Two rubber lines on road - what are they?

[Blanchie]

Utterpiffle said:

Yup, that was why I click on the topic.

Disappointed.

I was hoping for best number 11 you've created....oh sorry that sound like a hoon

[Swervin_Mervin]

Yes they can measure speed. Two would be required for direction, however. And as tvrgit says, most that you see will likely be being used predominantly to count traffic. Many will be commissioned by private consultancies.

[Moonhawk]

tvrgit said:

I don't know how they do that, but I do know that they do!

They probably look at data patterns.

.........Blip.......Blip........ Car

.........Blip.....Blip..Blip.....Blip..Blip..Blip....... HGV

.........Blip.......... Bike doing a wheelie

[tvrgit]

Moonhawk said:

They probably look at data patterns.

.........Blip.......Blip........ Car

.........Blip.....Blip..Blip.....Blip..Blip..Blip....... HGV

.........Blip.......... Bike doing a wheelie

An excellent explanation, and probably bang on!

[Centurion07]

Moonhawk said:

Centurion07 said:

What roads are those then?

I wasn't referring to actual roads - merely pointing out that the 85th percentile is supposed to be a measure of what a "reasonable person" considered to be an appropriate speed in the absence of a defined limit (see the text I quoted).

The presence of a speed limit will give a distorted view of the 85th percentile as some drivers will abide by the speed limit even if they would consider it reasonable to travel faster in the absence of it.

Could this be the reason we have seen wholesale reductions in limits. The wrong application of the 85th percentile?

Edited by Moonhawk on Tuesday 28th April 16:37

No road is opened to the public without a speed limit though, so are you saying the 85th percentile is completely irrelevant due to the fact it can only be calculated on roads with limits?

Maybe the fact that some drivers will be travelling slower due to the posted limit is taken into account when they came up with the figure of 85% i.e. the remaining 15% are the ones travelling at or below the limit simply because it's there?

[Mr2Mike]

Moonhawk said:

They probably look at data patterns.

.........Blip.......Blip........ Car

.........Blip.....Blip..Blip.....Blip..Blip..Blip....... HGV

.........Blip.......... Bike doing a wheelie

Until another vehicle goes over the lines in the opposite direction at the same time...

I'm pretty sure I have seen three lines used before which covers the case for traffic in both directions.

[tvrgit]

Mr2Mike said:

Until another vehicle goes over the lines in the opposite direction at the same time...

I'm pretty sure I have seen three lines used before which covers the case for traffic in both directions.

2-tube counters are pretty good at discerning traffic in both directions at the same time.

I have never used a 3-tube counter, don't know what they do that a 2-tube can't

[Dr Jekyll]

Moonhawk said:

I wasn't referring to actual roads - merely pointing out that the 85th percentile is supposed to be a measure of what a "reasonable person" considered to be an appropriate speed in the absence of a defined limit (see the text I quoted).

The presence of a speed limit will give a distorted view of the 85th percentile as some drivers will abide by the speed limit even if they would consider it reasonable to travel faster in the absence of it.

Could this be the reason we have seen wholesale reductions in limits. The wrong application of the 85th percentile?

The 50th percentile is now used instead specifically in order to reduce limits.

The 85th percentile might be a different figure from that which would be obtained if there were no speed limit, but that doesn't make it 'distorted'.

A stretch of London's Park lane is the best known example. Back in the 70s it had a 30 limit and speeds were generally regarded as excessive. The 85th percentile speed was measured as about 45, and accordingly the limit was increased to 40. The 85th percentile speed promptly dropped to the high 30s.

It may well be that the 85th percentile originally measured was different from what it would have been if there had not been a speed limit at all. But so what? It still provided useful information.

[Greengecko]

ka90 said:

I use the gym at the local University. There is a 1 mile straight road once in the grounds that has a 20mph limit. I don't think I've seen anyone go below 50mph, including buses. They've recently installed this monitoring kit.

Question: as it's private property they can't enforce any speed limits legally, so what would the point be in changing the speed limit as a result? Maybe it's used to monitor car volume as parking is scarce?

Essex?

[Dr Jekyll]

But the vital question is, should you drive over them as fast as possible to get the average speed up and discourage a limit reduction? Or as slowly as possible to get the average down and discourage a speed camera?

[Swervin_Mervin]

You should drive over them at the speed you normally would as it's most likely the data is being used by a private consultant in their assessment work for a new development scheme.

[0000]

Dr Jekyll said:

The 50th percentile is now used instead specifically in order to reduce limits.

Interesting. There surely has to be something wrong with using the 50th percentile when the percentage of cars having accidents is so very much lower.

[Gafferjim]

The twin rubber sensors, as has been mentioned, record both number of axles crossing them, the speed & direction. Around my area they are used in locations where the locals complain about speeding vehicles, they put the sensors down for a week or so to check what time of day it is when the speed limit is ignored by the most vehicles, then they will deploy a mobile speed camera van or bobby with speed gun for the couple of hours at that time so as to catch most numbers. often they will collate different locations together as a package to be checked that day, and move the van about between them to a *better* location once the numbers drop off at each location.

[tvrgit]

Gafferjim said:

The twin rubber sensors, as has been mentioned, record both number of axles crossing them, the speed & direction. Around my area they are used in locations where the locals complain about speeding vehicles, they put the sensors down for a week or so to check what time of day it is when the speed limit is ignored by the most vehicles, then they will deploy a mobile speed camera van or bobby with speed gun for the couple of hours at that time so as to catch most numbers. often they will collate different locations together as a package to be checked that day, and move the van about between them to a *better* location once the numbers drop off at each location.

And in my experience, said van will "catch" the very people who are complaining about other people speeding past THEIR house just up the street... happened so many times I've lost count, including the local councillor leading the "anti-speed" campaign and the chairman of another community council.

[Gareth79]

Some appeared near our office recently for a few weeks, it was at the end of a one-way street and we guessed it was to count the number of people contravening the no-entry sign.

ka90 said:

I use the gym at the local University. There is a 1 mile straight road once in the grounds that has a 20mph limit. I don't think I've seen anyone go below 50mph, including buses. They've recently installed this monitoring kit.

Question: as it's private property they can't enforce any speed limits legally, so what would the point be in changing the speed limit as a result? Maybe it's used to monitor car volume as parking is scarce?

Orders can be applied to private roads, I think the owners need to give permission though.

[GPSHead]

chrisga said:

is that a one way thing i.e. if its lower they will lower the limit but if higher they leave it as is?

Sadly, that's basically it, with the addition that if it's higher then that apparently indicates a "speeding problem" and therefore justifies cameras, road-narrowing and other anti-car crap that the self-righteous trolls round here like so much. (Oh, and sometimes this also apparently justifies lowering the limit further, just like when the speeds are lower than the limit...you couldn't make it up...)

Every few years, some councils will reluctantly raise one or two limits (usually 30s in the middle of nowhere which have previously been reduced from NSL, and which are now being generously put up to 40). But this is merely a token gesture so that they can deny that the aim is to ratchet limits down all the time. It's just a question of how often, by how much, and what excuse is offered.

As someone else said, you can't win. They will always find ways to justify lower limits, and trying to raise objections over shrill soundbites like "If it saves one life" and "Think of the children" is difficult. Of course, getting a limit raised back up (or even, shock horror, higher than it's ever been) is even harder. How sad that society is now run by the sort of person who gets a hard-on from the idea of a driver being made to go ludicrously slowly, and being punished if they dare not to comply. The lunatics truly have taken over the asylum (and SP&L to a large extent).