00769393

Component

https://doi.org/10.3141/1658-07

http://scholar.google.com...rham&publication_year=1999

To evaluate the use of zero-length vertical curves with respect to Texas Department of Transportation design practice, construction results, and vehicle dynamics, and to compare zero-length vertical curves with minimum-length design vertical curves, 20 zero-length vertical curves and 15 minimum-length vertical curves were evaluated. Evaluations performed included examinations of sight distance for zero-length vertical curves, surveying roadway profiles, and measuring vertical accelerations. Sight distance criteria were found to be generally inapplicable below 2 percent for sag vertical curves. For crest vertical curves, sight distance criteria were inapplicable below 1 percent for design speeds of 90 km/h or less and inapplicable below 0.5 percent for design speeds of 100 to 120 km/h. The results of vertical acceleration testing showed that, below 0.5 percent grade change, no practical difference was found between zero-length and minimum-design-length vertical curves. Between 1.0 and 0.5 percent grade change, significantly higher accelerations were measured for high-speed tests on zero-length vertical curves. Finally, it was found that zero-length vertical curves were more likely to meet drainage grade requirements than minimum-design-length vertical curves were.

This paper appears in Transportation Research Record No. 1658, Highway Geometric Design and Operational Effects Issues.

English

p. 52-59

1999

Transportation Research Record

0309070554

Figures (4) ; Photos (1) ; References (7) ; Tables (2)

Design speed; Highway design; Highway grades; Sight distance

Highway profile; Vertical acceleration; Vertical curvature

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

TRIS, TRB, ATRI

Sep 8 1999 12:00AM

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• RELATIONSHIPS BETWEEN BALL BANK INDICATOR READINGS, LATERAL ACCELERATION RATES, AND VEHICULAR BODY-ROLL RATES
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• SCHOOL BUS DESIGN VEHICLE DIMENSIONS
• SPEED VARIABILITY ON RURAL TWO-LANE HIGHWAYS