Grade Separation

General Description:

Grade Separation is the separation by physical means (e.g. an overpass) of different flows of traffic.  It is possible to separate pedestrians and railroads from traffic flows with either overpasses or underpasses.  Pedestrians and bicycles may also be separated with culverts or other features.

Effects of Solution:

¨ Increase Passenger Throughput

þ Increase Roadway Capacity (Reduces traffic conflicts)

þ Manage System Efficiency (Eliminates the need for an intersection)

¨ Reduce Local Demand

Grade Separation reduces traffic conflicts which results in an efficient use of the system as well as increase the overall capacity of the system. 

Examples of Implementation:

No specific examples available at the time of publication.

Cost/Financial Information:

The cost of building separated grades can be high due to construction costs, right-of-way requirements, and the disruption of traffic during construction. Costs vary depending on the type of separation used, and the length of the separation.

Additional Resources:

A Toolbox for Alleviating Traffic Congestion and Enhancing Mobility, available for order at http://www.ite.org/bookstore/index.asp

Washington State Department of Transportation I-405, SR 167 Grade Separation Ramp web page:

http://www.wsdot.wa.gov/Projects/i405/sr167ic/

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