Title
Review Educational Presentation on Roundabouts (Discussion Item)
Body
To: Honorable Chair and Members of the Transportation Commission
EXECUTIVE SUMMARY
As part of Vision Zero safety, City staff has contracted with Kittelson consultants to provide expertise and guidance on roundabouts. Modern roundabouts are a type of intersection characterized by a generally circular shape, yield control on entry, and features that create a low-speed environment while traveling counterclockwise around a central island. Modern roundabouts have been demonstrated to provide a number of safety, operational and other benefits when compared to other types of intersections.
BACKGROUND
As part of Vision Zero safety, City staff has contracted with Kittelson consultants to provide expertise and guidance on roundabouts. Kittelson consultants are contracted to provide an educational presentation on roundabouts to the Transportation Commission and the City Council, to identify top locations for potential roundabouts, to peer review the proposed Central Avenue roundabouts and to add policies related to roundabouts in the General Plan update. The work also includes a potential quick build pilot for mini-roundabouts along the City’s proposed bicycle boulevards as part of the Action Transportation Plan.
DISCUSSION
Modern roundabouts are a type of intersection characterized by a generally circular shape, yield control on entry, and features that create a low-speed environment while traveling counterclockwise around a central island. Modern roundabouts have been demonstrated to provide a number of safety, operational and other benefits when compared to other types of intersections. On projects that construct new or improved intersections, the modern roundabout should be examined as an alternative. Mini-roundabouts are a type of roundabout characterized by a small diameter and traversable islands, and are best suited to environments where speeds are already low and environmental constraints would preclude the use of a larger roundabout with a raised central island.
Roundabout Benefits:
• Traffic Safety: The physical shape of roundabouts reduces potential conflict points and the most severe of those conflict points. Studies show reductions of 35 percent in total crashes and 76 percent in injury crashes.
• Pedestrian and Bicyclist Safety: Due to the reduction of vehicle speeds, roundabouts can improve pedestrian and bicyclist crossing opportunities. Additionally, the splitter island refuge area provides the ability for people walking and bicycling to focus on one traffic stream at a time while crossing. Specific design treatments for visually impaired pedestrians need to be implemented while including these community members in the design and construction process. Bicyclists can have the flexibility of navigating the roundabout either as motor vehicles or as pedestrians depending on the size of the intersection, traffic volumes, their experience level and other factors.
• Traffic Calming: Roundabouts can have traffic calming effects on streets by reducing vehicle speeds using design rather than relying only on traffic control devices.
• Operational Performance: Roundabouts typically have lower overall delay than signalized and all-way stop-controlled intersections, and the reduced delay is often most significant during non-peak traffic periods. These performance benefits can often result in reduced lane requirements between intersections.
• Operations and Maintenance: A roundabout typically has lower operating and maintenance costs than a traffic signal due to the lack of technical hardware, signal timing equipment and electricity needs. Roundabouts also provide substantial cost savings to society due to the reduction in crashes, particularly fatal and injury crashes.
• Environment: Roundabouts can provide environmental benefits by reducing vehicle delay and the number and duration of stops compared with signalized or all-way stop-controlled alternatives, which can reduce noise and air quality impacts and fuel consumption.
• Aesthetics: The central island and splitter islands offer the opportunity to provide attractive entries or centerpieces to communities through use of landscaping, monuments and art.
Source: Federal Highway Administration, Roundabouts: An Informational Guide
ALTERNATIVES
The installation of roundabouts is considered best practices in that roundabouts are better at reducing fatal and severe injury collisions compared to traffic signals so roundabouts are consistent with the City Council’s new Vision Zero Policy. The Transportation Commission and the City Council could recommend continuing with more traditional traffic signals rather than pursuing roundabouts in the City and not implementing roundabouts.
FINANCIAL IMPACT
This item is a budget neutral request in that it is an informational item.
MUNICIPAL CODE/POLICY DOCUMENT CROSS REFERENCE
Roundabouts are consistent with the following City documents:
• The Safety and Noise Element of the General Plan (Policy SN-5) states: “Ensure that the City prioritize public safety through the implementation of a Vision Zero policy to reduce annual pedestrian and bicyclist fatalities and serious injuries resulting from collisions with faster moving vehicles and unsafe street design.”
• The Vision Zero Policy that focuses on eliminating fatal and severe injury collisions, and is the citywide guiding principle for transportation planning, the design of streets and sidewalks, and the maintenance of the public rights-of-way making safety as the highest priority when balancing competing needs and demands for space within the public right-of-way.
ENVIRONMENTAL REVIEW
This action is not a project under California Environmental Quality Act Guidelines, section 15378(b)(4).
CLIMATE IMPACT
Roundabouts will improve transportation operations and energy and water efficiencies to reduce greenhouse gas emissions, and also will improve the resiliency to the impacts of climate change with best practice stormwater management treatments that are possible in the center island such as rain gardens, street trees and pollutant reduction measures to mitigate flooding and the water quality impacts of storm water runoff.
RECOMMENDATION
Review educational presentation on roundabouts
Respectfully submitted,
Andrew Thomas, Planning, Building and Transportation Director
By,
Gail Payne, Senior Transportation Coordinator
Exhibits:
1. Presentation