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The project focuses on two major issues - the improvement of current work zone design practices and an analysis of vehicle interarrival time (IAT) and speed distributions for the development of a digital computer simulation model for queues and travel delays in work zones. Important considerations in the development of work zone design guidelines include guidance, delineation, and the safety of workers and drivers. A nationwide survey of current work zone best practices was conducted. Based on the review of the existing ODOT guidelines, superior practices available in other states, relevant research, and professional judgment of personnel involved in work zone activities, a set of guidelines for work zone design are proposed. It is anticipated that these research findings will result in the better design of work zones which will minimize traffic delays and improve safety. In the second part of the project trailers, each using two Wavetronix microwave radar units in side-fire mode, were developed to nonintrusively measure traffic. The traffic was measured at six work zones sites with different types of lane configurations at different freeways in Ohio. Traffic on the road was also independently measured using video and radar, and the results compared to records from the trailers to verify that the trailers were measuring the traffic with reasonable accuracy. IAT data of successive vehicles in freeflowing traffic ahead of work zones were analyzed and IAT distributions were generated as a function of the traffic volume for each lane and relationships between traffic volumes and cumulative IAT distributions were established allowing a direct conversion from hourly traffic counts to corresponding cumulative IAT distributions. This conversion method produces fairly accurate cumulative IAT distributions for selected hourly traffic volumes. It was also found that the same cumulative IAT distribution can be used to model the free-flowing traffic at other freeway locations in Ohio, which means that the IAT distributions are portable and scalable and a microscopic digital computer simulation model based on queueing theory may be developed to investigate traffic delays in work zones.
This Work Zone Best Practices Guidebook provides an easily accessible compilation of work zone operations practices used and recommended by various States and localities around the country. The Guidebook is a reference document that can be updated with new approaches, technologies, and practices for effectively managing work zones and reducing the impacts of work zones on mobility and safety as they are identified. The best practices are descriptive, not prescriptive. They describe approaches that have been successfully used by transportation agencies, along with contact information to find out more from the agency using the practice. Each organization must determine which of these practices are best suited for its particular situation, considering all the site-specific factors that affect work zone operations.
This project contains three major parts. In the first part a digital computer simulation model was developed with the aim to model the traffic through a freeway work zone situation. The model was based on the Arena simulation software and used cumulative interarrival times as the input. Its aim was to determine the traffic volumes through the work zone and the queue lengths in advance of lane restrictions. The program was designed to handle up to 15 miles in length, up to six lanes, and up to 20 entrance and exit ramps. The developed program has not been validated due to the lack of reliable field data and the program appears to produce unreasonably short queue lengths and low exit ramp traffic counts compared to the input traffic data for cases where the exit ramps are spaced closely together. In the second part a diversion analysis was performed to determine the effects of closed ramps. The work zone sites were assigned by Ohio Department of Transportation and the diversion effects for these situations were in one case very minimal and in the other case as expected (traffic shifted to the next open exit ramp). In the third part guidelines for ramp management and ramp metering were established on a 24/7 basis giving special considerations to freeway mainline throughput and local traffic access to freeway.
"Addresses various ways that transportation agencies can reengineer their day-to-day business practices to enhance traffic operations, address nonrecurring traffic congestion, and improve the reliability of travel times delivered to roadway system users"--Foreword.
RB’s National Cooperative Highway Research Program (NCHRP) Synthesis 432: Recent Roadway Geometric Design Research for Improved Safety and Operations reviews and summarizes roadway geometric design literature completed and published from 2001 through early 2011, particularly research that identified impacts on safety and operations.
The purpose of this manual is to provide clear and helpful information for maintaining gravel roads. Very little technical help is available to small agencies that are responsible for managing these roads. Gravel road maintenance has traditionally been "more of an art than a science" and very few formal standards exist. This manual contains guidelines to help answer the questions that arise concerning gravel road maintenance such as: What is enough surface crown? What is too much? What causes corrugation? The information is as nontechnical as possible without sacrificing clear guidelines and instructions on how to do the job right.