TravInfo Evaluation: The Target Study Phase 1 Results

Problem and Method

During the study, two significant incidents occurred in the study area: a multiple-vehicle injury accident on southbound US-101 in San Mateo blocked the left two of four lanes causing a backup of approximately 5 miles. Within three weeks of the southbound accident, a jack-knifed semi in South San Francisco blocked the number 5 lane and South Airport Boulevard on-ramp. Both accidents took over 30 minutes to clear and had significant effects on traffic conditions.

Approximately 15 percent of the total sample population actually modified their travel on the morning of each respective incident. About half of the participants recall hearing about the incidents, mostly from commercial radio broadcast. Approximately one third modified their travel behavior on the morning of the incidents. Over two thirds of the participants reported that they encountered congestion on the morning of the incident. Most survey participants (91.5 percent of southbound and 84.6 percent of northbound) were unfamiliar with the TravInfo TATS service.

The results of the survey suggest that individual incidents do not affect traveler behavior significantly. Even though a fair portion of commuters were aware of traffic problems on the mornings of the incidents, relatively few actually modified their trip. It does not seem to be the case that commuters do not care about being slowed down by traffic congestion, rather, the likely explanation for the lack of response to incident information is that commuters generally do not believe that changing their travel plans, in particular taking an alternate route, will result in shorter travel times.

Findings

TravInfo is a federally funded Field Operational Test (FOT) of an open-access traveler information system for the San Francisco Bay Area. In operation since September 1996, TravInfo Traveler Advisory Telephone System (TATS) disseminates real-time traffic information and multi-modal travel options to Bay Area travelers through a landline telephone system.

This research examined commuter response to traffic information on incidents along US-101 south of San Francisco. The purpose of the Target Study was to assess the impact of TravInfo on a selected corridor in the presence of incidents under which TravInfo impacts/benefits are likely to be greatest. A panel survey approach was chosen to assess changes in travel behavior over time. A panel was created of 563 southbound and 526 northbound commuters whose primary commute route includes the selected US-101 freeway segment during morning peak hours between 6-10 a.m.