This study used the HOWLATE (Heuristic On-line Web-Linked Arrival Time Estimator) model to simulate traffic activity with and without traveler information. Initially, the study questioned 19 transportation professionals to estimate the amount of extra time they would budget for personal or business related travel in unfamiliar areas of two major metropolitan areas. The amount of extra time allocated for unfamiliar trips in Washington, DC and Minneapolis, MN was then normalized and integrated into the HOWLATE model as an impact factor. The Washington, DC simulation model was then run using the impact factor to quantify the overall difference in early arrival times between advanced traveler information systems users (ATIS-users) and advanced traveler information systems non-users (ATIS non-users) if the overall objective for all trips was to arrive on-time.
The HOWLATE system compared millions of simulated paired (yoked) driving trials on a network of 169 arterial and freeway links in the Washington, DC metropolitan area. Baseline link travel times were obtained from an archive of travel time estimates reported by SmarTraveler.com, a traveler information website that provided link travel time updates every five minutes on weekdays between June and July of 2000.
During the survey, respondents used a city map to estimate the amount of time they would budget for various trips in each city depending on the need to arrive on-time for a job interview, or to meet an out-of-town friend for dinner. In general, the survey showed that drivers in unfamiliar areas were very conservative, and as travel time uncertainty increased, the time they allowed for their trips increased.
Based on all simulated trips on the Washington, DC network, both ATIS users and the ATIS non-users were on time approximately 99 percent of the time. Drivers that used ATIS, however, significantly reduced the amount of time spent on early arrivals.
Using ATIS, unfamiliar drivers arrived at their destination within 15 minutes of the target arrival time 79 percent of the time. Without ATIS, unfamiliar drivers arrived within 15 minutes 42 percent of the time.
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