2025 WZ-Safety-HB-2023-020123.pdf

South Carolina

Work Zone Safety Guidelines

For the South Carolina Department

Of Transportation, Municipalities, Counties, Utilities, and Contractors.

— 2023 —

WORK ZONE

SAFETY

It's serious.

Deadly serious.

i

Table of Contents Introduction Definitions Four Areas of a TTC Zone Buffer Space Tapers for Work Zones

Types of Tapers 5 Taper Lengths 6

Traffic Control Devices (TCDs) Signs

Regulatory Signs 7 Guide Signs 8 Warning Signs 8

Temporary Warning Signs Sign Spacing 10 Sign Size 11 Sign Illumination and Retroreflectorization 11 Sign Mounting 11 Ground-Embedded Supports 12 Portable Sign Supports 13

High-Level Warning Device (or Flag Tree) Signs Currently Not In Use

Ground-Embedded Signs 15 Portable Signs 15

Temporary EXIT Signs Temporary Steel Plates GROOVED PAVEMENT Signs Channelizing Devices

Standard Traffic Cones 17 42" Oversized Traffic Cones 18 Drums 18 Barricades 19 Vertical Panels 21 Device Spacing 21 ii

Lighting Devices Warning Lights 22

Pavement Markings Arrow Boards Changeable Message Sign (CMS)

Location of CMS 25 Truck Mounted CMS 25

Truck Mounted Attenuator (TMA) Direct Mounted TMA 26 Trailer Towed TMA 26 Ballast 27

Work Vehicles Auxiliary Warning Lights 27 Travel Direction 28

Duration of Work Location of Work Drawings Legend Closures

Lane Closure 33 Shoulder Closure 33 Road Closure 33 Drawing 1. Lane Closure Daytime Urban Low-Speed (£ 35 MPH) 34 Drawing 2. Lane Closure Nighttime Urban Low-Speed (£ 35 MPH) 40 Drawing 3. Dual Lane Closure Urban Low-Speed (£ 35 MPH) 46 Drawing 4. Lane Closure Daytime Multilane Primary Routes 49 Drawing 5. Lane Closure Nighttime Multilane Primary Routes 54 Drawing 6. Dual Lane Closure Multilane Primary Routes 59 Drawing 7. Center Lane Closure Multilane Primary Routes 62 Drawing 8. Work in Center of a Minor Urban Street

35 MPH or Less, Maintaining Two-Way Traffic 65 Drawing 9. Work in Travel Lane on a Minor Urban Street

35 MPH or Less, Maintaining Two-Way Traffic 67 Drawing 10. Center Turn Lane Closed on a Three-Lane, Two-Way Road 69 Drawing 11. Lane Shift on a Three-Lane, Two-Way Road 71 Drawing 12. Right Shoulder Closure (Case I / Case II) Primary Routes 73 iii

Drawing 13. Left Shoulder Closure (Case I / Case I) Primary Routes 76 Drawing 14. Left Shoulder Closure (Case I / Case II) Primary Routes 78 Drawing 15. Extended Road Closure 80

Mobile Operations Intermittent Mobile Operations

Stopping Sight Distance 85 Variable Distance Interval (VDI) 86 Pothole Patching Operations 87 Drawing 16. Intermittent Mobile Operations Low-Volume, Intermediate-Speed to High-Speed, Primary & Secondary Routes 88 Drawing 17. Intermittent Mobile Operations High-Volume, Low-Speed, Interior Travel Lane, Primary & Secondary Routes 91 Drawing 18. Intermittent Mobile Operations High-Volume, Intermediate-Speed to High-Speed, Primary & Secondary Routes 94 Continuously Moving Mobile Operations

Drawing 19. Mobile Operations Two-Lane, Two-Way, Primary & Secondary Routes 98

Drawing 20. Mobile Operations Multilane Primary Routes 102 Mobilized Shoulder Operations Equipment / Vehicles Pedestrian Safety

Drawing 25. Sidewalk Closure – Pedestrian Detour 110 Drawing 26. Sidewalk Closure – Pedestrian Diversion (or Bypass) 112

Worker Safety Work Safety Apparel 113Steps to Minimize Liability

Elements of a Good Inspection Program Minimum Documentation Supervisor's Checklist Important Notice Ordering Information

Introduction

The primary function of temporary traffic control (TTC) is to provide for the safe and efficient movement of motor vehicles, bicyclists, and pedestrians through or around TTC Zones while reasonably protecting workers and equipment. A concurrent objective of the TTC is the efficient construction and maintenance of the highway.

The purpose of this handbook is to present basic guidelines for Work Zone TTC installation and maintenance. This handbook complies with the basic requirements of the Manual on Uniform Traffic Control Devices (MUTCD), Part 6, latest edition, which contains the National Standards for Work Zone traffic control and the South Carolina Department of Transportation (SCDOT) specifications with particular emphasis on Short-Term work sites on roads and streets in rural and small urban areas. This handbook is not intended for TTC applications on Interstate Routes.

This handbook presents information and gives examples of TTC applications for Work Zones on two-lane and multilane Primary & Secondary Routes. This information is intended to illustrate the principles of proper Work Zone traffic control, but is not a standard.

This handbook does not cover Flagging Operations. Work Zones involving Flaggers are addressed in the SCDOT Flagger's Handbook, latest edition. Both of these handbooks should be used together to increase safety for workers and road users in Work Zones.

This handbook is not applicable to work performed under contract to the SCDOT. All Work Zones installed and maintained for SCDOT contract work shall comply with the typical traffic control standard drawings of the Standard Drawings for Road Construction.

Definitions

Flagger – An individual providing protection to workers and road users through the use of clear, positive directions to ensure the safety of the road users through or around the Work Area.

High-Speed – Consider a high-speed road to have a posted regulatory speed limit of 55 MPH or greater.

Intermediate-Speed – Consider an intermediate-speed road to have a posted regulatory speed limit of 40 MPH to 50 MPH.

Low-Speed – Consider a low-speed road to have a posted regulatory speed limit of 35 MPH or less.

Low-Volume – As a general rule, a low-volume road can be considered one on which the average daily traffic (ADT) volume does not exceed 400 vehicles per day. If the traffic volumes are not known, the following rule of thumb can be used.

Rule of Thumb – Count the number of vehicles that pass a single reference point over a 5 minute period. If not more than 3 vehicles pass the reference point in that period, then the road can be considered low-volume.

Special attention should be given to local, nearby facilities, such as schools, manufacturing plants, etc., that cause special traffic generation. Consideration should also be given as to whether the Work Zone location is subject to peak-hour traffic increases. Peak hours are usually 7 AM-9 AM and 4 PM-6 PM, but will vary in different areas.

Minor Urban Street – A low-volume, low-speed, two-lane urban street.

Spotter – An individual who observes traffic either for the Flagger or for the worker who is performing work in the Work Area.

Urban Street Conditions – These streets are characterized by relatively low speeds, pedestrian activity, intersections, and frequent driveways for businesses and houses. While urban Work Zones usually will be on a city or town street, a Work Area does not need to be within a municipality's corporate limits to be considered an urban condition.

Four Areas of a TTC Zone The TTC Zone is the area between the first Advance Warning Sign and the point beyond the Work Space where traffic is no longer affected. Below is a diagram showing the Four Areas of a TTC Zone.

Termination Area lets traffic resume normal driving may include: 5. Taper

Activity Area space for workers, equipment, material storage, and Shadow Vehicle, if used includes: 2. Work Space

3. Traffic Space may include: 4. Buffer Space

Transition Area moves traffic out of its normal path includes: 1. Taper

Advance Warning Area tells traffic what to expect ahead includes: Advance Warning Signs

Buffer Space

The Buffer Space is an optional part of the TTC Zone. It serves to separate traffic flow from the Work Area or a potentially hazardous area and might provide recovery space for an errant vehicle. Neither work activity nor storage of equipment, vehicles or materials should occur in this area.

The table below is taken from the MUTCD and provides guidelines for Longitudinal Buffer Space in a TTC Zone based on speed. These lengths are for normal conditions and may need to be adjusted due to vertical and horizontal curves that obstruct sight distance, driveways, intersecting roadways, etc.

A Lateral Buffer Space may also be used to separate passing traffic from the Work Area.

Its use and width are based on conditions at the work site.

Guidelines for Buffer Space Lengths

Speed Length Speed Length

0 MPH 115' 50 MPH 425'

25 MPH 155' 55 MPH 495'

30 MPH 200' 60 MPH 570'

35 MPH 250' 65 MPH 645'

40 MPH 305' 70 MPH 730'

45 MPH 360' 75 MPH 820'

SCDOT recommends that a Buffer Space be a part of every TTC Zone when space is available, and when one is used it shall be 200' to 400' in length.

Lateral Buffer Space

Lo ng itu di na l

Bu ff er S pa ce

Tapers for Work Zones

Tapers are created by using a series of channelizing devices and/or pavement markings to move traffic out of or into the normal path. There are 5 types of tapers used in TTC Zones. The length of Merging, Shifting, and Shoulder Tapers is based on formulas using the posted regulatory speed limit of the roadway prior to beginning the work and the width of the offset (or lane width). The length of a taper may require adjustments due to field conditions such as hills, curves, intersecting roads, etc.

Types of Tapers

One-Lane, Two-Way Taper

Merging Taper

Shifting Taper

Shifting Taper

Shifting Taper

Downstream Taper

(optional)

Shoulder Taper

Taper Lengths The tables below list the 5 types of tapers and their lengths used in TTC Zones as well as the formulas used to calculate the length of Merging, Shifting, and Shoulder Tapers.

Type of Taper Taper Length Merging Taper At least L Shifting Taper At least ½ L Shoulder Taper At least ⅓ L One-Lane, Two-Way Taper 50' Min. to 100' Max.

Downstream Taper (use is optional) 50' Min. to 100' Max.

Posted Regulatory Speed Limit Formula

40 MPH or Less

45 MPH or Greater L = WS L = Taper Length in feet W = Width of offset in feet S = Posted Regulatory Speed Limit, off-peak

85th percentile speed prior to starting work, or anticipated operating speed in MPH

L = WS2

Traffic Control Devices (TCDs)

All TCDs shall comply with AASHTO Manual for Assessing Safety Hardware (MASH) and NCHRP Report 350 requirements. To be effective TCDs should meet the following basic requirements.

• Fulfill a need.

• Command attention.

• Convey a clear, simple meaning.

• Command the respect of the road user.

• Give adequate time for a proper response.

The following are the 4 types of TCDs used in Work Zone traffic control:

• Signs.

• Channelizing Devices.

• Lighting Devices.

• Pavement Markings.

Signs

TTC Zone signs convey both general and specific messages by means of words, symbols, and/or arrows and have the same three categories as all road user signs – Regulatory, Warning, and Guide. The overall effectiveness of traffic signs is based on target value, priority value, visibility, legibility, and illumination.

Regulatory Signs Regulatory Signs impose legal restrictions and may not be used unless authorized by the public agency having jurisdiction. These signs are normally rectangular shaped, having a black symbol or message on a white background.

Exceptions include the STOP, YIELD, DO NOT ENTER, and WRONG WAY signs that have a white symbol or message on a red background.

SPEED

LIMIT

STOP

Guide Signs Guide Signs commonly show destinations, directions, and distances. These signs are normally rectangular shaped, having a white symbol or message on a green background, but may have a black symbol or message on an orange background when used in a TTC Zone.

Warning Signs Permanent Warning Signs have a black symbol or message on a yellow or fluorescent yellow background. In SC, the following signs are to be Type XI microprismatic fluorescent yellow sheeting:

• Horizontal Alignment (W1 Series).

• Advisory Speed Plaques (W13 Series).

• Advance Traffic Control (W3-1, W3-2, W3-3)

(Stop Ahead, Yield Ahead, Signal Ahead).

• Intersection Warning Signs (W2 Series & W1-7, W4-4P, W4-4aP, W4-4bP).

Permanent Warning Signs may remain in the TTC Zone if they are still applicable.

Yellow Fluorescent Yellow

Greenville 40

St. Louis 125

ROAD WORK

NEXT 5 MILES

Temporary Warning Signs give notice of conditions that are potentially hazardous to traffic. These signs are normally diamond shaped, having a black symbol or message on an orange background.

While Regulatory Signs, Guide Signs, and Warning Signs can appear in Work Zones, Temporary Warning Signs are by far the most extensively used, and therefore are the focus of this handbook.

BE

PREPARED

TO STOP

Temporary Warning Signs

Construction and Maintenance Warning Signs are used extensively in street and highway Work Zones. As a general rule, these signs are located on the right-hand side of the street or highway but may be located on both sides for some typical applications (e.g., four-lane multilane roads with grass medians).

Roll-up type material signs, or an approved composite type sign, may be used on portable sign supports. Mesh signs are not allowed.

Sign Spacing Distances shown in the table below are approximate. Sign spacing should be adjusted for curves, hills, intersections, driveways, etc., to improve sign visibility so road users can read the sign, understand it, and take the necessary action before being presented with the next sign. In addition, judgement should be used for good visibility (e.g., if blocking view of an existing sign).

Spacing between the signs can be determined by using one of these 4 methods:

• Distance Measuring Instrument (DMI) mounted on the dash of the vehicle.

• Measuring wheel.

• Odometer (one-tenth of a mile is approximately 500').

• Skip lines – length of skip line is 10' and spacing between skip lines is 30' for a total of 40'.

Advance Warning Sign Spacing Speed Limit â

Low-Speed 35 MPH or Less Intermediate-Speed

40 MPH – 50 MPH

High-Speed 55 MPH or Greater

200'

350'

500' â â â

Sign Size The standard size for Advance Warning Signs in TTC Zones generally is 48" ´ 48". For moderately low speeds and volumes, a minimum size of 36" ´ 36" may be used (see MUTCD, Part 6, latest edition for sign sizes).

Sign Illumination and Retroreflectorization All signs used during the hours of darkness shall be made of retroreflective material or shall be illuminated. Street or highway lighting is not regarded as meeting the requirements for sign illumination.

Reflectorize all orange Advance Warning Signs and any orange areas of a multi-colored advance sign with a fluorescent orange-colored prismatic reflective sheeting.

Sign Mounting Mount the Advance Warning Signs on either U-Channel or square steel tube posts (permanent supports), approved temporary sign supports, or approved Type 3 barricades. A High-Level Warning Device (Flag Tree) can also be used to mount signs. However, this device is used to supplement other TCDs in Short-Term Operations.

Mount rigid signs on ground-embedded sign supports.

Mount portable sign supports straight and level with the face of the signs perpendicular to the roadway surface.

When mounting signs on multiple ground-embedded sign supports, ensure that each post is of the same type. Combining and installing both ground-embedded U-Channel and square steel tube posts within the same sign assembly is prohibited.

Ground-Embedded Supports When sufficient shoulder space is available, install signs mounted on ground-embedded sign supports 6' to 12' from the near edge of an adjacent travel lane to the nearest edge of the sign if no paved shoulder is present.

Where paved shoulders are present, install these signs no less than 2' from the near edge of the paved shoulder. Where curb and gutter is present, install these signs no less than 2' from the face of the curb.

The mounting height for Regulatory Signs or Advance Warning Signs erected on a ground-embedded U-Channel or square steel tube post is no less than 7' nor no greater than 8' from the bottom edge of the sign to the grade elevation of the near edge of the adjacent travel lane or sidewalk when a sidewalk is present.

The minimum mounting height of a secondary sign mounted on the same assembly is 6' from the bottom edge of the secondary sign to the grade elevation of the near edge of the adjacent travel lane or sidewalk when a sidewalk is present unless otherwise specified. The secondary sign shall not overlap or encroach upon the face of the primary sign.

6' to 12'

ROAD

CLOSED

500 FT

7'-8'

Adjacent travel lane

ROAD

WORK

AHEAD

2' Min.

7'-8'

MPH

6' Min.

Paved shoulder or face of curb

Sidewalk

The minimum mounting height for Guide Signs, including Detour Sign assemblies with multiple sign panels, erected on ground-embedded U-Channel or square steel tube posts should be no less than 5' from the grade elevation of the near edge of the adjacent travel lane to the bottom of the route sign or the Detour Sign panel (M4-9) unless otherwise directed by the Owner.

Portable Sign Supports The minimum mounting height of signs mounted on portable sign supports is 1' from the ground to the bottom edge of the sign. (Minimum mounting height will change to 5’ effective January 1, 2026) However, in locations where the minimum sign height is specified to be 7', utilize portable sign supports capable of providing the minimum mounting height of 7' from the ground to the bottom edge of the sign in these locations. The legs on the sign supports should be flat on the ground and not in a raised position to achieve the minimum height requirements.

If 7' minimum is specified

6' to 12'

Adjacent travel lane

5' Min.

PROSPERITY

CLINTON

5' Min.

6' to 12'

5' Min.

Adjacent travel lane

RAMP

CLOSED

DETOUR

5' Min. above the traveled way

7' Min. above the traveled way

NOTE: The legs on the sign supports should be flat on the ground and not in a raised position to achieve the minimum height requirements.

Install signs mounted on portable sign supports no less than 4' from the near edge of the sign to the near edge of an adjacent travel lane on roadways with earth shoulders and no less than 6' from the near edge of the sign to the near edge of an adjacent travel lane on roadways with paved shoulders. When curb and gutter is present, install these signs no less than 2' from the near edge of the sign to the face of the curb.

Paved Shoulder

Earth Shoulder

Curb and Gutter

6' Min.

ROAD

WORK

AHEAD

4' Min.

ROAD

WORK

AHEAD

2' Min.

ROAD

WORK

AHEAD

High-Level Warning Device (or Flag Tree)

• Designed to be seen over the top of typical passenger cars.

• Used primarily in high-density road user situations to warn road users of Short-Term Operations.

• Used to supplement other TCDs.

• Shall consist of a minimum of 2 flags with or without a Type B High-Intensity Flashing Warning Light.

• Distance from the roadway to the bottom of the lens of the light and to the lowest point of the flag material shall not be less than 8'.

• The flag shall be 16" square or larger and shall be fluorescent orange-red or orange in color.

• An appropriate Advance Warning Sign may be mounted below the flags.

Signs Currently Not In Use

Ground-Embedded Signs When Advance Warning Signs mounted on ground-embedded U-Channel posts or square steel tube posts are not in use, cover the signs in their entirety with an opaque material or remove them from the Work Area.

When covering signs with opaque materials, do not attach a covering material to the face of the sign with tape or a similar product or any method that may leave a residue on the retroreflective sheeting.

Portable Signs When Advance Warning Signs mounted on portable sign supports are not in use, remove and relocate the portable sign supports to a location beyond 15' from the near edge line of a Primary & Secondary travel lane.

Ensure that all portable sign supports lie flat with the legs in a retracted position when not in use. Do not redirect a sign when not in use.

8'

MIN.

Min. 16" Square

Temporary EXIT Signs

Mount temporary EXIT signs (E5-1)(M-1025) located within temporary Gore Areas during Lane Closures on multilane roadways at a minimum height of 7' from the ground to the bottom edge of the sign in accordance with the requirements of the MUTCD, latest edition. The minimum mounting height of 7' for a temporary EXIT sign applies to installation on ground-embedded U-Channel posts, square steel tube posts, and portable sign supports.

The EXIT sign is required to be green with white legend and border.

Temporary Steel Plates

Install STEEL PLATE AHEAD signs (W8-24-48) in advance of an area of roadway where temporary steel plates are present. Install these signs no further than 300' in advance of locations where steel plates are present.

EXIT

7' Min. above the traveled way

EXIT

EXIT

STEEL

PLATE

AHEAD

GROOVED PAVEMENT Signs

Install GROOVED PAVEMENT signs (W8-15-48) supplemented with the "Motorcycle" plaque (W8-15P-30) in advance of milled or surface planed pavement surfaces. Install these signs no further than 500' in advance of the beginning of this pavement condition on Primary Routes.

Channelizing Devices

Channelizing devices are used to warn and alert drivers of hazards in Work Zones, to protect workers, to separate traffic from the Work Area, and to guide and direct road users as well as pedestrians past the hazards.

Channelizing devices include:

• Standard Traffic Cones.

• 42" Oversized Traffic Cones.

• Drums.

• Barricades.

• Vertical Panels.

Standard Traffic Cones Standard traffic cones are the most common channelizing device used in Work Zones.

Standard traffic cones shall be predominately orange in color and a minimum of 28" in height.

Standard traffic cones used at night shall be a minimum of 36" in height and shall have 6" and 4" retroreflectorized white collars.

GROOVED

PAVEMENT

28" Min.

to

36" Max.

3"-4" 6"

4" 2"

Re tr or ef le ct iv e

Ba nd s

42" Oversized Traffic Cones The 42" oversized traffic cones (also known as channelizer cones) are permitted for use during Flagging Operations on two-lane, two-way roadways, Lane Closures on multilane roadways, Daytime Shoulder Closures, and to mark specific hazards.

The 42" oversized traffic cones are unacceptable for delineation of a pavement edge. Portable plastic drums are required for delineation of a pavement edge.

Reflectorize the 42" oversized traffic cones with Type III flexible microprismatic retroreflective sheeting. Retroreflectorized bands, 2 orange and 2 white, shall be 6" wide and installed in an alternating pattern placing an orange stripe at the top. Separate each retroreflective band with not more than a 2" non-reflectorized area.

Ensure that each cone has a handle-type structure on top of the cone to facilitate relocation, installation, and removal operations.

Drums Portable plastic drums may be utilized to delineate travel lanes, channelize traffic through the tangent section or Activity Area of a Lane Closure, delineate Shoulder Closures, delineate the pavement edge of a roadway and delineate excavations and structures.

Portable plastic drums are the preferred TCD for channelization and delineation of a travel way during the hours of darkness.

Reflectorize portable plastic drums with Type III flexible microprismatic retroreflective sheeting. Ensure each drum has a minimum height of 36" and minimum width of 18". Reflectorized bands shall consist of 6" wide alternating bands, 2 orange and 2 white, with the top band always being orange. Ensure that any non-reflectorized area between the orange and white retroreflective bands does not exceed 3".

6"

6"

6"

6"

36" Min.

Re tr or ef le ct iv e

Ba nd s

18" MIN.

*not more than a 3" non-reflectorized area

6"

6"

6"

6"

42"

Re tr or ef le ct iv e

Ba nd s

*not more than a 2" non-reflectorized area

Barricades A barricade is a portable or fixed device having from 1 rail to 3 rails with appropriate markings and is used to control road users by closing, restricting, or delineating all or a portion of the right-of-way.

A warning light is optional unless required by the drawing.

Stripes on barricade rails slope downward at an angle of 45° in the direction traffic is to pass (see below). Reflectorize all barricades with Type III high-intensity or Type IX or Type XI microprismatic retroreflective sheeting.

Ballast shall not be placed on top of any striped rail. Barricades shall not be ballasted by non-deformable objects such as rocks or chunks of concrete.

Devices used on high-speed roadways and in other situations where they are susceptible to overturning in the wind should be ballasted with sandbags placed at or near ground level.

Type 1. SCDOT prohibits the use of Type 1 barricades in TTC Zones.

Type 2. Type 2 Barricades are used to develop taper sections and channelize traffic into Lane Closures, delineate travel lanes, and delineate excavations and structures.

Direction that cars pass.

45°

Type 2 barricades shall have 2 horizontal chevron rails that shall be 36" long and shall be 8"-12" wide. The rail stripe width shall be 6". The top of the top rail shall be a minimum of 36" above the surface level.

NOTE: A warning light is optional unless required by the drawing.

Type 3. Type 3 barricades are used to close a roadway to traffic and to prevent traffic from entering a Work Area rather than channelizing traffic around or away from a potential hazard.

Type 3 barricades should be a minimum length of 4'; have 3 horizontal chevron rails that are 8"-12" wide; and stripes shall be 6"wide. The top of the top rail shall be a minimum of 5' above the surface level.

Type 3 barricades may be supplemented with Advance Warning Signs fabricated from either an approved roll-up retroreflective fabric material or an approved rigid aluminum laminate composite substrate. These signs should not cover more than 50 percent of the top 2 rails or 33% of the total area of the 3 rails.

NOTE: A warning light is optional unless required by the drawing.

36" Min.

8"-12"

8"-12"

36"

45°

5' Min.

8"-12"

8"-12"

8"-12"

4' Min.

Vertical Panels Vertical panels are narrow devices with a width of 8" to 12" and at least 24" in height. They shall have orange and white diagonal stripes. The dimensional characteristics, color, and meaning of the sloping pattern of the reflective panel are identical to those of a Type 2 barricade panel. Vertical panels shall be mounted on a single light-weight post with the top a minimum of 36" above the roadway.

Vertical panels are used on a very limited basis by

SCDOT.

Device Spacing Channelizing devices should be spaced so that it is apparent that the roadway or Work Area is closed to traffic. There are several rules of thumb that can be used to guide you in the proper spacing of channelizing devices:

• The maximum spacing between devices in a taper should not exceed a distance, in feet, equal to the posted regulatory speed limit in MPH. For example, if the taper is on a street with a 35 MPH posted regulatory speed limit, the devices may be spaced up to 35'.

• All tapers should be made up of at least 5 channelizing devices.

• The spacing between devices in a Buffer Space or Work Area should not exceed a distance, in feet, of 2 times the posted regulatory speed limit in MPH; however, the spacing should not exceed 100'. For example, if the street has a posted regulatory speed limit of 35 MPH, the devices in the Buffer Space and Work Area may be spaced up to 70'.

• In urban areas shorter spacing between devices in the Buffer Space and Work Area may be more appropriate. For example, the spacing used in tapers could also be used in the Buffer Space and Work Area.

8"-12"

24" Min.

36" Min.

6"

6"

12" Max.

Lighting Devices

Lighting devices for Short-Term Work Zones are designed to supplement the retroreflective signs, barriers, and channelizing devices used in these zones.

During normal Daytime Maintenance Operations supplemental lighting may be provided by high-intensity rotating, flashing, oscillating, or strobe lights on a Maintenance Vehicle.

In areas where work is being performed during the hours of darkness, furnish, place, and maintain lighting facilities capable of providing light of sufficient intensity to facilitate good workmanship and proper inspection at all times.

Arrange the lighting so that it does not produce glare or diminish the road user's visibility.

Illuminate the Work Area by any combination of portable lights, standard electric lights, existing streetlights, etc., that provides the necessary illumination.

Warning Lights The principal types and uses of warning lights are listed below:

•. Low-Intensity Flashing Lights (Type A) – used at night to warn of an isolated hazard and must be visible from a distance of 3000'.

• High-Intensity Flashing Lights (Type B) – used both day and night to warn of an isolated hazard or draw attention to Advance Warning Signs and must be visible from a distance of 1000'.

• Low-Intensity Steady-Burn Lights (Type C) – used in a line to delineate the traveled way through and around obstructions in the Transition Area, Buffer Space, Work Space, and Termination Area of the TTC Zone and must be visible from a distance of 3000'.

The minimum mounting height of a warning light is 30" from the bottom of the lens of the light to the travel lane surface when placed in a roadway or to the grade elevation of the near edge of the adjacent travel lane when placed adjacent to a roadway.

All warning lights, including Types A, B, and C, must be lightweight and may not exceed 3.3 pounds in accordance with the requirements of AASHTO MASH and NCHRP Report 350.

Pavement Markings

For Long-Term Stationary projects, follow the guidelines of the MUTCD, Part 6, latest edition in placing and removing pavement markings.

The colors of temporary pavement markings and delineators follow the same standard as permanent markings.

White is specified along both sides of two-way roadways and the right side of one-way roadways. Yellow is used on the left side of one-way roadways. Centerlines and lane lines are yellow when separating opposing directions of traffic and white when separating lanes of the same direction. Where existing pavement markings conflict with the temporary travel path, additional signing and channelizing devices are appropriate.

Arrow Boards

An arrow board shall be a sign with a matrix of elements capable of either flashing or sequential displays. This sign shall provide additional warning and directional information to assist in merging and controlling road users through or around a TTC Zone.

Arrow boards have the following requirements:

• Panel face shall be non-reflective.

• Shall be legible from a distance of ½ mile.

• Elements shall be yellow in color.

• Elements shall be capable of at least a

50% dimming from full brilliance during nighttime hours.

• Should provide a minimum height of 7' from the bottom of the sign to the surface of the roadway.

• Can remain stable in winds up to 80 MPH when in operating position.

7' Min.

Roadway Surface

Trailer mounted arrow boards shall remain stationary when operating. Towing an operating trailer mounted arrow board in place of utilizing a truck mounted arrow board when a truck mounted device is required is prohibited.

Truck mounted arrow boards shall be a permanent fixture on the truck. Do not mount a trailer mounted arrow board on a truck.

The minimum sizes for each arrow board type are shown in the table below.

Arrow Board Type

Minimum Size

Minimum Legibility Distance

Minimum Number of Elements

A 48" ´ 24" ½ Mile 12

B 60" ´ 30" ¾ Mile 13

C 96" ´ 48" 1 Mile 15

For Mobile Operations on high-speed roadways Type B (60" x 30") Arrow Boards may be used.

Changeable Message Sign (CMS)

The primary purpose of a CMS in a TTC Zone is to advise the road user of unexpected situations. The CMS should consist of no more than 2 phases, and a phase should consist of no more than 3 lines of text and provide capital characters with a height of not less than 18". The message panel should have adjustable display rates so that the entire message can be read at least twice at the posted regulatory speed limit. Ensure that the sign panel provides a minimum height of 7' from bottom of the sign panel to the surface of the roadway when raised into its operating position.

A CMS should provide clear and legible messages from a distance of 1,000' and should be visible half-a-mile under both day and night conditions. The sign panel should be approximately 76" vertically and 113" horizontally. A CMS shall remain stationary when operating.

Location of CMS The CMS should be placed on the shoulder of the roadway not less than 6' from the edge of the sign to the near edge of the adjacent travel lane when space is available. When the space of 6' or right-of-way is unavailable, place the CMS at the greatest possible distance from the near edge of the adjacent lane.

Supplement the sign location with not less than 5 portable plastic drums placed between the sign and the adjacent travel lane for delineation of the sign location. Do not use standard traffic cones or 42" oversized traffic cones as a substitute for the portable plastic drums. Install and maintain the drums not closer than 3' from the near edge of the adjacent travel lane.

The spacing between the portable plastic drums is approximately 3' to 5'.

When non-operational for more than 72 hours, remove completely from the roadway.

Truck Mounted CMS Utilize a truck mounted CMS for slow-moving work activities and for the initial Shadow Vehicle encountered by road users during Mobile Operations. Use truck mounted CMSs to supplement stationary Lane Closures on high-volume, high-speed Primary multilane facilities with paved shoulders as directed by the Owner.

Ensure that the truck mounted CMS has the capability to provide clear and legible messages from a distance of 850'. The sign panel should be approximately 42" vertically by 76" horizontally. Do not mount a trailer mounted unit on a truck.

≥3'

≥6'

Truck Mounted Attenuator (TMA)

There are 2 types of attenuators used in TTC situations. With the first type, the attenuator is physically mounted to the truck. With the second type, the attenuator is mounted to a trailer that is towed behind the truck. While manufacturers typically refer to these as Truck Mounted Attenuators and Trailer Mounted Attenuators, in this handbook the terminology that has been adopted by the SCDOT is used. Therefore, in this handbook, the terms for the two types of attenuators will be Direct Mounted TMA and Trailer Towed TMA.

Use an AASHTO MASH and NCHRP Report 350 Test Level 2 or Test Level 3 TMA based on the posted regulatory speed limit of the roadway prior to the presence of Work Zones, temporary speed limits, or unforeseen roadway hazards.

Test Level 2 TMAs are approved for roadways with posted regulatory speed limits of 45 MPH or less.

Test Level 3 TMAs are approved for roadways with posted regulatory speed limits of 50 MPH or greater. Test Level 3 TMAs are acceptable for use on all roadways.

Direct Mounted TMA A Direct Mounted TMA is mounted and attached to brackets or similar devices connected to the frame of a truck. Attach each direct mounted TMA to the rear of a truck with a minimum gross vehicular weight (GVW) of 15,000 pounds (actual weight). If ballast is needed to supplement the weight of the vehicle, contain the ballast material within a structure constructed of steel.

Trailer Towed TMA A Trailer Towed TMA is towed from behind and attached to the frame of a truck via a standard pintle hook hitch. Attach each Trailer Towed TMA to the rear of a truck with a minimum GVW of 10,000 pounds (actual weight). If the addition of supplemental weight to the vehicle as ballast is necessary, contain the material within a structure constructed of steel.

Direct Mounted TMA Trailer Towed TMA

Ballast Construct this steel structure to have a minimum of 4 sides and a bottom to contain the ballast material in its entirety. A top is optional. Bolt this structure to the frame of the truck. Utilize a sufficient number of fasteners for attachment of the steel structure to the frame of the truck to ensure the structure will not part from the frame of the truck during an impact upon the attached TMA. Utilize either dry loose sand or steel reinforced concrete for ballast material within the steel structure to achieve the necessary weight. The ballast material shall remain contained within the confines of the steel structure and shall not protrude from the steel structure in any manner.

Work Vehicles

It is essential that Work Vehicles are highly visible at all times, and can be readily identified as Work Vehicles. In addition, Work Vehicles at all times should travel as safely as possible due to unexpected conditions that may be present within the TTC Zone.

Auxiliary Warning Lights Supplement all vehicles and equipment that must operate within or adjacent to a roadway within the highway right-of-way in an active Mobile Operation or stationary Work Zone with auxiliary warning lights. Also, this requirement shall include vehicles that must operate within the roadway or on a roadway shoulder at reduced speeds.

All auxiliary warning lights supplementing vehicles and equipment within active Work Zones shall be amber or yellow in color. All auxiliary warning lights shall be high-intensity rotating, flashing, oscillating or strobe lights.

Mount all auxiliary warning lights on vehicles and equipment in conspicuous locations to provide good visibility to approaching road users. Auxiliary warning lights should be mounted to ensure 360-degree visibility. Two rotating auxiliary warning lights provide good visibility from every direction, even if one light is not in view.

Standard vehicle hazard warning lights are only permitted as a supplement to the auxiliary warning lights.

Travel Direction When Work Vehicles operate within travel lanes open to traffic, the Work Vehicles shall travel in the same direction of roadway traffic.

When Work Vehicles operate within a closed travel lane or a closed Shoulder Area, they may travel in either direction as necessary. However, when operating within a closed travel lane or a closed Shoulder Area during the hours of darkness, the Work Vehicles should minimize travel in the opposite direction of roadway traffic. This is due to visibility limitations of road users due to darkness and the unpredictable reactions road users may have from seeing opposing headlights in an area where opposing traffic is not anticipated by road users.

On Primary & Secondary Routes, when Work Vehicles are required to cross from one side of a roadway to the other side of the roadway, utilize Flaggers to control the Work Vehicles entering or crossing the travel lanes of the roadway.

Consider sight distance, vertical and horizontal curves of the roadway, prevailing speeds of traffic, frequency of the Work Vehicles entering or crossing the roadway and other site conditions that may impact the safety of the workers and road users when determining the necessity of Flaggers.

Ensure Flaggers do not stop traffic, cause traffic to change lanes or affect traffic in any manner.

The Work Vehicles may not disrupt the normal flow of traffic or enter the travel lane of the roadway until a sufficient gap is present.

Duration of Work

Work duration is a major factor in determining the number and types of devices used in TTC Zones. As a general rule, the longer the operation will last, the more TCDs will be needed.

• Long-Term Stationary – Work that occupies a location more than 3 days.

• Intermediate-Term Stationary – Work that occupies a location from

12 hours to 3 days.

• Short-Term Stationary – Daytime work that occupies a location from

1 to 12 hours.

• Short-Duration – Work that occupies a location up to 1 hour.

• Mobile – Work that moves intermittently or continuously.

Location of Work

Location of work is another major factor in determining the number and types of devices used in TTC Zones. As a general rule, the closer the work is to traffic, the more TCDs will be needed.

• Outside the shoulder – greater than 15' from edge of pavement.

• On the shoulder with no encroachment – 1' to 15' beyond edge of pavement.

• On the shoulder with minor encroachment.

• Within the median.

• Within the roadway.

This page is intentionally blank.

Drawings

The numbered drawings in this handbook represent examples of the application of principles and procedures for safe and efficient traffic control in Work Zones but are not intended to be standards. MUTCD, Part 6, latest edition is the National Standard for Work Zone traffic control. It is not possible to include illustrations to cover every situation which will require Work Area protection. These typical layouts are not intended as a substitute for engineering judgment and should be altered to fit the conditions of a particular site.

In addition to the drawings, notes and tables are presented which provide important information for the user. Read all notes before using the drawings.

The information presented in the drawings and tables are generally minimums for standard street and highway conditions. Also, the condition of the area should be considered during application of these drawings.

The Work Zone setup should be based upon anticipated vehicle speeds and rural versus urban conditions instead of the posted regulatory speed limits or a municipality's corporate limits.

These drawings are not intended for application to Interstate Routes. For further information, consult the SCDOT, Director of Traffic Engineering.

NOTE: Taper lengths in the drawings are based upon 12' lanes and 10' shoulders.

Legend

The following symbols are used in the drawings that follow.

Flagger

Sign Support

High Level Warning Device

Work Area

Warning Sign

Type 2 Barricade

Cone

Drum

Travel Direction

Work Vehicle or Shadow Vehicle with Auxiliary Warning Light

Road Machinery

Truck Mounted Arrow BoardA

C Truck Mounted

CMS

A Trailer Mounted Arrow Board

C Trailer Mounted

CMS

Shadow Vehicle with Auxiliary Warning Light, TMA Required

Type 3 Barricade

Type 3 Barricade with Sign

Work Vehicle or Shadow Vehicle with Auxiliary Warning Light, TMA Optional

Closures

In a Work Zone there are several types of closures that may be used based on the specific work activity. These include Lane Closures, Shoulder Closures, and Road Closures. Each type of closure has its own traffic control requirements.

Lane Closure A typical Lane Closure is an installation of a specific array of TCDs to temporarily reduce the number of travel lanes on a multilane roadway through channelization and relocation of traffic from the closed travel lane into the remaining adjacent travel lane(s) open to traffic. The TCDs function to channelize the traffic and provide delineation of the separation of the travel lane(s) closed to traffic and the travel path open to traffic.

Shoulder Closure A standard Shoulder Closure is an installation of a specific array of Advance Warning Signs and TCDs to temporarily close the Shoulder Area of a roadway to vehicular and pedestrian traffic. When the work activity is conducted within 15' or less of the near edge of the adjacent travel lane, Advance Warning Signs and TCDs are required for a standard Shoulder Closure. When the work activity is conducted beyond 15' from the near edge of the adjacent travel lane, only Advance Warning Signs are required for a standard Shoulder Closure.

Road Closure A Road Closure is designed to eliminate the exposure of road users to Work Zones and workers to traffic by temporarily closing a facility for rehabilitation or maintenance. During a Road Closure, traffic is detoured, allowing workers full access to roadway facilities.

While not suitable for all construction situations, use of a Road Closure can result in positive public sentiment, increased productivity, reduced project duration, increased safety and/or a shortened risk period, and, in some cases, cost savings.

Drawing 1. Lane Closure Daytime Urban Low-Speed (≤ 35 MPH)

1. All sign locations are to be measured from the Work Area. Work limits for the project will be determined by the Owner.

2. Any special sign mounting assemblies and hardware that may be necessary for installing and mounting signs in areas of concrete median barrier, bridge parapet walls or double-faced guardrail shall be provided and utilized.

3. When an arrow board is required to operate in the caution mode, the arrow board shall display the "Four Corner" Caution Mode with one lamp in each corner. Display of any other type of caution mode such as the "Flashing Bar" or the "Alternating Diamond" is unacceptable and prohibited.

4. Conduct the work in such a manner that will minimize encroachment of TCDs, equipment, personnel, materials or any work related vehicles onto an adjacent travel lane open to traffic. Install, maintain and adjust the TCDs as necessary to ensure proper delineation of the Work Area.

5. Lane Closures are restricted to maximum lengths of 2 miles unless otherwise directed by the Owner.

6. If work is being conducted simultaneously at two different locations within the same travel lane under two separate Lane Closures on a low-speed urban roadway, separate the two Lane Closures by no less than 1 mile from the end of the first closure that a road user will encounter to the beginning of the taper of the second closure.

7. If work is being conducted simultaneously at two different locations in the same direction but within different travel lanes under two separate Lane Closures on a low-speed urban roadway, separate the two Lane Closures by no less than 2 miles from the end of the first closure that a road user will encounter to the beginning of the taper of the second closure.

8. Type 2 barricades shall have a minimum width of 3' unless otherwise directed by the Owner.

9. When using a TMA, locate it 100' in advance of the Work Area unless otherwise specified.

10. Supplement the shadow vehicle and work vehicle with an approved advanced warning arrow panel operating in the “Four Corner” Caution Mode.

11. Utilize a trailer mounted arrow board with a Secondary Arrow (W1-6-48) Sign mounted beneath it.

12. All arrow boards shall be 48" ´ 96" with a minimum legibility distance of 1 mile.

13. Place the trailer mounted arrow board as near the beginning of the taper as practical without encroaching upon the Shoulder Area when a sidewalk is present or blocking the visibility of any barricades within the taper.

14. Utilization of a CMS is optional with this traffic control setup. However, when a CMS is utilized, install the sign as illustrated on this drawing unless otherwise directed by the Owner.

15. Mount the portable EXIT Sign (E5-1)(M-1025) at a minimum mounting height of 7' from the pavement surface to the bottom of the sign.

16. Continue TCDs along ramp if ramp shoulder is being reconstructed.

Drawing 1A. Lane Closure Daytime Urban Low-Speed (≤ 35 MPH)

Drawing 1B. Lane Closure Daytime Urban Low-Speed (≤ 35 MPH)

W ork

Activity

PAVED M

EDIAN

CU

RB &

G U

TTER w ith SIDEW

ALK

E X I T

36" TRAFFIC CO

N

ES @

25' SPACIN

G

AN

D CO

N

TIN

U

E AS ILLU

STRATED

250' of 36" TRAFFIC CO

N

ES

25' SPACIN

G

150' O

PEN

IN

G

36" TRAFFIC CO

N

ES

25' SPACIN

G

AN

D

CO

N

TIN

U

E AS ILLU

STRATED

â â â â CONTINUE TCDs ALONG RAMP

IF RAMP SHOULDER IS

BEING RECONSTRUCTED.

âââ

MOUNT PORTABLE EXIT

SIGN (E5-1)(M-1025) AT MIN.

MOUNTING HEIGHT OF 7'

FROM PAVEMENT SURFACE

TO BOTTOM OF SIGN.

"TYPICAL EXIT RAM

P" APLICATIO

N

100'

PORTABLE

EXIT SIGN

(E5-1)(M-1025) (36" ´ 36") âââ

TMA & ARROW BOARD SHALL

OPERATE IN THE "FOUR CORNER"

CAUTION MODE AND SHALL

REMAIN 100' IN ADVANCE OF THE

WORK ACTIVITY AT ALL TIMES.

A

Not to Scale

Drawing 1C. Lane Closure Daytime Urban Low-Speed (≤ 35 MPH)

Drawing 1D. Lane Closure Daytime Urban Low-Speed (≤ 35 MPH)

ACTIVITY

NO LESS THAN FOUR

36" TRAFFIC CONES

ALIGNED TO CREATE

A RADIUS NO

LESS THAN 50'.

PAVED MEDIAN PAVED MEDIAN

"TYPICAL SIDE STREET"

APPLICATION

SIDE STREET

Drawing 2. Lane Closure Nighttime Urban Low-Speed (≤ 35 MPH)

1. All sign locations are to be measured from the Work Area. Work limits for the project will be determined by the Owner.

2. Any special sign mounting assemblies and hardware that may be necessary for installing and mounting signs in areas of concrete median barrier, bridge parapet walls or double-faced guardrail shall be provided and utilized.

3. When an arrow board is required to operate in the caution mode, the arrow board shall display the "Four Corner" Caution Mode with one lamp in each corner. Display of any other type of caution mode such as the "Flashing Bar" or the "Alternating Diamond" is unacceptable and prohibited.

4. Conduct the work in such a manner that will minimize encroachment of TCDs, equipment, personnel, materials or any work related vehicles onto an adjacent travel lane open to traffic. Install, maintain and adjust the TCDs as necessary to ensure proper delineation of the Work Area.

5. Lane Closures are restricted to maximum lengths of 2 miles unless otherwise directed by the Owner.

6. If work is being conducted simultaneously at two different locations within the same travel lane under two separate Lane Closures on a low-speed urban roadway, separate the two Lane Closures by no less than 1 mile from the end of the first closure that a road user will encounter to the beginning of the taper of the second closure.

7. If work is being conducted simultaneously at two different locations in the same direction but within different travel lanes under two separate Lane Closures on a low-speed urban roadway, separate the two Lane Closures by no less than 2 miles from the end of the first closure that a road user will encounter to the beginning of the taper of the second closure.

8. Type 2 barricades shall have a minimum width of 3' unless otherwise directed by the Owner.

9. When using a TMA, locate it 100’ in advance of the Work Area unless otherwise specified. Supplement the shadow vehicle and work vehicle with an approved advanced warning arrow panel operating in the “Four Corner” Caution Mode.

10. Utilize a trailer mounted arrow board with a Secondary Arrow (W1-6-48) Sign mounted beneath it.

11. All arrow boards shall be 48" ´ 96" with a minimum legibility distance of 1 mile.

12. Place the trailer mounted arrow board as near the beginning of the taper as practical without encroaching upon the Shoulder Area when a sidewalk is present or blocking the visibility of any barricades within the taper.

13. Utilization of a CMS is optional with this traffic control setup. However, when a CMS is utilized, install the sign as illustrated on this drawing unless otherwise directed by the Owner.

14. Mount the portable EXIT Sign (E5-1)(M-1025) at a minimum mounting

15. Continue TCDs along ramp if ramp shoulder…