Introduction

Purpose

In 2003, the Federal Highway Administration (FHWA) developed plans for a study to quantify the benefits of deploying Intelligent Transportation Systems (ITS) for mitigating impacts caused by highway construction and maintenance. The Work Zone Mobility and Delay Reporting Assessment began in August 2003 to document the tangible benefits of work zone ITS in a quantitative way. This study was intended to increase the body of knowledge regarding the effects of deploying work zone ITS so that practitioners have additional information to draw from in designing and deploying ITS in work zones.

In the recent past, some owner-agencies across the nation have deployed portable ITS technologies to monitor traffic and manage mobility and safety during construction. Portable systems provide a solution for deployment, maintenance, operation, and remobilization of monitoring systems, especially since the roadway characteristics often change dramatically during construction. Most of these systems take the form of mobile traffic monitoring and management through the use of portable sensors to collect traffic data and integrated portable changeable message signs (PCMS) to display speed and/or delay information in real-time. Agencies also often integrate a Web site into the overall system to provide motorists with pre-trip information to allow for better trip planning. A few agencies have also used portable ITS to help manage merging behavior approaching work zone lane closures.

Site Selection – Process and Criteria

To supplement a list of potential sites developed by FHWA, the study team performed research to learn about additional sites across the country. Out of over 30 initial sites, the study team eliminated more than 20 because they were not specifically work zone systems or because the deployments were already underway (which meant that there was little or no chance for comparison "without" data). The study team then developed a master site list and a technical memorandum that highlighted information on the sites that provided the best opportunity to quantify the benefits of using technology to mitigate the mobility, safety, and delay impacts caused by highway work zones.

The study team held conversations with deploying agency representatives to discuss the main goals and objectives of each system deployment, the schedule for construction, the status of system deployment, and estimated capacity reduction and construction impacts to traffic. The study team then applied primary and secondary site assessment criteria, as shown below, to the potential sites to determine which deployments would provide the best opportunity to measure impacts in and around the work zone. Some of the sites on this narrowed list of 10 potential sites did not appear to provide an opportunity for a quantitative evaluation. Other sites/systems had a design and concept of operations that would likely have proven very difficult to evaluate given cost constraints. The study team applied the criteria to help narrow the list and choose five sites to study.

Primary site selection criteria included:

Availability of archived data and the infrastructure for data collection.
Anticipated availability of "before" data (before the work zone).
Anticipated availability of "without" data (work zone without ITS applications).
Deployment probability.
Status of ITS system deployment schedule.
Existing relationships with either the vendor or the deploying agency that would facilitate a cooperative effort.
Anticipated availability of data from other evaluations at the site.
Location type (rural, urban, downtown).
Typical volume/capacity or level of congestion.
Percentage of local traffic versus through traffic, percent trucks, percent commuter traffic.
Roadway type and number of lanes.
Construction schedule.
The State's ability to articulate specific goals and objectives for what it hoped to accomplish by using the system.
Primary purpose or goal for using the system (safety versus mobility).
Type of system being implemented.
Type of traveler information to be provided by the system.

Secondary site selection criteria included:

Existence of a traffic management center for support/data.
Size of construction project.
Contractor's ability to change schedule for increased productivity.
State's experience with the use of ITS in work zones.
Geographic location.
System vendor.

Where appropriate, a rating of "high," "medium," or "low" was applied to each site for each criterion. For classification-based criteria such as location type, each site was classified based on its characteristics. Once this step was completed, the study team further eliminated sites based on these primary and secondary criteria, to remove those sites that may not be appropriate for inclusion in this project.

Based on discussions with local contacts and a preliminary assessment, the study team selected two sites, one in Arkansas' and one in North Carolina, early on in the process. For the other sites, the study team continued to use the assessment criteria to develop summary pros and cons and made recommendations based on this information. The study team also ranked the narrowed list of sites based on which sites illustrated the greatest opportunity to see quantified benefits.

Based on this process, the study team chose two additional sites—one in Texas and one in Michigan. The recommended sites are those where construction showed significant potential to have a measurable impact on traffic conditions, creating a situation where ITS could be used to reduce this impact. The study team chose the fifth site in the District of Columbia because the study team and local agency representatives expected significant construction impacts, especially due to the urban setting and high demand for the network.

Timing of the Evaluations

Planning for the evaluations often required long lead time ahead of data collection and analysis. For each site, the study team spent several months gathering and documenting information from stakeholders for use in developing the evaluation plans. The study team began by contacting stakeholders to determine system status, plans, goals and objectives, and progress on the deployment, followed by evaluation planning, data collection and analysis, and reporting. While the time for each site evaluation varied in length, the following bullets highlight the timeframe in which the study team performed data collection and analysis for each site.

Arkansas – Spring/Summer 2004.
North Carolina – Summer 2004.
Michigan – Fall 2004.
Texas – Summer 2006.
Washington, DC – Summer 2007.

The original length of the overall study was less than 1 year. However, due to several issues, the overall study spanned a period of several years. The issues that hindered the evaluation included the initial difficulty in finding sites that met the selection criteria (e.g., there was an absence of clear goals and objectives for some systems from which measures could be developed), construction delays, and ITS deployment delays.

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