Temporary Traffic Control Devices

Temporary traffic control devices (TTCD) provide for the reasonably safe and effective movement of road users through work zones; protect workers performing the many varied tasks within the work space, as well as road users and equipment; and improve mobility by minimizing congestion and community impact.

Description:

The use of a temporary traffic control device (TTCD) as a safety precaution is a proven and effective way of reducing struck-by injuries and fatalities in work zones by diverting traffic away from work zones. TTCDs use high-visibility equipment as delineators to warn and guide road users through the work zone. All reflective fluorescent orange sheeting used on TTCDs must meet ASTM D 4956 standards. 

These traffic control devices are more appropriate for short maintenance operations than long-term operations. Six typical TTCDs are commonly used in work zones:

  • Drums
  • Tubular Markers
  • Vertical Panels
  • Cones
  • Different Types of Barricade
  • Direction Indicator Barricade

Drums: Plastic work-zone drums are a commonly used TTCD for traffic diversion and vehicle restriction. Typically, drums are manufactured in a lightweight, deformable, and high-durability plastic material with a non-metallic, high-visibility orange finish, with reflective sheeting strips horizontally oriented for increased visibility at night. Most state departments of transportation require reflective sheeting to meet the ASTM D 4956 standard (please see Table 1 under "Additional Considerations"). Drums should have a minimum of three orange and two white reflectorized stripes. They are portable enough to be moved from place to place within the work zone to accommodate any changing conditions. Work-zone drums are equipped with a removable base for stability. The base can be fastened to the road pavement in long-term work situations. Drums can be used as a preliminary warning to motorists or as a channelizing/delineation device for motorists entering or leaving a work zone. Drums must not be filled with sand, water, or any other material since this would make them hazardous to workers and road users when struck.

Figure 1. Work-zone drums in use. Image source: mutcd.fhwa.dot.gov

 

 

Tubular Markers: Reflective post tubular markers are a TTCD device used to divide a lane of traffic from its oncoming counterpart or to channel traffic into an exit-only scenario or to a “merging” lane. Tubular markers are intended to be a replacement for pavement markings. Tubular markers must be manufactured with a non-metallic, high-visibility orange finish with reflective strips meeting the ASTM D 4956 (Table 1). Tubular markers can be temporary or permanent, depending on the application. They must be a minimum of 28 inches in height. Tubular markers can be used as a preliminary warning to motorists or as a channeling/delineation device for motorists entering or leaving a work zone. Because tubular markers are smaller than other TTCDs, they are to be used only when space does not permit the use of a larger, more conventional TTCD.

Figure 2. Tubular marker. Image source: mutcd.fhwa.dot.gov; gobizkorea.com

 

Vertical Panels: Vertical panels are similar in application and size to plastic drums, but have only two directions of projection of reflective material, so it is important to position them exactly as desired. While  drums have 360 degrees of reflective material, vertical panels need to be inserted at a 45-degree angle in the direction traffic is to pass. One advantage of vertical panels is that they require less space for storage compared to drums. As with other TTCDs, vertical panel coloring and reflective material must follow ASTM D 4956 standards (Table 1). Vertical panels can be used as a channeling/ delineation devices or as lane dividers in a work zone. They are convenient for use in areas in which space is limited. Vertical panels also can be used in situations where space does not allow for the placement of barricades.

Figure 3. Vertical panels. Image source: impactrecovery.com

 

Cones: Traffic cones are a common, standard delineation device and are used in a manner similar to reflective post tubular markers. Cones are to be used strictly in temporary applications and are very effective in short-term maintenance operations. Cones must follow ASTM D 4956 standards for coloring and reflective material (Table 1). Cones are separated into two types: night or freeway high-speed roadway cones, which are to be used in work zones with a speed limit of greater than or equal to 45 MPH, and day/ low-speed cones, which are to be used in work zones with a speed limit of less than 45 MPH (FHWA 2015). Cones have a multitude of uses, including channeling/delineation, dividing one lane of traffic from its oncoming counterpart, or dividing traffic into more than one lane traveling in the same direction. Due to the lightweight composition of traffic cones, they may be attached to a base filled with ballast to keep them stable under high wind or extreme weather conditions. The cone spacing must be 20 feet or less on centers to prevent any accidental intrusion of traffic into the work zones.

Figure4. (a) Cone. Image source: equipmentworld.com (b)High-speed roadway cones. Image source: mutcd.fhwa.dot.gov. (c) Low-speed roadway cone; Image source: mutcd.fhwa.dot.gov

 

Barricades: Barricades are used to completely restrict vehicles from entering a work zone. They consist of one or more rails of alternating reflective material and fluorescent orange, meeting ASTM D 4956 specifications (MoDOT 2016; Table 1). Barricades are classified as Type I, Type II, or Type III.

  • Type I barricades consist of a single rail, ranging in height from a minimum of 8 inches to a maximum of 12 inches (1 foot). The top of the rail must be a minimum of 36 inches (3 feet) above the ground, while the rail itself must be a minimum of 24 inches (2 feet) above the ground.
  • Type II barricades must satisfy all requirements of a Type I barricade, with an additional rail ranging from 8-12 inches in height.
  • Type III barricades have three rails, all of which range from 8-12 inches in height. Type III barricades must be a minimum of 5 feet (60 inches) in height overall, and the rails must be a minimum of 4 feet (48 inches) long.

Type I is appropriate for use on conventional roads and urban streets; however, types II and III can be used on freeways and other high-speed roadways. Barricades are to be used as a means of closing a road or restricting motorist traffic to a section of the right of way. Barricades may be weighed down by any deformable ballast, such as sandbags. It should be noted that barricades are subject to vehicle collision and should be supported accordingly.

Figure 5. Barricades. Image source: mutcd.fhwa.dot.gov

 

Direction Indicator Barricade: Direction indicator barricades increase convenience to motorists through visual redirection indicated by an arrow. A direction indicator barricade consists of two rails, one consisting of alternating reflective material and fluorescent orange color, meeting ASTM D 4956 specifications (Table 1). The top rail must be 12 inches (1 foot) in height and include a directional arrow to direct traffic away from the work zone. Finish requirements for the top rail are much less stringent than for the bottom reflective rail. Direction indicators can be used as a means of channeling/delineation, as well as a means of diverting traffic away from a lane by tapering the motorists into a single lane.

Figure 6. Direction indicator barricade. Image source: atksafetysupply.com

 

Here is the summary of application areas for all temporary traffic control devices:

 

Temporary Traffic Control Device

Suggested Work-Zone Use

Plastic Drums

 

Preliminary Motorist Warning

Channeling/ Delineation

Tubular Marker

 

 

Preliminary Motorist Warning

Channeling/ Delineation

* to be used only when space is restricted

Vertical Panel

 

Channeling/ Delineation

Traffic Division (Oncoming)

Plastic Cones

 

 

Channeling/ Delineation

Traffic Division (Oncoming)

Traffic Division (Same Direction)

Barricades

 

Road Closing

Lane Closing (by tapering)

Direction Indicator Barricades

Channelizing/ Delineation

Lane Closing through tapering

 

Risks Addressed:

Working on road construction sites increases risk of work zone struck-by injuries and fatalities. Road maintenance operations occur in close proximity to traffic and create potentially hazardous situations for both workers who are working in the work zone and road users. Among fatalities involving vehicles and heavy equipment at road construction sites, most involved workers on foot or non-passengers who were struck by vehicles or heavy equipment in the work zone or by passing vehicles that entered the work zone. The National Highway Traffic Safety Administration (NHTSA) reported that in 2010 in the U.S, 576 of the 32,885 vehicle crashes that involved fatalities (1.8%) occurred in construction work zones (NHTSA 2010).

To investigate more recent data from 2011 to 2015 (the latest data available) statistics were collected from the Census of Fatal Occupational Injuries (CFOI) provided by the Bureau of Labor Statistics (BLS). In this five-year period, 1,111 transportation-related fatalities happened in the construction industry, involving  aircraft, rail vehicles, animal and other non-motorized vehicle transportation, water vehicles, and pedestrian vehicular incidents. Among these, 319 incidents occurred in the pedestrian vehicular category, involving pedestrians who were struck by a vehicle in work zones. More specifically, 175 pedestrians (i.e., construction workers) died following struck-by-vehicle accidents on construction job sites between 2011 and 2015. This represents 64% of all fatalities of this kind in all industries in the United States. Federal Highway Administration also reported that on average, every 5.4 minutes, a work zone crashes occurred in 2015.  In terms of severity, 73.0% were property damage only, 26.4 % involved an injured party, and 0.7% involved a fatality.

TTC devices can reduce the risk of work zone struck-by injuries by separating the workers from traffic and restricting vehicles from entering a work zone.


How Risks are Reduced:

In a work zone, there are five “levels” of separation: the advance warning area, the transition area, the buffer space, the work area, and the termination area. The advance warning area signals to motorists that there is an upcoming work zone. In the advance warning area, the use of drums, cones, or tubular markers (when appropriate) is encouraged. The transition area begins the delineation of motorists and traffic away from ongoing work. In the transition area, the use of drums, cones, tubular markers, direction indicator barricades, and/or vertical panels would be appropriate. The buffer space is an area where motorists are settling into the new flow of traffic to be taken through the work zone. The buffer space could contain any and all of the TTCDs described here and would be a very appropriate location for barricades of any type. The work area is the space in which the actual roadway or bridge construction is being completed. In the work area, barricades could be used to indicate the location in which the work is physically beginning. The termination area is the effective end of the work zone. In the termination area, drums, cones, or direction indicator barriers could be used as a means of guiding motorists back to the general flow of traffic. TTCDs provide the general delineation for the flow of traffic through these areas, as well as a barrier between traffic and workers.

TTCDs are used to reduce the risk of struck-by injuries and fatalities in roadway work zones by using first warning signs through last traffic control devices where the traffic returns to its normal condition. TTCDs warn road users of potential hazards, advise them to appropriate changes in path through the work zone, and separate the road users from workers who are working in the work zone. TTCDs also address the secondary risk of motorist injuries due to speeding through a work zone, because the high-visibility equipment inadvertently signals drivers to slow down.


Effects on Productivity:

The goals of any employer should be to not only complete the project in a timely and satisfactory manner, but to also reduce injuries and prevent fatalities. In the case of a fatality, federal regulatory agencies may halt all work pending an investigation. TTCDs are much quicker to deploy compared to some barriers that require heavy equipment for lifting and installing. These devices help to reduce fatalities and keep work from slowing down.


Additional Considerations:

The minimum coefficient of retro-reflectivity specifications can be found in Table 1.

Table 1. ASTM D 4956: Minimum Coefficient of Retro-reflection for Fluorescent Orange Sheeting

Observation Angle (Degrees)

Entrance Angle (Degrees)

Candelas/Footcandle/Sq. Ft

0.2

-4

200

0.2

30

100

0.5

-4

80

0.5

30

30

 

*Listed above are the allowable specifications for fluorescent orange sheeting to be used for TTCDs as required by the Federal Highway Administration.


Contributors:

Brett Farquhar - SARMAD Research Group, University of Nebraska- Lincoln

Sogand Hasanzadeh - SARMAD Research Group, University of Nebraska- Lincoln

Behzad Esmaeili, Ph.D. - SARMAD Research Group, University of Nebraska- Lincoln

Pouya Gholizadeh - SARMAD Research Group, University of Nebraska- Lincoln


Hazards Addressed:

Availability

Plasticade Products
Products offered: Drums, Cones, Vertical Panels, Type I, II, and III Barricades, Direction Indicator Barricades http://www.plasticade.com/ or contact 1-800-772-0355

NDM Marking Systems, Inc
Products offered: Tubular Markers, Cones http://www.ndm-inc.com/ or contact 1-706-253-3040

Plastic Safety Systems, Inc.
Products offered: Drums, Tubular Markers, Cones, Vertical Panels, Type I, II, and III Barricades, Direction Indicator Barricades http://pss-innovations.com/ or contact 1-800-662-6338

Bent Manufacturing Company, Inc.
Products offered: Drums, Tubular Markers, Cones, Vertical, Type III Barricades http://www.bentmfg.com/ or contact 1-888-842-0600

Three D Traffic Works, Inc.
Products offered: Tubular Markers, Cones, Type I, II, and III Barricades http://www.trafficwks.com/ or contact 1-877-843-9757

Flexstake, Inc
Products offered: Tubular Markers http://www.flexstake.com/ or contact 1-800-348-9839

Work Area Protection Corporation
Products offered: Drums, Cones, Type I, and II Barricades http://workareaprotection.com/ or contact 1-630-377-9100

US Reflector
Products offered: Tubular Markers http://www.usreflector.com/ or contact 1-860-906-3390

Cortina Safety Products
Products offered: Drums, Tubular Markers, Cones, Vertical Panels, Type I, II, and III, Direction Indicator Barriers http://www.cortinaco.com/ or contact 1-847-455-2800

Return on Investment

To calculate the return on investment (ROI) for your specific application, please visit our Return on Investment Calculator. While a specific ROI example has not been developed for this particular solution, the ROI Calculator provides a useful tool and guidance on how to generate your own on investment analysis.