Speed bumps on junctions

amircp · June 2007

Has anybody encountered problems with speed bumps placed at t-junctions e.g. cars rolling onto the main road? Is placement in this way considered good practice?

4x4s - no better than flares

linfordlunchbox · June 2007

Not with placement, but with type - As a motorcyclist also, I find that 'speed cushions' are downright dangerous. the slope on either side forces you off line if you hit them. The gaps also force you into the oncoming traffic, or into the gutter.

Cunobelin · June 2007

I believe a raised platform is the suggested option.

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He that buys flesh buys many bones.
He that buys eggs buys many shells,
But he that buys good beer buys nothing else.
(Unattributed Trad.)

amircp · June 2007

The problem is mostly due to the downward slope onto the junction that is produced when the bump is up against the junction. This makes control more difficult.

4x4s - no better than flares

Simon L2 · June 2007

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Cunobelin

I believe a raised platform is the suggested option.
<hr height="1" noshade id="quote"></blockquote id="quote">

yes, but taken at speed on a bike they're no fun - especially if it's wet and the platform is brick paviors.

You're right about being the suggested option though. I received a paper from a transport consultant today suggesting one for a T-junction leading on to the A27. I wasn't convinced.

Cab · June 2007

Theres a road on my daily route that has several sets of the ones that have gaps down either side, so you can either go over the top or round in the gutter/middle of the road. Usually I go around in the middle of the road if there is space, but otherwise I go over the top. The problem that these humps cause is that they encourage motorists to accelerate hard to overtake and then brake sharply for the next hump, which means that even if you're well right of centre in your lane you're stull cut up badly.

Speed humps at junctions are a problem for those driers who have forgotten what hand brakes are for, and in general I dislike anything that causes extra distraction at a junction where a driver should really be looking out for traffic.

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slowfen · June 2007

No but having gone round the junction to be met with a speed ramp whilst still leaning is not fun, and as Simon says wet paviours make it way to interesting.

d_c · June 2007

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by slowfen

No but having gone round the junction to be met with a speed ramp whilst still leaning is not fun, and as Simon says wet paviours make it way to interesting.
<hr height="1" noshade id="quote"></blockquote id="quote">

...or black ice - I slid out on a left turn just like this last winter. Another cyclist witnessed the whole thing from the pavement where he was repairing his bike having done the exact same thing 2 minutes earlier.

-> flow with the go ->

Absinthe Minded · June 2007

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by linfordlunchbox

Not with placement, but with type - As a motorcyclist also, I find that 'speed cushions' are downright dangerous. the slope on either side forces you off line if you hit them. The gaps also force you into the oncoming traffic, or into the gutter.
<hr height="1" noshade id="quote"></blockquote id="quote">So why not ride over the middle of them? I'd say your front tyre needs looking at if a small slope is affecting your steering.

<hr noshade size="1">Ja sam napisao ovo ovde samo zbog toga da izgledam pametan...

See My route to work!

The Endorser · June 2007

get shot of speed humps and make all speed cameras totally covert - drivers are then forced to driv carefully at all times (and not just past the camera), and those that don't are soon banned from the roads.

The worying this is that these hings are slapped down anywhere, and there is not universal standard for height/gradient etc, and there is little evidence that these trafic calming measures do any good. indeed, in one recent celebrated local case the speedhumps and bottlenecks had to be removed as they'd seriously increased he number of accidents along one stretch of roa 9New bradwell high Street, if anyone knows it).

Taking the moral high ground since 1969

linfordlunchbox · June 2007

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Absinthe Minded

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by linfordlunchbox

Not with placement, but with type - As a motorcyclist also, I find that 'speed cushions' are downright dangerous. the slope on either side forces you off line if you hit them. The gaps also force you into the oncoming traffic, or into the gutter.
<hr height="1" noshade id="quote"></blockquote id="quote">So why not ride over the middle of them? I'd say your front tyre needs looking at if a small slope is affecting your steering.

<hr noshade size="1">Ja sam napisao ovo ovde samo zbog toga da izgledam pametan...

See My route to work!
<hr height="1" noshade id="quote"></blockquote id="quote">

The tyres (180/55/17 & 120/60/17) have less than 400 miles on them, this happens regardless of whatever age or type they are. I liken it to slope traversing. I take it you have not ridden a motorcycle recently ?

"I'd clean my car with a baby elephant - if I had a baby elephant !"

Absinthe Minded · June 2007

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by linfordlunchbox:

The tyres (180/55/17 & 120/60/17) have less than 400 miles on them, this happens regardless of whatever age or type they are.<hr height="1" noshade id="quote"></blockquote id="quote">None of that helps - I'm looking for pressure and eveness of wear.<blockquote id="quote">quote:<hr height="1" noshade id="quote"> I liken it to slope traversing.<hr height="1" noshade id="quote"></blockquote id="quote">Never heard of it.<blockquote id="quote">quote:<hr height="1" noshade id="quote"> I take it you have not ridden a motorcycle recently ?<hr height="1" noshade id="quote"></blockquote id="quote">This morning thanks, that might explain why I look at wear and pressure when evaluating tyres, and you look at what size they are and how many miles they've done.

Also, you forgot to answer my first point!

<hr noshade size="1">Ja sam napisao ovo ovde samo zbog toga da izgledam pametan...

See My route to work!

Asterixcp · June 2007

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by linfordlunchbox

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Absinthe Minded

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by linfordlunchbox

Not with placement, but with type - As a motorcyclist also, I find that 'speed cushions' are downright dangerous. the slope on either side forces you off line if you hit them. The gaps also force you into the oncoming traffic, or into the gutter.
<hr height="1" noshade id="quote"></blockquote id="quote">So why not ride over the middle of them? I'd say your front tyre needs looking at if a small slope is affecting your steering.

<hr noshade size="1">Ja sam napisao ovo ovde samo zbog toga da izgledam pametan...

See My route to work!
<hr height="1" noshade id="quote"></blockquote id="quote">

The tyres (180/55/17 & 120/60/17) have less than 400 miles on them, this happens regardless of whatever age or type they are. I liken it to slope traversing. I take it you have not ridden a motorcycle recently ?

"I'd clean my car with a baby elephant - if I had a baby elephant !"
<hr height="1" noshade id="quote"></blockquote id="quote">

As a motorcyclist myself, I don't understand why you are making such a big deal out of the issue. That is, unless you are trying to ride too fast for the area, possibly as a result of pressure from a tailgater.

Pour vivre heureux, vivons le v‚lo..

Absinthe Minded · June 2007

I'd say he's making a big deal of the issue because he doesn't like this kind of traffic calming measure. He's decided to try and put an 'it's unsafe' slant on it - just like evybody else does when they disagree with something these days.

<hr noshade size="1">Ja sam napisao ovo ovde samo zbog toga da izgledam pametan...

See My route to work!

linfordlunchbox · July 2007

On the plain humps, its not really a problem, but the speed cushions are a real nusance as they are not that small around here. The approach and departure angles of them is not the problem, its the sloped sides which is especially on a bike with dropped bars.

Absinthe Minded · July 2007

So you say, and I say:

i) You have a problem with your tyres.

or

ii) You are an inexperienced rider.

Greenbank · July 2007

The road shouldn't be an obstacle course for inexperienced riders though.

It's like the raised white lines that are often used to divide a shared use path. Absolutely sodding lethal when they are wet. But, of course, the designers just assume that there would never be a need to ever cross over them so "that's not going to be a problem then".

dondare · July 2007

When the aim is to "calm traffic" turning the road into an obstacle course is deliberate. But hazards such as road markings that are slippery when wet are not of that ilk, that's just sheer blundering stupidity.

Absinthe Minded · July 2007

What lunchbox is saying is that speed cushions (the bumps that cover the road partially), have magical sloped sides that disrupt his steering when on his motorbike.

He thinks that because his tyres are new(ish) it must be the fault of the magic slopes. I say that his tyres have worn unevenly, or he can't handle his machine.

linfordlunchbox · July 2007

Absinthe Minded wrote:

So you say, and I say:

i) You have a problem with your tyres.

or

ii) You are an inexperienced rider.

I've been riding a motorcycle since 82, I passed my test in feb 83, I've had motorcycles ever since with a break of about 3 years when my kids were born.

What experience do you have of motorcycle riding AM to make such assertions ?

christian dieu · July 2007

Can you not just get up a bit of speed and jump over it?
Okay, so I should never get a motorbike (and I am hitting my mid life crisis as well so could be bad news)

Absinthe Minded · July 2007

Lunchbox,

Passed my test 14 years ago, ridden a variety of bikes since - currently I have three.
For the past 12 years, I've used a bike regularly every week to go to work on - that's 54 miles round trip, from one side of London to the other.

I'm not saying you're an inexperienced rider, though when I asked you about your tyres in the first place, you told me what size they were and how old. Now, anyone with a bit of experience of bike handling would know that these factors are not worth considering when evaluating handling problems in relation to tyre condition (unless, of course, you have completely the wrong tyres on your bike).. Size and age don't matter, wear evenness and pressure does and I don't know why somebody of your experience would give me the info you did. That's how I came to the conclusion that MAYBE you were inexperienced. You may have good reason to have quoted your tyre sizes and age - let me know if I'm missing something.

If not inexperienced, you may have a problem with your tyres - hope this explains that I made not assertions, but considered the options that would cause your bike to handle dangerously over the speed bumps you mentioned. After considering the options, I made an evaluation based on my experience and came up with the two possibilities posted above.

linfordlunchbox · July 2007

Road pressures in the rear are 41, front 36, Track pressures are 30 front and rear.

Clip ons don't give you massive amounts of leverage and the tyre profiles are sports (Bridgestone BT014s), the bike turns in very quickly due to the forks being dropped 4mm, and the rear being raised 5mm.

What are you after a photo of the cushion, camber angles etc etc ?

If you doubt my ability, perhaps you would like to join me/my group on my next track day

Cycling along the edge of the camber with 700x23Cs doesn't make any difference, Its not a cycle problem

Absinthe Minded · July 2007

OK, I don't need actual pressures - just wanted to confirm that you check them regularly. You're still not giving me any indication of evenness of wear and this is important.

Clipons should give you more than enough leverage to go in a straight line over a slight slope, neither should your fork drop or rear raising cause your bike to handle dangerously. The steering or bike setup is not your first port of call - we're supposed to be looking at your tyres!

There is of course one more option and that is to ride over the centre of the hump - why not do that - that's what you're supposed to be doing anyways!

There's really no need for sarcasm - of course I don't need pictures or angle of the cushion. Why are you taking this line, is it because you've shown your ignorance regarding bike handling and you sort of blame me for it? I'm only trying to help you out here.

As for the track day, no thanks - I'm not really a track day sort of bloke and I'd rather ride in the real world. Track day blokes are all the same - there's something a bit sad about it all if you ask me.

linfordlunchbox · July 2007

Absinthe Minded wrote:

OK, I don't need actual pressures - just wanted to confirm that you check them regularly. You're still not giving me any indication of evenness of wear and this is important.

Clipons should give you more than enough leverage to go in a straight line over a slight slope, neither should your fork drop or rear raising cause your bike to handle dangerously. The steering or bike setup is not your first port of call - we're supposed to be looking at your tyres!

There is of course one more option and that is to ride over the centre of the hump - why not do that - that's what you're supposed to be doing anyways!

There's really no need for sarcasm - of course I don't need pictures or angle of the cushion. Why are you taking this line, is it because you've shown your ignorance regarding bike handling and you sort of blame me for it? I'm only trying to help you out here.

As for the track day, no thanks - I'm not really a track day sort of bloke and I'd rather ride in the real world. Track day blokes are all the same - "there's something a bit sad about it all if you ask me."

I think you are losing the plot a bit AM, This happens with all the tyres I've ever used on the bike, its the speed cushion which is the problem, not the bike not the tyres. The current tyres have about 400 road miles on them, and about 50 track miles.

Could you elaborate on the 'sad' track day bloke comment as track days are the route which all road racers start on nowadays, and are a much safer way of exploring the performance of a vehicle.

You will find that the 'all' the racers you see on TV on sunday afternoon do all their testing and practice on the same tracks which all us 'sad' blokes do -albeit riding in the fast groups.

So which part of riding in the 'Real' world is better, and what makes you think you are better qualified to make the judgment based upon your lack of track experience ?

Greenbank · July 2007

If you imagine a cross section of a road with speed cushions looking like this:-

|_

_--+--_

_|

| is a kerb, _ is a flat bit, - is raised and + is the centre line of the road.

It forces two wheelers (powered and unpowered) into slowing down (*) which is a good thing since their purpose is to slow down traffic. The other choice is inapprorpriate road position: either going into the gutter (bad) or near the middle of the road where oncoming four wheelers are often trying to straddle the middle cushion (bad again).

Because the cushion width is close enough to the axle length of most 4 wheeled vehicles they pretty much cruise over them. It doesn't force four wheeled vehicles to slow down anywhere near as much. This disparity is a big problem. And if the left hand side of the road has any obstructions then they will usually try and straddle the middle one, eating into the available road for oncoming traffic.

If it was designed like this:-

|_--_----+----_--_|

Two wheelers (powered or unpowered) would have a choice of gutter or primary position. Whilst few cars have the appropriate axle length to get both sets of wheels in the unraised parts, causing them to slow down or bounce around. They'll also be more likely to avoid swerving in towards the kerb to straddle a cushion because that option isn't open to them any more.

As for hitting a "magic slope". 30mph over a classic straight ramped sleeping policeman on a motorbike is a piece of cake. 30mph onto the slanting side slope of one of these cushions will cause the wheel to move out sideways and you'll be bouncing your way to spinal disability in no time. Doesn't matter what tyres you've got. I hated the speed cushions when I rode a motorbike for the reasons above, and I hate them now riding a bicycle.

Absinthe Minded · July 2007

Box,

How have I lost the plot? Just because you don't agree with what I say, doesn't mean I'm losing the plot - might mean that I'm wrong though. You use an odd choice of words here.
If I'd started talking about shopping bags, or icebergs halway through the post - then I would have been losing the plot, but maybe it means something else where you come from.

You still haven't got back to me on evenness of wear, why not? This might be your problem and it's woth checking out. You're still banging on about tyre age and mileage and as I said before, these don't really matter. You really need to answer my questions if you want me to help you.

As for elaboration on my track day comment - don't take this personally, I'm just saying that it's not my cup of tea. I didn't say the real world was better, just that I prefer it - no need to get in a twist over things. These are just differences of opinion - there is no right or wrong!

Absinthe Minded · July 2007

Alex,

I like your pictures - very illustrative and maybe speed cushions could be better placed as you say.

Still, we have to put up with what we've got and I still don't see what the problem is with riding over the middle of the hump.

I see you have the deflecting problem too, funny that - I've never experienced it, maybe just a little - but nothing near as dangerous as yourself and box seem to encounter. Then again, I rarely ride over this part of the cushion - better to ride over the middle as this is what we're supposed to do.

linfordlunchbox · July 2007

I think that is a fair and accurate description of speed cushions Alex.

The speed cushions we have in Cheltenham were actually amongst the first ones in the UK.

They were originally brought in after the bus drivers complained about conventional speed bumps giving them bad back problems having to go over hundreds each day on their routes, and so they were designed so that a vehicle (like a bus) with a wide axle track could pass over them without having to cause jarring (or slowing down).

linfordlunchbox · July 2007

What sort of bike do you ride AM ?

Absinthe Minded · July 2007

What bike do I ride? Well, like I say, I have three so it depends on my mood - how is this relevant to the thread?

Now, instead of asking me unrelated questions, why not answer the ones that I've repeatedly posted to you?

Speed bumps on junctions

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