30km/h is pretty overkill in my opinion with the exception of perhaps school zones and suburban retail precincts.
The reason 30 km/h is being proposed is that this is the point at which a collision with a human is unlikely to kill them. This should be the default speed limit in any environment where pedestrians, cyclists and motorists interact. If the speed limit is above 30 km/h, cyclists and pedestrians both require physically separated environments to be safe.
The great news (if youâre a driver) is that lower residential speed limits make very little impact on driving time, since the vast majority of time spent driving is on main roads (unless youâre rat running, which is illegal anyway).
Think of any trip you make by car - only the very start and very end of that journey will be on a residential street.
A summary of the benefits found when cities lowered default residential speed limits from 50 km/h to 30 km/h was explored in a meta analysis completed earlier this year (which was possibly the prompt for this video, I havenât watched it).
In the article they say:
The implementation of 30 km/h speed limit has profound positive effects on both road safety and environmental factors. As summarized in Table 3, crashes decreased on average by 30%, with pedestrian-involved crashes showing an even more substantial reduction of 43%. Fatalities and injuries also significantly decreased, with average reductions of 45% and 40%, respectively, while the most significant reductions were observed in incidents involving pedestrians. Moreover, there were substantial decreases in CO2 emissions (20%), NOx emissions (35%), and PM emissions (20%), contributing to improved air quality. Additionally, noise levels decreased by an average of 3.7 dB, and fuel consumption dropped by 7%, indicating not only safer roads but also environmental benefits.
Link to the article: Effectiveness of 30 km/h speed limit â A literature review - ScienceDirect
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Safety on residential streets are not the barrier to riding for any trips I take. It is the need to go via 60km/h roads with much busier traffic volume and larger vehicles without any separation. With the generally low density of Brisbane suburbs I doubt 30km/h residential streets would provide many meaningfully safer cycling options that could convert trips from cars.
The meta review you linked to also seems to mostly discuss benefits in terms of cities, urban areas and highly pedestrianised. I doubt many of Brisbaneâs residential suburbs really fit these descriptions. In the CBD and other densely developed areas sure. And we seem that to some extent with the 40km/h high pedestrian activity or shared zones.
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As someone who rides a bike daily in suburban Brisbane, I agree that the highest priority (and key to improving cycling uptake) is protected bikeways on main roads.
However, building protected bikeways is expensive, time-consuming and each individual route is subject to NIMBY objections, leading to endless delays and cancellations. Together this creates enormous inertia for the government to deliver anything resembling a network.
Whereas implementing 30 km/h default local street speeds is quick, inexpensive, and only needs to be implemented once (or perhaps a handful of times, if the council wants to trial specific areas first).
I am comfortable riding on a typical 50 km/h backstreet, but there is no way I would allow my kids to do so.
Fortunately, we live on a fairly narrow road signed 40 km/h. Because itâs fairly narrow, drivers generally travel no faster than 30 km/h. Under those conditions, I feel comfortable allowing my kids to ride their bikes on the road.
If we needed to ride on 50 km/h streets to access school, the park, shops, friendsâ houses etc, they would not be riding a bike.
I am sure there are many other people who do not currently cycle who are in the same boat.
Lowering default local street speed limits is a quick and easy way to encourage more people who donât feel safe mixing with 1 or 2 tonne vehicles moving at lethal speeds, to take up cycling.
Of course, increasing cycling uptake is only one of many benefits of 30 km/h streets. But even on its own merits, itâs a worthwhile initiative. Itâs an easy win and helps build momentum for building more separated bikeways on main roads.
I strongly believe that BTQ should throw its support behind this initiative.
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Personally I think that the built up area default speed limit should be lowered to 40km/h, I think that in an Australian context where people rarely speed due to how harsh the penalties are, and the fact that there is very little tolerance for speeding compared to a lot of other countries I think that 40km/h would achieve similar outcomes and be much easier of a pill to swallow for motorists in Queensland.
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Perfectly put.
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If you ever talk to a traffic engineer one of the (only) useful things theyâll tell you is that every single traffic model anywhere is built on the (correct) assumption that an appalling number of drivers break the posted speed limit as a matter of course.
Easily ~ 20% of people are breaking the law, and roads are simply designed to accommodate that fact.
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My understanding is new collector and arterial roads are sign posted for a speed that is generally 10km/h lower than the nominated design speed of the road.
The question is would as many people speed if the sign posted speed matched what the design speed was and what actually feels comfortable to drive at..
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