Predicting Lane-by-Lane Flows and Speeds for Freeway Segments

The Highway Capacity Manual is a major reference for evaluating the capacity and quality of service of road facilities. However, it holds the assumption that lanes perform equally, which can result in inaccuracies in performance estimation. The main purpose of this research is to develop a series of models for estimating flows and speeds by lane for various types of freeway segments, including basic, merge, and diverge types. These models consider the demand-to-capacity ratio, the presence of trucks, grade, and the presence of upstream and downstream ramps. To predict lane performance effectively, it is critical that capacity and free-flow speeds are also determined for individual lanes. Therefore, this study also investigates the relationship between segment average values and lane values for free-flow speeds and capacities, and proposes a method to estimate these parameters for each lane as a function of the segment average. Observed field data has shown that free-flow speeds and capacities have lowest values on the shoulder lanes and highest values on the median lanes. Speed and flow data were collected from 48 segments throughout the U.S.A., including basic, merge, and diverge segments, to develop flow and speed distribution models. A case example is provided to illustrate the application of the developed model and the predicted speed–flow relationship is compared with field data, with satisfactory results.

• Record URL:
  • https://doi.org/10.1177/0361198120933634
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/03611981
• Supplemental Notes:
  • The opinions and conclusions expressed or implied in this paper are those of the authors, and not necessarily those of the TRB, the National Research Council, FHWA, AASHTO, or the individual states participating in the NCHRP. © National Academy of Sciences: Transportation Research Board 2020.
• Authors:
  • Sasahara, Fabio
  • Staichak Carvalho, Luan Guilherme
  • Chowdhury, Tanay Datta
  • Jerome, Zachary
  • Elefteriadou, Lily
  • Skabardonis, Alexander
• Publication Date: 2020-9

Language

• English

Media Info

• Media Type: Web
• Features: References;
• Pagination: pp 1052-1068
• Serial:
  • Transportation Research Record: Journal of the Transportation Research Board
  • Volume: 2674
  • Issue Number: 9
  • Publisher: Sage Publications, Incorporated
  • ISSN: 0361-1981
  • EISSN: 2169-4052
  • Serial URL: http://journals.sagepub.com/home/trr

Subject/Index Terms

• TRT Terms: Flow speed relationships; Freeways; Geometric segments; Highway capacity; Highway grades; Interchange ramps; Traffic forecasting; Traffic lanes; Traffic models; Vehicle mix
• Geographic Terms: United States
• Subject Areas: Highways; Operations and Traffic Management; Planning and Forecasting;

Filing Info

• Accession Number: 01746603
• Record Type: Publication
• Files: TRIS, TRB, ATRI
• Created Date: Jul 23 2020 6:30PM