Tuesday, April 15, 2014

NZ road fatality and injury statistics plotted against average road speeds

We are often sold the message that 'speed kills' and that 'speed cameras save lives'. So I was interested in what the actual government statistics showed when it came to speeds and the injury and fatal statistics.

I utilised data from NZ Government websites to plot these values against each other. Interestingly enough, while there is an initial trend showing a reduction of speed did reduce injuries and fatalaties, the direct trend didnt seem to match. For example, although the average speed has continued to decline, the injuries and fatalaties have been both up and down. Sometimes increasing and sometimes decreasing. In fairness however it could be said that the trend overall has been in a downward manner and a decrease in both injuries and fatalities is always a good thing. Surely however if speed was such a major factor and speed kills then we should have had a linear trend of injuries and fatalaties matching the reduction in speed?

Unsurprisingly I didnt find this data being plotted anywhere on any NZ Government websites and given they are about to introduce more of the new digital speed cameras (up to 200 of them @ around $100k each) and lower the speed tolerance for fining people to just 4 km/h over the speed limit I am not surpirsed why! See for yourself.

Speed cameras have been in use in NZ since 1993 and initially netted $80m in revenue. In 2009 the revenue from speeding fines was down to $36m but in 2010 the revenue was up to around $50m after 43 new digital speed cameras were introduced in 2009, suppossedly in effort to reduce the road toll to 300. Now that the average road speed has come down to below the 10 km/h tolerance that the NZ Police said was safe, revenue is also declining and hence we are seeing a move to lower the speed tolerance to withing a few km/h over the speed limit.

Data is taken from Statistics NZ (www.stats.govt.nz motor vehicle casualties) and NZ Ministry of Transport  (www.transport.govt.nz speed survey results - car speeds) Injuries and deaths are not broken down by urban or open road speeds so these have been plotted against both to identify the trend and compare them against the various speeds.

Number of fatals per 100,000 population vs urban and open road speeds. Road speed is on the left vertical axis and number of people per 100k on the right

Number of injuries per 100,000 population vs urban and open road speeds. Road speed is on the left vertical axis and number of people per 100k is on the right

In 2009 when the new digital cameras were instigated the NZ Police had to refund a bunch of tickets for drivers of trucks and high side vehicles as the cameras were over-estimating the speed of the vehicle sometimes doubling it! I don't know if this has ever been fixed? That certainly puts pay to the old saying - don't speed and you wont get caught! See the article here

The digital camera systems do have the ability to be upgraded to include automatic number plate and facial recognition although apparently this technology will not be utilised yet. The NZ Police do however have 2 vans with cameras capable of reading vehicle number plates as they drive past and 4 mobile units which can be used in a patrol car. The technology raises concerns with privacy and has been discussed in articles here and also here and there is a question over whether the use of the technology is even legal given that a warrant is usually required for surveillance.

In a report by the Auditor General in 2002 on the Speed camera Program, the auditors admit that excessive speed was only a factor in 30% of accidents yet the focus on speed is what generates the most income. The report also spoke about revenue raising envy because in Melbourne their prosecution rate was well above what NZ was and there was a suggestion NZ should be getting more prosecutions (and hence more $$). The Melbourne speed camera system as I understand it is run by a private corporation who is only interested in revenue so it makes sense that they go after anyone and everyone whereas the NZ system is run by the NZ Police by the Road Safety department so perhaps that's why there was such a difference.

A report by Ian Wishart into speeding fines argued that raising speed limits actually decreases death rates. See that article here

NZ is also considering point to point speed camera detections systems. These work by having a device which captures your entry point and exit point. They can be km's apart (such as on a motorway) and they work out your average speed by calculating how long it took for you to get from point A to point B. A consultants report into utilising these cameras identified key areas where they could be utilised - mostly on the motorways and some main highways. I think as long as these are well sign posted (as they do in the UK) this is probably a fairer system than just arbitrarily fining you for an instance of a certain speed.  Somehow I don't think they will advertise the fact they are there though.

So what is the answer? I think a sensible approach to road safety should prevail. Nabbing Joe average driver for exceeding the posted road speed by 4 km/h does nobody any favours. I think the best campaign the government ever came up with was

Drive to the conditions and when its changes reduce your speed.

This is sensible stuff. Sometimes its not safe to do the posted speed limit and sometimes its safe to exceed it. Better driver education and safer roads are also key and given they make up 60% of the reason for serious accidents surely they should be the focus - not revenue gathering.

As a paramedic I have seen my fair share of road trauma  but at most car accidents speed was NOT the cause of the accident - rather inattention of the driver, following too closely, driver distraction (don't text and drive!) poor road design, bad driving decisions or simply failing to drive to the conditions. The ambulance service in NZ travels thousands of kilometres every year and often its at high speeds racing to an emergency, yet their accident rate is actually very low and the serious accident rate is almost non existent thanks to driver education and an improved and modern fleet of vehicles. So why cant this work with other drivers? Education is the key.

Disclaimer: the statistics shown were taken from NZ Government websites. I am not a statistician and do not claim that my representation is anything other than my own interpretation of these figures. Views expressed here are my own and do not represent that of the NZ Ambulance service or any other organisations.