PASSENGER CAR OVERHANG AND UNDERCLEARANCE AS RELATED TO DRIVEWAY PROFILE DESIGN. I. VEHICLE DATA

DATA ARE REVIEWED ON THE TREND IN AUTOMOBILE STYLING WHICH APPEARS TO BE TOWARD LOWER VEHICLES. MINIMUM GROUND CLEARANCE CURVES BEGIN TO SHOW A SLIGHT DOWNWARD TREND. THE DATA DO NOT SHOW THAT WHEEL BASES ARE GETTING LONGER. RAMP BRAKE-ANGLES HAVE DROPPED 6 DEGREES IN 6 YEARS. DURING SEVERE BRAKE STOPS, DIVE OR JOUNCE, PAVEMENT INTERFERENCE MAY BE ENCOUNTERED UNDER DYNAMIC CONDITIONS. ALTHOUGH THIS WILL BOTTOM THE SUSPENSION, CENTER CLEARANCE IS NEVER A PROBLEM ON SAG CURVES. THE SHORTEST VEHICLE IS EVEN MORE CRITICAL THAN THE LONG ONE UNDER DYNAMIC CONDITIONS. REAR CLEARANCES ARE ESPECIALLY AFFECTED BY PITCH, AND THE SHORT WHEEL BASE MORE THAN OFFSETS THE SHORTER OVERHANG AND SMALLER DEFLECTIONS. THE FOLLOWING CHECKS ARE SUGGESTED FOR THE HIGHWAY DESIGNER TO AVOID INTERFERENCES: (1) THERE SHOULD NOT BE MORE THAN A 5% CHANGE IN SLOPE BETWEEN ANY TWO 10-FT CHORDS, THE RAMP OVER A 6-IN. CURB SHOULD BE AT LEAST 10 FEET LONG AND (2) THERE SHOULD BE NO MORE THAN 1-1/2 IN. OF CLEARANCE BETWEEN THE PAVEMENT AND A 10-FT STRAIGHTEDGE.

Media Info

  • Monograph Title: Relation between vehicle characteristics and highway design
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00222861
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Aug 19 1994 12:00AM