Pneumatic two hose road testing.

[FMurtz]

Is there any poster in this group that works in the field of two tube pneumatic testing of traffic stats and how does the data affect traffic rules and speed restrictions. This form of testing can give number of, type of vehicle, speed of each vehicle type. I started a riot in an Australian news group by suggesting that if the testing showed that everybody traveled less than the limit they may reduce the limit, the consensus of opinion was that I was a stupid old goat and it would not happen and all the other factors measured would be the cause of the reduction. Be that as it may, does anybody have inside info as to the uses of this testing in councils or road authorities and whether the measured speed was a big or small portion of the consideration. I am asking in your group as it is a much bigger cross section, the Australian group would only have 10 to 15 contributors

[Adrian Caspersz]

You'd like more abuse than from 15?

Taking a time averaged survey before spending money on an issue is usually the norm. Often safety related, not a ticket cash raiser. If no real issue found, no need for restrictions.

There are other reasons for reduction of speed limits in heavy slow traffic (i.e. M25) but these are thankfully temporary.

[alan_m]

If they are anything like the pneumatic sensors used in the UK I would think that they are too close together to be any use for speed measurement.

[Michael Chare]

Does any other country have the variable speed limits that you find on UK motorways? I dislike them, partly because I find it very easy to exceed them.

[Steve Walker]

I find them annoying for two reasons:

1) they seem to have no logic to them. The other morning I got on the M60 clockwise at junction 10 and found a 50 sign illuminated at the bottom of the sliproad; gantry signs showing 40 at the top of the sliproad (beginning of Barton Bridge); gantry signs at the other end of the bridge showing national speed limit; and gantry signs at the following junction showing 40 again. 40/50/70/40 in a total distance of just over a mile! Surely they should be showing 40 from the start of the sliproad to that 3rd gantry. On top of that they were showing 40 on all three lanes of the M60 and on both lanes of the slip-road to the M62, plus an accident sign on that 3rd gantry ... with no indication of whether the accident was on the M60 or M62. The wrong decision of which way to go at this point can mean being stuck for an extra hour - from bitter experience! 2) It is very easy to keep up with the flow of the traffic and within the limit, but then have a lapse of confidence and a sudden panic, in case the gantry you have just passed had a lower speed displayed.

SteveW

[The Natural Philosopher]

I've seen them in Germany, I think..

[Vir Campestris]

There are two patterns; separated by a few inches, and by several feet.

Andy

[alan_m]

But not installed with any precision to give an accurate speed indication.

My annoyance is that often these monitoring devices are placed on the roads at non-representative times such as during school holidays.

I'm sure that the manned traffic surveys are only performed by teachers who are making extra money when the kids are off school and when traffic flow during rush hours is always at its best.

Around my way these surveys have resulted in at least 2 off multi-million road junction modifications having new dedicated long left hand turn lanes that only a hand full of people use each day.

[Andy Burns]

Just like when assessing the suitability of road to sustain e.g an additional 50 houses, they take all the photos during the day when most people are at work, rather than at night when dozens of extra cars are double-parked or half on the path.

[Steve Walker]

We've had the opposite.

A simple traffic-light controlled cross-roads where one leg had almost no traffic, as it lead to a dead end. From the road facing the dead end, it was clear that widening the road by 2 to 3 feet would allow left-turning traffic to pass the waiting right-turning queue. Instead they spent £1.5M completely redesigning the junction so it no longer aligns, traffic turning right must bear left, turn right at lights to the left of the road opposite and then wait at a second set of lights at the road opposite. The queue waiting to turn right still extends far enough to block left-turning traffic from reaching the left-turn filter!

SteveW

[harry]

The two tubes are to tell the DIRECTION of traffic and the numbers.

Nothing to do with speed.

[The Natural Philosopher]

Once upon a time a junction at the edgfe of a local town had no traiffic lights. To turn right one simply waited unril one could or there was a gap in te tyraqffic.

There were alomsot no delays. Now it has traffic lights there are always queues.

Same for pedestrian crossings. Before there were Zebras, and peope just crossed when they could and traffic stopped when it saw them. Now there are lights with hoplessly long delays and on periods which pisses off pedesatrians and motorists equally.

Its all been designed by a moron,.

[alan_m]

The common design solution around my way is not to synchronise the pedestrian crossing lights with the traffic lights at busy junctions.

After waiting many minutes in a car for the traffic lights to go green you are stopped in your tracks if you are third in the queue by the pedestrian crossing light often going red. By the time the pedestrian crossing light has turned green again the traffic light is now red! You now have to wait again in a car for many minutes during all of which time the pedestrian crossing could be made available to pedestrians.

[Chris J Dixon]

I greatly dislike crossing lights very close to roundabouts. It is easy to think that the actual roundabout is light controlled when it is not. Conversely, leaving a light-controlled roundabout it is possible to read the crossing lights as repeaters for the junction you have just been through.

Whilst on the subject of crossings, am I alone in hating the design with the pedestrian lights pointing up and down the road? I understand the reasoning is that you will see the light if you stand at the crossing and look towards oncoming traffic, whereas most folk, in my experience, look across the crossing, in the direction they want to walk, can't see the light, and there doesn't seem to be an audible warning.

If standing next to the pole, I occasionally make use of the tactile indicator, fitted for those with vision problems, but how many people know about them?

Chris

[Vir Campestris]

AIUI Cambridge city traffic planning is intended to make car journeys hard.

Andy

[newshound]

They are not always perfect but they do seem to damp down the oscillations. M25 ones are pretty good. The M6/M5 ones southbound were doing a reasonable job on Saturday

[FMurtz]

You are wrong, do some research,they can tell speed and the type of vehicle and the speed of differing vehicles

[Andy Burns]

I think it's closer to say they can imply the different types based on axle counts etc, but there will be errors when vehicles pass the strips on opposite carriageways at the same time.

Though even some firms who do video tracked vehicle surveys seem to concede that the errors in identifying vehicle type with pneumatic tubes do roughly cancel out in the long term.