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Case Study Snapshot #2

I-95 Operational Analysis for Lane Closures at Night

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Map showing multiple interstates and intersections affected by the Woodrow Wilson Bridge replacement project.

Maintaining roadway capacity is an important aspect in the ongoing Woodrow Wilson Bridge replacement project in the Washington, DC metropolitan area. Lane closures are conducted only at night to minimize impact on road users. In the fall of 2001, a contractor for the Maryland State Highway Administration was in the process of constructing one of many new bridges as part of the project at the MD 210/ I-295/I-95 interchange just east of the Potomac River shoreline. The plan included closing lanes during the overnight hours (12 a.m. to 4 a.m.) and was scheduled to take from 4 to 6 months to complete. When this phase of the roadwork began, it was clear the limited hours of lane closures were incompatible with required setup and takedown time.

Project engineers responded with a QuickZone analysis that included multiple scenarios for extending the lane closure duration time and the number of lanes closed. The results showed an insignificant difference for motorists if the lane closures began at 9 p.m. instead of the proposed 12 a.m. Opening all lanes by 5 a.m. would be sufficient to maintain traffic flow. As a result of this information the lanes were closed at 9 p.m. and reopened by 5 a.m. Consequently, total duration of the construction project was reduced from an estimated 6 months to 2 months, hence reducing the impact on motorists. Moreover, the increase in the contractor’s productive time (from 2.5 hours to 6 hours) resulted in better utilization of available resources and ultimately saved money on the overall construction project. QuickZone allowed the management team to easily test various work zone plan scenarios and determine the best compromise between the interests of the construction project and the public.



Deborah Curtis
Federal Highway Administration (FHWA)
Operations, Research and Development
Integrated Product Team


Andrew Lessner
QuickZone Analyst
Maryland State Highway Administration

Jawad Paracha
Transportation Engineer
Maryland State Highway Administration

Photo of elevated multiple lane bridge.  Bridge in foreground has white streaks made by the headlights of cars speeding to the right, moving out of the photo.  Bridge in the background has red streaks made by taillights indicating cars speeding to the left, moving out of the photo.

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