How can you design roundabouts for urban areas?

2 Step 2: Define the design parameters

The second step is to define the key design parameters that will influence the size, shape, and performance of the roundabout. These include the number and configuration of legs, the diameter and width of the circulatory roadway, the number and width of lanes, the entry and exit angles, the deflection and curvature of approaches, and the design speed and vehicle types. You should also consider the pedestrian and bicycle facilities, the landscaping and lighting features, and the signage and pavement markings.

3 Step 3: Develop the preliminary layout

The third step is to develop the preliminary layout of the roundabout based on the design parameters. You should use geometric design standards and guidelines, such as those from AASHTO, FHWA, or NCHRP, to ensure safety and functionality. You should also check the sight distance, the entry and exit capacity, the queue length, and the conflict points of the roundabout. You can use software such as AutoCAD, MicroStation, or SIDRA to assist you in this step.

4 Step 4: Refine the design details

The fourth step is to refine the design details of the roundabout to optimize its performance and appearance. You should review and adjust the alignment, grade, cross-section, and drainage of the roundabout. You should also finalize the pedestrian and bicycle facilities, the landscaping and lighting features, and the signage and pavement markings. You should ensure that the roundabout is accessible, attractive, and consistent with the urban context.

5 Step 5: Conduct the design review

The fifth step is to conduct the design review of the roundabout to verify its compliance with the standards and specifications, as well as the project objectives and stakeholder expectations. You should involve the relevant agencies, authorities, and consultants in this step. You should also solicit feedback from the public and the users of the roundabout. You should address any issues or concerns that arise from the design review and make the necessary revisions.

6 Step 6: Prepare the construction documents

The sixth and final step is to prepare the construction documents for the roundabout. These include the plans, specifications, estimates, and contracts that will guide the bidding, awarding, and building of the roundabout. You should ensure that the construction documents are clear, accurate, and complete. You should also coordinate with the contractors, engineers, and inspectors who will be involved in the construction process.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?