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Sponsored by ASCE Continuing Education and Transportation and Development Institute (T&DI).

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INSTRUCTOR:  Alfredo Cely, P.E., MSEM, M.ASCE

Purpose and Background

The traffic and geometry design of modern roundabouts is no longer a novelty. There are several national and local guidelines to help planners and engineers develop the horizontal design of roundabouts, such as the Highway Capacity Manual and the NCHRP Modern Roundabout Guide. However, what is not available in current design literature are guidelines for the grading and drainage design of modern roundabouts. This course will provide clear guidelines and directions to help engineers, architects, planners and contractors develop the vertical design of a modern roundabout that is consistent with its three core intended design features to improve the safety of our roadway network intersections.

Primary Discussion Topics

• Use of three core safety modern roundabout concepts in grading and drainage design
• Combine the use of a typical circulatory roadway section with key vertical design points to establish the vertical profiles for the roundabout intersection
• Develop drainage patterns that place catch basins in locations that preserve the prominence of the roundabout center island
• Use National guidelines and best practices to develop a roundabout intersection that can be incorporated into different elevation gradients

Learning Objectives

• Apply the three principal safety components of modern roundabouts into grading design
• Select a profile grade line point for the circulatory roadway that promotes the visibility of the roundabout
• Use at least two critical profile points to facilitate the iterative approach for developing the circulatory roadway profile
• Based on the application of at least 5 vertical design points, develop the profiles for the intersection returns and the approach/departure roadways

Webinar Benefits

• Discuss use critical profile points and revolving typical sections that can simplify construction plans development while at the same time providing clearer and easier to follow construction plans
• Receive guidelines for the grading and drainage design that will enhance the operations and safety benefits of modern roundabouts
• Identify common problem areas and prevent construction and operation issues through proactive design

• Building blocks for modern roundabout grading design
• Developing a typical section for the circulatory roadway
• Approach/departure lane profiles and critical points
• Circulatory roadway and curb return profiles
• Placement of stormwater catch basins and inlets