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Types of Tapers and Buffer SpacesFour AdditionalChannelizing DevicesLMergingTaperLongitudinalBuffer Space1/2 LDownstreamTaperShiftingTaperLateral BufferSpace(optional)WorkSpaceLongitudinalBuffer Space1/2 LShiftingTaperShifting 1/2 LTaperLateral BufferSpace(optional)LongitudinalBuffer SpaceFour AdditionalChannelizing Devices1/3 LShoulderTaper16

17Work Zone Applications inCurves and HillsFLAGGERDOWNSTREAM TAPER50' TO 100'BUFFER SPACE(LONGITUDINAL)ACTIVITY AREABUFFER SPACE (LONGITUDINAL)IS USED TO POSITION THE TAPERIN ADVANCE OF THE CURVEONE-LANE,TWO-WAY TAPER50 – 100 FEETFLAGGER*REFER TO THE“TYPICAL APPLICATION DIAGRAMS”FOR CORRECT INSTALLATION OFTRAFFIC CONTROL DEVICES.

Work Zone Applications inCurves and HillsWhen the work activity occurs in a curve or the downside of a hill, consideration should be given to theplacement of the advance warning devices. It is alwaysbest to place the warning signs, arrow board, andtaper devices in a tangent or straight section ofroadway for maximum visibility. This may involveextending the lane closure and increasing the bufferspace to accomplish. The figure above shows anapplication of this concept. If the lane closure cannotbe lengthened due to roadway constrains, then thelength of the taper should be increased to provideadditional merge area for vehicles. On hills, the signs,taper and arrow board should be seen prior toreaching the crest of the hill. This also applies to theplacement of flagger stations.Shadow VehiclesA shadow vehicle (see Truck MountedAttenuators) shall be placed 80’ to120’ in advanceof the first work crew encountered by travelingmotorists. A shadow vehicle should be used wheninstalling and removing TTC devices and be placed80’ to 120’ in advance of the each work crew. Eachshadow vehicle shall have at least one amber highintensity rotating, oscillating, or flashing lightfunctioning while in operation. A work vehicleshall be used to store, install and remove TTCdevices.18

19Truck Mounted AttenuatorsA shadow vehicle requires a truck or trailer mountedattenuator (TMA) in all lane and/or partial rampclosures on four or more lane roadways when theposted speed limit is 45 mph or greater, and for mobileoperations which fully or partially block a lane onroadways posted 45 mph or greater. All TMA unitsshall conform to the requirements of NCHRP 350 Test Level 3 or MASH regardless of where the unitwill be used.Placement of shadow vehicle with the TMA shallbe 80' to 120' in front of the first work crew,equipment, or hazard encountered by travelingmotorists. A shadow vehicle should be placed 80’ to120’ in advance of the each work crew. Each TMAvehicle shall have at least one amber high intensityrotating, oscillating, or flashing light functioningwhile in operation.Installing/Removing Lane ClosuresCare must be exercised when installing and removing laneclosures. All stationary lane closures begin and end asmobile operations. TTC devices shall not be stored,installed or removed from a shadow vehicle. AllTTC devices shall be stored, installed or removedfrom a work operation vehicle. The traffic controlneeded to perform the operation safely is dictated bythe location on the roadway the mobile operationwill occur; either on the shoulder or partially or fullyin the lane. A shadow vehicle with a TMA shall beused to protect workers and their work vehicleduring the installation and removal of TTC devices.

Installing Lane ClosuresStationary lane closures should be installed with theflow of traffic in the following sequence:1. Install all advance warning signs.2. Install shoulder taper if necessary.3. Place arrow board on the shoulder at the beginningof the merging taper.4. Install channelizing devices to form a mergingtaper.5. Install channelizing devices along the buffer space.6. Continue placing channelizing devices along the workarea at the appropriate spacing.7. Install channelizing devices for the terminationarea.8. Install the “END ROAD WORK” signapproximately 500' beyond the last device in thelane closure.9. Place a TMA vehicle, if required, 80'-120' fromfirst work crew or hazard approached by motorists.A “ride through” through the entire lane closure shouldbe performed (with adjustments made to the trafficcontrol devices if needed) to ensure that the laneclosure is installed and functioning properly. Majoradjustments to the work zone should be documented.20

21Removing Lane ClosuresStationary lane closures should be removed againstthe flow of traffic in the following sequence:1. Remove channelizing devices from end of closureback to the widest part of the merging taper.2. Place removal vehicle on shoulder and removedevices from taper by hand onto the work vehicle.3. Remove arrow board after ensuring roadwayis clear.4. Moving with the flow of traffic, remove all of theadvance warning signs beginning with the “ROADWORK AHEAD” sign and ending with the “ENDROAD WORK” sign.Use of a TMA vehicle when installing and removinglane closures on multi-lane roadways increases thesafety of the operation for both the worker and thetraveling public, and shall be used whenever theshoulder width prevents these operations from beingperformed completely off of the travelway. Workersrunning accross an open travel lanes of traffic toinstall and remove TTC devices is a dangerouspractice and should not be performed unless slow rolltemporary traffic control operations are beingperformed (see Sections 6G.24 and 6G.25, as well asTTC-62 in the Virginia Work Area ProtectionManual).

DefinitionsThe following are several important definitions forterms used in these guidelines. These definitions weredeveloped to aid the supervisor at the job site indetermining the appropriate traffic control for theexisting street or highway conditions.If the traffic conditions or work status changes duringthe course of the work, then the traffic control mustchange also.Low SpeedAs a general rule, a low speed road can beconsidered one on which the posted speed is less than30 miles per hour (MPH).Low VolumeAs a general rule, a low volume road can beconsidered one which the average daily traffic (ADT)volume does not exceed 500 vehicles per day. If thetraffic volumes are not known, the following rule ofthumb can be used to determine if the road can betreated as low volume for the purposes of installing workzone traffic control:Count the number of vehicles that pass asingle reference point over a five minute period.If no more than 3 vehicles pass the referencepoint in that period, then the road can beconsidered low volume.22

23Definitions (continued)The following are categories of work duration andtheir time at a location:Mobile OperationWork that moves intermittently or continuously (0-15minutes) and does not occupy the immediate area formore than 15 minutes. The immediate area istypically defined as a 1000 linear foot distance.Short DurationOccupies a location from 15 minutes to 1 hour.Short-term StationaryOccupies a location for more than 1 hour but less than12 hours within a single daylight period.Intermediate-term stationaryOccupies a location more than one daylight periodup to 3 days, or nighttime work lasting more than1 hour.Long Term StationaryOccupies a location longer than 3 days.Nighttime ActivitiesTraffic control should be installed for nighttimeoperations from 30 minutes before sunset to 30minutes after sunrise.

Typical Application DiagramsThe diagrams on the following pages representexamples of the application of principles andprocedures for safe and efficient traffic control intemporary traffic control zones and are not intendedto be standards. It is not possible to includeillustrations to cover every situation that requirestemporary traffic control. These typical layouts are notintended as a substitute for engineering judgementand should be altered to fit the conditions of aparticular site.The information presented in these diagrams areminimums for standard highway (non-Limited Access)conditions with posted speeds of 55 mph or less. Forurban conditions (a low speed, two-lane street locatedinside a municipality's corporate limit) shorter spacingsand lengths may be required. Limited Access highwayconditions will require longer distances. For furtherinformation, refer to the Virginia Work AreaProtection Manual; the standard for temporary trafficcontrol in the Commonwealth of Virginia.LegendChannelizing DeviceFlaggerPortable Sign SupportWarning SignFlashing Arrow BoardWork AreaFlashing LightTMA VehicleTravel DirectionShadow Vehicle24

25Work Outside the Shoulder(15' or More From the Edge of Travel Way)SEENOTE 1DITCHLINESEE NOTE 3

Work Outside the ShoulderNotes:1. If vehicle and work activity are both outside theright-of-way, behind the guardrail or barrier, morethan 4' behind vertical curb on urban roadways, oroutside the clear zone for all other roadways, thenonly an activated amber high intensity rotating,oscillating, or flashing light is needed.2. An advance warning sign should be used: if thework will be performed immediately adjacent to theshoulder, if equipment will cross or move along theroadway, or if the activity may distract motorists.3. Sign spacing: limited access 1300' - 1500'; postedspeed greater than 45 mph 500' – 800'; postedspeed 45 mph or less 350' – 500'; see spacing ofsigns for urban use on page 6.4. Other acceptable advance warning signs are thoseindicating shoulder work or utility work ahead.26

27Permitted Temporary EntranceTRUCKSENTERINGHIGHWAYSEE NOTE 3PERMITTEDTEMPORARYENTRANCESEE NOTE 3TRUCKSENTERINGHIGHWAY

Permitted Temporary EntranceNotes:1. Notify the appropriate state or local agencies priorto the installation of the entrance and placement ofany traffic control devices.2. The organization receiving the entrance permit isresponsible for removal of all debris (gravel, mud,dust, hauled materials, etc.), obstructions andirregularities caused by the operation. A flaggingoperation is required for removing debris on atwo-lane roadway. A mobile operation isrequired to remove debris on a multi-laneroadway.3. Sign spacing: posted speed greater than 45 mph500' – 800'; posted speed 45 mph or less 350' –500'; see spacing of signs for urban use on page 6.28

29Shoulder WorkMobile or Short Duration Operation(60 Minutes or less in Intermediate Area)80’-120’WORKVEHICLE REQUIREDSEE NOTE 2ILLUMINATED FLASHINGAMBER (CAUTION MODE)TYPE B OR C84” x 36”

Shoulder WorkMobile or Short Duration OperationNotes:1. The first shadow vehicle may be replaced with a48"x 48" “ROAD WORK AHEAD” or“UTILITY WORK AHEAD” sign.2. The minimum distance between sign and shadowvehicle should be 350'-500' where the posted speedlimit is 45 mph or less, and 500'-800' where theposted speed limit is greater than 45 mph. Themaximum distance between sign and work vehicleis 2 miles.3. Each shadow vehicle involved in the operation shallhave at least an arrow board operating in thecaution mode or at least one amber high intensityrotating, oscillating, or flashing light.4. When the work operation is off the shoulder witha work duration of 15-60 minutes, vehicle warninglights and a truck mounted sign (W20-V3,W20-V6, W20-V1, etc.) or a sign on a portablesign support should be placed behind the workoperations vehicle.5. The work area may be delineate by installingchannelizing devices.30

31Shoulder Work Stationary Operation(Greater Than 60 Minutes in the Immediate Area)500'80'-120'SHADOW VEHICLEREQUIRED(TMA SEE NOTE 6)BUFFERSEE NOTE 31/3 L TAPERSEE NOTE 2RIGHTSHOULDERCLOSEDSEE NOTE 2SEE NOTE 2

Shoulder Work Stationary OperationNotes:1. For operations less than 3 days in duration, signassemblies will only be required on the side wherethe shoulder is being closed (as shown). For longterm stationary work (more than 3 days) ondivided roadways having a median wider than 8',sign assemblies on both sides of the roadway shallbe required (ROAD WORK AHEAD andRIGHT SHOULDER CLOSED AHEAD).2. Sign spacing: limited access 1300' - 1500'; postedspeed greater than 45 mph 500' – 800'; postedspeed 45 mph or less 350' – 500'; see spacing ofsigns for urban use on page 6.3. For length of the buffer space, see Buffer SpaceLength Chart on page 14.4. A vehicle with at least one amber high intensityrotating, oscillating, or flashing light shall beparked 80'-120' in advance of the first work crew.5. A “UTILITY WORK AHEAD” sign may be usedin place of the “ROAD WORK AHEAD”.6. A truck/trailer-mounted attenuator (TMA) shallbe used on the shadow vehicle on Limited Accesshighways and multi-lane roadways with a postedspeed limit equal to or greater than 45 mph.32

33Shoulder Work With MinorEncroachment - Stationary Operation500'10'MIN.80'-120'SHADOW VEHICLEREQUIRED(TMA SEE NOTE 7)BUFFERSEE NOTE 31/3 L TAPERSEE NOTE 2SEE NOTE 2

Shoulder Work With MinorEncroachment - Stationary OperationNotes:1. On divided roadways having a median wider than8', left and right sign assemblies shall be required.2. Sign spacing: limited access 1300' - 1500'; postedspeed greater than 45 mph 500' – 800'; posted speed45 mph or less 350' – 500'; see spacing of signs forurban use on page 6.3. For length of the buffer space, see Buffer SpaceLength Chart on page 14.4. A vehicle with at least one amber high intensityrotating, oscillating, or flashing light shall be parked80'-120' in advance of the first work crew.5. A “UTILITY WORK AHEAD” sign may be usedin place of the “ROAD WORK AHEAD”.6. Lane widths less than the 10 foot minimum mustbe approved by the Regional Traffic Engineer.7. A truck/trailer-mounted attenuator (TMA) shallbe used on the shadow vehicle on Limited Accesshighways and multi-lane roadways with a postedspeed limit equal to or greater than 45 mph.34

35Four-lane Road Mobile Operation(15 Minutes or Less in the Immediate Area)WORK OPERATIONSVEHICLESEE NOTE 31000'84" x 36"84" x 36"( SEE NOTE 2)

Four-lane Road Mobile OperationNotes:1. Each vehicle involved in the mobile operation shallbe equipped with at least one amber high intensityrotating, oscillating, or flashing light. All vehiclesshown shall have an arrow panel operating in theflashing arrow mode.2. If the shadow vehicle occupies any part of thetravel lane, it shall have a TMA.3. When the work operations vehicle is stationary, theTMA vehicle shall be in a position 80' – 120' inadvance of the work operations vehicle. When thework operations vehicle is moving, the TMAvehicle shall follow at a distance of 240' .4. The static warning sign and arrow board may bereplaced with a vehicle mounted changeable messagesign (CMS) with a minimum of 10" height characters.5. On Limited Access highways an additional TMAvehicle (not shown) is required. Shadow vehicle1 is on the shoulder, TMA vehicle 2 and TMAvehicle 3 are in the closed lane.36

37Four-lane Road - Non LimitedAccess Short Duration Operation(16 Minutes to 60 Minutes in the Immediate Area)80'-120'84" x 36"SEE NOTE 2

Four-lane Road - Non LimitedAccess Short Duration OperationNotes:1. Each vehicle involved in the mobile operation shallbe equipped with at least one amber high intensityrotating, oscillating, or flashing light. All vehiclesshown shall have an arrow board operating in theflashing arrow mode.2. Minimum distance between sign/shadow vehicleand the TMA vehicle should be 350'-500' wherethe posted speed is 45 mph or less, and 500'-800'where the posted speed is greater than 45 mph.3. The shadow vehicle on the shoulder may be replacedwith a “ROAD WORK AHEAD” sign on lowspeed, low volume roadways. If the shadow vehicleoccupies any part of the travel lane, it shall have aTMA or be replaced with the “ROAD WORKAHEAD” sign.4. A TMA vehicle shall be used in the travel lane.5. The static warning sign and arrow board may bereplaced with a vehicle mounted changeable messagesign (CMS) with a minimum of 10" height characters.6. The work area may be delineate by installingchannelizing devices.38

39Four-lane Road Stationary Right Lane Closure(Greater Than 60 Minutes in the Immediate Area)500'80'-120'SHADOW VEHICLEREQUIRED(TMA SEE NOTE 4)BUFFERMERGINGTAPER (L)SHOULDER TAPER1/3 LSEE NOTE 1SEE NOTE 1SEE NOTE 1RIGHTLANECLOSEDAHEADRIGHTLANECLOSEDAHEADSEE NOTE 1

Four-lane Road Stationary Right Lane ClosureNotes:1. Sign spacing: Limited Access highway 1300' 1500'; posted speed greater than 45 mph 500' –800'; posted speed 45 mph or less 350' – 500'; seespacing of signs for urban use on page 6.2. For the length of the shoulder taper (1/3 L) andmerging taper (L), see Taper Length Chart onpage 15.3. For length of the buffer space, see Buffer SpaceLength Chart on page 14.4. A shadow vehicle with at least one amber highintensity rotating, oscillating, or flashing light shallbe parked 80'-120' in advance of the first workcrew. When posted speed limit is 45 mph orgreater, a TMA shall be used.5. The flashing arrow board shall be a Type C only.Cone SpacingLocation0-35 mph36 mphTransition20'40'Travelway40'80'40

41Four-lane Road Stationary Left Lane Closure(Greater Than 60 Minutes in the Immediate Area)500'80'-120'SHADOW VEHICLEREQUIRED(TMA SEE NOTE 4)BUFFERMERGINGTAPER (L)SHOULDER TAPER1/3 LSEE NOTE 1SEE NOTE 1SEE NOTE 1LEFTLANECLOSEDAHEADLEFTLANECLOSEDAHEADSEE NOTE 1

Four-lane Road Stationary Left Lane ClosureNotes:1. Sign spacing: Limited Access highway 1300' 1500'; posted speed greater than 45 mph 500' –800'; posted speed 45 mph or less 350' – 500'; seespacing of signs for urban use on page 6.2. For the length of the shoulder taper (1/3 L) andmerging taper (L), see Taper Length Chart onpage 15.3. For length of the buffer space, see Buffer SpaceLength Chart on page 14.4. A shadow vehicle with at least one amber highintensity rotating, oscillating, or flashing light shallbe parked 80'-120' in advance of the first workcrew. When posted speed limit is 45 mph orgreater, a TMA shall be used.5. The flashing arrow board shall be a Type C only.Cone SpacingLocation0-35 mph36 mphTransition20'40'Travelway40'80'42

43Center Tu

Urban Streets with 30 to 40 mph posted speed limit. 250' - 350' *All Other Roadways with 45 mph or less posted speed limit. 350' - 500' All Other Roadways with greater than 45 mph posted speed limit. 500' - 800' Limited Access Highways 1300' - 1500' *Urban streets with greater than 40 mph posted speed limits fall into this category. Removal of .