Crashes

In Minnesota snow presents a special problem for rural mailbox installations. So, Minnesota Department of Transportation (Mn/DOT) developed cantilevered mailbox support designs. Recent studies had shown that certain rural mailbox installations easily penetrated the passenger compartment of an impacting vehicle. These same studies pointed out that a large number of people are seriously injured or killed each year as a result of mailbox collisions Therefore, Mn/DOT initiated full scale crash test to ascertain the crashworthiness of its cantilevered design. The study results were: 1. The change in vehicle momentum was below the recommended limit. 2. The test vehicle remained upright with no tendency to spin out or roll over. (The four by four wood vertical support was not hit . Studies by others adequately document vehicle/post interaction) . 3. The windshield was broken in each test. However, no part of the test article penetrated into the passenger compartment. 4. There was no appreciable difference between the support designs- The study concluded that the Mn/DOT cantilevered designs are acceptable in terms of nationally recognized criteria. Some precautions are also given as to use and placement of the supports.

This Technical Summary pertains to Report 2023-05, “Evaluation and Refinement of Minnesota Queue Warning Systems,” published March 2023.

This study evaluates the first and a second implementations of the MN-QWARN queue warning algorithm developed by Hourdos et al. (1). This algorithm was developed to detect specific crash prone conditions created by traffic oscillations (shockwaves) on freeway systems. The MN-QWARN system was specifically calibrated for the freeway studied in Hourdos et al. (1) and was moved to a new location with minimal calibration. This evaluation found that the right-side model had a detection rate of 25% and a false alarm rate of 36%. The left-side model had a detection rate of 64% and a false alarm rate of 23%. We also note high over-warning rates on both lanes. Based on these findings, we recommend recalibrating the MN-QWARN algorithm at this location to examine improvements in performance.

As part of an emphasis on improving road safety, the Minnesota Department of Transportation seeks to identify the locations where older drivers were over-represented in accident records. This research project reports on the use of three methods to help improve the accuracy of identifying locations where older drivers were at increased risk: a basic statistical model, the Empirical Bayes statistical method and a clustering method. Overall, the basic statistical model preformed the best. The clustering method and the Empirical Bayes method could both be usefully applied to the traditional task of high-hazard identification--that of automatically screening a large number of accident sites to identify potential candidates for improvement. This information can point the way to areas that may require a more detailed engineering analysis.

This Technical Summary pertains to LRRB-produced Report 2018-09, “Work Zone Intrusion Report Interface Design,” published February 2018.

This Technical Summary pertains to Report 2017-22, “Safety Impacts of the I-35W Improvements Done Under Minnesota’s Urban Partnership Agreement (UPA) Project,” published June 2017.

This Technical Summary pertains to the LRRB-produced Report 2015-35, “Human Factors of Vehicle-Based Lane Departure Warning Systems,” published June 2015.

This Technical Summary pertains to Report 2016-04, “Evaluation of the Effectiveness of ATM Messages Used During Incidents,” published January 2016.

Cross median crashes occur on divided highways when a vehicle leaves the road, crosses the median and collides with a vehicle in the opposing lanes. Between 2001 and 2005, cross median crashes and head-on crashes in Minnesota took more than 600 lives. The Minnesota Strategic Highway Safety Plan targets these crashes for reduction, and Mn/DOT has begun installing median barriers, primarily cable guardrail, in strategic locations around the state as a cross median crash countermeasure.