ppendix Work Zone Traffic Control The purpose of this appendix is to present basic guidelines for work zone traffic control and to supplement the Highway Work Zone Safety Checklist. This appendix presents the requirements of Part VI of the Manual on Uniform Traffic Control Devices (MUTCD) with particular emphasis on short-term work sites on roads and streets in rural and small urban areas. These requirements apply to construction, maintenance, and utility work zones. This appendix presents information and gives examples of typical traffic control applications for twolane and multilane work zones. This information is intended to illustrate the principles of proper work zone traffic control, but is not a standard. Part VI of the MUTCD contains the national standards for work zone traffic control. Traffic Control Devices The following are four types of traffic control devices used in work zone traffic control: Signs Channelizing Devices Lighting Devices Pavement Markings Signs Signs used in work zone traffic control are classified as regulatory, guide or warning. Regulatory signs give notice of traffic laws or regulations. Guide signs commonly show designations, directions and distances. Warning signs give notice of conditions that are potentially hazardous to traffic. -1
Spacing of dvance Warning Signs * 100 feet 100 feet 100 feet 350 feet 350 feet 350 feet 500 feet 500 feet 500 feet 1000 feet 1500 feet 2640 feet *Dimension is the distance from the transition or point of restriction to the first sign. Dimension is the distance between the first and second signs. Dimension C is the distance between the second and third signs. (The third sign is the first one in a three-sign series encountered by a driver approaching a TTC zone.) Warning Signs - Construction and maintenance warning signs are used extensively in street and highway work zones. These signs are normally diamond shaped, with a black legend and border on an orange background. s a general rule these signs are located on the right-hand side of the street or highway. Size - The standard size for advance warning signs in work zones is generally 48 inches by 48 inches. Where speeds and volumes are relatively low, a minimum size of 36 inches by 36 inches may be used (see part 6F.03 of the MUTCD for specific sign sizes). Mounting - Standards for height and lateral clearance of roadside signs are included in Part 6F.03 of the MUTCD. Signs mounted on barricades, or temporary supports, may be at lower heights but the bottom of the sign shall be not less than one foot above the pavement elevation. Higher mounting heights are, however, desirable. Illumination and Retroreflectorization - Regulatory, warning, and guide signs shall be retroreflective or illuminated to show the same shape and color by both day and night (street or highway lighting does not meet the sign illumination requirements). -2
Facing Traffic Channelizing Devices 18 in MIN. 8 to 12 in 4 in 4 in 4 to 6 in 36 in MIN. 36 in MIN. 24 in MIN. 45 12 in MX. DRUM Retroreflective and More than 36 in 28 in MIN. 2 in 3 in 2 to 6 in 3 in Night and/or Freeway High-Speed Roadway (45 mph or more) TUULR MRKERS 18 in MIN. TUULR MRKERS Retroreflective and 4 to 6 in 3 to 4 in 6 in 28 in 2 in MIN. 4 in VERTICL PNEL Retroreflective and Day and Low-Speed Roadway (40 mph or less) 3 in 18 in MIN. 2 in Night and/or Freeway High-Speed Roadway (45 mph or more) 45 CONES Day and Low-Speed Roadway (40 mph or less) 45 24 in 36 in 8 to 12 in TYPE I RRICDE** 36 in MIN. 24 in MIN. 8 to 12 in TYPE II RRICDE** 45 24 in 5 ft MIN. 4 ft MIN. 8 to 12 in 45 TYPE III RRICDE** DIRECTION INDICT RRICDE** *Warning lights **Rail stripe widths are 6 inches, except that 4 inch wide stripes may be used if rail lengths are less than 36 inches. The sides of barricades facing traffic are retroreflective. -3 36 in 12 in 8 in
Channelizing Devices Channelizing devices are used to warn and alert drivers of hazards in work zones, protect workers, and guide and direct drivers past the hazards. Channelizing devices include cones, tubular markers, vertical panels, drums, barricades, and temporary raised islands. Traffic Cones - Traffic cones must be orange in color and a minimum of 18 inches in height. Traffic cones used on freeways and other high-speed roadways and on all facilities during hours of darkness shall be a minimum of 28 inches in height. Cones used at night shall be retroreflectorized or equipped with lighting devices for maximum visibility. Spacing - Channelizing devices should be spaced so that they make it apparent that the roadway or work area is closed to traffic. 1. The spacing between devices in a taper channelization should be a distance, in feet, which is approximately equal to the speed limit in MPH. However, tapers should include a minimum of 5 devices. 2. The spacing between devices in a buffer or work area may be up to a distance, in feet, of 2 times the speed limit in MPH. For example, if the street has a speed limit of 35 MPH, the devices in the buffer and work area may be spaced up to 70 feet. 3. In urban areas, shorter spacings between devices in the buffer and work areas may be more appropriate. For example, the spacing used in tapers could also be used in buffers and work areas. 4. When used to lead traffic out of the intended traffic space, the devices should be extended a distance of two times the speed limit in MPH beyond the end of the transition zone. -4
Lighting Devices Lighting devices for short term construction and maintenance work zones are designed to supplement the signs and channelizing devices used in these zones. Typical lighting devices include warning lights, flashing warning beacons, floodlights, and steady-burn electric lamps. Warning lights - the principal types and use of warning lights are: 1. Low Intensity Flashing Lights (Type ) used at night to warn of a potentially hazardous area. 2. High Intensity Flashing Lights (Type ) normally mounted on either advanced warning signs or independent supports to draw attention to a hazard, both day and night. 3. Low Intensity Steady-urn Lights (Type C) used in a series to delineate the edge of the travelway at night. -5
Component Parts of a Temporary Traffic Control Zone The traffic control zone is the distance between the first advance warning sign and the End Road Work sign or last TTC device. Downstream Taper Termination rea lets traffic resume normal operations uffer Space (longitudinal) Traffic Space allows traffic to pass through the activity area uffer Space (lateral) provides protection for traffic and workers Work Space is set aside for workers, equipment, and material storage ctivity rea is where work takes place uffer Space (longitudinal) provides protection for traffic and workers Transition rea moves traffic out of its normal path Shoulder Taper dvance Warning rea tells traffic what to expect ahead -6
Taper Length Criteria for Work Zones There are five types of tapers used in work zone traffic control. The length of each type of taper is based on formulas using the speed of the traffic and the width of the offset (or lane width). The following are the five types of tapers and their lengths. Min. = Minimum Max. = Maximum Type of Taper Taper Length Merging Taper L Min. Shifting Taper 1/2 L Min. Shoulder Taper 1/3 L Min. Two-Way Traffic Taper 100 feet Max. Downstream Tapers 100 feet per lane (use is optional) Formulas for L Speed Limit Formula 40 MPH or less L= WS 2 /60 45 MPH or greater L= WxS L = Taper Length in feet W = Width of offset in feet S = Posted speed or off-peak 85 percentile speed in MPH prior to work starting -7
Installing Lane Closures Stationary lane closures should be installed with the flow of traffic in the following sequence: 1. Install all advance warning signs. 2. Place arrow panel on the shoulder at the beginning of the merging taper. 3. Place channelizing devices to form a merging taper. 4. Install the buffer space. 5. Continue placing channelizing devices through the work area at the correct spacing. 6. Install an End Road Work sign approximately 500 feet beyond the last device in the lane closure. 7. Place a truck-mounted attenuator (TM) vehicle, if required, 50 feet to 100 feet from first work crew or hazard approached by motorists. ride through through the entire lane closure should be performed (with adjustments made to the traffic control devices if needed) to ensure that the lane closure is installed and functioning properly. -8
Removing Lane Closures Stationary lane closures should be removed against the flow of traffic in the following sequence: 1. Remove channelizing devices from end of closure back to the widest part of the merging taper. 2. Place removal vehicle on shoulder and remove devices from taper by hand onto backing vehicle. 3. Remove arrow panel after ensuring roadway is clear. 4. Moving with the flow of traffic, remove all of the advance warning signs beginning with the Road Work head sign and ending with the End Road Work sign. Use of a TM vehicle when installing and removing lane closures on multi-lane roadways increases the safety of the operation for both the worker and the traveling public, and should be used whenever the shoulder width prevents these operations from being performed completely off of the travelway. -9
Definitions The following are several important definitions for terms used in these guidelines. These definitions were developed to aid the supervisor at the job site in determining the appropriate traffic control for the existing street or highway conditions. If the traffic conditions change during the course of the work then the traffic control must change also. Low Speed - s a general rule, a low speed road can be considered one on which the posted speed limit is 35 miles per hour (MPH) or less. Low Volume - s a general rule, a low volume road can be considered one on which the average daily traffic volume (DT) does not exceed 500 vehicles per day. If the traffic volumes are not known, the following rule of thumb can be used to determine if the road can be treated as low volume for the purposes of installing work zone traffic control. Rule of thumb - Count the number of vehicles that pass a single reference point over a five (5) minute period. If not more than 3 vehicles pass the reference point in that period, then the road can be considered low volume for the purpose of installing work zone traffic control. In addition, 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 7-9 M and 4-6 PM, and will vary in different areas. Urban Street - type of street normally characterized by relatively low speeds, wide ranges of traffic volumes, narrower lanes, frequent intersections and driveways, significant pedestrian traffic, and more businesses and houses. Minor Urban Street - low volume, urban street. -10
Typical pplication Diagrams The diagrams on the following pages 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. 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 particular diagrams, tables are presented which provide information on taper lengths and buffer spaces. The information presented in these diagrams and tables are minimums for standard highway conditions. For urban conditions, shorter spacings may be used and are listed in parentheses in the typical diagrams. Expressway and freeway conditions will require longer distances. For further information, refer to Part VI of the MUTCD; it is the national standard for work zone control. Legend Channelizing Device Flagger Sign (shown facing left) rrow Panel High Level Warning Device Work Space -11
Work eyond the Shoulder 1. If the work space is behind a barrier, more than 24 inches behind curb, or 15 feet or more from the edge of any roadway, the Road Work head sign may be omitted. 2. Other acceptable advance warning signs are those indicating shoulder work ahead. 3. If the work space is in the median of a divided highway, an advance warning sign should also be placed on the left side of the directional roadway. -12
Shoulder Work Shoulder Taper 1/3 L 1/3 L Shoulder Taper Shoulder Taper 1/3 L 1. Shoulder Work sign should be placed on the left side of the roadway for a divided or oneway street only if the left shoulder is affected. 2. For operations of 60 minutes or less, all signs and channelizing devices may be eliminated if a vehicle with an activated high intensity rotating, flashing, oscillating, or strobe light is used. -13
Shoulder Work with Minor Encroachment Truck-Mounted ttenuator uffer Space 1/3 L 1. For high speed traffic conditions, a lane closure should be used. 2. The lane encroachment should either permit a remaining lane width of 10 feet, or the lane should be closed. However, a 9-foot width is acceptable for use on low volume, low-speed roadways, provided the traffic does not include long and/or wide heavy commercial vehicles. 3. Temporary traffic barriers may be used along the work space. 4. dditional advance warning may be appropriate, such as a Road Narrows sign. -14
Work in Center of Road with Low Traffic Volumes (Maintaining Two-Way Traffic) 1/2 L 1/2 L 10 ft minimum to edge of pavement or outside edge of paved shoulder 1. minimum lane width of 10 feet should be provided in both directions as measured from the channelizing devices to the edge of pavement. 2. Workers in the roadway should wear high-visibility safety apparel. -15
Interior Lane Closure on Multi-lane Street L uffer Space Truck-Mounted ttenuator uffer Space L 1. This layout applies to low-speed, low-volume urban streets. Where speed or volume is higher, additional signing such as Left Lane Closed XX Feet should be used between the signs shown. 2. The closure of the adjacent interior lane in the opposing direction may not be necessary, depending upon the activity being performed and the work space needed for the operation. 3. Shadow vehicles with a truck-mounted attentuator may be used. -16
Lane Closure on Minor Street (No Flagger, Traffic Self-regulating) Work Vehicle Truck-Mounted ttenuator uffer Space 100 ft MX. 1. This layout is only appropriate for low-volume, low-speed streets. 2. Traffic can regulate itself while volumes are low and the length of the work space is short, thus allowing traffic to readily see the roadway beyond. 3. Where traffic does not self-regulate effectively, use one or two flaggers. -17
Lane Closure on Two-Lane Road (With Flaggers) C The buffer space should be extended so that the two-way traffic taper is place before a horizontal (or crest vertical) curve to provide adequate sight distance for the flagger and a queue of stopped vehicles. 100 ft MX. One Lane Two-Way Traffic Taper 100 ft MX. C 1. For short-duration operations, the Road Work head and End Road Work signs may be omitted. 2. For low-volume situations with short work zones on straight roadways where the flagger is visible to road users approaching from both directions, a single flagger, positioned to be visible to road users approaching from both directions, may be used. 3. Flashing warning lights and/or flags may be used to call attention to the advance warning signs. e Prepared to Stop sign may also be added. -18
Lane Closure on Two-Lane Road with Low Traffic Volumes Lane Closure on Two-Lane Road with Low Traffic Volumes C 100 ft MX. uffer Space uffer Space 100 ft MX. 15 ft C 1. This TTC application may be used instead of the one on page -18 if: a) Vehicular traffic volume is such that sufficient gaps exist for vehicular traffic that must yield. b) Road users from both directions should be able to see approaching vehicular traffic through and beyond the work site and have sufficient visibility of approaching vehicles. -19
Temporary Road Closure (Not to Exceed 20 Minutes) C uffer Space uffer Space C 1. Conditions represented are for work which requires closure during daytime hours only. 2. This application is intended for a planned temporary closure not to exceed 20 minutes. 3. flagger or uniformed law enforcement officer shall be used for this application. -20
Multiple Lane Closures at Intersection 1/2 L C 1. If the left through lane is closed on the near-side approach, the Left Lane Must Turn Left sign should be placed in the median to discourage through vehicular traffic from entering the left-turn bay. 2. Flashing warning signs and/or flags may be used to call attention to the advance warning signs. -21
Lane Closures on Street with Uneven Directional Volumes L uffer Space 1/2 L 100 ft Temporary solid white lane line uffer Space 1/2 L 4S ft if S is in mph 1. This shall only be used when the vehicular traffic volume indicates that two lanes of vehicular traffic shall be maintained in the direction of travel for which one lane is closed. 2. The procedure may be used during a peak period of vehicular traffic and then changed to provide two lanes in the other direction for the other peak. -22
Stationary Lane Closure on Divided Highway 500 ft 100 ft 500 ft uffer Space Temporary white edge line L Truck-Mounted ttenuator L uffer Space Shoulder Taper Shoulder Taper C C LONG-TERM ND INTERMEDITE SHT-TERM 1. When work is being performed in the lane adjacent to the median on a divided highway, the Left Lane Closed and Lane Ends signs shall be substituted. 2. When paved shoulders having a width of 8 feet or more are closed, channelizing devices should be used to close the shoulder in advance of the merging taper to direct traffic to remain within the traveled way. 3. truck-mounted attenuator may be used on the work vehicle and/or shadow vehicle. -23
Closure at Side of Intersection 100 ft MX. 100 ft MX. 100 ft MX. 1. The situation depicted can be simplified by closing one or more of the intersection approaches. If this cannot be done, and/or when capacity is a problem, through vehicular traffic should be directed to other roads or streets. 2. Depending on road user conditions, flaggers or uniformed law enforcement officers should be used to direct road users within the intersection. -24
Right Lane Closure on Far Side of Intersection 1.For intersection approaches reduced to a single lane, left-turning movements may be prohibited to maintain capacity for through vehicular traffic. 2. Flashing warning lights and/or flags may be used to call attention to the advance warning signs. 3. The normal procedure is to close on the near side of the intersection any lane that is not carried through the intersection. However, when this results in the closure of a right lane having significant right turning movements, then the right lane may be restricted to right turns only, as shown. This procedure increases the through capacity by eliminating right turns from the open through lane. -25
Left Lane Closure on Far Side of Intersection 100 ft L C 1. Flashing warning lights and/or flags may be used to call attention to the advance warning signs. 2. The normal procedure is to close on the near side of the intersection any lane that is not carried through the intersection. However, when this results in the closure of a left lane having significant left-turning movements, then the left lane may be reopened as a turn bay for left turns only, as shown. -26
Half Road Closure on Far Side of Intersection C L uffer Space 1/2 L Optional pavement markings C 1. When turn prohibitions are implemented, two turn prohibition signs should be used, one on the near side and, space permitting, one on the far side of the intersection. 2. For intersection approaches reduced to a single lane, left-turning movements may be prohibited to maintain capacity for through vehicular traffic. 3. Flashing warning lights and/or flags may be used to call attention to advance warning signs. -27
Lane Shift on Freeway Temporary yellow edge line 1/2 L Temporary solid white lane lines Crash Cushion Lighting 1/2 L 1/3 L Temporary white edge line Lighting C 1. The lane shift should be used when the road work space extends into either the right or left lane of a divided highway and it is not practical, for capacity reasons, to reduce the number of available lanes. 2. warning sign shall be used to show the changed alignment. 3. If a Stay in Lane sign is used, then solid white lane lines should be used. 4. The minimum width of the shoulder lane shall be 10 feet. 5. For long-term stationary work, existing conflicting pavement markings shall be removed and temporary markings shall be installed before traffic patterns are changed. -28
Double Lane Closure on a Freeway Truck-Mounted ttenuator uffer Space L 2L L C Shoulder Taper 1. Flashing warning signs and/or flags may be used to call attention to the initial warning signs. 2. truck-mounted attenuator may be used on the shadow vehicle. -29
Partial Exit Ramp Closure 500 ft 1. Truck off-tracking should be considered when determining whether the minimum lane width of 10 feet is adequate. -30
Use of Hand-Signaling Devices by Flaggers 18 in MIN. 36 in 24 in 24 in -31
Liability Steps to Minimize Liability: have a traffic control plan follow the MUTCD (Manual on Uniform Traffic Control Devices) minimize traffic disruptions promptly remove devices train all personnel inspect work zone sites periodically for conformance Elements of a Good Inspection Program: routine schedule report form hazard identification adequate personnel and inventory repair verification formal documentation Minimum Documentation: starting and ending time of work location of work type, condition and position of traffic control devices names of personnel type of equipment used any change in temporary or permanent regulatory devices additional information should be gathered in the event of an accident Supervisor s Checklist 1. Follow Part VI of the Manual on Uniform Traffic Control Devices (MUTCD). It is the national standard for work zone control. 2. State and local manuals should be used to supplement the MUTCD. 3. Have a plan before going to the work site. -32
Daily Checklist Daily Top Ten Checklist for Temporary Traffic Control 1. ll devices meet specifications and quality standards. 2. ll signs properly installed and legible; covered or removed when not needed. 3. rrow displays and PCM s properly aligned and maintained. 4. Proper taper and buffer lengths established. 5. Channelizing devices are clean, aligned, and properly spaced. 6. Flaggers certified, properly equipped and using hand signals. 7. Temporary barriers and attenuators properly installed and maintained in serviceable condition. 8. Inapplicable traffic control devices removed when not required. 9. Pavement markings in place at end of the work shift. 10. Day and night drive-through inspections conducted and logged or recorded. -33
Notes -34