Brylee Drive, Conifer Grove - Traffic calming measures Brylee Drive, Conifer Grove - Traffic calming measures

Auckland Transport is proceeding with its plan to install traffic calming measures along Brylee Drive in Conifer Grove. This will involve installation of eight speed humps and a raised pedestrian crossing. We expect these changes to take place later in 2021.


Project status: Under construction from 13 December 2021 to 28 February 2022
Project zone: South (reference number MIP2021-025)


Project overview

As part of resource consent conditions for the neighbouring Waiata Shores development, a link road connection has recently been built joining Brylee Drive to Gosper Road in Waiata Shores. The consent also requires AT to implement traffic calming measures on Brylee Drive before this road is opened.

During November and December 2020, AT consulted with the community. This included a public drop in session about installing speed humps along Brylee Drive, to slow speeds and discourage people taking short cuts once the link is open.

From 11 May to 4 June 2021 we consulted again, including a public drop in session. This was to determine if the speed humps are appropriately positioned and whether the raised pedestrian crossing will improve safety. The majority of respondents told us that the speed humps are positioned appropriately and think that the raised crossing will improve safety.

This project is another step towards our goal of achieving no deaths or serious injuries on our roads. We are guided by the Vision Zero approach to transport safety, which prioritises human safety over other measures (like minor time saving).

Design


Download the Brylee Drive Traffic Calming Public Feedback (PDF 812KB, 25 pages)

Why speed humps are the preferred option

We have explored a range of traffic calming measures that would be suitable for Brylee Drive, these included speed humps, speed tables, Swedish-style raised tables, roundabouts, speed cushions and chicanes.

See Other traffic calming measures for details on these devices.

Render of a speed hump on a street.
Figure 1. Example of a speed hump.

We identified speed humps (see Figure 1) as the most suitable option for this location for the following reasons:

  • Performance and feasibility: speed humps are very effective in reducing driver speeds. Data from previous projects have demonstrated that speed humps generate fewer noise and vibration issues than speed tables. Due to the short length and the profile of speed humps, it also means vehicles can park on them so no on-street parking is removed.
  • Safety and accessibility: the speed humps are expected to calm the full length of the road so that driver speed is lowered enough to allow people to cross safely at any point along the route. The profile of the speed humps is also more comfortable for people cycling.
  • Cost-effectiveness and deliverability: speed humps are the most cost-effective option to achieve slower speeds. While speed reduction impact is similar to other measures, speed humps require less materials and less construction time compared to other alternatives. It will also result in lower maintenance and whole of life costs while still enabling effective traffic calming.
  • Public Transport: Brylee Drive is intended to become a low frequency bus route. The use of speed humps in other recently completed projects has shown that there were minimal and/or acceptable impacts in terms of bus passenger numbers, user experience, travel time, noise/vibration from the devices, and overall speed reduction.

Other traffic calming measures

We explored a range of traffic calming measures that would be suitable for Brylee Drive and the following were the other options considered:

Vertical treatments

Speed tables

A speed table is a raised table (a speed hump that is flat and wide) that aims to slow vehicles to a safe speed. Speed tables are typically considered where pedestrian crossing demand is expected. However, for Brylee Drive, high pedestrian crossing demand is not anticipated given that it is a residential area. It is considered better to calm the full length of the road so that the general speed environment is low enough to allow for pedestrians to cross safely at any point along the route.

From other recent AT projects, it has been demonstrated that bus routes with speed humps generated fewer noise/vibration issues than those with speed tables. Also, qualitative ratings of passenger comfort were higher on the route with speed humps compared to the one with speed tables. In addition, there seemed to be no difference between the impact of speed tables vs. humps on bus passenger numbers and travel time.

Swedish-style raised tables

Swedish speed tables are a raised table with only one sharp ramp and a more gentle exit which gives a smoother ride for vehicles and passengers.

Swedish tables are typically considered where there are large numbers of heavy vehicles and high frequency / double decker buses are expected. For a residential street like Brylee Drive, heavy vehicle numbers are expected to be low. Having heavy vehicle friendly devices would not be likely to deter heavy vehicles from using Brylee Drive as a rat-run.

Swedish tables cover a longer length of road compared to speed humps. On residential roads such as Brylee Drive, the significant number of residential driveways potentially means that device spacing would exceed 120m, therefore undermining the ability to achieve the desirable operating speed.

Swedish tables also cover a wider width and a central traffic island is required to separate the different slope profiles on each direction. This will result in the loss of on-street parking in order to fit the Swedish tables.

Roundabout controls at intersections

Roundabout controls were considered at various intersections, complemented with vertical treatments at mid-block locations. This however is considered less effective than having all vertical treatments, due to the need to cater for buses turning at the roundabouts. Due to the boundaries of the nearby properties there may also be issues creating enough space for buses to safely navigate the roundabout.

Speed cushions

Speed cushions are a series of a small speed humps that allow vehicles with larger wheel track to straddle the cushion, while vehicles with a smaller wheel track must drive over the edges of the cushion.

Speed cushions are not effective in reliably slowing vehicles, especially SUVs, on their own. It was determined that speed cushions will not result in the necessary slowing of speeds.

Horizontal treatments

Chicanes, pinch points or similar

Chicanes or similar were considered but are not preferred as they are less effective than the above vertical treatments at deterring non-local through traffic and reducing speeds. Vertical treatments are preferred from a safe system perspective.

As Brylee Drive is a future bus route, horizontal treatments such as chicanes will need to be designed to cater for bus tracking. This means it would have little impact on smaller vehicles as they would be able to negotiate through the chicanes easily, especially as the road is already wide. It would not be effective in terms of deterring non-local through traffic.

Chicanes or other horizontal treatments also cover a longer length of road compared to speed humps. On residential roads such as Brylee Drive, the significant number of residential driveways potentially means that device spacing would exceed 120m, therefore undermining the ability to achieve the desirable operating speed.

Removal of on-street parking spaces would also be required for the chicane or other horizontal treatments.


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