Evaluate the effectiveness of the speed monitoring display for work zones in Las Vegas.

摘要

The objective of this thesis is to evaluate the performance of the SMD with different features of display sign: the size of the display sign, flashing the measured speed (with different flashing rate), and displaying warning message. In addition, this thesis will also evaluate the performance of the second SMD in a work zone. With these objectives, two testing sites, one on Cr-215 and the other on I-15, were chosen for this study. Six scenarios were developed which included (1) before condition (no SMDs in the work zone), (2) smaller sign, (3) larger sign without flashing, (4) larger sign with a fast flashing rate, (5) larger sign with a slow flashing, and (6) warning message sign. Comparisons on the speeds collected for these scenarios will be made. From the comparison among the scenarios, the effectiveness of the SMDs with different message displaying features can be evaluated. The comparisons will be made for all types of vehicles together, different types of vehicle separately, vehicles running in free flow conditions, vehicles running at excessive speeds, and vehicles operated on different lanes. From the analysis based on these comparisons, the patterns of the performance of the SMDs with different features can be better understood. After the identification of the performance patterns for the first SMD, the performance of the second SMD will be evaluated.;This thesis will make contributions in the following two aspects. First, a sequential algorithm will be developed to determine whether a vehicle is running in platoon on arterials or bunching on freeways. It is important to determine these conditions because the vehicles running under these conditions would have their full liberty to make response to the tested technologies, rather than having to be influenced by vehicles running in a group. From studying the behavior of those vehicles that were not influenced by the interaction with other vehicles in a group, the identified impact of the testing technologies on them can be more revealing. In the past, to determine whether a vehicle is running in a free flow condition was conducted by using a fixed threshold on headway. This study will adopt a classification algorithm, the CUSUM algorithm, which incorporate the probability distributions of headway in free flow and platoon (or bunching) conditions. This algorithm will be calibrated based on the headway data collected at the test sites in this study. The calibrated algorithm will be operated on the headway data to determine whether a vehicle was running in platoon (bunching) or free flow conditions. By calibrating such a classification algorithm, the results from the comparisons based on free flow condition can be more reliable.;The second contribution of the thesis will be developing disaggregated regression models for the probability for a vehicle to be speeding under different scenarios and the relative impact of the scenarios on the speed reduction. From these models, the effectiveness of all scenarios on reducing speed could be derived statistically.;At last, the cost and benefit analysis will be provided to determine the characteristics of work zones that can receive benefits from using speed monitoring displays on arterials, like Cr-215, and freeways like I-15. Also, the recommendations for speed monitoring displays being appropriately used on arterials and freeways will be discussed. (Abstract shortened by UMI.)