Sponsored by ASCE Continuing Education and ASCEs Transportation and Development Institute (TDI).  

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

"ASCE webinars are great for us. We are in a remote location and it is difficult to get quality training for our staff without much expense."

Purpose and Background

This webinar will focus on the best practices for designing the geometric aspects of roundabouts to maximize the safety of all road users using guidance from the latest publications from FHWA and TRB.  About 65% of all crashes in urban areas and 40% of all crashes in rural areas occur at or near intersections or driveways. Safety improvements at these locations have always been a priority and pose a challenge for most transportation agencies. Because crashes are typically complex events, a variety of mitigation measures have been tried with varying degrees of success, including the modern roundabout. This webinar will focus on the best practices for designing the geometric aspects of roundabouts to maximize the safety of all road users using guidance from the latest publications from FHWA and TRB. Case studies will be used to highlight problems that can result from roundabouts that are not designed in accordance with best practices.

Primary Discussion Topics

• Geometric aspects of roundabout design  
• The best sources of information about roundabouts  
• The latest FHWA Roundabout Reports and, NCHRP Report 672 and also the research from NCHRP Report 572 
• Threecase studies highlighting various issues that arise from improperly designed roundabouts

Learning Outcomes

Participants will become more familiar with the various aspects of the design of geometric aspects of modern roundabouts as discussed in the latest FHWA Roundabout Guide, NCHRP Report 672 and also the research that was reported in NCHRP Report 572. Three case studies will highlight the various issues relating to the design of modern roundabouts and operational problems caused by roundabouts that did not follow the guidance provided in NCHRP 672.
 
Webinar Benefits

• Learn how to design various types of modern roundabouts to maximize capacity
• Understand the key horizontal and vertical geometric design parameters
• Recognize the relationship of geometry to safety and geometry to capacity from a design perspective
• Become more familiar with the latest edition of FHWAs Roundabout Guide (NCHRP 672)
• Learn best practices for handling pedestrians and bicyclists at modern roundabouts

Webinar Outline

• Right of way impacts
• Design parameters affecting capacity
• Relative importance of entry and exit radii
• Geometric design to reduce path overlap
• Addressing potential crash patterns
• Splitter islands
• Truck aprons
• Spacing to adjacent traffic signals
• Sight distance
• Lesson

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