20mph limits & speed humps do not work - IAM on DfT data

[Type R Tom]

OpulentBob said:

This.

Blame the 70year old ex-Doctor who plays golf with the Councillor who has pushed for the 20mph zones - when not outside schools, they are normally outside the houses of people with the ear of MP's/council officers.

Further, if the 20 zones had no speed bumps, then do you REALLY think Mr VAG TDi/Master lowered-euro-look Polo/Mrs blinkered bint in her Picasso would obey a 20 limit? Of course not. Then, when there's an accident outside a school, everyone points fingers at the Engineers for not putting in speed bumps. Damned if you do, damned if you don't.

The main reason speed humps exist in 20mph areas is because the Police chiefs won't send officers out to enforce a 20 limit, they have to be "self enforcing" in order for the CC to sign off the TRO (speed limit document).

Nail on the head there mate!

As a fellow highway engineer, I spend a lot of time unfortunately installing things I don’t really agree with due to political pressure when I could spend the money somewhere else.

I spend a lot of time going through speed count data and calculating 85th percentiles etc. Some of the speeds I see (usual late at night) are absolutely shocking but these are down to the individual drivers not the council to prevent.

Most people out there for some reason think that the council are responsible for individual driver behaviour and that we must prevent drivers from being able to drive quickly in residential areas, the only way this can be done is with server traffic calming. It is another case of the minority ruining it for the majority and until something can be done to stop the idiots you will continue to see an increase in traffic calming.

Very few accidents are down to the road layout, most of the time its driver / pedestrian error and these people are usually prosecuted but that doesn’t stop the“you need to do something before someone gets killed” or “I’ve just seen a car going 70mph past my house, do something” type request coming in.

So I put it out there to the PH world, there is evidence of people speeding on a residential street (and some high speeds at night) and a couple of collisions. You don’t like traffic calming, how do you solve the problem?

[CoolHands]

occasional police with radar gun is the most effective imo. Cos I am always more cautious on roads where I've seen the occasional speed trap, and also on roads that clearly are obvious speed gun territory.

however, that should only be used on roads where there is genuine risk of pedestrian impact imo; not long straight safe roads with houses set back 20m from the road

[GoneAnon]

Zuffen said:

Comparing the absolute numbers killed and injured year-on-year is about as meaningful as comparing the growth in aviation accidents between the nineteenth and twentieth centuries. Unless we know how many people are travelling along all of the 20mph roads in each of the years the statistic merely serves to mislead the innumerate. I would wager that the amount of travel along 20mph roads also increased by approximately 25% between 2010 and 2011, and that 20mph roads were likely no more dangerous in 2011 than they were in 2010.

I agree with your first sentence and, largely, to the second.
We will have to disagree on the third though: -
1) where do you think the additional 25% of traffic has came from, given that at least some drivers will seek routes avoiding the traffic calming, and
2) few - if any - will divert onto the route with the new calming measures, and
3) finally, what changed in the locality to give so many more people a reason to go to or from any specific point along that route?

It's kind of like politicians pointing to increasing car ownership and predicting gridlock at some point in the future, forgetting that although we own more cars nowadays we can still only drive one at a time!

[mybrainhurts]

Type R Tom said:

So I put it out there to the PH world, there is evidence of people speeding on a residential street (and some high speeds at night)

How do you know what those vehicles were?

Do you eliminate the emergency services?

[Type R Tom]

mybrainhurts said:

How do you know what those vehicles were?

Do you eliminate the emergency services?

We can only distinguish the vehicles by class so that isn’t beyond the realms of possibility but the location I’m currently thinking of its unlikely as alternative routes are faster (unless they were attending that exact location).

When you have 85% of drivers below or very close to the speed limit what do you do about the 15% that are over and the 10% that are over the ACPO guidelines?

Or do you think 10% of drives in a residential street driving above the prosecution level is acceptable?

In this location there are no accidents so we wouldn’t look to do any traffic calming as the speeding figures are low but that still doesn’t stop the local’s complaining.

Residents will say “I see people driving at 50mph” and I have to reply,“yes they occasionally are”. “So what you going to do about it?” “Nothing I’m afraid, people are generally abiding by the speed limit” How would you feel if you got that response about the street you live in?

So it comes down to the locals living on a street vs. the people using it to travel. Who is more important?

[roachcoach]

Type R Tom said:

So I put it out there to the PH world, there is evidence of people speeding on a residential street (and some high speeds at night) and a couple of collisions. You don’t like traffic calming, how do you solve the problem?

Ironically, a speed camera would work rather well, but we still seem to have lengthy, open, high visibility straights in need of them first


@The original article - could as easily be because these zones are proliferating. As the coverage area grows, so too will bumps

[mybrainhurts]

Type R Tom said:

mybrainhurts said:

How do you know what those vehicles were?

Do you eliminate the emergency services?

We can only distinguish the vehicles by class so that isn’t beyond the realms of possibility but the location I’m currently thinking of its unlikely as alternative routes are faster (unless they were attending that exact location).

When you have 85% of drivers below or very close to the speed limit what do you do about the 15% that are over and the 10% that are over the ACPO guidelines?

Or do you think 10% of drives in a residential street driving above the prosecution level is acceptable?

In this location there are no accidents so we wouldn’t look to do any traffic calming as the speeding figures are low but that still doesn’t stop the local’s complaining.

Residents will say “I see people driving at 50mph” and I have to reply,“yes they occasionally are”. “So what you going to do about it?” “Nothing I’m afraid, people are generally abiding by the speed limit” How would you feel if you got that response about the street you live in?

So it comes down to the locals living on a street vs. the people using it to travel. Who is more important?

If there aren't any accidents, you have your answer. There isn't a problem. Except for the few moaners, but they'd be moaning about something else if they didn't have this to moan about.

[Guybrush]

Type R Tom said:

So I put it out there to the PH world, there is evidence of people speeding on a residential street (and some high speeds at night) and a couple of collisions. You don’t like traffic calming, how do you solve the problem?

You certainly don't solve the "problem" by taking measures that don't work but only irritate. Sometimes the do nothing approach is the one to take. Why the constant knee jerk? Job justification is a lot of the reason I guess, but you will never stop deaths on the road or anywhere else.

[rs1952]

mybrainhurts said:

If there aren't any accidents, you have your answer. There isn't a problem. Except for the few moaners, but they'd be moaning about something else if they didn't have this to moan about.

But as you know or ought to know, telling moaners there isn't a problem generally doesn't work.

There was a woman in my street, a new arrival about 3 years ago, who tried to start a campaign to have traffic calming installed. In the "blurb" she put out to residents, she said she had seen people doing 50 down the street. Its an ordinary suburban street filled with 1930s 3-bed semis in a 30 by the way and, according to Google Earth, 288 yards from one end to the other. It is used as a short cut between two main roads so there is some non-local traffic, but the main road they are trying to get to isn't at the other end of the street - our street is just on the way, so to speak.

Now, it quite simply ain't possible to speed along this street - God knows I've tried OK, you might get up to 35 (so within ACPO guidelines) if there are no parked cars around at the time but, 50? Absolute bullshyte. Doing my public-spirited thing, I pointed this out to her, but she was having none of it - "she had seen people doing 50 with her own eyes." When I asked her how she got hold of the radar gun, I got an old-fashioned look, and was told she didn't need one - she saw what she saw and that was what she saw and that's what happened and that was that.

The trouble is, bleedin' idiots like this live in different streets all over the country and, whilst I'm not a Highway Engineer, I have worked for local councils and know it is rarely possible to convince people that their concerns are not founded in fact. This is made worse by the pathetically small turnout in most local elections, where councillors who want to get back in next time are well aware that they can't go round telling their constituents they're talking a load of dingo's kidneys, because a couple of votes swing either way may well put the other lot in in this ward next time round.

The true problem here is "localism" which, unfortunately, is the byword for "all things good" in the corridors of power at the moment. No it ain't "all things good" - it allows the lunatics to take over the asylum, and more lunatics are being let loose in more spheres of local authority work by the minute as the agenda spreads.

What we need are national guidelines for speed limits, traffic management, traffic calming etc that we used to have before all this nonsense started.

Unfortunately, give the current climate you're more likely to see a pig with wings going over your house than you are to see rationality and common sense come back to this area of endeavour.

By the way, that bloody woman has now moved out - I think she took rather a large loss on the house to sell quickly

[mybrainhurts]

rs1952 said:

What we need are national guidelines for speed limits, traffic management, traffic calming etc that we used to have before all this nonsense started.

Yes, you have Blair's lot to thank for that nonsense, and Blair's lot (Gwyneth Dunwoody, mostly) to thank the spread of lower speed limits.

Back to the question of what to do about casualties in built up areas. As 84% of pedestrian casualties get hurt through their own negligence, education on pedestriancraft would be the correct approach.

[BlueMR2]

Type R Tom said:

mybrainhurts said:

How do you know what those vehicles were?

Do you eliminate the emergency services?

We can only distinguish the vehicles by class so that isn’t beyond the realms of possibility but the location I’m currently thinking of its unlikely as alternative routes are faster (unless they were attending that exact location).

When you have 85% of drivers below or very close to the speed limit what do you do about the 15% that are over and the 10% that are over the ACPO guidelines?

Or do you think 10% of drives in a residential street driving above the prosecution level is acceptable?

In this location there are no accidents so we wouldn’t look to do any traffic calming as the speeding figures are low but that still doesn’t stop the local’s complaining.

Residents will say “I see people driving at 50mph” and I have to reply,“yes they occasionally are”. “So what you going to do about it?” “Nothing I’m afraid, people are generally abiding by the speed limit” How would you feel if you got that response about the street you live in?

So it comes down to the locals living on a street vs. the people using it to travel. Who is more important?

I'd be happy with people speeding up round here. As the roads go from 70's and 60's down to 30's and 40's as the council lowers them for less than obvious reasons.

It can be a nightmare crossing the street or getting the car out of the drive in the non stop traffic.

[Type R Tom]

Accident statistics are a difficult one; they include things like a joy rider / drunken person smashing into a lap post injuring themselves and the others in the car, this could mean 4 people injured which could have a massive effect on the figures for an area, leading to a lovely headline in the paper about accident rates increasing. They also include the old dear on a bus that fell over when the bus stopped a little quick so they can’t be taken as a gospel!

That is why you have professionals to analyse all the available data to make a decision, its got nothing to do with justifying our existence.

I hate to say it but the point made by rs1952 is spot on! It all comes down to political pressure

We all have a boss, be public or private sector and we are all asked to do things we don’t agree with. We can advise and comment but at the end of the day if we are told to do something then we must do it, or your boss will find someone that will!

[TonyHetherington]

Interesting posts, Type R Tom.

I do like a bit of data and how it relates to the real world, and everything you've said makes perfect sense.

[Type R Tom]

TonyHetherington said:

Interesting posts, Type R Tom.

I do like a bit of data and how it relates to the real world, and everything you've said makes perfect sense.

Thanks mate, roads and transport are such a tricky subject as they are something we all have no choice but to use!

[carinaman]

They're going to discuss the statistics of whether 20MPH limits reduce accidents on More or Less the BBC Radio 4 Statistics show tomorrow at 16.30, repeated Sunday at 20.00 and available on the BBC iplayer from tomorrow evening I'd have thought.

I don't know if it contains speed bumps.

[Chimune]

yes - i hear that trailer too - will be interesting and from a man who knows how statistics work !!

[Fueltank]

I read that a number of people sounded there horns when passing over humps in a village which resulted in residents asking to take them out which they did. Lets all start sounding our horns.

[Chimune]

I only caught the program in bits, but i think i have spotted why this thread has died ...

[carinaman]

My take from the programme was that the methods used weren't that good if they wanted to come to an accurate and objective conclusion and it ended with some precautionary principle catch all like 'we all know accidents at lower speeds are less harmful'.

[carinaman]

http://www.bbc.co.uk/radio/player/b01lv7yn

From 14 mins to 18 mins 40 secs.

Seems the 17% increase comes from 7 people dying, an increase of 1 over the previous year and cites 'unhelpful' reporting. I think it also mentioned how the number of 20 limits had increased ten fold over a two year period, so with 20 limits covering more roads then some increase in accidents could be easily predicted.