Acceleration, deceleration, and stopping sight distance (SSD) criteria are key factors in determining roadway geometric design requirements. These elements are influenced by variables such as grade, vehicle type, maneuver type, brake reaction time, object height, and driver’s eye height. TRB hosted a webinar on Thursday, February 6, 2025 from 1:00 PM to 2:30 PM Eastern that covered the findings from recent studies that assess design policies related to these criteria and informed recommendations for updates to the AASHTO Green Book.
This webinar was based on NCHRP Research Report 1081: Acceleration, Deceleration, and Stopping Sight Distance Criteria for Geometric Design of Highways and Streets.
This webinar was sponsored by TRB’s National Cooperative Highway Research Program and the Standing Technical Committee on Performance Effects of Geometric Design.
The slides are available. Please contact trbwebinar@nas.edu for a link to the recording. There may be a $90 fee.
 
Webinar agenda and presenters

• Overview of NCHRP 15-75 and related field and crash studies – Peter T. Savolainen, Michigan State University
• Development of revised design guidelines – Eric T. Donnell, Pennsylvania State University
• Translating results into practice – James A. Rosenow, Minnesota Department of Transportation
• Question and answer session moderated by Eric T. Donnell, Pennsylvania State University

The first 60 minutes of the webinar were for presentations and the final 30 minutes were reserved for audience questions.
 
Learning Objectives
At the end of this webinar, participants can:

• Understand the differences between current design assumptions and associated parameters that describe driver behavior and vehicle performance
• Design acceleration and deceleration lanes in consideration of revised guidance based on driver behavior
• Determine the recommended SSD for various scenarios and relate anticipated safety performance to available sight distance

 
Professional Development Hours
This webinar was delivered as a scheduled – e-learning live event and is categorized within RCEP as Technical, Health and Safety.
Professional Development Hours (PDHs) earned on completion of this program were reported to the Registered Continuing Education Program (RCEP). Certificates of Completion are issued to all participants via the RCEP.net online system. Complaints about registered providers may be addressed to RCEP, 1015 15th Street, NW, 8th Fl., Washington, DC, 20005.