Safe-D: Safety through Disruption

Influences on Bicyclists and Motor Vehicles Operating Speed within a Corridor


This research explored (1) the relationship between suburban vehicle operating speed and roadway characteristics, especially the presence of bicyclists and (2) if crowdsourced speed data could be used to estimate the unconstrained speed for a location. Both vehicle volume per lane and bicycle volume were found to be influential in affecting average speed on lower speed urban arterial roadways. For 40.3 km/hr [25 mph] sites, an increase of 19 vehicles per 15-min period will decrease average speed by 1.6 km/hr [1 mph], and an increase of more than 39 bicyclists per 15-min period will decrease average vehicle speed by a similar amount. Because of the limited number of 15-min periods with bicycle counts greater than 1, the research team also developed a model using all available 15-min periods with on-road speed data. Speed and volume data in 15-minute increments for two weeks at nine sites were obtained using on-road tubes and from a vendor who sells crowdsourced speed data. The difference between the tube data and the crowdsourced data was calculated and called TMCS. The geometric variables that had the greatest influence on TMCS were the number of signals and the number of driveways within a corridor. When only including non-congested periods, weekends (Saturday or Sunday) were associated with the smallest TMCS.

Project Highlights

  • Knowledge of whether existing big datasets are currently usable to evaluate the impacts of roadway, traffic control devices, and/or traffic characteristics on vehicle operating speed.
  • Better understanding of the relationship(s) between bicyclist presence and vehicle operating speed on streets.

Final Report

TTI-01-04 Final Research Report (PDF)

EWD & T2 Products

Student Impact Statement – Maria C. Rodriguez (pdf): The student(s) working on this project provided an impact statement describing what the project allowed them to learn/do/practice and how it benefited their education.

Project Brief (pdf): This document provides a brief description of the project and summary results.


Das, S., K. Fitzpatrick, M. C. (2018, June). Effects of Bicyclists on Vehicle Operating Speed: A Study on urban Arterial Roadway. ITE Joint Meeting of the Western District and the Texas District. (Published)

Fitzpatrick, K. and S. Das. “Using Crowdsourced Data to Estimate Operating Speed on Suburban Streets”. Submitted for consideration for the publication in the IATSS Journal. (Submitted; anticipated 2019)

Final Dataset

The final datasets for this project are located in the Safe-D Collection on the VTTI Dataverse; DOI: 10.15787/VTT1/KCNRS7 and DOI: 10.15787/VTT1/WXR1I0 .

Research Investigators (PI*)

Kay Fitzpatrick (TTI/TAMU)*

Subasish Das (TTI/TAMU)

Project Information

Start Date: 2017-03-01
End Date: 2018-08-31
Status: Completed
Grant Number: 69A3551747115
Total Funding: $286,773
Source Organization: Safe-D National UTC
Project Number: TTI-01-04

Safe-D Theme Areas

Big Data Analytics

Safe-D Application Areas

Operations and Design

More Information

UTC Project Information Form

Sponsor Organization

Office of the Assistant Secretary for Research and Technology
University Transportation Centers Program
Department of Transportation
Washington, DC 20590 United States

Performing Organization

Texas A&M University
Texas A&M Transportation Institute
3135 TAMU
College Station, Texas 77843-3135