Speed zones should make our roads safer - so why are they so confusing?Alan Finlay reports.
"Speed kills". "There is no such thing as safe speeding". "How fast are you going now?" Readers will no doubt be familiar with these road safety slogans, but judging by the letters, emails and phone calls that NRMA receives, the issue of speed limits is not as clear cut as these slogans would have us believe. How fast or slow we should drive and on which roads is a confusing, frustrating and controversial subject for many motorists.
Older readers will recall we used to have just two speed limits: one for built-up areas (35 mph) and one for all other areas (50 mph 'prima facie'). With the conversion to metric units, we moved to four speed limits: 60, 80, 100 and 110 km/h. Now we have speed limits ranging from 10 km/h (in shared zones) to 110 km/h on high standard roads such as freeways, and from 40 km/h upwards, they can change in 10 km/h steps.
As a result, knowing what speed you should be adhering to at any given time can be baffling. Lack of adequate signage and seemingly inconsistent speed zones are just two of the problems we face.
To help address the issue, NRMA researched community attitudes to speeding and speed enforcement. Most recently, we commissioned an audit of speed zoning on four major routes in the Sydney metropolitan area, with very interesting results.
According to the Roads and Traffic Authority of NSW, speeding is the single most significant factor in road deaths in NSW, contributing to an estimated 40 per cent of fatalities. Research has also found that the more a driver exceeds the speed limit, the higher their chances of becoming a statistic. For example, in a 60 km/h zone, it is estimated that travelling at 65km/h doubles the risk of a casualty crash, while travelling at 75 km/h increases the risk by 11 times.
These claims are problematic for two reasons. Firstly, it is very difficult to determine accurately what contribution speeding made to a crash in hindsight. All of the crash statistics in NSW are based on crashes reported to Police. With the exception of serious injury and fatal crashes where there may be criminal charges, the attending police officer is not highly trained in crash investigation.
Understandably, the officer may decide that speed was a prime factor, when in fact most crashes have multiple causal factors. Secondly, the increasing crash risk with increased travelling speeds in any one speed zone assumes that the speed zoning is correct in the first place.
However, while speeding may not necessarily be the 'primary cause' of all crashes, there's little doubt that excessive speed will increase the likelihood of a crash and make the outcome of any crash worse.
It comes back to basic physics. The braking distance increases with the square of the speed, and so does the energy dissipated in a crash. So there are good reasons to encourage road users to drive at appropriate speeds. Even in a modern car, at 60 km/h it will take an alert driver around 46 metres to perceive a hazard, react and brake to a stop on a dry road (or 55 metres on a wet road).
'Speeding' is not necessarily just an issue of exceeding the speed limit. It also includes driving at speeds inappropriate for the conditions, even well below the speed limit. For example, on a wet night through a busy shopping strip, 60 km/h could be too fast, even if the limit is 70 km/h.
The setting of speed limits involves balancing mobility desires and needs (moving with reduced delay), safety (keeping risks as low as possible or acceptable) and amenity (other impacts on the community). Any speed limit is a compromise between these factors.
Authorities decide to give a greater bias towards safety and amenity on some roads, such as local residential streets or high pedestrian activity areas, with lower speed limits such as 50 km/h or 40 km/h. In more sparsely populated areas, or on very high standard roads, the bias tends towards mobility.
Some of the factors that come into consideration include the history of crashes and casualties along a road, how many 'conflicts' there are with moving traffic (such as access points and traffic controls), the road alignment, and the use of the land either side of the road. Traffic authorities have guidelines established to match road conditions with speed limits. In NSW and the ACT the relevant authorities are the NSW Roads and Traffic Authority and the ACT Department of Urban Services.
NRMA commissioned telephone surveys in October 2002 (553 drivers) and June 2003 (1000 drivers) to explore community attitudes to speeding and speed zones. The main determinants of driving speed were considered to be the weather conditions, the speed of other vehicles, the volume of traffic and the amount of time available to reach one's destination. A general trend from the surveys was that males were much more likely to speed than females.
Speed zones generally: Uncertainty about the posted speed limit is common - 77 per cent of drivers said they are at times unsure of the limit on city roads while 60 per cent have this problem on country roads. In the June 2003 survey, 56 per cent of drivers were aware of the impending introduction of the 50 km/h general urban speed limit (which became effective on 1 November 2003). Just less than half of the drivers (45 per cent) thought that leaving up the existing 50 km/h signs (that had been installed as part of the trial of 50 km/h zones) would be too confusing. [Note: RTA has decided not to remove the trial 50 km/h signs; rather as they gradually fade or become damaged, they will not be replaced. RTA has installed extra 60 km/h signs on those roads that will not default to 50 km/h.]
School zones and pedestrian zones: Support of 40 km/h School Zone limits was almost universal, with 83 per cent expressing strong support and 96 per cent in total nominating at least some support. The use of speed cameras to enforce School Zone limits was supported by 64 per cent of drivers. However, 76 per cent of drivers thought that flashing lights should be used to alert drivers to the operation of the zone.
Drivers' attitudes to 40 km/h limits in areas of high pedestrian activity were explored in both surveys. Acceptance is increasing, with 77 per cent nominating at least some support in the later survey, whereas 59 per cent were opposed in the first survey. However, support for these zones on highways and main roads is low - 12 per cent and 29 per cent, respectively. Further, only 21 per cent of drivers supported 24-hour, seven day operation of these zones.
Tolerances: The majority of drivers (58 per cent) thought that there should be some leeway around the posted speed limit. The expected margin of tolerance increases in line with the speed limit, from 6 km/h in 40 km/h zones to 10 km/h in 110 km/h zones.
Speed cameras: Most of the drivers considered that speed cameras are effective in making them comply with the speed limit, and around two-thirds supported wider use of cameras. While there is strong support for the use of speed cameras in crash black spots, many doubted whether cameras are effective in actually reducing the crash rate. Drivers would like to see speed camera revenue directed to improving the roads and improving driver education.
When asked about their behaviour around speed camera locations, 90 per cent of drivers claimed that they checked their speedometer on seeing a speed camera sign, and 60 per cent reported that they usually slowed down. One in five were likely to increase their speed on exiting the camera zone.
To closer examine the impact of the current speed zone system, NRMA asked an independent and expert engineering firm to conduct an audit on the application of current speed zoning guidelines to four of Sydney's 'Metroads'. These are arterial routes that traverse large sections of the metropolitan area, from freeways to shopping strips, plus urban and rural developments.
The routes surveyed were: Metroad 2 from Macquarie Street, Windsor to the Sydney Harbour Bridge; Metroad 3 from Pittwater Road, Mona Vale to Princes Highway, Blakehurst; Metroad 6 from Pennant Hills Road, Carlingford to Princes Highway, Engadine; Metroad 9 from George Street, Windsor to Hume Highway (F5), Campbelltown.
The audit compared the actual speed zones on these routes with both the RTA speed zoning guidelines (the latest available version of which was a 'draft' dated 1995) and the Australian Standard AS1742.4 published in 1999. It also included driving the routes in both directions and collecting data (geographic and photographic) related to speed zone changes.
Firstly, the audit found that the current RTA guidelines do not provide sufficient guidance on the appropriate speed limit for undivided urban roads with medium levels of driveway access. This leads to inconsistent application of speed limits on these roads. There is also poor guidance for 'shopping strips' and toll plazas. Not surprisingly, given the recent introduction of 50 km/h as the general urban speed limit, there is also insufficient guidance on the application of 50 km/h and 60 km/h zones.
Secondly, the survey found that sections of the Metroads do not comply with either the RTA guidelines or the Australian Standard. There are numerous examples of non-compliant speed zoning as well as speed zone lengths shorter than recommended. On most of the Metroads, around 50 per cent of the sections were assessed as having non-compliant speed limits, but on Metroad 9, the figure was 80 per cent.
Another finding from the audit was that there were inconsistent applications of speed limits, both along individual routes and across the four routes surveyed. For example, on Metroad 3, a 70 km/h limit applies on Mona Vale Road, Pymble (6-lane divided road with central crash barrier - see photo 1, page 17) but the same limit also applies on King Georges Road, Hurstville (4 lanes, undivided with more frequent access - see photo 2, page 17). Another example is on Metroad 9, where there is a 60 km/h zone on the Northern Road on the outskirts of Narellan (wide lanes, shoulders, overtaking lane), but an 80 km/h zone on the section of Northern Road near Badgerys Creek (2 narrow lanes, no shoulders).
NRMA has supplied a copy of our audit report to the RTA, and we are having detailed discussions with the RTA about how the speed zoning on the four Metroads might be adjusted to better match both the RTA guidelines and the Australian Standard. More generally, we will discuss with the RTA how to update the RTA guidelines, and we will then be seeking a broader review of speed zoning across all of NSW.
In our initial discussions with the RTA, NRMA has made it clear that we are not seeking increases in speed limits on most sections that do not comply with the guidelines. In some cases we are recommending reductions. What we are seeking is a 'fair go' for motorists, while we continue to encourage motorists to comply with speed limits.
NRMA is calling on the RTA to:
Speed limits are important in reducing both excessive speeds and a wide spread of speeds in the traffic stream. Research has shown that both of these can increase crashes. For speed limits to be effective, drivers must be aware of them and prepared to comply. If a speed limit is vastly different from a driver's reasonable expectation (with no explanation or obvious clues), then there is likely to be poor compliance. The 'acid test' might be if all speed limit signs and road markings suddenly disappeared, what speed would most drivers choose, based on their perception of road conditions?
Further, if drivers regularly encounter different speed limits in what appear to be identical road conditions, there is likely to be confusion and lack of respect for the limits. If speed limits change too frequently, especially over very short lengths of road, drivers are more likely to be unaware of the prevailing limit, and thus drive inappropriately for the conditions and risk being penalised.
If a speed limit is vastly different from most drivers' reasonable expectations, the reason should be clearly communicated. A good example of this is the special 40 km/h speed limit at road works. A 'Road Works' plate is installed under the '40' sign. NRMA will urge RTA to consider wider application of this principle, so that a road which has a history of speed-related crashes might have a lower than usual speed limit with an extra sign plate 'Crash Zone'.
In summary, there needs to be a balance between ensuring the speed limit is appropriate for the relative conditions but not changing so frequently that drivers have no chance of keeping up with the changes.
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