Prediction Models for Free Flow Speed on Urban Streets

This paper investigates the relationship between vehicle free flow speed and geometric variables on urban street segments. Geometric and spot speed data were collected from 35 different two lane segments located in Fairfax County in Virginia. To gain a better understanding of the relationships between free flow speed and geometric variables, speed data were visualized and descriptive statistics were computed. In addition to this, linear regression models were developed to estimate the relationship between mean free flow speed and roadside variables and 85th percentile free flow speed and roadside variables. The results showed a significant impact of posted speed limit on free flow speed. The predicted mean free speed at sites with 45 mph posted speed was found to be 5 mph and 8 mph higher than sites with 40 mph and 35 mph posted speed respectively. The other significant factors were found to be affecting free flow speed were the presence or absence of median and spacing between the signals.

• Corporate Authors:

  Transportation Research Board

  500 Fifth Street, NW
  Washington, DC  United States  20001
• Authors:
  • Ali, Asma Tayyab
  • Flannery, Aimee
  • Venigalla, Mohan M
• Conference:
  • Transportation Research Board 86th Annual Meeting
  • Location: Washington DC, United States
  • Date: 2007-1-21 to 2007-1-25
• Date: 2007

Language

• English

Media Info

• Media Type: CD-ROM
• Features: Figures; References; Tables;
• Pagination: 21p
• Monograph Title: TRB 86th Annual Meeting Compendium of Papers CD-ROM

Subject/Index Terms

• TRT Terms: 85th percentile speed; Free flow speeds; Operations; Speed data; Speeding; Traffic flow; Traffic speed; Two lane highways; Urban areas; Urban highways; Urban transportation
• Geographic Terms: Fairfax County (Virginia)
• Subject Areas: Administration and Management; Highways; Operations and Traffic Management; Planning and Forecasting; I72: Traffic and Transport Planning;

Filing Info

• Accession Number: 01049608
• Record Type: Publication
• Report/Paper Numbers: 07-1954
• Files: TRIS, TRB
• Created Date: May 21 2007 1:18PM