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Guidelines for Traffic Control inShort Duration / Mobile Work Zones

Table of Contents

PageIntroduction .......................................................... 1Work Duration ...................................................... 2Major Traffic Control Considerations .................. 3Fundamental Principles ........................................ 4Guidance, Options, and Support for Short Duration or Mobile Operations in Work Zones ............... 5Component Parts of a Temporary Traffic Control Zone ..................................................... 8Tapers .................................................................... 9Flaggers ................................................................ 9Arrow Panels ...................................................... 11Warning Lights ................................................... 12Nighttime Operations ......................................... 13Signs ................................................................... 13Table A, Table B ................................................. 14Typical Application Diagrams .......................15-25Supplemental Diagrams ................................. 26-28Supervisor’s Checklist .............. Inside Back Cover

The contents of the guide do not reflect the officialviews or policies of the Kentucky TransportationCabinet, the Kentucky Transportation Center, orthe Federal Highway Administration. Thisdocument does not constitute a standard,specification, or regulation.

1

IntroductionThe Technology Transfer Program of the Kentucky

Transportation Center is pleased to bring you thishandbook as part of our ongoing effort to meet thetraining needs and demands of transportation agenciesand employees in Kentucky.

The Technology Transfer Program offers a widevariety of training including the Work Zone EmployeeQualification Program, brought to you in conjunctionwith the Kentucky Transportation Cabinet. In late 2007,the Cabinet issued a policy and procedure for safemobility through work zones with a primary goal ofreducing crashes and injuries in and around highwaywork zones, as well as providing a safe and efficientenvironment for workers. The Technology TransferProgram has developed a series of courses aimed atqualifying workers under the Cabinet’s new policy. TheWork Zone Traffic Control Employee QualificationProgram provides training in Basic Work Zone andFlagger, Work Zone Traffic Control Technician and WorkZone Traffic Control Supervisor. Call 800-432-0719 toregister, or visit www.kyt2.com for more information.

About this handbookThis handbook is printed in cooperation with the

Kentucky Transportation Cabinet. It summarizesguidelines listed in the MUTCD, adopted as thestandard for traffic control devices on public highwaysin Kentucky (KRS 189.337 and 603 KAR 5.050), withspecific focus on temporary traffic control (TTC) inshort duration and mobile work zones. It contains basicprinciples, a description of standard traffic controldevices used in work areas, guidelines for the applica-tion of the devices, and typical application diagrams.They are not intended as substitutes for engineeringjudgment and should be altered to fit the conditions of aparticular site.

2

Work Duration

Work duration is a major factor in determining thenumber and types of devices used in TTC zones. Theduration of a TTC zone is defined relative to the lengthof time a work operation occupies a spot location. Thefive categories of work duration and time at a location(as defined in the MUTCD) shall be:

Long-term stationary - Work that occupies alocation more than three days.Intermediate-term stationary - Work thatoccupies a location more than one daylightperiod up to 3 days, or nighttime work lastingmore than 1 hour.Short-term stationary - Daytime work thatoccupies a location for more than one hour andwithin a single daylight period.Short duration - Work that occupies a location upto one hour.Mobile - Work that moves intermittently orcontinuously.

This handbook focuses on short duration andmobile activities with additional examples given forshort-term maintenance on two-lane and multi-laneroads.

3

Major Traffic Control Considerations

The TTC needed at a specific location variesrelative to the characteristics of that location and thework being conducted. Following is a list of somequestions that should be considered when determiningthe TTC needed.

1. Where is the work zone located (on the roadway, onthe shoulder, or off the roadway)?

2. What type of road is involved?

3. What is the speed of the traffic?

4. What is the traffic volume on the roadway? Shouldthe work be rescheduled to avoid heavy volumeconditions?

5. Will the nature of traffic change while work isunderway?

6. Do the local law enforcement agencies need to benotified?

7. What kind of signing will be required?

8. Are cones, drums, barricades, or an arrow panelneeded for traffic channelization?

9. Will a flagger be required?

10.What will be the duration of the work?

11.What type of work is being performed?

12.What are the weather conditions?

4

Fundamental PrinciplesThe control of road users through a TTC zone shall

be an essential part of highway construction, utilitywork, maintenance operations, and incidentmanagement. The following principles provideguidance to assist road users and help protect workersin the vicinity of temporary traffic control zones.1. Road user and worker safety in temporary traffic

control zones should be an integral and highpriority element of every project from planningthrough design and construction.

2 General plans or guidelines should be developed toprovide safety for drivers, bicyclists, pedestrians,workers, enforcement/emergency officials, andequipment.

3. Road user movement should be inhibited as little aspractical.

4. Drivers, bicyclists, and pedestrians should beguided in a clear and positive manner whileapproaching and traversing temporary trafficcontrol zones and incident sites.

5. Routine day and night inspections of temporarytraffic control elements should be performed.

6. Attention should be given to the maintenance ofroadside safety during the life of the temporarytraffic control zone.

7. Each person whose actions affect temporary trafficcontrol zone safety should receive trainingappropriate to the job decisions each individual isrequired to make.

8. Good public relations should be maintained.9. All temporary traffic control devices shall be

removed as soon as practical when they are nolonger needed.

5

Guidance, Options, and Support for Short Durationor Mobile Operations in Work Zones

The following standard, support, guidance, andoption information is given in Part 6 of the MUTCDrelative to short duration or mobile operations.STANDARD

Mobile operations that move at speeds greater than20 mph (such as pavement marking operations) shallhave appropriate devices on the equipment (high-intensity lights, signs) or shall use a separate vehiclewith appropriate warning devices.

All traffic control devices shall be retroreflective orilluminated if work is performed during nighttime hours.

A mobile operation involving a lane closure on amulti-lane road does not require a transition areacontaining a merging taper.

Vehicle mounted signs shall be mounted in a mannersuch that they are not obscured by equipment orsupplies. Sign legends on vehicle-mounted signs shallbe covered or turned from view when work is not inprogress.SUPPORT

Mobile operations include work activities whereworkers and equipment move along the road (usually atslow speeds) without stopping and with the advancewarning area moving with the work area.

Devices having greater mobility than for stationaryoperations (such as signs mounted on trucks) might benecessary.

In mobile operations, the transition area moves withthe work space.

Maintaining reasonably safe work and road userconditions is a paramount goal.

During short duration work, it often takes longer toset up and remove traffic control devices than toperform the work.

6

Work in an intersection usually involves a smallwork force with only a few vehicles and a minimalnumber of traffic control devices.

Except for short duration and mobile operations,when a highway shoulder is occupied, a shoulder worksign should be placed in advance of the activity area.

Type B arrow panels, (minimum size 60 x 30 inches)are appropriate for mobile operations on high-speed,multi-lane roadways.GUIDANCE

Fewer devices should not be used just because theoperation will frequently change its location.

In mobile operations a shadow vehicle (equippedwith an arrow panel or sign) should follow the workvehicle.

Where feasible, in mobile operations, warning signsshould be placed along the roadway and movedperiodically as work progresses. The distance betweenwarning signs and the work should not exceed twomiles.

Under high-volume conditions, consideration shouldbe given to scheduling mobile operations work duringoff-peak hours.

If there are mobile operations on a high-speed travellane of a multi-lane divided highway, arrow panelsshould be used.

When practical and when needed, the work andshadow vehicles should pull over periodically to allowvehicular traffic to pass.

Whenever adequate stopping sight distance exists tothe rear, the shadow vehicle should maintain theminimum distance from the work vehicle and proceed atthe same speed. The shadow vehicle should slow downin advance of vertical or horizontal curves that restrictsight distance.

7

OPTIONAppropriately marked vehicles with high intensity

lights may be used in place of signs and channelizingdevices. The high intensity lights may be rotating,flashing, oscillating, or strobe lights (typically LED).

Simplified control procedures may be warrantedwith a reduction in the number of devices offset by useof more dominant devices such as high-intensity lightson work vehicles.

For mobile operations that move at speeds less than3 mph, mobile signs or stationary signing that isperiodically retrieved and repositioned in the advancewarning area may be used.

At higher speeds, vehicles may be used ascomponents of the traffic control zone for mobileoperations. Appropriately marked vehicles may follow atrain of moving work vehicles.

For some continuously moving operations a singlework vehicle with appropriate warning devices may beused to provide warning.

For mobile operations, a sign may be mounted on awork vehicle, a shadow vehicle, or a trailer stationed inadvance of the TTC zone or moving along with it. Thework vehicle, the shadow vehicle, or the trailer may ormay not have an impact attenuator.

For mobile and constantly moving operations, suchas pothole patching and striping operations, a shadowvehicle, equipped with appropriate lights and warningsigns, may be used to protect the workers from impactsby errant vehicles. The shadow vehicle may beequipped with a rear-mounted impact attenuator.

Flaggers may be used for mobile operations thatoften involve frequent short stops.

The distance between the work and shadow vehiclesmay vary according to terrain, paint drying time, andother factors.

8

Component Parts of a TemporaryTraffic Control Zone

Following is a description of the general sections ofa work zone (specifically related to short duration/mobile work zones).Advance Warning Area: In this section of highwayroad users are informed about the upcoming work zoneor incident area. In short duration or mobile operationsadvance warning signs could be placed along theroadway and moved periodically as work progresses orplaced on work vehicles which move with the workarea.Transition Area: Road users are redirected out oftheir normal path. Stationary areas usually involve useof tapers while the transition area moves with the workspace in mobile operations.Activity Area: This is the section of highway wherethe work activity takes place and includes the workspace, traffic space, and buffer space. In short durationand mobile operations the work space moves as workprogresses.

Work Space: Area for workers, equipment, andmaterials storage.Buffer Space: Lateral and longitudinal areaproviding protection for traffic and workers.

Termination Area: This area returns road users totheir normal path. It is not typically used in shortduration and mobile operations.

9

TAPERSTapers are used as the transition area in stationary

operations. Taper lengths are given in the followingtable. Typical channelizing devices include cones (28”minimum), vertical panels, and barricades. In shortduration and mobile operations other methods are usedto provide advance warning and transition around andpast the work area. This may typically include a shadowvehicle (equipped with an arrow panel or sign)following the work vehicle.

Taper Length (L)*

*Following are the formulas used to calculate taperlength:

Posted Speed Formula40 mph or under L = WS2/6045 mph or over L = WS

where: L = taper length; W = width of lane or offset,and S = posted speed, or off-peak 85th percentile speedNote that the spacing for a one-lane, two-way tapershall be 20 feet for all conditions.

FlaggersFlaggers are typically used in stationary operations,

and may be used for mobile operations that often involvefrequent short stops. Guidelines for the minimumqualifications, devices to use, flagger stations, flaggingprocedures, and communications are given in theMUTCD (Chapter 6E). The following guidelines for highvisibility clothing apply to all workers in a work area.

Speed Limit(MPH) Lane Width (feet)

Spacing BetweenDevices (feet)

10 11 1225 105 115 125 2535 205 225 245 3545 450 495 540 4555 550 605 660 5565 650 715 780 6570 700 770 840 70

10

The use of the flag and sign paddle are displayed inthe following illustration.

PREFERRED METHOD EMERGENCY SITUATIONS ONLYSTOP/SLOW PADDLE RED FLAG

11

High Visibility ClothingHigh visibility retroreflective safety apparel shall be

worn at all times. The retroreflective material shall beeither orange, yellow, white, silver, yellow-green, or afluorescent version of these colors, and shall be visibleat a minimum distance of 1,000 feet. The retroreflectiveclothing shall be designed to clearly identify the weareras a person. All clothing shall meet ANSI 107-2004standards.

Arrow Panels

Arrow panels are effective day and night, for movingtraffic out of a lane to the left or right, and may be usedfor tapered lane closures and mobile operations. Theminimum size (for any roadway) must be 48” x 24” withat least 12 panel lamps to provide a minimum legibilitydistance of 1/2 mile. The minimum size on high-speed,multi-lane highways is 60” x 30”. Arrow panels should beequipped with a dimming device capable of 50 percentdimming for use at night along with circular hoods. Theonly permissible use of an arrow board on a two-lane,two-way street or road is the flashing caution mode.

An arrow panel shall be a sign with a matrix ofelements capable of either flashing or sequential displays.This sign shall provide additional warning and directionalinformation to assist in merging and controlling roadusers through or around a temporary traffic control zone.The arrow panel shall be mounted on a vehicle, a trailer,or other suitable support.

An arrow panel should be used in combination withappropriate signs and other temporary traffic controldevices. A vehicle displaying an arrow panel shall beequipped with high-intensity rotating, flashing,oscillating, or strobe light. When arrow panels are used toclose multiple lanes, a separate arrow panel shall be usedfor each closed lane.

12

Warning Lights

If used, warning lights shall be mounted on signs orchannelizing devices in a manner that, if hit by an errantvehicle, they will not be likely to penetrate the windshield.Flashing warning lights shall not be used for delineation,as a series of flashers fails to identify the desired vehiclepath. Warning lights shall have a minimum mountingheight of 30 inches to the bottom of the lens.

Type A Low-Intensity flashing warning lights areused to warn road users during nighttime hours that theyare approaching or proceeding in a potentiallyhazardous area. Type A warning lights may be mountedon channelizing devices.

Type B High-Intensity flashing warning lights areused to warn road users during both daylight andnighttime hours that they are approaching a potentiallyhazardous area. Type B warning lights may be mountedon advance warning signs or on independent supports.

Type C Steady-Burn warning lights may be usedduring nighttime hours to delineate the edge of thetraveled way. When used to delineate a curve, Type Cwarning lights should only be used on devices on theoutside of the curve, and not on the inside of the curve.

13

Nighttime OperationsAll traffic control devices shall be retroreflectorized

when used at night. Workers shall wear ANSI approvedretroreflective apparel. Cones shall be equipped with areflective collar when used at night. When barricadesare used, it is desirable to add flashing lights when thebarricades are used singly and steady burn lights whenthey are used in a series for channelization. If a flaggeris used, the flagger stations should be adequatelyilluminated.

SignsTypes1. Regulatory signs inform road users of traffic laws or

regulations and indicate the applicability of legalrequirements that would not otherwise be apparent.Regulatory signs shall be authorized by the publicagency or official having jurisdiction. They aregenerally rectangular with a black legend and borderon a white background.

2. Warning signs in temporary traffic control zonesnotify road users of specific situations or conditionson or adjacent to a roadway that might not otherwisebe apparent. Temporary traffic control warning signsshall be diamond-shaped with a black symbol ormessage and border on an orange background.

3. Guide signs provide road users with information tohelp them along their way through the temporarytraffic control zone. The design of guide signs ispresented in Part 2 of the MUTCD.

SizeAdvance warning signs for higher-speed locations

shall have a size of 48 x 48 inches. Where speeds andvolumes are moderately low or, where there is a lack ofshoulder width, a minimum size of 36 x 36 inches, maybe used for advance warning signs. Deviations fromstandard sizes shall be in 6-inch increments. The bottomof the sign shall be a minimum of 12 inches from theground.

14

Sign PlacementSigns should normally be located on the right side of

the roadway. Where special emphasis is needed, signsmay be placed on both the left and right sides of theroadway. Signs mounted on barricades and barricade/sign combinations shall be crashworthy. For mobileoperations, a sign may be mounted on a work vehicle, ashadow vehicle, or a trailer stationed in advance of theTTC zone or moving along with the work.

Advance Warning AreaThe distance from the first sign to the start of the

transition area should be long enough to give motoristsadequate time to respond to the conditions. The firstwarning sign may have a flag or cone. Guidelines arepresented in the summary of layout dimensions asreferenced in Table A (with A, B, and C distancesindicated in the typical application diagrams.)

Table ASummary of Layout Dimensions Sign Spacing

Distance Between Signs (feet) Road Type A B CUrban (<40 mph) 100 100 100Urban (Eq. or >45 mph) 350 350 350Rural 500 500 500Expressway/Freeway 1,000 1,500 2,640

Buffer SpaceWhen a longitudinal buffer space is used, the values

shown in the following table may be used.

Table BLongitudinal Buffer Space Dimension

Speed (mph) Distance (feet)25 15535 25045 36055 49565 64570 730

15

The diagrams on the following pages representexamples of the application of principles andprocedures for safe and efficient temporary trafficcontrol in work zones. The layouts represent minimumrequirements. It is not possible to include illustrations tocover every situation which will require work areaprotection. They are not intended as a substitute forengineering judgment and should be altered to fit theconditions of a particular site. All traffic control devicesused must be in compliance with the MUTCD. Thediagrams represent short duration and mobile operationsexcept for two diagrams describing short-termmaintenance operations. For further information, referto Part 6 of the MUTCD.

Arrow panel

Arrow panel support or trailer

Traffic Cone

Direction of traffic

Flagger

Warning Flags

Sign (Shown facing left)

Work space

Work vehicle

Shadow/protective vehiclewith attenuator (TMA)

Typical Application Diagrams

Note: The application diagrams are not to scale.

16

Aerial Work at SignalizedIntersection (AD-1)

1. This diagram is not intended to represent all applica-tions using aerial lifts at intersections. Engineeringjudgment should be used to determine appropriatetraffic control applications for a specific site.

2. The use of police officers is suggested where signalsare mounted diagonally across the intersection. Ifpolice officers are not an option and conditionswarrant, place the traffic signal on all-red flash and/orplace stop signs on all approaches.

3. No portion of an aerial lift platform, or the supportingstructure, shall extend over an open lane of traffic,regardless of working height.

4. A TMA and arrow panel may be used in affected lanes onfive or more lane roads with posted speeds of 45 MPH orgreater.

5. The aerial lift vehicle shall be appropriately illuminated atnight.

17

Attenuator optionalon shoulder vehicle

Optional(for shoulder

work)

Arrow Panel Optional(caution mode)

Mountedon vehicle

Optional(min. 18 x 18 in.)

Buffer Space(see Table B, pg. 14)

500’ to 2 Miles

Place conewith lead sign

SHOULDER

WORK

SHOULDER

WORK

ROAD

WORK

AHEAD

ROAD

WORK

AHEAD

Short Durationor MobileMaintenance

ShoulderClosure (AD-2)

NEXTX MILENEXT

X MILE

Note: Shoulder work with minorencroachment permitted ifminimum 10-foot lane widthmaintained.

(Multi-Laneand Two-LaneRoadways)

18

19

20

21

22

23

24

25

26

27

28

SUPERVISOR’S CHECKLIST

1. Follow Part 6 of the MUTCD. It is thenational standard for work zone trafficcontrol.

2. Have a plan before going to the worksite.

3. Remove the devices in a timely manner.

4. Ask yourself, “What is the driver’s view ofthe work site - at night, during peak hours,etc.?”

5. Ask yourself, “Would I feel safe drivingthrough this work zone?”

6. Investigate crashes/incidents to identifyif changes are needed in the trafficcontrol plan.

Take photographs of all trafficcontrol devices.

Sketch and dimension all devices.Indicate size of signs, placementfrom the edge of the travelway, andthe height to the bottom of the sign.

The MUTCD (http://mutcd.fhwa.dot.gov/) is the finalauthority for all questions.

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