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Tue 16 Nov 2021 17:41

Any - Speed bumps - wantstolearn

Last week twice visited an NT site in the Lake district.

There is a speed bump just before the exit ( poor visibility going on to a narrow road ). I believe speed bumps are valuable and I support their use.

even though I was very careful , very slow and smooth, on both occasions there was a horrible grating sound from the exhaust as the car went over. I drive an mpv so no low suspension.

Any suggestions to avoid this, other than don't go, welcome.

Is there any legislation covering speed bumps ?

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Tue 16 Nov 2021 17:46

Any - Speed bumps - _

Is there any legislation covering speed bumps ?

There is . Google is your friend, but applies to public roads.

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Tue 16 Nov 2021 18:07

Any - Speed bumps - Andrew-T

even though I was very careful , very slow and smooth, on both occasions there was a horrible grating sound from the exhaust as the car went over. I drive an mpv so no low suspension.

If the noise was from the exhaust, is it hanging a bit low ? You might avoid the contact by aiming the wheels at the bumps instead of straddling them, as you are driving slowly ?

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Tue 16 Nov 2021 18:14

Any - Speed bumps - wantstolearn

Thanks orb, quite right.

Thanks Andrew. Only motd and b service a couple of weeks ago so assume O.K. Unfortunately no longer able to go under myself.

I'm not straddling them, going over bump directly. Not sure what else I can do.

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Tue 16 Nov 2021 18:17

Any - Speed bumps - badbusdriver

What kind of car do you have?. MPV's don't generally have any more ground clearance than whichever hatchback they are based on.

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Wed 17 Nov 2021 15:23

Any - Speed bumps - Engineer Andy

even though I was very careful , very slow and smooth, on both occasions there was a horrible grating sound from the exhaust as the car went over. I drive an mpv so no low suspension.

If the noise was from the exhaust, is it hanging a bit low ? You might avoid the contact by aiming the wheels at the bumps instead of straddling them, as you are driving slowly ?

It could easily be the front bumper scraping the speed hump because people mostly brake just as they reach the speed bump, and as a result, the nose of the car drops.

Another possibility could be an underbody engine bay or sump cover that maybe not properly attached or that (even when fitted properly) hang down quite low.

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Tue 16 Nov 2021 18:22

Any - Speed bumps - Bromptonaut

even though I was very careful , very slow and smooth, on both occasions there was a horrible grating sound from the exhaust as the car went over. I drive an mpv so no low suspension.

If you drove over it as you describe and caught your car's exhaust then, unless the exhaust is hanging lower than it should, the issue needs reporting to the National Trust.

Please share their reply on this thread.

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Tue 16 Nov 2021 18:37

Any - Speed bumps - mcb100

Assuming it’s a speed bump that runs all the way across the road, not one of the flat topped pyramid type, if you’ve got space to manoeuvre go across it an angle - as close to 45 degrees as possible.
That way you’ll go over it one wheel at a time and will spend longer with the exhaust away from catching on the hump.

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Tue 16 Nov 2021 18:42

Any - Speed bumps - movilogo

Any suggestions to avoid this, other than don't go, welcome.

Get a car with higher ground clearance?

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Tue 16 Nov 2021 21:39

Any - Speed bumps - wantstolearn

Clever tack to change cars, not at current prices

Mentioned mpv because not low suspension.

Will be contacting NT and will share.

Will try angled approach.

Thanks all

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Tue 16 Nov 2021 22:10

Any - Speed bumps - Brit_in_Germany

Difficult to see how the exhaust could scrape if is higher off the ground than the height of the speed bump. Could you perhaps have a broken spring or was the car heavily laden?

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Wed 17 Nov 2021 00:19

Any - Speed bumps - focussed

As with everything, there are standards that speed bumps must adhere to on public roads.

If it is on an NT property which the public has access to it is classed as a public road.

Speed bumps have the potential to damage vehicles and even make roads hazardous, and so there are regulations which must be adhered to.

Dimensions

All speed bumps must be at least 900mm in length.
The minimum height for a speed bump is 25mm at its highest point.
The maximum height for a speed bump is 100mm at its highest point
No vertical face or material forming the speed hump may exceed 6mm.
The gradient of a speed bump must be no more than 1:10, however, you may need to consider a shallower gradient if the route is used by service vehicles to prevent vehicle grounding.

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Wed 17 Nov 2021 07:34

Any - Speed bumps - badbusdriver

Mentioned mpv because not low suspension.

This is the second time you have said this, but as I said before, MPV's do not (in general) have any more ground clearance than a 'normal' car.

But regarding the actual speed humps, wear and tear will often result in a depression immediately in front and behind the hump as you approach it exacerbating the height/steepness. As the wheel drops down the other side, the compression of the suspension can result in contact being made with the undercarriage. If this is the case here, being an NT property, they may well not have the funds to fix it due to the reduced visitor numbers with covid.

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Wed 17 Nov 2021 10:03

Any - Speed bumps - wantstolearn

Just wanted to make clear it was a normal not a low suspension.

Thanks for your informative responre, appreciated.

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Wed 17 Nov 2021 12:26

Any - Speed bumps - sammy1

In my experience there are not many speed bumps that do not have damage caused by gouging from passing vehicles especially those rubber ones that are bolted to the road. You see some vehicles going far to fast over humps, straddling them with one wheel and so on. There are some if on a strange road to the driver that are difficult to spot and in some pedestrian areas are a b***** nuisance.

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Fri 26 Nov 2021 11:16

Any - Speed bumps - wantstolearn

Sorry to be so long in updating. I'm embarrassed and red faced.

The NT replied in a couple of days. The bump was camouflaged by dirt etc. It turns out it was some kind of metal system. What I heard was metal flaps banging, oops.

On the plus side I've learned a lot about them.

Apologies to all.

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Fri 26 Nov 2021 12:09

Any - Speed bumps - RT

Some places use "dragons' teeth" to enforce one-way operation - these clang when driven over correctly.

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