"Active traffic calming"

[FosseWay]

On the main road into the town centre in my local town, Kungsbacka, they've installed aktiva farthinder, or "active traffic calming" (perhaps "dynamic traffic calming" is a better translation). Article on the council's website here (in Swedish).

They consist of panels in the road surface which sink, creating an anti-hump, if approaching traffic is exceeding the speed limit. Somehow (it doesn't explain how) they can sense if there is an emergency vehicle approaching that is legitimately exceeding the limit. You don't notice them at all if you drive over them at the limit.

Have such things been trialled in the UK at all?

[cb a1]

Only version I can think of in the UK is on the A75 at Springholm. These lights go to red if it detects a vehicle entering the village exceeding 30mph.

[Chris5156]

Never heard of anything like it - how interesting! My immediate question is why they sink down, rather than rising up to mimic a speed bump?

[FosseWay]

Never heard of anything like it - how interesting! My immediate question is why they sink down, rather than rising up to mimic a speed bump?

I don't know, but it may have to do with the practicalities of installation and sturdiness of the components when subject to stress from a speeding vehicle. Alternatively, it may have to do with noise. Speed humps can cause annoying noise for local residents; it may be quieter this way round, though I'm just guessing. I haven't experienced them in action.

One thing that would possibly militate against their use in the UK is that cyclists tend to cycle in the roadway more there, and the last thing you want to do when some muppet is close-passing a cyclist at over the limit is to have a pit open up under the cyclist! On the road in question, Kungsgatan crossing W-E here, there is a cycle path alongside, which is perfectly adequate for cyclists (I certainly wouldn't feel the need to use the roadway instead there), and the roadway is D1, preventing overtaking of cyclists and mopeds. You therefore won't get a car alongside a bike while they both cross the device. A car tailgating a moped/cyclist will probably not be speeding anyway.

I'm not sure of the safety performance of these with motorcycles, though. Sure it's as much a motorcyclist's responsibility to obey the limit as a car driver's, but being catapulted at >40 km/h over the handlebars is a whole different ball game to getting your front suspension knackered.

As a driver, though, I like them. They are far preferable to the tank traps installed on my road, which has a perfectly reasonable 30 km/h limit but you have to take the humps at walking speed to avoid bottoming out.

[Ruperts Trooper]

On the main road into the town centre in my local town, Kungsbacka, they've installed aktiva farthinder, or "active traffic calming" (perhaps "dynamic traffic calming" is a better translation). Article on the council's website here (in Swedish).

They consist of panels in the road surface which sink, creating an anti-hump, if approaching traffic is exceeding the speed limit. Somehow (it doesn't explain how) they can sense if there is an emergency vehicle approaching that is legitimately exceeding the limit. You don't notice them at all if you drive over them at the limit.

Have such things been trialled in the UK at all?

I'd love the chance to experiment with that, on a closed road, as I've observed that a softly-sprung SUV with long travel suspension has a surprisingly high "comfort" speed where faster or slower gives a much less comfortable ride - my Subaru Outback was smoother at 40 mph on unmade roads than any lower speed - I suspect my present VW Touareg (with air suspension) is even higher but I haven't had the bottle to find out!

[Fenlander]

I'm amazed we haven't gone for the simple option of fitting a normal set of traffic light controlled pedestrian crossings with a speed detector and putting a red phase to the driver if they're going over the limit. They can still work as a normal crossing for compliant traffic but add a delay for the speeders.

[Big L]

I'm amazed we haven't gone for the simple option of fitting a normal set of traffic light controlled pedestrian crossings with a speed detector and putting a red phase to the driver if they're going over the limit. They can still work as a normal crossing for compliant traffic but add a delay for the speeders.

Like this, a few posts above…

Only version I can think of in the UK is on the A75 at Springholm. These lights go to red if it detects a vehicle entering the village exceeding 30mph.

[Fenlander]

Exactly that, seems a sensible way to do it to me.

[FosseWay]

I'm amazed we haven't gone for the simple option of fitting a normal set of traffic light controlled pedestrian crossings with a speed detector and putting a red phase to the driver if they're going over the limit. They can still work as a normal crossing for compliant traffic but add a delay for the speeders.

The problem with that solution is that they are an all-or-nothing tool. There is no particular benefit to anyone (other than possibly council bureaucrats who want to demonstrate that the *average* speed over a stretch of road has reduced) of making drivers stop, whether or not they were speeding beforehand. What we want them to do is drive at a sensible and legal speed throughout the area in question, not accelerate and brake sharply. In any case, my gut feeling is that a driver who is willing to ignore the speed limit may well also be willing to ignore a red light, especially one that they suspect has been put in mainly with traffic calming in mind. Something that will directly damage your car if you disrespect it may be taken more seriously.

While the dynamic speed pits (or whatever you want to call them!) in Kungsbacka won't have been cheap, I would imagine that installing traffic lights will be even more expensive (though I'm happy to be proved wrong on that).

[Nicola_Jayne]

On the main road into the town centre in my local town, Kungsbacka, they've installed aktiva farthinder, or "active traffic calming" (perhaps "dynamic traffic calming" is a better translation). Article on the council's website here (in Swedish).

They consist of panels in the road surface which sink, creating an anti-hump, if approaching traffic is exceeding the speed limit. Somehow (it doesn't explain how) they can sense if there is an emergency vehicle approaching that is legitimately exceeding the limit. You don't notice them at all if you drive over them at the limit.

Have such things been trialled in the UK at all?

I'd love the chance to experiment with that, on a closed road, as I've observed that a softly-sprung SUV with long travel suspension has a surprisingly high "comfort" speed where faster or slower gives a much less comfortable ride - my Subaru Outback was smoother at 40 mph on unmade roads than any lower speed - I suspect my present VW Touareg (with air suspension) is even higher but I haven't had the bottle to find out!

similar effect noticed on a not especilly well graded limestone 'gravel' road or two that there was a particualr speed ina car or 4*4 which was 'floating' top to top of the corrugation

[Dougman]

I recall in the dim and distant past looking to install pneumatic speed humps that deflated if you were going below 30mph or if it was a heavy vehicle like a fire engine, but remained inflated above that speed. A quick google suggests I didn't imagine it, the were made by Dunlop and called Transcalm. Not a lot of information available though now.

[tom66]

I recall in the dim and distant past looking to install pneumatic speed humps that deflated if you were going below 30mph or if it was a heavy vehicle like a fire engine, but remained inflated above that speed. A quick google suggests I didn't imagine it, the were made by Dunlop and called Transcalm. Not a lot of information available though now.

I wonder how rugged they would be. With thermal and road cycles I could see the "boot" needing replacement from time to time and council budgets already can't cover repainting road lines or repairing potholes.

[ROAD ROVER]

Our speed pits aren't dynamic. They're called potholes.

[Berk]

Sounds like something you’d find on escape lanes.