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Title:

IMPROVED DESIGN OF VERTICAL CURVES WITH SIGHT DISTANCE PROFILES

Accession Number:

00966549

Record Type:

Component

Availability:

Transportation Research Board Business Office

500 Fifth Street, NW
Washington, DC 20001 United States
Order URL: http://www.trb.org/Main/Public/Blurbs/154643.aspx

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Order URL: http://worldcat.org/isbn/030908587X

Abstract:

Design of vertical alignment is one of the main tasks in highway geometric design. This task requires, among other things, that the designer ensure drivers always have a clear view of the road so they can stop before hitting an unexpected object in the road. Therefore, the ability to determine the required and available stopping sight distance (SSD) at any point of the vertical alignment is essential for the design process. Current design guides in the United States and Canada provide simple analytical models for determining the minimum length of a vertical curve that would satisfy the sight distance requirement. However, these models ignore the effect of grade on the required SSD. Alternative approaches and models have also been suggested but cover only special cases of vertical curves. Two specific models were expanded to determine the required SSD on crest and sag vertical curves. By comparing profiles of available SSD and required SSD on examples of vertical curves, it was shown that current North American design practices might yield segments of the vertical curve where the driver's view is constrained to a distance shorter than the required SSD. An alternative design procedure based on the models was developed and used to determine the minimum lengths of crest and sag vertical curves. Depending on the approach grade, these new values of minimum curve length might be greater than or less than values obtained through conventional design procedures. Design aids were therefore provided in tabular form for designers' easy and quick use.

Supplemental Notes:

This paper appears in Transportation Research Record No. 1851, Highway and Facility Design 2003.

Language:

English

Corporate Authors:

Transportation Research Board

500 Fifth Street, NW
Washington, DC 20001 United States

Authors:

Hassan, Y

Pagination:

p. 13-24

Publication Date:

2003

Serial:

Transportation Research Record

Issue Number: 1851
Publisher: Transportation Research Board
ISSN: 0361-1981

ISBN:

030908587X

Features:

Figures (8) ; References (7) ; Tables (6)

Uncontrolled Terms:

Vertical alignment; Vertical curvature

Geographic Terms:

North America

Subject Areas:

Design; Highways; Planning and Forecasting; I21: Planning of Transport Infrastructure

Files:

TRIS, TRB, ATRI

Created Date:

Dec 8 2003 12:00AM

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