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Case Studies

Case One

Dunedin City Council 
Winter June – August 2012
Pre-Product Trial



Loss of control was a factor in 39 percent of deaths and 38 percent of serious injuries over the period 2005 to 2009.  

According to Safer journeys – New Zealand’s road safety strategy to 2020 this area is of “high concern”. One of the first focus areas is targeting high-risk rural roads and high-risk urban intersection thus maximise the cost effectiveness of reducing deaths and serious injuries.

Ice is well known for forming sometimes without any notice and formation can happen very quickly, while ice warning signs are in place on most roads and State Highways along with grit, drivers needed to still be aware that conditions could change without warning.

Pre-trial two high risk areas in Otago, Dunedin, where geographically the south is prone to icy conditions and harsh weather patterns in the winter than other areas in NZ.

The Pre-trial will take place on two renowned icy dangerous roads.  Both are of medium/high volume in order to improve safety for road users and reduce the likelihood of crashes, these two spots have been chosen to determine if the presence of the flashing Ice RRPMs change the drivers behaviour.

Following criteria have been used to select sites for this trial:

1. North Road – Montigue St. to Birchfield.
2. Main South Road – Thomson St to Abbots Bridge

  • Minimum length 2.0km- Moderate to high traffic volume ( 4000-10000 vehicles per day)
  • Moderate to high crash rate during winter months
  • Both sites are chipseal
  • No works programmed affecting the road alignment during the 8 week pre- trial period within the two proposed sites.
  • Roads chosen as both are monitored by RWIS to compare information/data
  • Implementation proposed 8 weeks commencing end of June 2012 winter period.

If the Ice RRPM are to be adopted into the rules, it is intended to be used on high-risk road renowned for icy/danger spot i.e. mainly rural roads or high volume urban roads.


Impacts and risks

Due to the product being in its infancy it would require new safe system road safety conversation to develop and distribute a wide range of resources such as Media, local body, AA, ACC incentives, pamphlets, website, posters, guidance materials especially in rental vehicles.

Should the product be implemented it is expected to provide a higher level of safety and reduce crash rate on icy roads.  Implementation would be based on local authority, emergency services knowledge and past data in areas where ice related conditions are renowned.

Performance Indicators which are being monitored as part of the pre-trial comparing with same period in previous years:-

  • Decreased of motorist speed on approaching Ice RRPM
  • Decreased accidents during the same period
  • Increase awareness of product
  • Increase awareness of the meaning of the colour and features
  • General public questionnaire of awareness of a new product and its meaning 

Safety and efficiency gains

The Ice RRPM is a low cost addition to the roads of NZ used to enhance the safety and reduce the crash risks which are prevalent in our winter months.  

It will only be implemented on roads, walkways, bridges that have been identified by local authorities, police etc… as high risk areas, therefore, the cost is low compared to social costs and impact after accidents have occurred.

The real time warning of these devices provided would greatly assist to modify driver behaviour but they are only an early warning system the Councils normal gritting regime would still continue.


Consultation: Undertaken and Proposed

Due to Dunedin’s challenging set of characteristics the maintenance of their roads during winter months can be tricky.  Due to geographic position they are always going to be susceptible to cold snaps, the topography of their network and the coastal positioned lead to a variety of different frost scenarios.  As much as they have temperature gauges positioned around the network that help guide early morning decision making there is always the potential to get the level of treatment wrong.  The Council believe in informing the travelling public with more direct driver feedback such as signage and more recently with pre-trials of thermochromic paint which proved to be unreliable.  The question was put to the industry what could be developed to indicate freezing temperatures.  A critical aspect of this initiative would be producing a product that the public would easily understand.

Proposed Assessment Method

Prior to pre-trial speed surveys will be undertaken at each pre-trail site.  Automatic tube counters will be set up upstream and downstream of the study sites to record speeds (axles) continuously for at least seven consecutive days.

During the pre-trial the Ice RRPM will be videoed to record with date and time of activation along with temperature.  Data will be collated with data at the RWIS.

A large number of free-vehicles will randomly monitor the performance along with heavy goods vehicles will pass over the devices to test compression and strength.

Towards the end of the pre-trial a public survey will be carried out to determine how road users perceive the product.  The questionnaire will be carried out asking general public on North Road (one of the sites) and CBD of Dunedin.  

The analysis of the above surveys will be included in the pre-trial evaluation report.  This will summarise the findings related to the project objectives.