Project: #16 Analysis of Effects of Tire Tread Deterioration on Safety Impacts from Analysis of Inspection Data Progress Report - Reporting Period Ending: March 31, 2018 Principal Investigator: H. Scott Matthews Status: Completed Start Date: Jan. 1, 2017 End Date: Aug. 31, 2018 Research Type: Applied Grant Type: Research Grant Program: MAP-21 TSET National (2013 - 2018) Grant Cycle: 2017 TSET UTC Progress Report (Last Updated: March 31, 2018, 8:51 a.m.) % Project Completed to Date: 80 % Grant Award Expended: 55 % Match Expended & Document: 100 USDOT Requirements Accomplishments We have already created initial estimates of the deterioration rates of tire tread in all passenger vehicles in Pennsylvania over the past 10 years. We estimate that the rate is 0.2 inches per 1000 miles, or 2/32" per 10,000 VMT. We have also begun to create the 'policy model' that considers the risk associated with the current tire tread inspection threshold of 2/32", to be able to consider the percentage of vehicles that meet the tread depth requirement at the time of inspection, but that would be expected to "fail an inspection" before the next annual inspection. Our current estimates are that about 25% of vehicles fall into this category. Further, we have created initial estimates of the percentages of vehicles with questionable tires that wait until the time of inspection to replace their old tires, which causes serious safety issues in PA. Impacts We have been prioritizing work on the methods, but have shared results with several stakeholder groups to date. We have already presented interim results to attendees at several national and PA conferences since May 2017 (see presentation details below). We have some discussions with tire companies (eg Bridgestone) about potential follow-on work. We plan to submit a paper to the 2019 TRB conference in August of 2018. We also seek, when done, to open a dialogue with PennDOT officials about altering the tire tread depth thresholds given modern use of vehicles (10k VMT per year) and given the knowledge of sizable fractions of the fleet driving with unsafe tires. We hope to help them consider modifications of the current thresholds which anticipate consumer behavior. Other We are considering the development of a web-based mechanism to display the data, but want to have discussions with various stakeholders (e.g., AAA) first. Outcomes New Partners As discussed separately, we would appreciate assistance in engaging consumer safety advocacy groups like IIHS or the National Safety Council to help disseminate our work. Issues We have not experienced any significant issues in this project.