Roundabouts

Roundabouts are controlled intersections with one or more marked traffic lanes, all of which are for the use of vehicles travelling in a clockwise direction around a central traffic island.  They work well for motor vehicles if the traffic volumes on all legs are about equal.

Conversion of give-way or stop controlled local road intersections to roundabouts is often undertaken to address safety issues.  Doing so can also reduce pedestrian level of service by requiring pedestrians to move from their desire line to use the designated crossings setback from the roundabout and removing any priority pedestrians may have over motorists within the road rules.

Roundabout with pedestrian refuges and zebra crossings, Hataitai, Wellington. (Photo: Ann-Marie Head)

Contextual considerations

Although treatments can be provided for pedestrians and cyclists at roundabouts, they may not be the most appropriate intersection treatment at locations where there are high levels of cycle and pedestrian traffic and alternative treatments should be considered.  Compared to signal controlled intersections roundabouts can present a significant impediment to pedestrian movement, particularly larger roundabouts with high volumes or speeds of motor vehicles.  In such cases it may be very difficult for mobility impaired pedestrians in particular to find an acceptable gap in traffic to cross at the roundabout. Compact roundabouts with slow vehicle speeds and refuge islands or zebra crossings to assist pedestrians to cross can be appropriate in some contexts.

Roundabouts have the following benefits and implications for pedestrians crossing.

Benefits

• Roundabouts can be designed to ensure low vehicle speeds.
• Roundabouts generally reduce the severity of pedestrian crashes due to the slower vehicle speeds.
• Pedestrian islands can be incorporated into splitter islands dividing the crossing into two movements which reduces pedestrian delay.

Implications

• Roundabouts can cause problems for the vision impaired due to confusing auditory signals from approaching and circulating vehicles.
• They can be more difficult to cross when higher volumes of traffic and multiple traffic lanes are present and the large number of possible vehicle paths. Pedestrians can find it particularly difficult to cross the exit lanes of high speed multi-lane roundabouts, and drivers exiting these roundabouts may not notice pedestrians crossing if there is not a large pedestrian presence in the area.
• They can push pedestrians away from their desire lines.

Recommended parameters

• Solid splitter islands with pedestrian refuges can assist in staging the crossing of each leg of the intersection.
• Can be combined with kerb extensions to minimise crossing distances for pedestrians and/or vertical deflection to reduce vehicle speeds.
• Wherever possible, pedestrians should only be required to cross one lane at a time (unless on a zebra crossing).
• Primary Safe System treatment if operating speeds are below 30km/h.[1]
• May be a standard safety intervention if key criteria are met (in particular the use of raised safety platforms) which can lead to a streamlined investment pathway. Refer to the Standard safety intervention toolkit
• Some vision impaired people find roundabouts particularly difficult to negotiate owing to confusing audible information from cars approaching and exiting the roundabout. This means some vision impaired pedestrians prefer to cross mid-block away from the roundabout. It is recommended to ensure there are alternative mid-block crossing facilities upstream of the roundabout approaches.

Legal considerations

Section 10.4 of the Traffic Control Devices Rule 2004 outlines the marking and signage requirements for roundabouts. This section also includes requirements for roundabout metering signals and lane marking for multi-lane roundabouts.

Land Transport Rule: Traffic Control Devices 2004

Design considerations

Where a roundabout is the intersection selected then the following design considerations apply to help accommodate pedestrians:

• Design speed – In urban areas where there is likely to be significant cyclist or pedestrian demand, speeds should be designed to a Safe System speed of under 30 km/h to minimise the risk of serious or fatal injury. In such circumstances the tangential approach that is adopted for higher speed roundabouts is unlikely to be appropriate.  Compact roundabout design could be more appropriate.
• Pedestrian crossing demand – It should be expected that pedestrians are using the road network at all urban roundabouts and some rural roundabouts and that they are likely to need to cross every leg of the roundabout. Therefore, crossing facilities should be provided on each leg.
• Pedestrian visibility - Pedestrians crossing the roundabout should be visible to motorists approaching and departing from the roundabout and pedestrians should have sufficient sight distance to be able to detect and respond to an acceptable gap in order to cross. This will apply both from the kerb and any central splitter island.  Street furniture (especially fencing and vegetation) should be either sufficiently low or transparent that pedestrians, including children, can readily see beyond the obstacle (and equally, that they are not masked to motorists).  Providing adequate sight distance may mean banning parking on the approaches and also moving or lowering property fences/hedges.
• Pedestrian desire lines - Footpaths, kerb ramps and pedestrian refuges in splitter islands should be located to minimise pedestrians needing to deviate from their desire line but also ensure adequate visibility.

Design elements

Speed reduction

If aligned with the Safe System principles, a well-designed roundabout achieves lower relative speeds of vehicles primarily owing to the application of appropriate entry curvature, which improves safety including limiting the potential risk of a fatal or serious injury to pedestrians and cyclists.  Austroads provides detailed guidance on roundabout design.

Austroads Guide to Road Design Part 4B: Roundabouts(external link)

Compact roundabouts are designed to contribute to a speed environment that is low enough for all users in urban situations including pedestrians and cyclists.

Cycling Network Guidance: Compact roundabout design

Vertical deflection

To further reduce vehicle speeds at roundabouts, vertical deflection or road humps can be used on each approach.  These can also function as pedestrian platforms in low-speed urban areas if vertical deflection is applied at the crossing location, as shown below.  These can also be retrofitted to an existing roundabout to reduce speeds.

Roundabout with pedestrian platforms on all approaches. (Source: Canterbury Maps)

Alternatively the whole roundabout can be raised to slow vehicles and make the crossings for pedestrians more visible as shown in the typical layout in Figure 13-3 of the TCD Manual Part 4.

TCD Manual Part 4 (draft for consultation) [PDF, 35 MB]

Crossings for pedestrians at roundabouts

It is best to aim for consistency in the crossing type across all legs of a roundabout. However, differences in traffic volumes, speeds and pedestrian demand or type may lead to different facility types being more appropriate across one or more legs.

Refuge in splitter islands

The provision of refuges in roundabout splitter islands will facilitate multi-stage crossing.  Splitter islands should be as large as the site allows, with cut-throughs (designed similar to pedestrian islands) ideally (6m) back from the limit line so the crossing by queued vehicles.  The refuge can be integrated with a pedestrian platform as shown below.

PNG: Crossings (refuge islands)

Raised platform crossing operating as a pedestrian platform, Kaiapoi. (Photo: Jeanette Ward)

Pedestrian crossings (zebras)

Pedestrian crossings (zebra) may be installed near roundabouts. There is no required setback from the intersection however, providing a setback of one vehicle between the zebra crossing and the limit line means a vehicle stopped at the roundabout limit line will not block the crossing. Zebras at roundabouts can be raised on platforms, this is recommended to reduce speeds and improve the awareness of the crossing.

There are also signs and marking matters to consider in TCD Manual Part 4 Section 5.5.1. Pedestrian crossing signs and markings may not apply to all approaches if there are zebra crossings only on some legs of the intersection. The entire length of the pedestrian crossing must be visible to approaching drivers.

TCD Manual Part 4 (draft for consultation) [PDF, 35 MB]

Sometimes a dual zebra/cycle crossing will be appropriate to enable pedestrians and cyclists to cross a roundabout leg as shown below.

TCD Manual Part 4 (draft for consultation) [PDF, 35 MB]

Cycling Network Guidance: Cycle crossing design

Dual zebra/cycle crossing at a roundabout, Champion Road, Richmond. (Photo: Mark Edwards)

Pedestrian operated signals at roundabouts

Some roundabouts may have a high pedestrian demand on one leg only and to assist pedestrians to cross (for example, a multilane roundabout) signals may be an appropriate crossing option. This is not appropriate in town centre environments. To reduce the likelihood of a driver mistakenly thinking the green signal gives them priority to enter a roundabout, where a signalised pedestrian crossing is provided on the approach, the limit line for the signalised crossing and the limit line for the roundabout must be at least 30m apart. This may mean pedestrians (and possibly cyclists) are diverted off their desire line which is not desirable and should be minimised. Signalised pedestrian crossings at roundabouts also act as a form of roundabout metering.

PNG: Signalised crossings

Cycle and pedestrian signalised crossings

TCD Manual Part 4 (draft for consultation) [PDF, 35 MB]

An example of a signalised crossing for pedestrians and cyclists at a roundabout is shown below.  A new high school (2,500 students) was built less than 1km from the school and that increased demand on one of the roundabout legs.

Multilane roundabout with pedestrian signals on north leg. (Source: Canterbury Maps)

Signalised pedestrian/cycle crossing on Frosts Road approach to Travis Road roundabout. (Photo: Jeanette Ward)