7 days. (2) Short term — from overnight to 7 days. (3) Short duration — up to 12 hrs or less than a day’s shift. (4) Short duration mobile — works that move intermittently or continuously.

3-4.3 Road speed determines the design of the TCP. Permanent road design standards shall apply to temporary road design. Traffic diversion and detour shall be provided with suitable road geometry. Detour usually 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 right-of-way. The geometric design elements are summarised in Tables 3.1, 3.2, 3.3 and 3.4. The design speed limit in the work zone should not fall below more than 20 km/hr of the existing permanent gazette speed limit.

3-4.4 Road Type refers to the hierarchy of roads in Singapore. Roads are classified in accordance with the planning and building control requirements. (1) Expressway — Major road for continuous, high speed, high volume and long distance travel. (2) Semi -expressway – Major road built for distributing traffic between residential, industrial and business areas to complement expressways. (3) Arterial — Major road for distributing traffic between residential, industrial and business area etc. major arterial and minor

arterial are to complement expressways. (4) Primary Access — Minor road for distributing traffic within local area. (5) Local Access — Minor road for direct access to buildings and land within local area.

3-4.5 Important characteristics of roads are summarised in Table 3..

3-4.6 Road Location determines the types of road-related facilities and traffic control measures to be provided for the road users. The important considerations of locations are: - (1) Local traffic (2) Pedestrian volume/movement (3) Local business (4) Bus stop locations (5) Parking facilities (roadside, etc) (6) Access to properties/buildings (7) Vehicles stopping

3-4.7 The locations as stated above can be differentiated by the following types: - (1) Public Housing — has more road-related facilities and more commuters. (2) Private Housing — has very few facilities and low pedestrian volume, but many property accesses. (3) CBD — has more road-related facilities and heavy pedestrian volume during office hours. (4) Industrial Areas — have special provision during working hours. (5) School Zones — have special provision for school children during school peak.

3-4.8 Work Location determines the design of the TCP in guiding drivers through the obstruction safely and how work access and work traffic are being controlled. Work on the fast lane is hazardous due to higher speed of vehicles while work on the middle lane will result in an island situation. Where possible, access on the fast and intermediate lanes should only be done as a last resort. As far as possible, access points should also not be located after the inside of a bend

Geometric Design Tables (Cont.’)

Table 3.3 : Downgrades Stopping Sight Distance

Design Parameter Symbol Units

Recommended Boundary Values

Design Speed Kph 90 80 70 60 50 40

Downgrade Gradient

-2%, m 145 120 95 75 55 40

Downgrade Gradient

-4%, m 150 125 100 75 60 40

Downgrade Gradient

-6%, m 155 125 100 80 60 45

Downgrade Gradient

-8%, m - - - 80 60 45

Table 3.4 : Upgrades Stopping Sight Distance

Design Parameter Symbol Units

Recommended Boundary Values

Design Speed Kph 90 80 70 60 50 40

Upgrade Gradient +2%, m 140 115 90 70 55 40

Upgrade Gradient +4%, m 135 110 90 70 55 40

Upgrade Gradient +6%, m 135 110 90 70 55 40

Upgrade Gradient +8%, m - - - 70 55 40

Table 3.5 : Road Characteristics

Types Expressway Semi- Expressway

Major Arterial

Minor Arterial

Primary Access

Local Acces s

Desirable Speed (km/h)

90 80 70 60 50 50 to 40

Access Control

Full Restrictive Restrictive Partial None None

Junction Grade Separated

At grade or Separated

At grade or Separated

At Grade At Grade At Grade

Shoulder Yes Yes No No No No

Stopping/ Waiting

No Restrictive Restrictive Restrictive Yes Yes

Parking/ Driveway

No No No Restrictive Restrictive Yes

2006 Edition (23 rd^ July 2010) – Revision R

3-4.9 Traffic Condition refers to road capacity and traffic demand. Traffic condition will determine the need for temporary lane closure, road widening and/or traffic diversion. The two basic conditions are: Traffic Condition I

Traffic demand is always less than road capacity. Closure of lane will not cause road congestion. Works shall be allowed to proceed in all traffic flow conditions. Lane closure may be allowed for long- term works.

Traffic Condition II

Traffic demand at peak is equal to or higher than road capacity. Closure of lane will cause serious road congestion. Works shall be allowed to proceed only when demand is less than the available carriageway’s capacity. Temporary road widening or traffic diversion is required before works are allowed to remain in all traffic flow conditions.

3-4.10 Type of Work refers to the ability to suspend the work in progress and remove the obstruction quickly when traffic congestion has reached an unacceptable level. The two basic types of works are: Work Type I

Work can be suspended and obstruction can be removed quickly. Traffic can be restored to normal condition once the obstruction has been removed. Simple planning would suffice

Work Type II

Work cannot be suspended and obstruction cannot be removed quickly. Traffic can be restored to normal condition once the obstruction has been removed. Detailed planning shall be needed before site possession.

3-4.11 Mode of Operation refers to the need for workers’ presence in operating the traffic control plan. There are basically two modes of operation and the choice of devices is related to it in the following ways:

Mode I

Operates only when work is in progress and workmen are in attendance. Workmen can reinstate the devices that have been displaced. Simple/ portable devices should be used.

Mode II

Operates day and night and would be left unattended. Devices that are displaced could be dangerous to motorists. Devices used should be sufficiently robust and placed clear of the traffic lanes to prevent them from being buffeted by passing vehicles.

3-5 Design Process

3-5.1 Work Zone is typically subdivided into four zones, ADVANCE WARNING ZONE, TRANSITION ZONE, ACTIVITY ZONE and TERMINATION ZONE, each serving different functions as shown in Figure 3.1.

3-5.2 Design of a traffic control plan normally follows the sequence as shown below: - (1) ACTIVITY ZONE (2) TRANSITION ZONE (3) ADVANCE WARNING ZONE (4) TERMINATION ZONE

Figure 3.1 Components of a Work Zone

3-5.3 Designing the Activity Zone. The Activity Zone comprises the following components (shown in Figure 3.2 ): (1) Work Area – Area occupied physically by the works. (2) Work Space — Space set aside around the works area for workers, equipment and material. Method of construction will determine the space needed for the work. (3) 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. (4) 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 workspace. The recommended dimensions are as shown in the Table 3.7.

(b) Lateral safety buffer is to separate workspace from traffic space. The recommended dimensions are as shown in Table 3.8.

Zones should be treated as safety zones. Vehicles and workers should not be inside these zones

3 rd^ sign

2 nd^ sign

1 st^ sign

IV TERMINATION ZONE Traffic resumes normal path

III ACTIVITY ZONE Where work takes place

II TRANSITION ZONE To move traffic out of its normal path

I ADVANCE WARNING ZONE To warn motorist of what to expect ahead

Works area Lateral safety buffer

Longitudinal safety buffer

3.5-4 Shadow vehicles are considered hazardous and the same safety buffers are recommended to protect road users.

3.5-5 Typical cross-sections of activity zone shown in Figures 3.3 to 3.6 will

assist the engineer in the design of an activity zone.

3-5.6 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..

3-5.7 The definitions of the tapers (shown in Figure 3.7 ) referred to in the above 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.

Table 3. 7 : Longitudinal Buffer Speed (km/h) Length (m) => 80 60 70 30 60 20 50 10 40 10

Table 3. 8 : Lateral Buffer Speed Minimum Width (m) Km/h Desirable Absolute => 80 1.2 0. 70 0.9 0. 60 0.5 0. 50 0.5 0. 40 0.5 0.

BUFFER SPACE Longitudinal Safety Buffer. Provides protection for traffic and workers

TRAFFIC SPACE Allows traffic to pass through the activity zone

WORK SPACE

BUFFER SPACE Lateral Safety Buffer. To separate work space from traffic space

WORK AREA Is set aside for workers, equipment and material storage. ACTIVITY ZONE

Figure 3.2 Components of an Activity Zone