hi folks

thanks mark for working on this. I am going to post it up at can.org.nz/rotorua. might find more audience and maybe facilitate easier comment. I just googled: "bicycle roundabout best practice" and came up with the bits below. Most cases say that best practice is merging bike lanes into traffic.

Is it possible to get speed bumps put in the traffic lanes to force cars to slow down and thus make it easier for bikes to integrate into traffic lanes (especially if turning right). Some specific signage reminding cars that bikes have "full lane rights" at roundabouts would be good, too.

from wikipedia "roundabouts":
"Statistically, roundabouts are safer than both traffic circles and traditional intersections.[1] The only exception to that exists in large and multi-lane roundabouts where cyclists have a significantly increased crash rate, although fatalities are fewer."

there is an entire wiki section on "Roundabouts and cyclists". from this wike page:

Cycle facilities at roundabouts
Research has shown that even in large circular junctions that lack modern roundabout design features, a high rate of bicycle/motor vehicle crashes occurs when bicyclists are riding around the outside. Design guidance for modern roundabouts recommends terminating cycle lanes well before the entrances, so bicyclists merge into the stream of motor traffic.[24][25]
A 1992 study[26] from the German Transport Ministry's research institute has cast particular light on this issue. The study found that bicyclists' risk is high in all such intersections, but it is much higher when the junction has a marked bicycle lane or sidepath around its outside (see "Marked perimeter cycle lanes" below). The results of this study concerning circular junctions are summarised on the web (in German, but partially translated below).[27] A report about accidents at four-arm roundabouts was published[28] by the UK Transport and Road Research Laboratory (TRRL) (now TRL) in 1984.
Collisions typically occur when a motorist is entering or leaving the circular roadway. A motorist entering the circular roadway must give way to traffic in it, but such traffic will generally keep away from the outside of the circular roadway (as with a vehicle in the photo) if passing an entrance. A bicyclist close to the edge of the roadway is not in the usual position where an entering motorist expects to look for circulating traffic.
When exiting the circular roadway, a motorist must look ahead to steer, and to avoid colliding with another vehicle ahead or with pedestrians on a footpath. As the circular roadway curves away from the exit, the path of a vehicle exiting the circular roadway is relatively straight, and so the exiting motorist may often not need to slow substantially. However, if it is necessary to give way to a bicyclist riding around the outside, the exiting motorist must look toward the rear, to the outside of the intersection. With many vehicles, such as vans, the driver's view in this direction is obstructed. The task burden of the motorist is therefore substantially increased if bicyclists ride around the outside. The resulting conflicts, and more frequent requirements for motorists to slow or stop, also reduce the efficiency of traffic flow which is one of the major advantages of the circular junctions. Cycle lanes around the outside of circular junctions are therefore falling out of favour.

[picture edited out] Marked perimeter cycle lanes
Cycle lanes on St John's roundabout in Newbury, Berkshire, England. This example is from a country where traffic keeps to the left, and traffic in the circular roadway of the roundabout travels clockwise.
An early attempt to deal with the problem was to mark preferential lanes for cyclists. With cycle lanes, bicyclists do not merge into the flow of motor traffic in the roundabout, but rather, they travel around the outside, relieving them of the requirement to merge. The coloured road surface and edge lines of the cycle lanes indicate that motorists are required to give way to bicyclists at all locations where their paths may cross.

[picture edited out] Modern design guidance
The special features of modern roundabouts, including splitter/diverter islands and small diameter of the circular roadway, decrease the speed of motor traffic and so reduce the risk of collisions for motorists as well as cyclists below that of conventional junctions. Design guidance[24] for modern roundabouts recommends terminating cycle lanes well before the entrances, so cyclists merge into the stream of motor traffic. Cyclists who lack the confidence to do this may use the footpaths as pedestrians. Modern design guidance also recommends placing the footpaths far enough from the roundabout so that at least one exiting vehicle can wait without blocking the circular roadway. A roundabout with 2 lanes should place the footpath two car lengths from the junction. (FYI citation 24 is: Roundabouts: An Informational Guide FHWA-RD-00-67, June 2000 (US dept of transport) avail at: http://www.tfhrc.gov/safety/00068.htm)
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Roundabout retorts
By Joe Ingegeneri: Sans Souci, NSW : 01-Jul-2009
As an avid cyclist and engineer, I have to respond to David Hanson's letter relating to the intersection of Todman Ave and Baker St, Kensington, NSW (AC, Mar/Apr). Mr Hanson stated his frustration at the interruption of bicycle lanes by traffic facilities forcing cyclists to move into the traffic. He indicated these designs contradict the "safety in design" principles and would make the RTA and local Councils liable in the event of an accident.

Traffic practitioners utilise the RTA's NSW Bicycle Guidelines, which are intended to be a best-practice guide and are supported by the Austroads Guide to Traffic Engineering Practice, Part 14 - Bicycles and the Australian Standard AS1742.9 - Manual of Uniform Traffic Control Devices, Part 9 Bicycle Facilities.

The guidelines acknowledge that integration of bicycles and vehicles is necessary for some intersections because of the geometry and available area at the intersection. The Austroads guidelines state:

"If the roundabout is designed correctly speeds should be low enough to ensure safe integrations."

And:

"Separate channelisation for cyclists on roundabout approaches is not recommended because of the propensity for left-turning motor vehicles to conflict with cyclists travelling through a roundabout."

Integration of bicycles and motor vehicles through a local roundabout is best practice.

Joe Ingegeneri
Sans Souci, NSW
[http://www.australiancyclist.com.au/article.aspx?aeid=14730]