EVALUATION OF ZERO-LENGTH VERTICAL CURVES

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.

• Record URL:
  • https://doi.org/10.3141/1658-07
• Summary URL:
  • http://scholar.google.com/scholar_lookup?title=EVALUATION+OF+ZERO-LENGTH+VERTICAL+CURVES&author=M.+Wooldridge&author=R.+Nowlin&author=A.+Parham&publication_year=1999
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/isbn/0309070554
• Supplemental Notes:
  • This paper appears in Transportation Research Record No. 1658, Highway Geometric Design and Operational Effects Issues.
• Corporate Authors:

  Transportation Research Board

  500 Fifth Street, NW
  Washington, DC  United States  20001
• Authors:
  • Wooldridge, M D
  • Nowlin, R L
  • Parham, A H
• Publication Date: 1999

Language

• English

Media Info

• Features: Figures; Photos; References; Tables;
• Pagination: p. 52-59
• Serial:
  • Transportation Research Record
  • Issue Number: 1658
  • Publisher: Transportation Research Board
  • ISSN: 0361-1981

Subject/Index Terms

• TRT Terms: Design speed; Highway design; Highway grades; Sight distance
• Uncontrolled Terms: Highway profile; Vertical acceleration; Vertical curvature
• Subject Areas: Design; Highways; Planning and Forecasting; I21: Planning of Transport Infrastructure;

Filing Info

• Accession Number: 00769393
• Record Type: Publication
• ISBN: 0309070554
• Files: TRIS, TRB, ATRI
• Created Date: Sep 8 1999 12:00AM