An evaluation in Oregon measured the impacts of expanding the Oregon DOT (ODOT) Region 2 Incident Response program freeway service patrol operations on two 50-mile test corridors (Highway 18 and Interstate 5).

Researchers selected Highway 18 and Interstate 5 to represent corridors with variable usage patterns and contrasting distance to emergency response resources. Highway 18 was a rural road with heavy weekend and recreational traffic and few nearby emergency response resources. In contrast, Interstate 5 was a typical commuter corridor near Eugene, with emergency resources nearby.

The impacts of expanded operations on incident duration were determined from a statistical analysis of archived incident data logged from 1995 to 2000. The data enabled estimation of incident duration before and after increased freeway service patrol support was implemented. The before period (Phase 1: February 1995 to March 1997) included part-time patrol support on each corridor. The after period (Phase 2: March 1997 to December 2000) included expanded support on each corridor, with one full-time staff providing weekend coverage (Friday through Monday) along Highway 18, and increasing levels of weekday coverage along I-5 (beginning with one staff, and growing to 2.5 staff over the evaluation period).

The data archive included specific information for each recorded incident (i.e., incident type, location, time reported, arrival time, time cleared) from which incident duration could be estimated. The number of recorded incidents nearly doubled from 1996 to the year 2000. This increase was due in part to the increase in use of radios by incident response personnel and increased use of cellular phones by the public.

RESULTS

After implementation of expanded freeway service patrol operations, the duration of delay-causing incidents decreased by approximately 30 percent on Highway 18, and 15 percent on Interstate 5. This represents an average decrease of 39 minutes on Highway 18, and 9 minutes on Interstate 5. Researchers analyzed the archived incident reports for consistency, and then sorted the data in terms of incident severity, duration, timing, and location to isolate the potential delay-causing incidents. After filtering through approximately 2,500 individual incident records, 485 delay-causing incidents were identified. On Highway 18 there were 28 delay-causing incidents recorded during Phase 1 and 104 delay-causing incidents recorded during Phase 2. On Interstate 5 there were 67 delay-causing incidents recorded during Phase 1 and 286 delay-causing incidents recorded during Phase 2.

The average cost to travelers of delay-causing incidents on Highway 18 decreased approximately $42,000 (66 percent), with expanded freeway service patrols. The I-5 corridor experienced a drop of approximately $12,000 36 percent) per incident. The study used a deterministic queuing model to estimate the impact of reduced incident duration on vehicle delay. Estimated delays from the model were then converted into person-delay using an average vehicle occupancy factor of 1.53 for Highway 18 and a factor of 1.43 for Interstate 5, and an average value of time of 17.87 dollars per hour. The delay findings were also input into a fuel consumption model, which yielded additional, though comparatively small, cost savings for motorists.