Browsing by Author "Loutfi, Andrew"

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    Evaluation of the Effectiveness of Stop Lines in Increasing the Safety of Stop-Controlled Intersections
    (Minnesota Department of Transportation, 2020-07) Duhn, Melissa; Dirks, Peter; Loutfi, Andrew; Hourdos, John; Davis, Gary
    Stop lines are ubiquitous, but do they really impact intersection safety? Prior to this project, no long-term studies on intersection safety with stop lines had been completed. This project was developed with two parallel research efforts: a safety study and an observational study. The safety study was developed to address stop lines’ effects over the long term and used crash data from five cities’ stop-controlled intersections to perform regression and see if stop lines actually influenced safety. The observational study was developed to determine if stop lines have an effect on driver behavior at intersections and to look at where drivers were stopping. Video was collected at 16 different intersections before and after a stop line was painted. The safety study and observational study showed that stop lines did not have a significant impact on driver behavior or intersection safety, but other factors like speed limits and sight distance did. Implications for practice include carefully examining sight distance at the intended stopping point to ensure drivers have adequate sight distance in both directions. If sight distance is not adequate, moving the intended stop location or reconsidering whether the intersection should have signage -- stop or yield -- or be uncontrolled could yield better driver compliance and safety.
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    Work Zone Mapping and Tag Deployment System
    (Center for Transportation Studies, University of Minnesota, 2019-10) Parikh, Gordon; Duhn, Melissa; Loutfi, Andrew; Hourdos, John
    Roadway construction is an inevitable part of functional transportation infrastructure. However, work-zone incidents have increased overthe years. This report is the third part of an interdisciplinary project to improve driver safety in work zones. The first component was ahuman factors study, performed by Craig et al. (2017), determining the most effective way to alert drivers to work zones without disrupting driver behavior. The second component, by Liao (2019), sought to determine whether Bluetooth low-energy tags could be deployed in work zones to provide real-time updates to drivers’ mobile phones through an app. The third component, the Statewide Work Zone Information System (SWIS), establishes a real-time database of active work zones from the first advanced warning sign being placed to the time the crews pack up. SWIS uses beacons attached to traffic control devices, called assets, that send messages to a central cloud repository. From there, messages are processed, categorized into Projects, Traffic Control Plans, and Work Zones. SWIS continuouslyupdates based on asset messages it receives. Users can access SWIS through a web interface, to view active, past or future projects, plan aproject, or update existing projects. SWIS provides an online, real-time portal for storing, monitoring, and inspecting work zone traffic-control operations.