Intelligent Transportation Systems, or ITS, is the application of electronics, communications, and/or information processing to improve the efficiency and/or safety of surface transportation systems. ITS can improve transportation safety, mobility, and societal productivity through the integration of advanced communications technologies into the transportation infrastructure and in vehicles. ITS encompasses a broad range of wireless and wire line communications-based information and electronics technologies. This report documents several case studies of how agencies used work zone intelligent transportation systems (ITS) to mitigate safety and mobility issues in work zones. The report illustrates how to apply a systems engineering-based decision-making process to designing, selecting, and implementing a system to address work zone needs. The report presents the steps followed by the agency/contractor in this decision-making framework for five specific projects. The work zone ITS deployments documented provide examples of selecting and deploying commercial off-the-shelf (COTS) systems; a tailored design and integration of ITS for a specific work zone purpose; and using and supplementing permanent ITS deployments for work zone management purposes. Tips are provided for how to effectively apply ITS to other work zones.

This document provides quantitative benefits of using Intelligent Transportation Systems (ITS) in highway construction and maintenance work zones. The summary report covers case study sites in the District of Columbia, Texas, Michigan, Arkansas, and North Carolina and provides insights into the mobility and safety benefits of ITS for work zone traffic management.

In recent years, there has been a considerable increase in the amount of construction work on the U.S. national highways. Most of the work undertaken is the reconstruction and rehabilitation of the existing transportation networks. Work zones in the United States are likely to increase in number, duration and length due to emphasis on repair and highway reconstruction as a significant portion of all federal-aid highway funds are now geared toward highway rehabilitation. The challenge of mobility is particularly acute in work zone areas as road repair and construction intensifies traffic issues and concentrates them in specific locations and at specific times. Due to the capacity drop, which is the result of lane closure in work zone area, congestion will occur with a high traffic demand. The congestion increases number and severity of traffic conflicts which raise the potential for accidents; furthermore traffic operational properties of roadway in work zone area become worse. Intelligent Transportation System (ITS) technologies have been developed and are being deployed to improve the safety and mobility of traffic in and around work zones. In several states in the US, the use of Dynamic Merge Controls also known as Dynamic Lane Merge (DLM) system has been initiated to enhance traffic safety and to improve traffic flow in work zone areas. The DLM usually takes two forms; dynamic early merge and dynamic late merge. The use of variable speed limit (VSL) systems at work zones is also one of those measures. VSL systems improve safety by helping the driver in determining the maximum speed that drivers should travel. Besides adding improvement to safety, they are also expected to improve mobility at the work zones. The main goal of this study is to evaluate the safety and operational effectiveness of the dynamic merge systems i.e. the dynamic early lane merge and dynamic late lane merge, in the presence of VSL system. More specifically, the VISSIM model is utilized to simulate a two-to-one lane configuration when one out of the two lanes in the work zone is closed for traffic. Six different scenarios were adopted to assess the effectiveness of these scenarios under different traffic demand volumes and different drivers' compliance rates to the messages displayed by the systems. These scenarios are; [bullet] Work Zone without VSL and without SDLMS or the current Motorist Awareness System (MAS) [bullet] Work Zone with VSL and without SDLMS [bullet] Work Zone with VSL and Early SDLMS [bullet] Work Zone with VSL and Late SDLMS [bullet] Work Zone with early SDLMS and without VSL [bullet] Work Zone with early SDLMS and without VSL An already calibrated and validated VISSIM model for Simplified Dynamic Lane Merge System (SDLMS) in accordance with the real life work zone was modified with a VSL through Vehicle Actuated Programming (VAP) code. Three different logics were coded each for VSL alone, early SDLMS+VSL and late SDLMS+VSL. All these logics were fine tuned with several test runs before finalizing it for the final simulation. It is found through the simulation of above mentioned scenarios that for low and medium volume levels (V0500, V1000 and V1500), there is no significant difference between the Maintenance of Traffic (MOT) plans for mean throughputs. However, for higher volume levels (V2000 and V2500), late SDLMS with and without VSL produced higher mean throughputs for all compliance rates and truck percentages except when the demand volume was 2,500 vph and compliance of 60%, where it produces the significantly lower mean throughputs. In terms of travel time through the work zone, results indicated that there is no significant difference between MOT types for demand levels of V0500 and V1000 when compliance is 40% or less but for compliance of 60% and more, only demand volume level that is not significantly different from other MOT types is V0500. This study revealed that VSL increases travel time through the work zone. This might be due to non-compliant vehicles that follow the compliant vehicle ahead unless they find a sufficient gap in adjacent lane to pass the compliant vehicle. It is also found out that VSL makes the system safer at higher volumes (2,000 vph and 2,500 vph). This was observed through safety surrogate measures selected for this study. Another outcome of this study is that the addition of VSL to the dynamic merge systems helps in improving the overall safety of the system by lowering speed variances and deceleration means of the vehicles travelling through the work zone. The passage of traffic through the work zone is made safer when a speed control is integrated to a dynamic merge system. It can be inferred from the simulation results that integrated SDLMS and VSL systems have better performance in terms of traffic mobility and safety than existing individual controls and also show that the integrated SDLMS and VSL system has more potential than each individual systems.

This book increases the level of knowledge on road safety contexts, issues and challenges; shares what can currently be done to address the variety of issues; and points to what needs to be done to make further gains in road safety.

This primer has been developed to assist agencies in establishing and monitoring a useful set of work zone safety and mobility performance measures. Work zone performance measures are metrics that help to quantify how work zones impact travelers, residents, businesses and workers. Work zone performance measures help agencies improve their understanding of how their decisions during planning, design, and construction affect work zone safety and mobility, and thus can help improve how they make decisions for future work zones. The primer describes possible work zone performance measures, and provides guidance to help agencies select and implement measures that make sense for their own work zone programs. The primer outlines the methods and technologies that are available to gather data to monitor the various possible measures and procedures for calculating specific performance measures from different types of work zone traffic monitoring data. The primer also discusses the use of measures across multiple projects to assess an agency's overall efforts and outcomes against its policies and goals.