Designing Safe Multi-lane Roundabouts For Cyclists: The 'C' Roundabout Approach.pdf

This research project, led by GHD Ltd and the University of Auckland, aimed to design safer multi-lane roundabouts for cyclists in New Zealand. The primary focus was on reducing crash rates and improving visibility for both cyclists and drivers.

Background:

- Multi-lane roundabouts are considered hazardous for cyclists, with police data supporting this view.
- Existing design guides provide off-road solutions but lack adequate on-road alternatives for cyclists.
- The project aimed to create an on-road design that is safe, attractive to cyclists, and benefits other users while maintaining or improving junction capacity.

Literature Review:

- Cyclist crashes at roundabouts are predominantly 'entering vehicle versus circulating cyclist' types.
- Lowering vehicle speeds can reduce crash numbers and severity, improve driver perception of cyclists, and assist cyclists in their maneuvers.
- Visibility should be limited to prevent excessive approach and entry speeds, with recommendations varying between guidelines.
- No satisfactory design solution exists internationally for multi-lane roundabouts catering to cyclists.

Design Concept: "C" Roundabout

The project resulted in the "C" Roundabout design, which aims to:

1. Reduce vehicle entering speeds to 30 kph or less.
2. Improve visibility of circulating cyclists through radial approaches and lower speeds.
3. Potentially reduce crash numbers and severity for all users.
4. Maintain or slightly increase junction capacity by enabling drivers to accept gaps easier at lower speeds.

Alternative Measures:

- Vertical deflection devices on approach roads can also reduce speeds but may impact bus passenger comfort, emergency, and heavy vehicles.

Conclusion:

The "C" Roundabout is a novel design concept that addresses the safety concerns of cyclists at multi-lane roundabouts. It is not a one-size-fits-all solution but offers a valuable tool for traffic engineers in improving the road network for cyclists while considering other users' needs.