In 2004, the Federal Highway Administration (FHWA) implemented the Work Zone Safety and Mobility Rule to focus on improving work zone operations. State Departments of Transportation (DOTs) are always looking for tools and applications that can help improve mobility and safety by actively managing traffic through the work zone. ITS applications provide a number of tools that should be considered when looking at options for mitigating traffic impacts that occur during construction. In 2003 an assessment was performed to highlight benefits, lessons learned, and tips from five DOT sites that implemented ITS solutions for work zone traffic management.
The study analyzed data from five sites:
- District of Columbia
- North Carolina
These sites were selected because the construction project showed significant potential to have a measurable impact on traffic conditions, creating a situation where ITS applications could be used to reduce the impact. Each DOT developed a list of lessons learned for other DOTs to weigh when considering work zone traffic management.
In 2000, the Arkansas Highway and Transportation Department (AHTD) began construction of more than 350 miles of roadway throughout the state. Construction included widening approximately 17 of these miles on I-30 from Little Rock to Benton. Seven projects comprised the I-30 work zone corridor and included interchange reconstruction, installing a concrete barrier wall in the median and converting all frontage roads to one-way. The complexity of the projects and extensive work zones lead the AHTD to install an Automated Work Zone Information System (AWIS) covering the entire I-30 Little Rock to Benton work zone corridor.
The objective of adding AWIS to these extensive work zones was to improve the safety and mobility of the travelers and to reduce crashes. The complete system of monitoring equipment included: Dynamic Message Signs (DMS), video cameras, detection sensors, Highway Advisory Radio (HAR), and a website that provided traffic speeds through the work zones. The main areas of evaluation for the work zone encompassed safety, mobility, and productivity as well as the impact on travelers and construction workers. The AHTD shares the following experiences with other implementers should they consider deploying ITS in a work zone.
- Maintain flexibility when deploying ITS in highly variable environments. Arkansas' effort to reconstruct and repair more than 350 miles of roadway was a large, complex undertaking (including seven separate projects by two contractors) with a constantly changing configuration. As a result, the calibration of ITS became an important issue and required one full-time employee devoted exclusively to maintaining all sensors.
- Realize that ITS is just one part of a successful work zone management plan. ITS is only one part of a work zone management plan. ITS components can be instrumental in improving the safety of a work zone; however, it is not a cure all for eliminating the traveler’s exposure to hazards that a work zone imposes. Based on the Arkansas' experience, ITS helped reduce the number of crashes, but crashes, including fatal ones, were not fully avoided.
- Recognize variability in work zone system requirements for all affiliated parties. For example, the emergency dispatchers' use and requirements for the system are very different from those of the contractors. A detailed study of user requirements coupled with revised operating procedures may enhance the system’s capabilities to improve safety and mobility.
- Advertise work zone web site to a greater audience through various media. The evaluation of the Arkansas construction projects found that there is a high level of satisfaction experienced by work zone ITS web site users in comparison to the low level of the number of users. A more targeted advertising campaign may reach a larger audience.
- Use ITS in the work zone to enhance the safety performance of the highway. The construction workers within the construction zones felt that the ITS components deployed improved the safety of both the workers and the travelers.
This lesson suggests that an agency preparing to implement a work zone should consider the impacts it will have on the workers and travelers and consider adding an ITS component to the work zone management plan. Agencies need to understand that implementing ITS components will not eliminate crashes, but they can have an impact on reducing the number of crashes and providing sufficient information for travelers to make educated travel decisions. A work zone that deploys ITS components in a system similar to the AWIS will improve the safety and mobility of the work zone and provide a higher level of satisfaction to the traveling public.