Ground clearance

[GeoffSmith]

I've caught my exhaust a couple of times (at ridiculously low speeds) on a particularly vicious speed bump at work. It's started puffing a bit and appears to be hanging lower than it was a couple of weeks ago when I bought it. The ground clearance behind the cat seems closer to 4" than 5" and the pipe is not parallel with the floor but it doesn't look like I've lost any of the rubber hangers.

Any thoughts or words of wisdom would be appreciated before I try and squeeze myself underneath!

Geoff

[Low Profile]

Cant help you with the technical side of things but might be able to help with the speed hump!

[ailwyn]

Might be worth some foot stamping at work and trying to get them to shell out for a new exhaust.

I go over speed bumps which I would class as large without grounding the car, maybe they have been a little excessive in the speed bump they installed and the prospect of financial payouts for damaged cars may spur them into reducing the bump.

Don't know what the law is, but I believe there is a limit on how high a speed bump can be (or how deep a pothole can be) before there is a liability for damage.

Ailwyn

[Low Profile]

The following letter is reproduced from the Honest John motoring column in the Daily Telegraph of 29 October 2005. Further specific examples are sought of compensation payments having been made owing to inept design and construction of road humps in the UK. Staffordshire County Council are reputed to have paid out large sums of money - all at taxpayers' expense.


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Concrete and the claim

Last year I cracked the sump on my VW Passat while going over a speed hump in a 20 mph zone. I was not breaking the speed limit. I claimed for the damage from the Watford/Herts council on the basis that the hump had been hit several times before and that I was not doing anything wrong. It claimed the hump met all regulations and that it was regularly inspected and maintained, although a copy of the inspection report barely stated that the hump existed. I found a document by the Transport Research Laboratory - Project Report 18, Road Humps for Controlling Vehicle Speeds - that gives details of recommended dimensions. The hump at Watford was too high by 10% (10mm) and the top was too short by one metre. On presentation of this information I received a cheque for the sump replacement. They don't give up without a fight - it took me about six months to get a result. A. M. Watford.

YOU DIDN'T PUT THE HUMP THERE! THEY DID!

[nitroman]

Hmm. Here in the USA you can be dismissed for no reason at all. They don't even have to tell you why you're getting canned. It's called "right to work", in typical double-speak.

You probably think I'm kidding, but complaining about company speed-bumps when they are outsourcing at 1/6th your pay to India would be a good route to cleaning your desk out!

Now if it's on a public street then go for it. It all comes down to how pissed you are and what your time's worth.

[Low Profile]

Cushion dimensions
Recommended dimensions (see TA Leaflet 4/94) for speed cushions are:

side ramp gradients not steeper than 1:4
off/on ramps not steeper than 1:8, (curved on/off ramps should have an average gradient not steeper than 1:5)
a maximum height of 80mm (though 75mm has since been found to be a preferable maximum)
maximum length 3700mm
maximum width 2000mm (for bus routes a width of between 1600mm to 1700mm is preferred)
Most of the schemes investigated adhered to the above dimensions, but some differences occurred. Widths generally ranged from 1500mm to 2100mm, lengths from 1700mm to 4750mm, and height 60mm to 100mm. The gradients of on/off ramps varied from 1:3.5 to 1:12, and side ramp gradients varied between 1:3.5 to 1:5.25. Small circular cushions of 1380mm in diameter were used in one scheme as part of a bus route, and in another location cushions only 1000mm wide were installed.

There was no indication from the study that the variation in dimensions used offered any particular advantage over the recommended dimensions. However, where the proportion of heavy commercial vehicles is high, the narrower 1500mm wide cushion may have some advantage in limiting any adverse traffic noise and ground-borne vibrations (see TA Leaflet 2/97).

To avoid the possibility of vehicles grounding on the cushions, in some schemes cushion heights were only 65mm high: in one case a 65mm high cushion was subsequently lowered to 55mm. Despite this, generally the evidence suggests that a maximum height of 75mm should be satisfactory. Speed cushions less than 2000mm long may result in cars being able to straddle the cushion lengthways, increasing the chance of a vehicle grounding on the top of the cushion. Consequently, when short length cushions (2000mm or less) are to be used it may be advisable to limit the maximum height to 65mm. TRL have suggested that to limit grounding, particularly where there are vehicles with low ground clearances combined with long wheelbases or low front overhangs, the cushion plateau should not be less than 800mm in length, with the overall length not less than 2000mm, and ramps no steeper than 1:8.

[GeoffSmith]

Thanks for all the help but I think we're fixing the wrong problem!


Cushions! Cushions!!! Not my lot. I think they got a contractor with some leftover tarmac to make an impression of a ploughed field (worthy of a Turner prize nomination) - we've got three huge humps within 50 yards.

The job is pretty safe but it could affect my chances of early retirement (75 at the rate we're going) and recently gone through protracted litigation (neighbours disputed 6 inches of the boundary - judge awarded all costs [mine were ~£18k] and damages [£1k] against them so our solicitors did very nicely thank you very much ). I'll probably just put a new stainless one on - to be honest, I don't know if it was hanging low before the scrapes.

Thanks for your first suggestion LowP - ILSHITMTWND.

Geoff

PS Is that a custom hardtop on your Mustard Yellow?