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Application of Clear Zones for Roadway Departures Departure Crashes - An Interactive Approach Identifying Effective Mitigation Measures

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INSTRUCTOR: Nazir Lalani, P.E., M.ASCE

Course Length: 1.5 Hours

Sponsored by ASCE's Transportation & Development Institute and ASCE Continuing Education.

The instructor clearly knew the information and had real-world experience to relate. - Anonymous Attendee

Purpose and Background

The fourth edition of the AASHTO Roadside Design Guide presents information on the latest state-of-the-practice in roadside safety. It presents procedures to determine a recommended minimum clear zone on tangent sections of roadway with variable side slopes and adjustments for horizontal curvature. The AASHTO Sixth Edition of A Policy on Geometric Design of Highways and Streets (Green Book) enumerates a clear zone value for various functional classes of highway. This webinar will provide information on how roadside clear zones are to be provided in area with and without curbs. Clarification of the terminology used in various FHWA publications will be provided including the understanding of clear zones and their importance. The first half of the presentation will focus on how to minimize roadway departures. The second half of the presentation will focus on what should be done to mitigate  crashes resulting from drivers drifting out of the travel lanes.

Learning Outcomes

  • Identify publications in which clear zones are discussed
  • Become familiar with various clear zones that these publications suggest
  • Learn variations among the different clear zones
  • Gain knowledge on possible best practice
  • Identify treatments to mitigate lack of adequate clear ones and roadway departure crashes
  • Address tort liability incurred by clear zone violations
  • Application of clear zones to curbs

Webinar Benefits

  • Improved understanding of the importance of clear zones
  • Better understanding of the recently updated applicable terminology
  • Clarifying the most appropriate clear zones in rural and urban areas
  • Improving safety using roadside delineation and warning systems to reduce roadway departure
  • Identifying safety systems for reducing the severity of single vehicle crashes
  • Improve knowledge of the most relevant sources of information


  • Transportation professionals
  • Engineers
  • Technicians
  • Field maintenance staff who work for cities, counties, and state agencies involved in designing and maintaining roadways where there is a need to provide clear zone and roadside safety systems.
  • Participants on AASHTO/TRB current research and guidance on clear zones and various aspects of roadside safety as it relates to run of the road crashes.

Webinar Outline

  • Clear zones distances
  • Lateral offsets
  • Recoverable and traversable slopes
  • Roads elements requiring lateral offsets with and without curbs
  • Shoulder widths
  • Providing a more forgiving roadside to reduce the severity of roadway departure crashes 
  • Warning drivers of road departure
  • Mitigating measures for inadequate clear zones
  • Above ground utility structures
  • Guard rails and median barriers
  • Wildlife detection and warning devices
  • Truck escape ramps
  • Design and placement of mailboxes