Rumble strips, or Audio Tactile Profiled (ATP) road markings, to give them their proper name, are an increasing occurrence on our rural roads to improve safety. Where installed, they give drivers an improved visual cue regarding line markings, an auditory cue from the ‘rumble’ they give emit when driven over and a physical cue from the vibration.
Multiple studies have demonstrated their effectiveness, when installed on the centreline they can reduce head-on and opposite direction sideswipe crashes by 30% and run off road crashes by 15%.
Over the last couple of years, Abley has assessed 1,248 kilometres of road across New Zealand and recommended the placement of 1,350 linear kilometres of ATP. Based on estimated safety outcomes, we believe that this has made a real difference to help make our roads safer for all users.
Although ATPs can be applied on most rural roads, there are a few elements to consider before installation including:
- Road shoulder width – A minimum shoulder width of 1m is required to enable cyclists to cycle on the outside of the edgeline, but this can be reduced if the road is not located on a busy cycling route. Especially on rural roads where the speed difference is high between cyclists and vehicles, even for experienced cyclists it is safer for cyclists to be on the shoulder of the road and there should be enough width for this. If there isn’t adequate width, cyclists will be required to cycle over the edgeline which may lead to cyclists losing control and crashing. Research has also shown drivers need approximately 300mm of additional seal to recover when they have driven over the ATP edgeline.
- Noise – Given that one of the main features of ATP markings is the audio warning it creates, noise can be an issue for residents who may live close to any areas where ATP is installed and regularly driven over. For this reason, ATP is excluded on sections of road which are within hearing proximity to residential dwellings. It is up to the road authority applying the ATP to decide on how far away to install ATP from dwellings to make sure they will not be heard by residents.
- Maintenance – If the road that ATP is proposed on has a windy alignment, this can lead to vehicles regularly tracking over the edgeline which can lead to accelerated deterioration of the installed ATP. of ATP reinstatement should be considered as ATP can be about four times the cost of regular white edgeline paint. If there are a low number of run-of-road crashes occurring on a road, then ATP can be omitted along windy sections of the road.
Using GIS for ATP application
As part of Abley’s significant road safety activities, we support Waka Kotahi and local authorities in determining where ATP should be installed. To make it easier to define locations where edgeline ATP will be effective, we map locations, while considering the guidance requirements using a GIS web map. The screenshot below shows a web map of where ATP can be installed.
For example, using the RAMM (Road Assessment and Maintenance Management) system, which is used by New Zealand’s road controlling authorities to manage their road networks, we can map the available shoulder width and if this was below 300mm, this could be highlighted in orange.
For proximity to residential dwellings, a data set of building outlines was used to approximate locations of dwellings. A 200m radius was drawn around the dwellings and any section of road that was located in this area was marked in red as shown in the map. Similarly, proximity to bridges and intersections was mapped out using LINZ data.
After the requirements are mapped, they can be laid on top of each other which provides sections of roads where ATP application will be possible and will satisfy all requirements.