Crossing Structure Recommendations for At-grade Rail Crossings of U.S. Routes 29 and 15 in Prince William County, Virginia

Report No: 05-R12

Published in 2005

About the report:

The intersection of a rail line and a roadway at an at-grade crossing represents the meeting of two vastly different transportation modes. Although they may share a common crossing where they intersect, the typical structural design of the supporting foundation for each is quite different. The design of a roadway consists of multiple layers of low-permeability materials, whereas the design of a rail line includes rails and crossties supported by open-draining aggregate ballast. Because of the use of highly permeable materials, the open draining nature of a rail line substructure can cause the early deterioration of a nearby roadway unless steps are taken to provide adequate drainage. In addition to structural differences, the rail line is designed to accommodate a substantial vertical deflection from passing loaded rail cars; it is common for a rail line to undergo up to 0.3 inch of vertical displacement. This large deflection can result in a greatly reduced service life for nearby pavements because of fatigue failure. Although it is inevitable that a rail crossing structure will have to undergo periodic reconstruction, selection of an optimum crossing surface constructed over an adequately prepared foundation will greatly increase the service life of the crossing. An optimum crossing structure can be viewed as one that combines safety, cost-effectiveness, long service life (reducing user costs by increasing the time between successive replacements), good performance, and ease of maintenance.

This report discusses the advantages and disadvantages of several crossing types that are the most appropriate for the conditions expected at the U.S. Route 29 and U.S. Route 15 crossings in Prince William County, Virginia. Specific recommendations for each crossing type are provided. It is the author’s opinion that the following crossing types represent the optimum alternatives for these locations and conditions in the following order: precast concrete platform panels, high rutresistant hot-mix asphalt; and steel-reinforced rubber panels. It is expected that these crossing alternatives will exceed the typical service life if the recommended materials and design elements are used.

Disclaimer Statement:The contents of this report reflect the views of the author(s), who is responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the Virginia Department of Transportation, the Commonwealth Transportation Board, or the Federal Highway Administration. This report does not constitute a standard, specification, or regulation. Any inclusion of manufacturer names, trade names, or trademarks is for identification purposes only and is not to be considered an endorsement.

Last updated: November 29, 2023

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