Benefit

Driver Assist System improves bus operations, with bus speeds increasing by 3.5 miles per hour.

Experience of Minnesota Valley Transit Authority in deploying DAS for shoulder-running buses in the Minneapolis metro area.


March 2013
Minneapolis,Minnesota,United States


Summary Information

In November 2010 as part of its Urban Partnership Agreement for congestion reduction, the Minnesota Valley Transit Authority (MVTA) implemented a Driver Assist System (DAS) for bus shoulder operations on Cedar Avenue (Trunk Highway 77). The DAS is a Global Positioning System (GPS) based technology suite that provides accurate lane position feedback to the bus driver. It includes a head-up display (HUD) mounted at eye level in front of the driver that digitally displays the shoulder boundaries under all weather conditions. Other features include a virtual mirror that digitally displays vehicles in the left adjacent lane, a vibrating seat that simulates the sensation of a rumble strip, and a steering activator that provides mild corrective torque to the steering wheel when the bus drifts over the fog line.

MVTA’s primary goal for the DAS was to enhance driver confidence when driving on the shoulders. Secondary goals included reducing travel times and increasing reliability, safety, and customer satisfaction.

Methodology

The evaluation looked at six broad areas: efficiency/productivity, technical performance, bus driver satisfaction, customer satisfaction, safety, and maintenance. It involved two test periods, first with the DAS set to passive mode with the onboard computer collecting lane position and speed data not available to the driver. During the second test period the DAS was switched to active mode. Although 25 drivers drove a DAS-equipped bus at some point in the evaluation, only 6 used the shoulder during both test periods and could be included in the evaluation.

All 25 DAS-trained bus drivers completed a survey, and 16 participated in 2 focus groups. A passenger survey was distributed on all DAS-equipped buses, resulting in a response rate of 29.5 percent.

Results

Efficiency and Productivity
  • Overall, drivers stayed in the shoulder 4.3 percent longer when the DAS was active. However, this change was not statistically significant at the 95 percent confidence level.
  • All of the drivers drove faster when the DAS was in use, with an average increase of 3.5 mph (5.6 km/hr). This increase was statistically significant at the 95 percent confidence level.
Technical Performance
  • Overall, side-to-side movement was reduced by 4.7 inches, going from 17.6 to 12.9 inches (44.7 to 32.8 cm). This change was statistically significant at the 95 percent confidence level.
Safety
  • The empirical data confirmed that bus shoulder operations continue to be safe. There were zero accidents in the shoulder during both periods. As of September 2012 (17 months after the evaluation), there still had been no accidents in the shoulder with the DAS-equipped buses.
  • In the bus driver surveys, 62.5 percent agreed or strongly agreed that the DAS made driving in the shoulder safer.
Bus Driver Satisfaction
  • In the bus driver survey, 88 percent agreed or strongly agreed that the DAS was easy to use, and 64 percent agreed or strongly agreed that the DAS made driving in the shoulder less stressful.
  • However, there were some negative comments in the focus groups. Some drivers indicated that the HUD was distracting.
  • In contrast, the vibrating seat was highly regarded in both the survey and the focus groups, with 80 percent of the survey group agreeing that it was valuable.
  • A total of 32 percent of bus drivers said their level of confidence in driving in the shoulder was greater when using the DAS, and 60 percent said it was the same.
Customer Satisfaction
  • More than 80 percent of passengers rated various aspects of the ride quality of the bus such as merging in and out of the shoulder, vehicle swaying, accelerating/decelerating, and overall smoothness of the ride as good or very good.
Maintenance
  • Based on a review of the maintenance log, the 10-vehicle DAS fleet was operative 91.9 percent of the time during the evaluation period.
  • The most frequently cited malfunction was a lack of feedback to the vibrating seat.
These results suggest that the DAS improves driving performance for shoulder-running buses.

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Source

Impacts of the Cedar Avenue Driver Assist System on Bus Shoulder Operations

Author: Brian Pessaro

Published By: Journal of Public Transportation

Source Date: March 2013

URL: http://www.nctr.usf.edu/wp-content/uploads/2013/03/16.1_pessaro.pdf

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Typical Deployment Locations

Metropolitan Areas

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Benefit ID: 2014-00916