Construction and maintenance work zones have traditionally been hazardous locations within the highway environment. Studies show that the accident rates during road construction are generally higher than during periods of regular traffic operations. The increase in the number of crashes may be attributed to ( a) general disruption to the flowing traffic due to sudden discontinuities caused by closed lanes, ( b) improper lane merging maneuvers, ( c) the presence of heavy construction equipment within the work area, ( d) inappropriate use of traffic control devices, and ( e) poor traffic management. Research was conducted to develop regression models predicting the expected number of crashes at work zones on rural, two-lane freeway segments. Crashes on approaches to work zones and those inside the work zones were analyzed separately. For developing these models, an extensive database was obtained, including freeway data, crash data, and work zone characteristics. Negative binomial models were developed with average daily traffic, the length of the work zones, and the duration of the work projects as exposure-to-risk variables. The cost of the various work projects was found to be a good substitute for some of the exposure-to-risk variables. The investigated variables included the number of on and off ramps, both on approaches and inside the work zones; the type of work; and the intensity of the road work involved. The models may be used to evaluate beforehand the expected number of crashes on the work zone, given the work zone characteristics.
This research is focused on: (1) drivers' compliance with the system, (2) delays and travel times on approaches to work zones, (3) optimal configuration of the system, and (4) warrants for the system's use. The simulation and field studies indicate a significant reduction in the number of merging maneuvers near work zones after the IMLS is applied. Also, the travel time on continuous lanes is reduced. The increased fairness of the system improves the perception of the traffic conditions among the majority of drivers. A slight reduction in the capacity of the merge point is the second finding of the field observations. This finding should be confirmed through long-term measurements of capacity during regular use of the IMLS units.The final report is divided into two parts. Part I presents the performed research, including the simulation model development and simulation experiments. Part II contains the system description, guidelines for its use, and rules for its setting. The system description includes presentation of the concept and the system components. The guidelines for the system use provide the traffic conditions where the system is expected to provide benefit. Finally, the manual gives a set of simple rules useful in setting all the system parameters to achieve the maximum reduction in the travel time in the continuous lane. DOT F 1700.7 (8-69) (TRB, 1975; TRB, 1996). Evidently, the assumption requires the qualification that speed is a function of density, but only at equilibrium. Because equilibrium can rarely be observed in practice, a satisfactory speeddensity relationship is hard to obtain, and it is often assumed or inferred theoretically. Higher-order Continuum ModelsThe higher order models take into account acceleration/deceleration and inertia characteristics of traffic mass by replacing the equilibrium speed-density relationship with a momentum equation (Whitham, 1974; Payne, 1979 where v is the viscosity coefficient. (Whitham, 1974; Payne, 1979 -v,) Cl dk,where U, is the equilibrium speed and T is the relaxation time. Typically, the value of U, is calculated using an empirical speed-density relationship developed from field data.The left-hand side of the above equation gives the acceleration/deceleration rate of the flow observed at location x. The acceleration/deceleration rate is a sum of several components:
Video detection technologies have been emerging in recent years as a viable alternative to inductive loop detectors to actuate intersection signal controllers. There is a need for quantitative evaluation procedures for documenting the performance of video detection technologies. This quantitative data is needed to qualify systems for procurement and provide benchmarks for training traffic signal technicians that deploy and maintain these systems. This research makes use of two new evaluation procedures for video detection, with several measures of performance. The first of these evaluation procedures involves the comparison of the occupancy times of inductive loop detectors and video detectors to find the amount of discrepancy between the two. The second evaluation method involves calibrating a statistical model in order to determine which weather and traffic characteristics have the greatest effects on the operation of video detectors. This report describes the test facilities used, the evaluation methods used, and documents results of this research. Problems documented in this report were independently corroborated by INDOT personnel by conducting spot inspections at over a dozen intersections with deployed video detection systems. Key Wordsvideo detection evaluation, likelihood analysis, video detector error, inductive loop detector error, sensitivity analysis Distribution Statement
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