This paper describes twelve innovative work-zone traffic control devices which were evaluated in closed track field testing under the Strategic Highway Research Project (SHRP) program, Project H-109. "Standard" devices, consisting of those currently applied in operational practice, were also included in the testing to provide an experimental control baseline. Subjects drove an instrumented vehicle through simulated highway work zones in an industrial park which included a non-active airport runway. Applied study measures consisted of driver cognitive responses and vehicular behaviors. Tested innovative traffic control devices consisted of flagging procedures (mechanical gate, hand-held paddle with flashing lights), maintenance vehicle-mounted flashing lights (providing an illusion vehicle deceleration), and barricades (incorporating arrow designs) indicating lane closures and two-way traffic flow. Ninety-six driving subjects were utilized, equally divided between daytime and night-time. The age distribution was determined to approximate the general, driving public (i.e., an even male/female split, with age groupings as follows; 25 percent 16-24 years, 50 percent 25-54 years, and 25 percent 55-plus years.). Designated traffic control device M.O.E.s (measures of effectiveness) were derived from desired device effects and consisted of appropriate vehicle performance and in-depth driver interview responses. Vehicle instrumentation gathered the following performance data: speed profiles approaching test devices, longitudinal and lateral acceleration, approach lane change point, and brake pedal activations. An interior-mounted video camera was also used to record the driver's field of view and structured commentary. Obtained driver intrusive measures were: 1) device detection, e.g., time required to discern that a target device would affect driving, following its appearance in the driver's view; 2) device interpretation, e.g., time required to assess appropriate vehicle action; 3) driver subjective ratings of device helpfulness and safety value; and 4) higher order perception, e.g. driver estimate of closure speed when following a slow maintenance vehicle. Closed track testing was completed in December. The reported results compare the effects of innovative devices with baseline devices. Those devices showing positive results will be subsequenctly evaluated in open highway testing. (A)
Samenvatting