A COMPARISON OF SOME ALTERNATIVE FORMS OF GRAVITY FUNCTION FOR MODELLING ROAD FREIGHT FLOWS

REFERENCE IS MADE TO THE MINISTRY OF TRANSPORT'S ROAD GOODS SURVEY DATA AND THE EXTENSIVE ANALYSIS OF THESE DATA CARRIED OUT BY CHISHOLM AND O'SULLIVAN WHO USED BOTH LINEAR PROGRAMMING AND GRAVITY APPROACHES TO MODELLING FLOWS. THESE STUDIES ASSUMED THAT DISTANCE COSTS VARIED IN PROPORTION TO THE LOG OF PHYSICAL DISTANCE, INDICATING THAT THE MOST PROBABLE RELATION BETWEEN TRIPS AND DISTANCE INCOPORATED A NEGATIVE POWER FUNCTION. THE AUTHOR CONSIDERS THE ALTERNATIVE USE OF A NEGATIVE EXPONENTIAL FUNCTION IN PLACE OF THE POWER FUNCTION. THE RESULTS OF EXERCISES WITH THE EXPONENTIAL FORM OF THE DISTANCE FUNCTION INDICATE THAT WHEN THE FULL, DOUBLY CONSTRAINED GRAVITY MODEL IS IMPLEMENTED, ANY VARIATION IN DISTANCE EXPONENT FOR TOTAL ROAD GOODS FLOWS BETWEEN ORIGINS IS SUBSTANTIALLY LESS THAN THAT SUGGESTED BY UNCONSTRAINED REGRESSIONS SUCH AS WERE CARRIED OUT BY O'SULLIVAN.

• Corporate Authors:

  Kent State University

  ,    
• Authors:
  • Gordon, I R
• Publication Date: 1972-5

Language

• English

Media Info

• Features: References; Tables;
• Pagination: 14 p.
• Serial:
  • Issue Number: 3

Subject/Index Terms

• TRT Terms: Costs; Distance; Economics; Freight transportation; Gravity models; Linear programming; Statistics; Traffic flow; Trucking
• Subject Areas: Data and Information Technology; Economics; Finance; Freight Transportation; Highways; Motor Carriers; Operations and Traffic Management;

Filing Info

• Accession Number: 00228551
• Record Type: Publication
• Source Agency: Transport and Road Research Laboratory (TRRL)
• Report/Paper Numbers: R&d Report
• Files: TRIS
• Created Date: Apr 20 1974 12:00AM