01473824

Component

Existing geometric design guides provide deterministic design standards for highway elements which ignores the uncertainty associated with many design parameters. Reliability analysis has been advocated as an approach to account for this uncertainty and to evaluate the risk associated with a particular design feature. This paper discusses one important application of reliability analysis: the calibration of geometric design models to yield consistent safety (risk) levels. The paper provides calibrated design charts for the middle ordinate (M), defined as the lateral distance between edge of median barriers and centerline of the adjacent traffic lane, at different probability of non-compliance levels. The results show that the calibrated values of middle ordinate (M) are generally lower than those derived from the AASHTO design guide. The calibrated design charts can offer designers dealing with highways with constricted right-of-way an option to use lower middle ordinate values and enable them to estimate the safety consequences of their decisions. Overall, the calibrated charts can aid the decision maker in determining the safety implications of deviating from geometric design standards and quantifying the safety level built in design values that are deemed acceptable.

This paper was sponsored by TRB committee AHB65 Operational Effects of Geometrics.

01470560

13-0877
13-0877

English

15p

2013

Transportation Research Board 92nd Annual Meeting

Digital/other

Figures; References; Tables

Calibration; Design standards; Geometric design; Highway design; Reliability; Uncertainty

Design; Highways; I22: Design of Pavements, Railways and Guideways

Transportation Research Board Annual Meeting 2013 Paper #13-0877

TRIS, TRB, ATRI

Feb 5 2013 12:17PM