Turner-Fairbank Highway Research Center

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NCHRP Report 633: Impact of Shoulder Width and Median Width on Safety.

Product Type

Research Report


Stamatiadis, N., J. Pigman, J. Sacksteder, W. Ruff, and D. Lord




This report contains the findings of research performed to quantify the safety and operational impacts of design element trade-offs and their associated risks. The report details the research performed and includes specific recommended crash prediction models and Accident Modification Factors (AMFs) for shoulder width and median width on rural four-lane roads. Thus, the report will be of immediate interest to engineers in state highway agencies responsible for geometric design and traffic operations and safety.

Link To Research Report

NCHRP Report 633: Impact of Shoulder Width and Median Width on Safety.


Accident modification factors
Crash prediction models
Four lane highways
Geometric design
Highway safety
Road shoulders
Rural highways

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HSIS Summaries

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