The goal of this study is to determine the impact of Non-Recurring Congestion (NRC) on freeway and arterial traffic operations, and to identify suitable countermeasures for each road environment. This study has two key objectives: - Gain a better understanding of the role played by various random incidents related to traffic, weather, and special events that result in non-recurring traffic congestion on the freeway system and on the arterial system in the region.
- Identify effective countermeasures, best practices and recommend a plan to test them in the Phoenix metropolitan region. These countermeasures should help regain some of the lost road capacity due to NRC, thus reducing the need for adding new road capacity.
BACKGROUND Non-Recurring Congestion on both freeway and arterial systems have been identified, in general, as the unexpected traffic delays caused primarily by crashes and incidents, vehicle breakdowns, road construction activities, special events, extreme weather events etc. In addition, NRC is also caused by rubbernecking motorists, police investigations at crash sites, in some instances by improper usage of Dynamic Message Signs that display long complex messages. A number of existing programs in the Phoenix metropolitan region support traffic management functions that aim to mitigate the overall impact of NRC on traffic operations. The ALERT emergency response team of Arizona DOT, responds to major crashes or hazardous material spills on the freeway system. The Freeway Service Patrol, funded by MAG and operated by the Department of Public Safety, provides emergency roadside assistance to well over 10,000 motorists stranded on the regional freeway system each year. The REACT traffic incident management team of Maricopa County, responds to incidents on the arterial street system within all unincorporated areas of the County, and within a few local communities in the west valley. Nationally, it has been estimated that nearly 60 percent of all urban traffic congestion could be attributed to NRC. However, the NRC phenomenon has not been examined in detail in large metropolitan regions to clearly identify the true magnitude of its impact, which is a goal of this study. The findings from this study could be used as justification to direct more resources for effective NRC countermeasures. If, for instance, the overall impact of NRC in the I-10 corridor is shown to be equivalent to the reduction of one lane of freeway capacity during the peak traffic demand periods, a new countermeasure such as a focused corridor incident management program would be a much less expensive alternative for the region than adding a new freeway lane. The same would be true for arterial operations. How much of available road capacity is wasted by traffic blockages due to random incidents, attributable to NRC causal factors, will be estimated by this project. The data to be utilized would include actual traffic incident data gathered from Arizona DOT crash data, DPS reports, Phoenix Fire CAD reports, 911 logs, logs based on crashes reported by AM and FM radio stations, REACT reports, RADS data archive, and other internet sources for real-time traffic information. A review of police reported crashes for 2006 in the Phoenix metropolitan region, indicate that nearly 50 percent of the 21,000 freeway crashes occurred during the AM and PM peak traffic periods. In comparison, nearly 55 percent of 73,000 reported crashes on the arterial street system occurred during peak traffic periods. It must also be noted that nearly two thirds of all travel in the MAG region occur on the arterial street system. Therefore, it is possible that arterial travel is more affected by NRC than freeway travel. The countermeasures for NRC that are sought through this project may require a special focus on solutions that are applicable on the arterial system. Oversight for this study will be provided by a Technical Advisory Group (TAG) which will consist of members of the MAG Intelligent Transportation Systems Committee. TASKS This study will accomplish the tasks listed below as a minimum. Additional tasks may be proposed to enhance this approach. | Task 1: | Literature Review of NRC, Potential Countermeasures | | Task 2: | Develop a Methodology for Quantifying NRC and a Data Collection Plan | | Task 3: | Data Collection, Analysis and Estimation of the Impact of NRC on Freeway and Arterial Systems, Transit and Freight | | Task 4: | Identify Countermeasures & Required Resources | | Task 5: | Develop an Implementation Plan | | Task 6: | Develop the Framework for a Pilot Project | | Task 7: | Final Report and Executive Summary |
AVAILABLE BUDGET: $ 300,000 ANTICIPATED STUDY DURATION: 18 months STATUS: An RFP was announced on July 1, 2009. The project will commence following MAG approval of the consultant to be selected. See more information posted below under Upcoming Events and Resources. |
