Tests are described in which a vehicle was driven into beds of gravel of different depths and types, at entry speeds of between 10 mile/h (16.1km/h) and 60 mile/h (96.6km/h). The tests showed that small stones graded 3/8-1/4 in. (9.5-6.3 mm) decelerate a car somewhat better than large stones graded 1 1/2-3/4 in. (38.0-18.9 mm), and that rounded gravel is a little more efficient than angular gravel. however, angular gravel is generally available at about half the cost of rounded gravel, and 3/8-1/4 in. (9.5-6.3 mm) angular gravel to a depth of 12 in. (30.5 cm) provides a good compromise between efficiency and cost. The deceleration rate for this gravel bed was 0.45 g for unbraked runs at about 30 mile/h (48.3 km/h), and 0.098 g for braked runs at about 40 mile/h (64.4 km/h), the stopping distance in the latter case being 55 ft. (16.8 m). The mean deceleration rate of the test vehicle braked on a good road surface was 0.6 g from 40 mile/h (64.4 km/h). It is concluded that gravel beds might be used at sites where conventional guard rails, if erected, would be struck at angles approaching 90 degrees./Author/

  • Corporate Authors:

    Ministry of Transport, England

    Road Research Laboratory
    Crothorne,   England 
  • Authors:
    • Laker, I B
  • Publication Date: 1966

Media Info

  • Features: Figures; Photos; References;
  • Pagination: 9 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00127322
  • Record Type: Publication
  • Report/Paper Numbers: RRL #19
  • Files: TRIS, ATRI
  • Created Date: Apr 21 1976 12:00AM