Shoulder Rumble Strips For Improving Safety On Rural Interstates

Author : Md Julfiker Hossain
Publisher :
ISBN 13 : 9780438570528
Total Pages : 117 pages
Book Rating : 4.5/5 (75 download)

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Download or read book Development of Crash Modification Factors for Shoulder Rumple Strips and Passing Lanes on Rural Two-way Two-lane Highways written by Md Julfiker Hossain and published by . This book was released on 2017 with total page 117 pages. Available in PDF, EPUB and Kindle. Book excerpt: According to the Wyoming Strategic Highway Safety Plan, lane departure crashes contribute to 72% of all critical crashes in Wyoming. Critical crashes are defined as events that lead to a fatality or incapacitating injury. In the US, single vehicle run off the road crashes contribute to a total of 54% of all crashes and a total societal loss of $80 billion every year. Shoulder Rumble Strips (SRS) have been proven to have a significant effect on reducing lane departure crashes. Passing lanes have also been considered as another effective countermeasure in reducing lane departure crashes though the primary objective of implementing passing lanes is to improve operation of two-way two-lane highways. The main objective of the study is to develop Crash Modification Factors for Shoulder Rumble Strips and Passing Lanes on two-way two-lane highways. Three main tasks were completed in this study to achieve the goal such as: 1) To develop Wyoming-specific full Safety Performance Functions, 2) To quantify the safety effectiveness of shoulder rumble strips, and 3) To develop Crash Modification Factors for Passing Lanes. Safety Performance Functions (SPFs) are needed to calibrate Crash Modification Factors for any countermeasure using before-after with Empirical Bayes (EB) analysis. The Highway Safety Manual (HSM) provides simple SPFs that consider Average Annual Daily Traffic (AADT) only to predict crashes. Also, the SPFs were developed utilizing data from limited number of states which may not represent the actual site conditions in Wyoming. Therefore, Wyoming-specific full Safety Performance Functions were developed in this study for total, fatal and injury, and lane departure crashes. Initially the data for Safety Performance Functions were collected for 12 years from 2003 to 2014. While verifying the data through navigating the Pathway Video Logs, an intermittent application of shoulder rumble strips was noticed. Therefore, a more accurate final data set was developed considering 7 years from 2008 to 2014. CMFs are dependent on the accuracy of the calibrated SPFs. A Normal Regression model with a Log-Link model was utilized to develop Wyoming-specific full Safety Performance Functions. While it is simple to quantify the safety effectiveness of permanent shoulder rumble strips, the process becomes challenging when resurfacing and shoulder rehabilitation may result in an intermittent presence of SRS in some locations. This study quantified the safety effectiveness of shoulder rumble strips for three different conditions; 1) assuming that SRS are present at all times since their initial implementation, 2) considering only verified sections with existing SRS for a continuous period of time, and 3) considering the intermittent nonexistent time periods of SRS as before period with after period when SRS are implemented. The thesis utilized cross-sectional and observational before-after with Empirical Bayes (EB) methods for the aforementioned three different conditions. The results from this study indicate that the safety effectiveness of shoulder rumble strips might be underestimated in case of not considering the intermittent implementation practice in the state. Specifically, it was found that SRS are 30% and 17% more effective in reducing fatal and injury, and lane departure crashes when considering the intermittent implementation compared to assuming their continued presence, respectively. Shoulder rumble strips resulted in about 50 and 40 percent reduction in fatal and injury crashes and lane departure crashes, respectively, considering the intermittent use. When the intermittent use was not considered, the shoulder rumble strips yielded only 14 to 28 percent reduction in different type of crashes which might be misleading. It is recommended that transportation agencies should consider immediate reapplication of SRS after resurfacing projects in order to help in reducing fatal and injury, and lane departure crashes. The final task of this study was to develop Crash Modification Factors for passing lanes. Passing lane is a potential countermeasure to reduce fatal and injury, and lane departure crashes. In this study, Crash Modification Factors for passing lanes were calculated by utilizing before-after with Empirical Bayes (EB) analysis. It is worth mentioning that the developed Wyoming-specific Safety Performance Functions were used to predict crashes in EB analysis. The result of the observational before-after analysis showed that the Crash Modification Factors for passing lanes were 0.58, 0.69 and 0.69 for total, fatal and injury, and lane departure crashes, respectively. Implementation of passing lanes in two-way two-lane highways is a cost-effective countermeasure to reduce crashes along with improving operations compared to four-lane construction.