Bewildered by British speed bumps
September 24, 2019 2:37 AM   Subscribe

Question from an American learning to drive in England about the right way to go over bumps in the road that you can straddle.

What's the best way to drive over a speed bump in Britain? Not the kind that crosses the entire length of the road but the kind like this.

My driving instructor wants me to straddle the bump with the tires, so that it's completely smooth. But I've had trouble finding official guidelines on whether this is right. And the above-linked letter to the editor claims that this practice is actualyl bad for wheels.

Is it better to roll over the bumps at a slow speed and not to worry about precisely getting my tires on either side? If not, is there a good rule of thumb for how to position my car so that my tires glide around the traffic calming measures?

In other words, is this your preferred way to go over a hump?

to put one wheel over the hump and the other on the road space beside it, or, without causing problems for oncoming traffic, go very slowly over two adjacent humps – one wheel on the top of one, the other on the top of the hump adjacent to it.
posted by johngoren to Travel & Transportation around England (19 answers total)
 
p.s. Or at least I think this is how he wants me to go over bumps. We have had some communication problems.
posted by johngoren at 2:40 AM on September 24, 2019


There is not, as far as I know, an official/"correct" way to do it. For the purposes of learning to drive, probably best to do what the instructor says and concentrate on more important matters. Personally I've never really thought about this very much - sometimes parked cars mean I can't straddle it, so I generally just go over slowly enough that it's not uncomfortable for passengers (going slowly is, after all, the point of the things).
posted by EndsOfInvention at 2:46 AM on September 24, 2019 [3 favorites]


That article reads like it's overstating the case. A car straddling the speed cushion (and that's what they're widely called) will have a momentary deflection (as distinct from monetary deflection) that should be within the tolerance of the wheel/axle design.

In practice, people choose the approach that fits the moment. Veering to one side or another can be annoying to other drivers, parked cars can make it impossible to straddle the cushion, and your vehicle may have a wheelbase wide enough to glide past without touching the cushion.
posted by rustipi at 2:55 AM on September 24, 2019


Generally straddle them, but sometimes have to go over with one wheel due to traffic or cars parked.

I just don’t really buy the argument that straddling causes damage to a car if you’re going over them at a sensible speed.

Generally speaking, I wouldn’t take a letter written to a local paper as a credible source.
posted by chrispy108 at 2:56 AM on September 24, 2019 [1 favorite]


As a further aside, your driving instructor should be credible enough that you take his/her word at everything. If you're going with a larger firm that will be the case. If you've picked a lad from the neighbourhood who isn't particularly trained in all sorts of related topics, he may well be leading you astray. We see that in Birmingham a lot. Small Heath seems the be the UK ground zero for drivers trained by cowboys.
posted by rustipi at 3:00 AM on September 24, 2019 [3 favorites]


(Funny you should mention Birmingham, my guy is a lone wolf from Wolverhampton.) Yeah I mostly just wanted to faithfully follow his guidance, but I can never seem to understand the explanations of how to make him happy. It's mostly just "you did that wrong..." and so I feel like I'm in that Mike Leigh movie "Happy Go Lucky." I guess my question was more to work out what technique would put an end to the criticism on every loop around the neighborhood, rather than to dispute his knowledge...I'll stop threadsitting. Thanks for the replies so far.
posted by johngoren at 3:23 AM on September 24, 2019 [2 favorites]


Sounds like you could do with a different driving instructor. Your instructor's JOB is to tell you how to succeed and drive correctly in all road scenarios, not to abstractly criticise and send you second-guessing and asking the internet for advice. This guy does not sound like he is setting you up to be a good driver who can make independent, confident and safe decisions on the road.

To answer your question, and to nth the others, road and traffic conditions will affect how you approach a speed bump. For what it's worth I have never seen anyone do either of the "recommendations" from that article. It's fine to just drive slowly and straight over the bump.
posted by Balthamos at 3:32 AM on September 24, 2019 [2 favorites]


FWIW, I think your instructor is right - you want to be straddling the bump if you can. Aim the centre of the car through the centre point of the bump, and you won't go far wrong.

Is it better to roll over the bumps at a slow speed and not to worry about precisely getting my tires on either side? Yes. If you get it right, you'll barely notice the bump (and so the letter-to-the-editor guy is worrying about nothing).
posted by rd45 at 3:43 AM on September 24, 2019


I straddle if possible, if not, treat as regular speed bump. The point is to slow down, not to accurately position the car.

(I have never heard it called a speed cushion. Sleeping policeman, yes.)
posted by corvine at 3:47 AM on September 24, 2019 [1 favorite]


I make a game of trying to perfectly straddle for that smooth experience. Only going over it with 1 wheel is deeply unpleasant at any speed. Its not always possible due to parked cars an oncoming traffic but for me, straddling is the ideal. So long as you're obeying the speed limits you shouldn't have a problem on your test whether you straddle or not. Its likely your driving instructor wants you to straddle because that's better for him. From years of being a passenger and then learning to drive last year, its much worse for the passenger when you don't go over the speed bump evenly than it is for the driver.
posted by missmagenta at 3:56 AM on September 24, 2019


That letter to the editor is absurd. Your car’s suspension and tires endure far greater twisting and bending and impact forces whenever you make a curve at speed or hit a bridge joint or even turn up a steep driveway at speed than when you roll slowly over the outer edges of a speed hump. And they are engineered to do so, while supporting 3000 pounds of metal. Cars (ok most, lowered Lambo drivers) aren’t fragile to the extent that you should ever worry about a small bump in the road approached at appropriate speed. Your struts and control arms and tires have more than enough built in flex to manage something a lot less gentle than that little bump, or no one could drive in any American city with average potholes. Unless you’re accelerating to hit the speed bumps as hard as possible, there is no reason to avoid them except for your own ass’s comfort.
posted by spitbull at 4:04 AM on September 24, 2019 [2 favorites]


Road repairs in the UK have been underfunded for some years now and the roads are in poor condition, especially in urban areas outside London. Some of the speed bumps here are degraded to the point where they're breaking up, so you get a double bump as you go through the pothole and then immediately over the bump. No one driving their own car does more than 10mph over them. (You can tell who are the guys driving work's vans because they just race over them. They aren't paying their own repair bills.)

I have a fairly small and narrow car and tend to straddle the bumps, but I also go pretty slowly. Perhaps it's because I used to drive a Ford Ka which had springs that were seemingly made of glass and broke alarmingly regularly. My thinking is that the jerk behind me getting impatient isn't going to be paying my car repair costs.
posted by winterhill at 6:13 AM on September 24, 2019


There's no correct way. Two extremes of asymmetric:
1) a friend who can't really be argued with (...issues, so he's excused) maintains that the best way is to re-locate toward the driver's side, so it doesn't make a bump – on his side! The passenger, obviously, goes through the roof (while he still explains his technique...).
2) I have a tendency to place the car so I (the driver) get most of the bump, and I drive somewhat extra slowly.

But the most logical way if you want to maintain a straight course is to place both wheels equidistant from the center of the bump, so you get a bit of a wobble but nothing too bad if you drive slowly (as the speed bump wants you to). I can't believe that this is anything that makes a statistically relevant difference to the progress of car's inevitable eventual demise.
posted by Namlit at 7:56 AM on September 24, 2019


That letter to the editor is absurd. Your car’s suspension and tires endure far greater twisting and bending and impact forces whenever you make a curve at speed or hit a bridge joint or even turn up a steep driveway at speed than when you roll slowly over the outer edges of a speed hump.

Concur. To the point that I laughed out loud at that article. Utter, clueless nonsense.

Is it better to roll over the bumps at a slow speed and not to worry about precisely getting my tires on either side?
The point of them is to get traffic to slow down and respect the environment around the speed humps. So slow down, aim roughly central and roll over them. The point of them is to make going over them too fast uncomfortable, so if it is uncomfortable you are going too fast. Simple. So keeping the severity of the rise down by reducing the vertical height and the approach speed makes the most sense.

Also - the only vehicle related reason to affect what you do is how you initially approach the bump - even if you suddenly see a speed bump (or a pothole/road surface change etc that may damage the car to hit it at current speed) and are going way too fast, try and do all your slowing before the bump and then release the brake at least *some* (ideally all) before you actually hit the bump. It is better not to hit that bump too hard with the front suspension fully compressed while braking. Coming off the brakes a fraction before gives the car time for the front to rise up and give the suspension room to absorb the bump and, crucially, stops the front of the car being so low to the ground and getting smacked. So brake before, come off brakes and roll over at constant speed.
posted by Brockles at 8:16 AM on September 24, 2019 [3 favorites]


@corvine, my understanding is that sleeping policemen are longer, like body length, more like the humps that span the centre and most of the way across each lane. But unless the Highway Code spells out the name somewhere I suppose it's a matter of local convention.
posted by rustipi at 8:35 AM on September 24, 2019


@johngoren, sounds like it's time to find another instructor. Not that Wolverhampton isn't a lovely place in its way, but it sounds like the two of you are operating at cross purposes, and what you need is someone who is going to drill down to the very broad basis that some UK driving rules/conventions are based on, rather than saying something like "that's just the way it is". Your guy might be very good in other respects, but if he doesn't inspire confidence, and you are peppering him with what ifs and whys in a way that confounds him, it's not a happy match.
posted by rustipi at 8:49 AM on September 24, 2019


rustipi, yes, I would only really use that name to refer to the long narrow ones. Just thinking of speed bump names generally rather than specifically the little ones. I'm pretty sure it's not in the highway code!
posted by corvine at 9:51 AM on September 24, 2019


I straddle if I have road room to do so.

As someone who spent over a year with one instructor trying to 'make it work', failed twice and then passed after seven lessons with another instructor, please - consider changing your instructor. If you're not communicating well, all you're doing is padding their bank account.
posted by Happy Dave at 11:24 AM on September 24, 2019 [1 favorite]


Unless your instructor is completely useless, he will be teaching you the way that is most likely to get you through your test. I assume it's not your car that you are learning in, so there's no need for you to worry about the tyres.

Just follow his advice. If you are not sure what it is, ask.
posted by StephenB at 1:57 PM on September 24, 2019


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