TRAFFESSIONALS have developed some new concepts for roundabouts which have great potential for space constrained urban areas that need to provide for all types of road user including pedestrians and cyclists.  We call them Compact Urban Roundabouts.

To a large extent these ideas stem from New Zealand Transport Agency funded research to improve multi-lane roundabouts for pedestrians and cyclists (NZTA 2006, NZTA 2012a, NZTA 2012b).  Reducing vehicle entry speed for safety reasons was a main objective, and it so happens that the methods to achieve this do also lend themselves to more compact designs than otherwise might be possible – in other words a great way to optimise road space.  We don’t think you will find anything else quite like them in other roundabout design guidelines.

Compact Urban Roundabouts use the following for speed control:

1/ Raised Platforms

2/ Narrow Lanes

3/ Restricted Sight Lines

The above links also show some examples in practice, and a technical paper on this topic was presented in March 2015 at the IPENZ Transportation conference in Christchurch, New Zealand.

Compact Urban Roundabouts are low speed, low cost, and low tech – but they are not cookie-cutter solutions and can do with a smart engineer to make them work well for each situation.  Unfortunately there are more than enough real world examples of roundabouts that do not work well, or at least as good as they could do.

Below are a few concept layouts for Compact Urban Roundabouts, which shown alongside a conventional roundabout design on left, can be seen to fit quite a lot into a little road space.  Note that blue triangle markings indicate directional raised platform ramps.  A simulated three-lane example with narrow lanes and platforms is shown here.

A few frequently asked questions:

Why put roundabouts in, say instead of traffic signals?

• SAFETY – Safer form of intersection control compared to most other types
• MOBILITY – less delay for drivers in off-peak periods, and can be less delay for pedestrians
• COST – Compact roundabouts like these are relatively cheap to build and maintain

So less of this:                                          And more of this:

   

 

 

What about cyclists and pedestrians at roundabouts?

• On-road cyclists can use roundabouts safely enough if vehicle speeds are 30 km/hr or less, and road crossings for cycle paths can be used at/near roundabouts
• Even sight-challenged pedestrians or similarly disadvantaged pedestrians are able to be catered for at multi-lane roundabouts, by the use of raised platforms or signalised crossing points if necessary
• Zebra crossings can give convenient priority over drivers

 

 

 

 

 

 

If I want to know more about putting in a Compact Urban Roundabout, where do I look?

• A preliminary guideline for designers wishing to apply narrow lanes can be found in the appendices of this NZTA research report
• Preliminary guidelines for designers wishing to apply raised platforms or restricted sight lines can be found in the appendices of this NZTA research report  (note that use of restricted sight lines are somewhat experimental at this stage)
• Otherwise you are best to contact us at at info@traffessionals.com, and we’d like to hear from you anyway