The 85th Percentile Speed Prediction Model for Four-Lane Divided Highways in Ideal Free Flow Condition

Researchers had proposed several models to predict preferred vehicle speed in two lane undivided highways and correlate it with safety. Most of these models are calibrated considering strong lane discipline. However, in multilane divided highways, presence of vehicle in the adjacent lane can influence speed and absence can provide opportunity to use full pavement width. So, the free-flowing speed characteristics of vehicles are different in the multilane divided horizontal curves. In this study, ideal free flowing speed data at the center of twenty-nine horizontal curves in a four-lane divided highway are analyzed to develop a linear speed prediction model. Various geometric parameters are considered for developing the 85th percentile speed prediction models for passenger cars and heavy commercial vehicles. Both stepwise entry and backward elimination methods are used for the multi-linear regression analysis. It is found that backward elimination methods yielded better models in terms of R2 value and selection of explanatory variables. The developed model depends on deflection angle, curve length and preceding tangent length. Validation process confirmed more than 90% accuracy of the developed model. Sensitivity study indicated curve length as the most significant parameter for predicting the 85th percentile speed at the center of the curve. The explanatory variables in the obtained models can explain speed at center of a horizontal curve based on driver’s perception of the curve and influence of the preceding section.

• Supplemental Notes:
  • This paper was sponsored by TRB committee AFB10 Standing Committee on Geometric Design.
• Authors:
  • Sil, Gourab
  • Nama, Suresh
  • Maji, Avijit
  • Maurya, Akhilesh Kumar
• Conference:
  • Transportation Research Board 97th Annual Meeting
  • Location: Washington DC, United States
  • Date: 2018-1-7 to 2018-1-11
• Date: 2018

Language

• English

Media Info

• Media Type: Digital/other
• Features: Figures; References; Tables;
• Pagination: 6p

Subject/Index Terms

• TRT Terms: Behavior; Divided highways; Drivers; Four lane highways; Highway curves; Highway safety; Lane occupancy; Mathematical models; Speed; Traffic flow
• Subject Areas: Highways; Operations and Traffic Management; Safety and Human Factors;

Filing Info

• Accession Number: 01658987
• Record Type: Publication
• Report/Paper Numbers: 18-02808
• Files: TRIS, TRB, ATRI
• Created Date: Feb 5 2018 11:26AM