The Advanced Transportation Management System provides the following benefits:
According to the ATMS system-wide evaluation benefits analysis performed by an independent consultant, the number of trips is expected to grow between Montgomery County and all other neighboring counties, except Fairfax County, VA. With a 22 to 31 percent increase (from 1996 and 2010) in origin-destination County work trips, travel conditions are expected to deteriorate. The average travel speed will drop by six to ten miles per hour, and an increase in travel time of three to eight minutes is projected. The vehicle-miles of travel and vehicle-hours of travel will also increase, causing increased delays to trips and resulting in worse levels of service to traffic on all County roadways.
Without the County ATMS the total vehicle-hours of travel spent on Montgomery roads in 1996 was estimated as 180,658 hours, based on work trips. By the year 2010, without an ATMS the vehicle-hours of travel will increase by approximately 74 percent (313,661 hours), with only a 27-percent increase in work trips. Considering a projected 75 percent growth rate in traffic over the next 25 years with only a 20 percent expansion rate in road capacity, these conditions can only be compounded without the benefits of additional capacity to accommodate the traffic growth or other traffic management strategies such as the ATMS.
Given these projections, the benefits of an ATMS can be expected to gradually reduce the adverse impacts of congestion with full deployment of all ATMS subsystems. The maximum ITS benefits from the implementation of all system components should be realized in reducing future congestion.
In the case of traffic management, a reduction in travel time can be expected to be a major benefit in improving the flow of traffic both in recurring and non-recurring congestion. Estimated benefits to the County from the traffic responsive signal control system can be expected through improvements in travel time of about 8 to 10 percent, which leads to a reduction of vehicle hours traveled and average speed increases of 14 to 20 percent. This improves travel speeds on the County roadways by about 6 miles per hour (from 28 to 34 miles per hour), in addition to reducing travel delays by 17 to 37 percent.
The information dissemination component of the ATMS which includes the Variable Message Signs (VMS), Travelers Advisory Radio System (TARS), Internet, and Cable TV will reduce travel times by giving travelers the information needed to select the most appropriate routes, mode, or departure time for their trips. These benefits are being realized, with about an 8 to 11 percent reduction in travel time for en-route motorists using advisory messages from the VMS and TARS. These devices have great potential in reducing traffic congestion along some of the County’s busiest roadways, such as MD 650, U.S. 29, Interstates 270 and 495. The Internet, Cable TV, and radio provide benefits for pre-trip planning and route guidance with reductions in system travel times of about 2 to 7 percent. The expected mode shifts from single occupancy auto to rideshare and transit should provide a significant improvement in travel time from about 11 to 35 percent.
The County benefits from the incident management program, which reduces travel time by 10 to 42 percent. In Montgomery County, the state operated Chesapeake Highway Advisory Routing Traffic (CHART) is responsible for freeway incident management and the Montgomery County DOT is responsible for arterial incident management. In a study performed by Maryland State Highway Administration (MSHA), the total annual delay due to non-recurring congestion was 40 million vehicle hours. As a result of the CHART incident management program the delay due to incidents has been reduced by 2 million vehicle hours. This results in a benefit in annual fuel savings of 398,000 gallons and an annual public cost savings of $30.5 million.
The transit management use of the GPS/AVL system will be beneficial in improving the transit schedules and the on-time performance for the County’s bus system. Over the last 12 months, the on-time performance for the transit fleet was reported as Metrobus 80.4 percent; Silver Spring Ride On 94.3 percent; Gaithersburg Ride On 90.1 percent; and ATE (Contract Buses) Ride On 93 percent. The on-time performance will improve with the completion of the GPS/AVL system installation.
The following table shows a summary of ATMS components, measures-of-effectiveness and their potential benefits:
|ATMS Component||Measure of Effectiveness||Potential Improvement|
|Traffic Signal System||Travel Time
Number of Stops
|Decrease 8 -10%
Increase 14 - 20%
Decrease 17 - 37%
Decrease 1 - 35%
Decrease 4 – 10%
Decrease 5 - 13%
Decrease 6 -12%
|Incident Management||Incident Clearance Time
Decrease 5 - 8 minutes
Decrease 10 - 42%
Decrease 300,000 hrs per year
Decrease 17 min (20%) in incidents
Decrease up to 1900 vehicle-hrs
Decrease 25% for diverted drivers
Decrease 33% for diverted drivers
Decrease 1.5% for diverted drivers
Incident Response Time
Decrease 15 - 18%
Decrease 4 - 13%
Increase 12 - 28%
Decrease 40 - 50%
|Transit Signal Priority||Travel Time<||Decrease 5 - 8%|
|Red Light Enforcement||
Number of injuries/fatalities
Number of Accidents
Decrease 20 - 80%