An Evaluation of ITS for Incident Management in Second-Tier
Cities: A Fargo, ND Case Study
Authors: Birst, Shawn and Ayman Smadi
Summary Information
This paper describes the results of a simulation study to determine the impact of a freeway
management system on incident-related congestion in Fargo, North Dakota. The study also
investigates the benefit of coordination between the freeway management system and an arterial
management system to enable adaptive signal control based on the demands of the additional
traffic diverted from the freeways during an incident. Simulation allowed the estimation of the
impacts of both systems on travel times during an incident resulting in the closure of one freeway
lane for twenty minutes.
The highway network investigated in this study consisted of the area surrounding the intersection
of Interstates 29 and 94 in Fargo. At this point, the interstates serve primarily local traffic in Fargo,
which is the largest city in the four-city Fargo-Moorhead metropolitan area. The area had a
population of approximately 166,000 in 1996. Included in the study area were four of the area’s
most heavily traveled arterials, providing travelers with alternative routes for diversion around the
incident, which was simulated to occur in the northbound lanes of I-29 just north of the
intersection with I-94.
The simulation provided traveler information to drivers in the form of link travel times for all
possible routes and, for the relevant cases. For the case investigating the integration of freeway
information dissemination with adaptive signal control, the simulation software emulated the Split
Cycle Offset Optimization Techniques (SCOOT), optimizing arterial cycle lengths, phase splits
and offsets every 5 minutes with phase lengths ranging from 60 to 120 seconds.
Results of the investigation indicate that a freeway management system consisting of variable
message signs to alert motorists of upcoming incidents can have a significant positive impact on
freeway operations in a city of moderate size, such as Fargo. Simulation revealed an 8%
decrease in network travel times and an 8% increase in speeds with the installation of the VMS
signs. Integrating this freeway management system with an adaptive signal control system on
adjacent arterial roadways compounded the benefits of the improvements, resulting in an 18%
reduction in travel times and a 21% increase in vehicle speeds.