National Cooperative Highway Research Program NCHRP Report 350 Recommended Procedures for the Safety Performance Evaluation of Highway Features Transportation Research Board National Research Council TRANSPORTATION RESEARCH BOARD EXECUTIVE COMMITTEE 1992 OFFICERS Chairman: William W. Millar, Executive Director, Port Authority of Allegheny County, Pennsylvania Vice Chairman: A. Ray Chamberlain, Executive Director, Colorado Department of Transportation Executive Director: Thomas B. Deen, Transportation Research Board MEMBERS MICHAEL ACOTT, President, National Asphalt Pavement Association (ex officio) ROY A. ALLEN, Vice President, Research and Test Department, Association of American Railroads (ex officio) MARION C. BLAKEY, National Highway Traffic Safety Administrator, U.S. Department of Transportation (ex officio) GILBERT E. CARMICHAEL, Federal Railroad Administrator, U.S. Department of Transportation (ex officio) BRIAN W. CLYMER, Federal Transit Administrator, U.S. Department of Transportation (ex officio) FRANCIS B. FRANCOIS, Executive Director, American Association of State Highway and Transportation Officials (ex officio) JACK R. GILSTRAP, Executive Vice President, American Public Transit Association (ex officio) DOUGLAS B. HAM, Research and Special Programs Acting Administrator, U.S. Department of Transportation (ex officio) THOMAS H. HANNA, President and Chief Executive Officer, Motor Vehicle Manufacturers Association of the United States, Inc (ex officio) THOMAS D. LARSON, Federal Highway Administrator. U.S. Department of Transportation (ex officio) WARREN G. LEBACK, Maritime Administrator. U.S. Department of Transportation (ex officio) THOMAS C. RICHARDS, Federal Aviation Administrator, U.S. Department of Transportation (ex officio) ARTHUR E. WILLIAMS, Chief of Engineers and Commander, U.S. Army Corps of Engineers (ex officio) JAMES M. BEGGS, Chairman, SPACEHAB, Inc. KIRK BROWN, Secretary, Illinois Department of Transportation DAVID BURWELL, President, Rails-to-Trails Conservancy L. GARY BYRD, Consulting Engineer, Alexandria, Virginia L. STANLEY CRANE, former Chairman and CEO of CONRAIL RICHARD K. DAVIDSON, Chairman and CEO, Union Pacific Railroad JAMES C. DELONG, Director of Aviation, Philadelphia International Airport JERRY L. DEPOY, Vice President, Properties & Facilities, USAir THOMAS J. HARRELSON, Secretary, North Carolina Department of Transportation LESTER P. LAMM, President, Highway Users Federation LILLIAN C. LIBURDI, Director. Port Department, The Port Authority of New York and New Jersey ADOLF D. MAY, JR., Professor and Vice Chairman, Institute of Transportation Studies, University of California. Berkeley WAYNE MURI, Chief Engineer, Missouri Highway & Transportation Department (Past Chairman, 1990) CHARLES P. O'LEARY, JR., Commissioner. New Hampshire Department of Transportation NEIL PETERSON, Executive Director. Los Angeles County Transportation Commission DELLA M. ROY, Professor of Materials Science, Pennsylvania State University JOSEPH M. SUSSMAN, JR East Professor of Engineering, Massachusetts Institute of Technology JOHN R. TABB, Director, Chief Administrative Officer, Mississippi State Highway Department JAMES W. VAN LOBEN SELS, Director, California Department of Transportation C. MICHAEL WALTON, Paul D. & Betty Robertson Meek Centennial Professor and Chairman, Civil Engineering Department, University of Texas at Austin (Past Chairman, 1991) FRANKLIN E. WHITE, Commissioner, New York State Department of Transportation JULIAN WOLPERT, Henry G. Bryant Professor of Geography, Public Affairs and Urban Planning, Woodrow Wilson School of Public and International Affairs, Princeton University ROBERT A. YOUNG III, President, ABF Freight Systems, Inc NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Transportation Research Board Executive Committee Subcommittee for NCHRP THOMAS D. LARSON, U.S. Department of Transportation WILLIAM W. MILLAR, Port Authority of Allegheny County (Chairman) A. C. MICHAEL WALTON, University of Texas at Austin RAY CHAMBERLAIN, Colorado Department of Transportation L. GARY BYRD, Consulting Engineer FRANCIS B. FRANCOIS, American Association of State Highway and THOMAS B. DEEN, Transportation Research Board Transportation Officials Field of Design Area of Vehicle Barrier Systems Project Panel C22-7 ROGER L. STOUGHTON, California Department of Transportation F. J. TAMANINI, Energy Absorption Systems, Inc., Virginia (Chairman) THOMAS TURBELL, VTI, Sweden JAMES E. BRYDEN, New York State Department of Transportation HARRY W. TAYLOR, Federal Highway Administration CHARLES E. DOUGAN, Connecticut Department of Transportation (The late) EDWARD N. POST, University of Nebraska-Lincoln DENNIS L. HANSEN, Hennepin Co. Department of Transportation, Minn. MARTY HARGRAVES, FHWA Liaison Representative JAMES H. HATTON, JR., Federal Highway Administration FRANK R. McCULLAGH, TRB Liaison Representative WALTER J. JESTINGS, Parsons, Brinckerhoff Quade & Douglas, Georgia JAMES F. ROBERTS, Jefferson City, Missouri Program Staff CRAWFORD F. JENCKS, Senior Program Officer ROBERT J. REILLY, Director, Cooperative Research Programs ROBERT B. MILLER, Financial Officer KENNETH S. OPIELA, Senior Program Officer DAN A. ROSEN, Senior Program Officer LOUIS M. MAcGREGOR, Program Officer SCOTT SABOL, Senior Program Officer DANIEL W. DEARASAUGH, JR., Senior Program Officer EILEEN P. DELANEY, Editor AMIR N. HANNA, Senior Program Officer National Cooperative Highway Research Program Report 350 Recommended Procedures for the Safety Performance Evaluation of Highway Features H. E. ROSS, JR., D. L. SICKING, and R. A. ZIMMER Texas Transportation Institute Texas A&M University System College Station, Texas and J. D. MICHIE Dynatech Engineering Inc. San Antonio, Texas Research Sponsored by the American Association of State Highway and Transportation Officials in Cooperation with the Federal Highway Administration TRANSPORTATION RESEARCH BOARD NATIONAL RESEARCH COUNCIL NATIONAL ACADEMY PRESS Washington, D.C. 1993 NATIONAL COOPERATIVE HIGHWAY RESEARCH NCHRP REPORT 350 PROGRAM Systematic, well-designed research provides the most effective Project 22-7 FY'89 approach to the solution of many problems facing highway ISSN 0077-5614 administrators and engineers. Often, highway problems are of local interest and can best be studied by highway departments individually ISBN 0-309-04873-7 or in cooperation with their state universities and others. However, the L. C. Catalog Card No. 92-61950 accelerating growth of highway transportation develops increasingly complex problems of wide interest to highway authorities. These Price $13.00 problems are best studied through a coordinated program of cooperative research. Areas of Interests In recognition of these needs, the highway administrators of the Bridges, Other Structures, Hydraulics and Hydrology American Association of State Highway and Transportation Officials Materials and Construction initiated in 1962 an objective national highway research program Safety and Human Performance employing modern scientific techniques. This program is supported on Modes a continuing basis by funds from participating member states of the Highway Transportation Association and it receives the full cooperation and support of the Federal Highway Administration, United States Department of Transportation. The Transportation Research Board of the National Research NOTICE Council was requested by the Association to administer the research program because of the Board's recognized objectivity and The project that is the subject of this report was a part of the National Cooperative understanding of modern research practices. The Board is uniquely Highway Research Program conducted by the Transportation Research Board with suited for this purpose as: it maintains an extensive committee the approval of the Governing Board of the National Research Council. Such approval reflects the Governing Board's judgment that the program concerned is of structure from which authorities on any highway transportation subject national importance and appropriate with respect to both the purposes and may be drawn; it possesses avenues of communications and resources of the National Research Council. cooperation with federal, state and local governmental agencies, The members of the technical committee selected to monitor this project and to universities, and industry; its relationship to the National Research review this report were chosen for recognized scholarly competence and with due Council is an insurance of objectivity; it maintains a full-time research consideration for the balance of disciplines appropriate to the project. The opinions correlation staff of specialists in highway transportation matters to and conclusions expressed or implied are those of the research agency that performed the research, and, while they have been accepted as appropriate by the bring the findings of research directly to those who are in a position to technical committee, they are not necessarily those of the Transportation Research use them. Board, the National Research Council, the American Association of State Highway The program is developed on the basis of research needs identified and Transportation officials, or the Federal Highway Administration, U.S. Department of Transportation. by chief administrators of the highway and transportation departments and by committees of AASHTO. Each year, specific areas of research Each report is reviewed and accepted for publication by the technical committee needs to be included in the program are proposed