Start date: 08/15/14
End date: 09/30/16
About the research
Travel time and its reliability are intuitive performance measures for freeway traffic operations. The objective of this project was to quantify segment-based and corridor-based travel time reliability measures on urban freeways. To achieve this objective, a travel-time estimation model and a travel-time reliability prediction framework were developed.
The proposed travel-time estimation model considers spatially correlated traffic conditions. Segment-level and corridor-level travel-time distributions were estimated using travel time estimates and compared with estimates based on probe vehicle data. Corridor-level travel-time reliabilitymeasures were extracted from travel-time distributions. The proposed travel-time estimation model can well capture the temporal pattern of travel time and its distribution.
For the corridor-level travel-time reliability prediction framework, travel time observations are classified based on weather conditions, segment travel-time distributions are estimated, and segment travel-time distributions are synthesized to corridor travel-time distributions. The segment travel-time distribution estimation model was found to capture the pattern of actual travel-time distributions and could adequately represent the short-term corridor-level travel-time distributions. The proposed travel-time reliability prediction framework provides a systematic way to estimate real-time and near-future corridor travel-time reliability by considering weather impact.
A Vissim simulation calibrated to Iowa compared travel-time distribution based on simulated data to that based on probe vehicle data. The simulated travel-time distribution is similar to thetravel-time distribution based on probe data.
Report: Assessing Segment- and Corridor-Based Travel-Time Reliability on Urban Freeways (2.78 mb pdf) October 2016
Tech transfer summary: Assessing Segment- and Corridor-Based Travel-Time Reliability on Urban Freeways (371.72 kb pdf) Oct 2016
- Iowa Department of Transportation
- Midwest Transportation Center