Traffic Safety Evaluation of Nighttime and Daytime Work Zones (2008)

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72 Revisions to Existing Definitions Activity Area—currently defined as “Located adjacent to actual work area, whether workers and equipment were present or not.” This definition is inconsistent with the definition in the MUTCD and with the Diagram in appen- dix L of the Guideline. This definition should be made consistent with the MUTCD by changing it to “the part of the work zone where the work takes place. It includes the traffic space, work space, and buffer spaces.” Advance Warning Area—currently defined as “Located after the first warning sign but before the work area.” This defi- nition is also with the MUTCD and appendix L, and should be revised to “From the first warning sign to the start of the transition area.” Concrete Traffic Barrier—currently defined as “A type of permanent median made of concrete that is usually fixed but sometimes can be moved by special equipment to shift lane direction.” This definition is inconsistent with high- way terminology, and is incorrect in that this feature is a traffic barrier, not a median. The suggested revised defini- tion would read “a type of permanent traffic barrier made of concrete that is located in a highway median or on the roadside. Although usually fixed in place, some versions on this barrier can be quickly moved from side-to-side by a special machine to open and close lanes.” It is suggested that the term itself be revised to “Concrete Traffic Barrier— Permanent” to distinguish from the two new terms “tem- porary work zone concrete barrier-non-moveable” and “temporary work zone concrete barrier-moveable” defined below. Crossover—the current definition “Area where motor vehi- cles are permitted to travel across the opposing lanes of traffic or do a U-turn” is potentially confusing, especially in work zones, because it seems to include intersections. The term crossover has a very specific meaning in WZs, and this term should be revised to read “Area in the median of a divided trafficway provided to enable vehicles to do a U-turn, or a work zone type with a connection between the two roadways of a divided highway where vehicles are diverted from one roadway onto the other, such that both directions of travel use a single roadway.” Flagger—the current definition “Traffic control person con- trolling traffic with a flag applicable to the motor vehicle at the crash location” is incomplete in that the required device is now a stop-slow paddle, with a flag used for only limited situations. The definition should be revised to read “Traffic control person controlling traffic with a stop-slow paddle or flag applicable to the motor vehicle at the crash location.” Helmet—the current definition “Safety helmet worn by non- motorist (bicyclist) or driver (motorcyclist)” should be expanded to read “Safety helmet worn by non-motorist (bicyclist) or driver (motorcyclist) or a protective hardhat worn by a worker.” The term itself should be changed to “Helmet or Hardhat.” Impact Attenuator/Crash Cushion—the current definition is “A barrier at a spot location, less than 25 ft. (7.6 m) away, designed to prevent an errant motor vehicle from impact- ing a fixed object/hazard by gradually decelerating the motor vehicle to a safe stop or by redirecting the motor ve- hicle away from the hazard.” This term should be revised to “Impact Attenuator/Crash Cushion – Permanent” and its definition changed to “A barrier permanently fixed at a spot location, less than 25 ft. (7.6 m) away, designed to pre- vent an errant motor vehicle from impacting a fixed object/hazard by gradually decelerating the motor vehicle to a safe stop or by redirecting the motor vehicle away from the hazard.” A new term for “Impact Attenuator/Crash Cushion—Work Zone” is defined below. Intermittent or Moving Work—currently defined as “Type of work zone.” This definition is too brief, and in incomplete. A suggested revised definition is “Type of work zone that moves intermittently or continuous along a highway, and remains in one location for no more than a few minutes.” A P P E N D I X D Suggested Revisions to MMUCC Guideline Definitions

Lane Closure—the current definition “Type of work zone” should be expanded to read “Type of work zone in which one or more travel lanes are closed to traffic, with traffic moved into the remaining open lanes, thus resulting in a reduction in the total number of lanes available for travel.” Lane Shift/Crossover—the current definition of “Type of work zone” is incomplete, and is inconsistent with the sug- gested revised definition for crossover provided above. It is recommended that this term be shortened to “lane shift” and that the definition be revised to “a traffic lane is moved laterally in either direction, but the total number of lanes is not reduced. Non-Highway Work—the existing definition “Maintenance or other types of work occurring near or in the trafficway but not related to the trafficway” does not clearly explain what should be included under this category. It appears it is in- tended to identify work on utility infrastructure such as overhead transmission lines. It could also include work on property adjacent to a highway, such as building repair or demolition, which requires closing or shifting a sidewalk, shoulder, or even a travel lane. It is not clear whether an ex- cavation or similar work within the roadway to install or repair an underground facility would be categorized as Non-Highway Work. A related major concern is that the law enforcement officer that enters this information may not be able to determine whether the activity necessitating a work zone is Highway Work or Non-Highway Work. This attribute is included in data element C15. “Contributing Circumstances, Road,” but its purpose is unclear. It is rec- ommended that definition should be re-examined in the planned next edition of the guideline. Stop Signs—the current definition reads “A six-sided red sign with “STOP” on it, requiring motor vehicles to come to a full stop and look for on-coming traffic before pro- ceeding with caution.” Stop signs are required by the MUTCD to include eight sides, and this definition should be revised accordingly. Transition Area—the current definition “Where lanes are shifted or tapered for lane closure” is incorrect in that the transition area includes any change in the normal traffic pattern, not just lane closures or shifts.” It should be re- vised to read “That part of a work zone located prior to the Activity Area where traffic is moved out of its normal path, such as at a lane closure, lane shift, lane width reduction or median crossover.” Work on Shoulder or Median—the current definition “Type of work zone” should be redefined for clarity to read “Type of work zone in which the activity takes place on a shoul- der or median, but not in a travel lane, and no travel lanes are disrupted.” Work Zone/Maintenance Equipment—It was suggested in the discussion of attribute revisions that this term be revised to include equipment and vehicles. Accordingly, the cur- rent definition “Equipment related to the work zone or roadway maintenance” should be revised to read “Equip- ment or vehicles related to the work zone or roadway con- struction, maintenance, or utility work.” Suggested Additional Definitions Activity area—the part of the work zone where the work takes place. It includes the work space as well as the traffic space and any buffer spaces. Buffer Space—Area within the activity area provided for the protection of traffic and workers by providing room for an errant vehicle to stop or to return to the traffic space. Impact Attenuator/Crash Cushion—Work Zone—A bar- rier temporarily placed at a spot location in a work zone, less than 25 ft. (7.6 m) away, designed to prevent an errant motor vehicle from impacting a fixed object/hazard by gradually decelerating the motor vehicle to a safe stop or by redirecting the motor vehicle away from the hazard.” Temporary Work Zone Concrete Barrier—Moveable— similar to Temporary Work Zone Concrete Barrier— Non-Moveable, except it can be quickly moved from side-to-side by a special machine to open and close lanes. Temporary Work Zone Concrete Barrier—Non-Moveable— a type of traffic barrier made of concrete that is located in a highway median or roadside in a work zone. This barrier consists of individual sections that are set in place and pinned together. This barrier can be relocated within the work zone, and is removed at the completion of the work. Traffic Space—the part of the activity area available for the use of traffic (vehicles, pedestrian, bicycles) to pass through the activity area. Work Space—the part of the activity area set aside for work- ers, equipment, and material storage. The work space is typically marked by traffic cones, drums or similar devices or by the presence of work vehicles. Work Space Intrusion—A vehicle traveling through a work zone enters the work space and collides with a worker, work zone/maintenance equipment or vehicle, or another work zone feature such as an excavation of material stockpile. 73