Modeling of 85th percentile speed for rural highways for enhanced traffic safety.

Details

• Creators:
  Singh, Dharamveer ; Zaman, Musharraf M. ; White, Luther
• Corporate Creators:
  University of Oklahoma
• Corporate Contributors:
  Oklahoma. Dept. of Transportation. Planning & Research Division
• Subject/TRT Terms:
  • Speed limits
  • Traffic regulations
  • Traffic speed
  • Speed and delay studies
  • Traffic safety
  • Rural highways
  • Mathematical models
  • Speed limits--Oklahoma
  • Speed limits--Mathematical models
  • Neural networks (Computer science)--Oklahoma
• Publication/ Report Number:
  FHWA-OK-11-07
• Resource Type:
  Tech Report
• Geographical Coverage:
  Oklahoma
• Edition:
  Final report; Oct. 2008-Dec. 2010.
• Corporate Publisher:
  Oklahoma. Dept of Transportation
• Abstract:
  Traffic operation on two-lane rural highways and setting posted speed limits are some of the difficult tasks faced by the ; Oklahoma Department of Transportation (ODOT) and other transportation agencies. The present study was undertaken to ; develop artificial neural network (ANN) models to predict 85th percentile speed (V85) of two-lane rural highways in Oklahoma. ; Several input parameters, namely, roadway characteristics, traffic conditions, and accident experience were considered in ; developing the ANN models. Physical characteristics of road include, surface width (SW), shoulder type (ST), and shoulder ; width (SHW). Traffic parameters cover average daily traffic (ADT), posted speed (PS), and V85. Pavement condition includes ; skid number (SN), and international roughness index (IRI). The location collision rate, statewide collision rate (overall, fatal, and ; injury), and percentage unsafe speed drivers (USD) were covered in the accident data. ; Data from a total of 241 two-lane rural highway sites were collected and used in developing the ANN models. The ; following four different ANN models were developed: Model 1 includes Posted Speed but does not include Accident Data; Model ; 2 includes neither Posted Speed nor Accident Data; Model 3 includes both Posted Speed and Accident Data; and Model 4 does ; not include Posted Speed but includes Accident Data. Model 1 included physical characteristics of road, and traffic parameters ; including PS, while Model 2 covered all the parameters included in Model 1 except PS. Similarly, Model 3 considered accident ; data with all the parameters included in Model 1. Model 4 used all the parameters included in Model 3 excluding PS. The ; developed models provided an overall accuracy of more than 90%. For example, Model 1 and Model 2 developed without ; accident data gave an overall accuracy of 97%, and 91.5%, respectively. Similarly, Model 3 and Model 4 developed using ; accident data resulted in an overall accuracy of 97.5%, and 94.1%, respectively. It was found that inclusion of accident data ; improves the performance of the model only marginally. ; The present study was pursued with the goal that ANN models for V85 would provide a cost effective alternative for ; estimating site-specific V85 of two-lane rural highways in Oklahoma. Also, the developed models are expected to be useful for ; prediction of V85 when roadway characteristics and/or traffic operational factors change.
  More +
• Format:
  PDF
• Funding:
  ODOT SPR Item Number 2211
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/23203/dot_23203_DS1.pdf
• File Type:
  [PDF - 1.64 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:9287e6fbb98ec0e32b915d954c2bfa86e3b958b9c541421c56ec909fd6c35ebf722262d1847827d2679a81048b9a36a9439d95b619c861efa9b589426e588ac9