Can advanced technologies really help curb highway congestion?
- 21 April, 2012 01:32
According to the Department of Transportation (DOT), congestion costs America an estimated $200 billion a year in lost travel time and fuel, and drivers in metropolitan areas spend more than one-quarter of their total annual travel time in congested conditions.
In a report out this week by congressional watchdogs at the Government Accountability Office noted that state and local governments have used technologies it calls Intelligent Transportation Systems (ITS) that consist of a range of communications, electronics and computer program to help manage congestion. But, while there's even more technology in the pipeline, state and local governments face many challenges in planning and funding ITS use, ensuring that staff and leaders have adequate knowledge of the technology, and coordinating ITS approaches to make the most effective use of such technologies.
The GAO spotlighted these emerging technologies which include:
1.Traffic management applications: State and local governments within some metropolitan areas, such as Washington, D.C., are employing new traffic management applications that make use of data integrated from various, previously siloed databases. The objective of these approaches is to collect, manage, integrate, and apply real-time transportation data. Agencies integrate a variety of real-time information -- including incident information, travel time, and weather advisories -- obtained from various sources to manage the transportation system and provide relevant information to travelers. The expansion of real-time data collection technologies and coverage in recent years has allowed for greater use of these data in daily traffic operations. As one expert noted, data are the foundation of managing congestion, and the more and better quality the data, the better the tools that can be brought to bear on managing traffic. In addition to supporting a more active role in managing traffic, such data allow management agencies to provide real-time traffic advisories and support performance measurement, the GAO stated.
Collection and integration of data -- such as traffic and emergency services data -- across jurisdictions can enhance incident management by allowing quick detection and response to incidents. For example, the I-95 Corridor Coalition makes vehicle probe data available to 19 agencies, which use the data to monitor traffic patterns across state boundaries and to respond to incidents and congestion. In 2009, the New York State Police used these vehicle probe data along with data from the New York 511 website to assist in managing holiday traffic congestion. This proactive approach to traffic management led to a 50% reduction in traffic queues over previous years.
The Regional Integrated Transportation Information System (RITIS) program in the Washington, D.C., area is an example of data integration that allows for improved traffic operations, incident management, and traveler information. RITIS is a system that compiles data across modes of transportation from agencies throughout the metropolitan area, including data on incidents, weather, managed lane status, signal status, and data from public safety computer-aided dispatch systems. RITIS then standardizes these data, and makes them available to participating agencies. Previously, many of the area transportation agencies had implemented stand-alone systems and relied on ad hoc communications that were driven by personal relationships between staff for coordination.
2. Active traffic management: The proactive management of roadway capacity and transportation demand is the next step in congestion relief. In Seattle, the Washington State DOT has instituted active traffic management systems. These systems, which are among the few such systems in the country, use overhead signs that display changing speed limits and real-time traffic information for drivers over each lane. These signs automatically reduce speed limits to alert drivers to slow their vehicles when they approach congestion, collisions, or backups at off-ramps. The signs also alert drivers to upcoming lane closures because of traffic incidents or road work and direct them to open lanes. The system also includes message signs that alert drivers of downstream backups and signs that display estimated travel times, the GAO stated.
Although a formal evaluation of the systems in Seattle is forthcoming, the government has reported that similar systems in Europe, depending on the location and the combination of strategies deployed, have resulted in increases in overall capacity ranging from 3 to 22 percent, increases in travel time reliability, and reductions in primary incidents ranging from 3 to 30 percent.
Technical advances now make it possible to move from relatively passive monitoring to proactive control of traffic through mechanisms like variable speed limits, congestion pricing, and ramp metering. Active transportation and demand management is a proactive approach for dynamic management and control of existing transportation infrastructure based on current traffic conditions using real-time data and information. This approach considers the real-time management of both supply and demand to prevent, delay, or minimize facility breakdown when travel demand exceeds system capacity.
Active transportation management can also include managed lanes, in which officials control traffic lane use by granting access to only certain types of vehicles, such as high occupancy vehicles; controlling access, such as designing express lanes where access is restricted to a few points; or congestion pricing, where vehicles pay a toll to use the lane.
3. Road pricing: Some say one strategy to reduce congestion is road pricing or congestion pricing -- assessing tolls that vary with the level of congestion and the time of day. This demand management strategy aims to improve the flow of traffic by motivating drivers to travel by other modes, such as carpools or transit, or by traveling at less congested times. For example, in Los Angeles, the California Department of Transportation and the Los Angeles County Metropolitan Transportation Authority are converting over 50 miles of freeway from High Occupancy Vehicle, or carpool, lanes, to High Occupancy Toll lanes. This is to allow use of excess capacity in the lanes by single occupancy vehicles for a price. Agencies have used electronic fare collection and traveler information ITS technologies to accomplish this conversion. Officials can also proactively manage traffic conditions through ramp metering, which can maintain smooth freeway flow by regulating vehicle entry at entrance ramps. DOT's 2010 deployment survey found that freeway agencies believe ramp control has high benefit, despite the fact that the technology is lightly deployed.
4. Work zone technology: Work zone management is another emerging use of ITS applications to proactively manage traffic. Transportation agencies can use work zone management to reduce the congestion normally associated with construction activities such as lane closures. Agencies use ITS to mitigate the effects of lane closures, detours, and other factors. Examples of ITS technologies used in work zones include using electronic signs to control merging for lane closures and variable speed limit signs. Agencies also use traveler information ITS technologies to notify the public of road closures and work zone-related delays.
5. Wireless everywhere: Connected vehicle technology, still under development, could significantly change traffic management, both in terms of the amount of traffic data transportation agencies will collect and in how agencies proactively manage traffic. DOT's current ITS research agenda focuses on the department's vision to provide the nation with a national, multimodal transportation system that features wireless communications among vehicles, infrastructure, and portable devices. The importance of data management and integration will continue given that connected vehicle technology has the potential to significantly increase the amount of transportation data available to state and local governments, the GAO stated.
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