BS: U.K. Traffic flow question

Subject: BS: U.K. Traffic flow question
From: GUEST,Tunesmith
Date: 21 Jun 11 - 08:59 AM

Can anyone out there advise me on the following matter.

The road I live in ( which isn't an A or B road) is attracting a lot more traffic (four times I would say) than an A and B road which does the same job.

The attraction of the road I live down is that it is a sighly shorter route(maybe a 100 yds) and avoids a set of traffic lights.

Now, the A and B roads are wider and straighter than my road, and have a lot less traffic accidents.

From what I have read, A and B type roads are supposed to carry more traffic than a C(?)road ( if they are both serving the same purpose)

Any thoughts on the matter.

Subject: RE: BS: U.K. Traffic flow question
From: Silas
Date: 21 Jun 11 - 09:19 AM

YEP. Its all down to Sat Navs.

Subject: RE: BS: U.K. Traffic flow question
From: GUEST,Shimrod
Date: 21 Jun 11 - 09:46 AM

It's also down to silly sods who think that they are being clever by avoiding traffic lights. This only means that they have to force their way out when joining main roads (particularly when turning right) which leads to congestion on the main roads. Other silly sods, who are travelling on the main road and hence have right of way, aid and abet this process by stopping in order to let the traffic light avoiding silly sods out!

Subject: RE: BS: U.K. Traffic flow question
From: G-Force
Date: 21 Jun 11 - 01:10 PM

Shimrod may be basically right, but you can't odds human nature.

The supposedly main roads which the traffic is meant to use have been allowed to become so obstructed by traffic lights which take an eternity to change, pointless traffic 'calming' measures, roundabouts built up so high you can't see which way the oncoming traffic is indicating, etc. etc., that it is no wonder people resort to rat running.

Subject: RE: BS: U.K. Traffic flow question
From: Doug Chadwick
Date: 21 Jun 11 - 01:27 PM

You could always complain to the local authority. They would be only too happy to put in speed bumps for you to bounce your car over every time you leave or return home.

If you're really lucky, one of them might be sited right outside your house so you could hear the squeaking brakes, as the cars slow down, and the revving engines as they speed away on the other side.


DC

Subject: RE: BS: U.K. Traffic flow question
From: JohnInKansas
Date: 22 Jun 11 - 03:49 AM

Some years ago, my associates in Boston were deliriously enthusiastic about the opening of a new "expressway" that they were quite sure would significantly reduce their commuting time.

I failed, I'm afraid, in my attempts to explain to them that when a "better road" appears, traffic will always increase until it takes the same time to drive the new route as for any alternate routes.

But three months later, one of them was at my desk requesting that I "explain that idea you had about the traffic again, John."

In actual fact, since it took half a year for most of them to realize that the expressway was choked up and took longer than the "surface roads" they'd used before, a couple of the alternates actually became a "quicker way;" but of course that only lasted until even the slow ones figured it all out.

Back then, of course, I used a bicycle and beat them all, but it was only a 3 mile commute each way; and as a student I could "hang out at the lab" and avoid the rush times fairly flexibly.

It's not just a matter of more vehicles. There's also the factor that if the commute time is reduced, the existing drivers will make more side trips for errands (and discover all the shortcuts?).

John

Subject: RE: BS: U.K. Traffic flow question
From: GUEST
Date: 22 Jun 11 - 04:28 AM

Unfortunately villages do suffer the brunt of commuter's impatience. One traffic calming method I think might help is having a single lane with the right of way exiting the village at *both ends* of the high street.

Subject: RE: BS: U.K. Traffic flow question
From: Geoff the Duck
Date: 22 Jun 11 - 08:55 AM

Personal experience, which seems to be backed up by recent research, tells me that on crossroads without traffic lights (and that includes light operated crossings when the lights have broken), traffic moves more smoothly. Everyone has to slow down, but the overall flow of traffic means that nobody is held up as long as when lights turn red and create a queue.
Part of it seems to be that if a light is at green, everyone goes through it regardless of any other traffic, whereas without lights, those going forward are more likely to give way to cars wanting to cross in front of them. This lets the traffic trying to turn (UK) right actually get where they need to go rather than waiting in a long line where only the front one or two cars can get through the lights as they change. This in turn means that the need to find a rat run disappears.
Quack!
GtD.

Subject: RE: BS: U.K. Traffic flow question
From: Jack Campin
Date: 22 Jun 11 - 09:36 AM

Potholes are your friend.

If you haven't got them already, dig some.

Subject: RE: BS: U.K. Traffic flow question
From: Dave MacKenzie
Date: 22 Jun 11 - 09:38 AM

I remember hearing recently that roundabouts are half as dangerous as traffic lights, so our local council (CWAC - don't think it's any relation to GtD) takes every opportunity to put 24 hour lights on existing rounabouts!

Subject: RE: BS: U.K. Traffic flow question
From: McGrath of Harlow
Date: 22 Jun 11 - 12:57 PM

All these things depend on the actual level of traffic. So long as the traffic flow isn't too heavy it's likely to work better without lights, with minimal controls.

Above that point if the lights aren't there it rapidly becomes a nightmare.

Drivers emerging and trying to turn right hold on until they are liable to lose patience, and try to force their way out, risking life and limb for themselves and everyone else.

Roundabouts with two heavy streams of traffic at right angles jam solid, because there are always some people who don't understand the common sense and courtesy that enables roundabouts to work smoothly. (Or of course they might be bewildered visitors from places where they don't have roundabouts, such as the USA - and I don't envy them trying to work out how to negotiate them.)

Harlow, where I live, was built with roundabouts all over the place, and was intended to have no traffic lights. (The legend is that when the Master Planner was designing the town he had a party and the guests put their drinks down on the map and left round marks...) Over the years a fair number of traffic lights have been introduced, and at rush hours they are a godsend, even if they can be a nuisance at some other times.

Anyone who finds it difficult to be patient shouldn't be allowed to drive a car.

Subject: RE: BS: U.K. Traffic flow question
From: Geoff the Duck
Date: 22 Jun 11 - 02:11 PM

The best way to control traffic flow to busy roundabouts is actually to put light operated pedestrian crossings on the approach roads rather than AT the junction. The lights create breaks in the busiest flow that would let the minor road traffic get onto the roundabout, but unlike the ridiculous idea of stopping traffic half way round, it would allow them to leave at the junction they need.
Quack!
GtD.

Subject: RE: BS: U.K. Traffic flow question
From: McGrath of Harlow
Date: 22 Jun 11 - 02:23 PM

So if the two traffic streams have jammed the roundabout solid, everyone waits until some pedestrian comes along and pushes the button to make the traffic lights change...

Of course if it's an intersection where there aren't any pedestrians around it could be quite a long time until "the lights create breaks".

Sometimes the lights can be put in the wrong place, or set the wrong way, but the right lights in the right place can save time and lives. No point having an all-or-nothing attitude about stuff like that.

Subject: RE: BS: U.K. Traffic flow question
From: Gurney
Date: 22 Jun 11 - 07:47 PM

Here, they've put traffic lights on the feeder roads to motorways, to thin out the cars entering. Haven't worked that one out yet. There isn't much of an alternative route.

A large roundabout near my home is congested solidly in morning rush-hour, but works smoothly in evening rush-hour. This is because in the evening, it feeds two separate suburbs, but in the morning, traffic from one suburb gets priority over the other due to the feeder road onto the island. Consequently, traffic from the largest suburb DRIVES TO THE OTHER SUBURB to get a priority onto the roundabout. No-one has yet had the sense to put a traffic-light onto the feeder-road to slow it down.
I'm not holding my breath until they do.

I suppose we could pay a team of elderly ladies to cross and recross using McGrath's system above. Hmmm.

Subject: RE: BS: U.K. Traffic flow question
From: JohnInKansas
Date: 23 Jun 11 - 12:03 AM

a single lane with the right of way exiting the village at *both ends* of the high street.

For a time, there was an intersection at the end of a Boston alley with a "One Way" sign pointing in, directly beside the sign that said "No Exit."

Sort of a city street "Roach Motel."

The signs lasted most of a year before somebody tipped off the media, and I suppose the frat boys who put them up were sorry to see them go.(?)

John

Subject: RE: BS: U.K. Traffic flow question
From: Newport Boy
Date: 23 Jun 11 - 01:04 PM

Here, they've put traffic lights on the feeder roads to motorways, to thin out the cars entering. Haven't worked that one out yet. There isn't much of an alternative route.

It's called "ramp metering" - which pretty well explains it. If the motorway is to congested, allowing more traffic to force it's way on simply slows the whole traffic stream. Restricting the number of vehicles being added to the flow is about the best solution.

Phil

Subject: RE: BS: U.K. Traffic flow question
From: Gurney
Date: 23 Jun 11 - 05:28 PM

Phil, the idea is to get the traffic to where it is going! If you only slow SOME of it down, how does that help?
It just irritates people on the feeder lanes and people who can't get past the stopped traffic to get elsewhere.
The best, -only -solution is more roads nearer the city/destination.
Is Ramp Metering going to make people 20k from the city leave home earlier? Not if they have priority, it isn't. It just makes people in the nearer suburbs' journey to work longer, or forces them to find alternative routes, which is the gist of Tunesmith's original post.

Why should drivers who live miles from the city get priority over those who live nearer? Riddle me that one, Batman.;-)

Subject: RE: BS: U.K. Traffic flow question
From: McGrath of Harlow
Date: 23 Jun 11 - 06:50 PM

"...the idea is to get the traffic to where it is going!..."

The idea isn't just "to get the traffic to where it is going"; it is to enable drivers to get to where they are going, which is a slightly different thing.

For example, if you are pulling out from a side road and need to turn right, you are never going to be able to do it, if there is very heavy traffic without any breaks in it. Traffic lights can be the only practical way of ensuring that there are such necessary breaks from time to time.

There's a limit to how many new road systems can or should be constructed to avoid that kind of situation.

Subject: RE: BS: U.K. Traffic flow question
From: Herga Kitty
Date: 23 Jun 11 - 06:59 PM

Here's the Highways Agency's explanation of Ramp metering .

Kitty

Subject: RE: BS: U.K. Traffic flow question
From: Gurney
Date: 24 Jun 11 - 12:50 AM

McGrath, that is sophistry. The driver is part of the traffic, until such time as all traffic is driven by computers. And, if anyone turns right on a motorway, which is where where ramp metering takes place, then the whole motorway is going to be closed until the the mess is cleaned up. England, OZ, NZ, Japan, anyway.

Kitty's link gives the following advantages of Ramp Metering.

1. Greater throughput at peak periods.
No it doesn't. Faster motorway traffic, but slower feeder and other-road traffic, including people who aren't going on the motorway. We all want to be somewhere at a given time.
Although (here) some feeders do encourage carpooling by giving multi-occupied cars access to the truck-and-bus feeder lane.
2. Less congestion and improved traffic flows.
Yeah, for the traffic from miles away. They're already ON the motorway.
Smoother and more reliable journey times.
Yeah, for the traffic from miles away.
3. Reduced risk of accidents.
Faster traffic and frustrated drivers mean less accidents, do they? They are still COMING onto the motorway, they are just more irritated because they are late for work.
4. Environmental advantages as a result of noise reduction and improved fuel economy.
A big row of idling cars waiting to get on the motorway means clean air, good fuel economy, and little noise, does it?

I've really tried to see some advantage to suburban commuters like I used to be, but I can't. If I lived way out-of-town I certainly could, but I don't, so I can't. And since the city dwellers are the greatest contributors to the cost of the motorways, because there are more of them, then I see making other drivers journey faster at my expense as blatant favouritism.
And, motorway lanes can be stacked above existing ones, as sometimes American ones are. But that would mean spending some of the taxes they've been gouging from fuel prices.

Subject: RE: BS: U.K. Traffic flow question
From: Gurney
Date: 24 Jun 11 - 12:52 AM

Make that five 'advantages.' I missed a number.

Subject: RE: BS: U.K. Traffic flow question
From: Newport Boy
Date: 24 Jun 11 - 09:37 AM

I've never understood why a city dweller would need a car, and specifically why they would try to use it to travel in or into the city. It wasn't really tolerable in 1959 when I left London, and it's absolutely impossible now.

The only answer to city travel is good public transport - which costs real money, but not as much as is wasted on cars in cities.

Phil

Subject: RE: BS: U.K. Traffic flow question
From: DMcG
Date: 24 Jun 11 - 09:47 AM

Got into a nice jam today. I wanted to turn off a main road into a minor road to the right. Since this is the UK that meant I had to cross the busy stream of oncoming traffic, so I waited for a gap. After a little while another car came down the minor road and wanted to turn right as well (ie onto the stream I wanted to leave. After 30 seconds or so her decided to force his way across the stream and began to do so, blocking the oncoming stream ... Which couldn't because he was in the way. But he couldn't move because I was in the way. And I couldn't move because the cars he had blocked was I my way. Brilliant driving!

Subject: RE: BS: U.K. Traffic flow question
From: Bert
Date: 24 Jun 11 - 12:51 PM

Design a roundabout that has tangential access and enforce alternate merge onto it.

Subject: RE: BS: U.K. Traffic flow question
From: Musket
Date: 24 Jun 11 - 02:29 PM

The software they use to predict traffic flow was used recently to demonstrate why we won the battle of Agincourt.

Anyway, that out of the way...

They didn't have such software when they planned Agincourt, neither did they when major road routes were designed. The clue being what we call roundabouts were designed as gyratory circuses by men with pipes, plummy voices and dandruff.

Subject: RE: BS: U.K. Traffic flow question
From: Don(Wyziwyg)T
Date: 24 Jun 11 - 03:07 PM

""The only answer to city travel is good public transport - which costs real money, but not as much as is wasted on cars in cities.""

Since you left London in 1959, when the public transport system was marginally fit for purpose, you would probably have been right at that time.

However, when I left London in 1966 that was no longer so, and it hasn't shown any serious improvement since (I can attest to that, as I visit regularly).

Getting on to a tube train in morning or evening rush hour requires intensive training as a member of a top Rugby Club forward line up.

To persuade people to leave their cars and use public transport, the system needs to be operating with the spare capacity, which is emphatically NOT the case in London, nor I suspect in other cities.

In addition to that, people who live in cities do, on occasion, visit relatives and take day trips to the seaside and tow caravans on holiday.

The cost of a day's travel by car for a family is far less than the same trip by train, so even in the city a car can indeed be a necessity, and much more so in rural areas which in many cases have no public transport at all on weekends, while some still have only one bus each way per week.

Where I live I cannot go to the local cinema in the evening because the last bus to or from it leaves at about 6.45pm. I can't go to London to the theatre because the last connection by train leaves Strood at 10.35pm and the last train from the other direction leaves Maidstone at 10.35pm.

A car is absolutely essential if I wish to have any social life at all.

The answer is give us the transport system and we'll use it!

Don T.

Subject: RE: BS: U.K. Traffic flow question
From: McGrath of Harlow
Date: 24 Jun 11 - 04:13 PM

...if anyone turns right on a motorway etc...

Obviously - but most roads aren't motorways. (And when I'm driving I generally do my best to get away from the main flow of traffic.)

Subject: RE: BS: U.K. Traffic flow question
From: Gurney
Date: 24 Jun 11 - 04:44 PM

Me too, McGrath, and since I became self-employed, and lately retired, I generally manage to. But having to wait for access to 'my' motorway while non-residents fly by, sometimes for 15mins or so, well, it irritates me.
Not enough to do anything stupid.

Subject: RE: BS: U.K. Traffic flow question
From: Geoff the Duck
Date: 25 Jun 11 - 04:12 AM

The software they use to predict traffic flow was used recently to demonstrate why we won the battle of Agincourt.

Don't tell me....

Were the French stuck on the M25 at the Dartford Tunnel?


Quack!
GtD.

Subject: RE: BS: U.K. Traffic flow question
From: HuwG
Date: 25 Jun 11 - 05:54 AM

Ramp metering has been introduced on the slip road leading to the M60 (the Manchester outer ring road) from the roundabout at the junction with the M67.

At rush hour, the lights come on and dribble one or two cars every thirty seconds onto the M60. However, the queue of traffic then backs up the slip road, and onto the roundabout, completely jamming it.

It is illegal to join a clogged roundabout, when the intended exit is obstructed e.g. by a queue of cars. However traffic joining from the A57, from the direction of Manchester, is unaware of the obstruction unless they have been paying very careful attention to traffic reports on local radio stations, which are also marked by diabolically irritating jingles, presenters and music selections.

Subject: RE: BS: U.K. Traffic flow question
From: PatrickRose
Date: 25 Jun 11 - 07:27 AM

What are these "cars" of which you speak? You mean people don't travel on horseback?

Question: Those who are complaining about the motorway back up, what are your thoughts on lowering the speed limit to 50? Traffic will flow better and it's more economical.

Subject: RE: BS: U.K. Traffic flow question
From: McGrath of Harlow
Date: 25 Jun 11 - 02:14 PM

The logical thing would be to halt the traffic on the motorway every now and then, to allow the cars on the slipway move on to the road. Using some kind of traffic signals.

Subject: RE: BS: U.K. Traffic flow question
From: Penny S.
Date: 25 Jun 11 - 05:28 PM

Geoff has raised the very spot that I was thinking of. The M25 at the tunnel isn't half of it. South of the tunnel are three junctions. One very close to the tunnel links with a road which bypasses Dartford to the north: this I shall now ignore.
Next is the junction where the M25 is crossed by Princes Road, the old A2, which carries a lot of local traffic at peak times, mostly going westwards in the morning, east in the evening. This uses a roundabout above the M25, with ramps onto and off the motorway. In the past, this was the simple setup, allowing local traffic to travel without involvement with the M25 traffic.
However, when the tunnel approach jam built up, tunnel traffic, including HGVs, would come up the ramp from the M25, cross the roundabout and go down the ramp to overtake the stationary traffic. There were lights controlling them coming onto the roundabout, but once the system had seized up, the HGVs could not get off the roundabout, and the local traffic was blocked. (Thus other local routes also became gridlocked as people sought increasingly complex ways to get to work.)
Improvements were made at the third junction, with the present M25, including a bridge which bypassed the roundabout there for tunnel traffic, and a separate road for local traffic from the A2 roundabout. Which would work fine, except the HGVs have found it, and tunnel traffic aware of the jam now comes off at the A2, and blocks the Princes Road roundabout again. Despite the box markings and the words Keep clear.

They need someone on the lights to modify the sequence to keep the local stuff moving.

Penny

Subject: RE: BS: U.K. Traffic flow question
From: Geoff the Duck
Date: 26 Jun 11 - 08:38 AM

A 50 mph speed limit doesn't answer the problem It just leads to nose-to-tail traffic ALL at 50mph. That takes more intense concentration than if you are able to vary your speed and so increases the likelihood of a shunt. On a long stretch of motorway, it will increase journey times even if there is no holdup, leading to needless driver fatigue and, once again, a greater likelihood of accidents through loss of judgement.
The one traffic system that has worked every time I have been on it (about twice a year since it appeared - so it may be rubbish the rest of the time - I wouldn't know!) is the M 42 around Birmingham where they have ACTIVE traffic management with variable speed limits that go UP when traffic is flowing, as well as down. During rush hours, the hard shoulder is opened as a lane for the next exit (unless it is needed to keep a breakdown separate from the traffic). If there is clear road ahead, the speed limit goes back to 70mph rather than the usual system of reducing everything to a blanket 40mph when the road ahead is empty, where all you are doing is creating longer queues at the back end of the traffic. That helps nobody!
Quack!
GtD.

Subject: RE: BS: U.K. Traffic flow question
From: Dave MacKenzie
Date: 26 Jun 11 - 09:03 AM

Hi Geoff. I've used the M42 fairly regularly since the system was installed, and it's made quite a difference. They've got a similar system on parts of the M25, and those are the bits that grind to a slow crawl rather than a complete stop most of the time.

Subject: RE: BS: U.K. Traffic flow question
From: Geoff the Duck
Date: 26 Jun 11 - 09:59 AM

Last time I was on M25, on our way home from a holiday in France, so already tired from a long drive before England. Apart from queueing about an hour to go through Dartford Tunnel (there aren't enough toll booths for even light traffic), the whole stretch North to the M11 exit was a 50mph restriction because of alleged roadworks or traffic incident. At no point during the (according to Google Maps) 18 mile/20 minute journey did we see any evidence of either, or any reason the traffic shouldn't be travelling at 70.
On the M62 near Bradford/Leeds the light up signs regularly tell you to slow to 40 because of fog - on days when you can see the length of the Pennines in the bright sunshine. All this does is encourage drivers to completely ignore anything the signs say.
Quack!
GtD.

Subject: RE: BS: U.K. Traffic flow question
From: Dave MacKenzie
Date: 26 Jun 11 - 10:09 AM

I don't normally use that bit of the M25 - just the bit between the M40 and the A3, which is actively managed. Beyond the A3 there's a stretch towards Gatwick that always seems to be unmanaged and staionary. I agree that on unmanaged motorways, the warning signs should usually be filed under fiction.

Subject: RE: BS: U.K. Traffic flow question
From: Dave MacKenzie
Date: 26 Jun 11 - 10:10 AM

PS. The managed sections use speed cameras to help enforcement - often on the back of the gantries.

Subject: RE: BS: U.K. Traffic flow question
From: Richard Bridge
Date: 26 Jun 11 - 05:09 PM

"Dog sniffing" is the safest way to turn right (UK) as it enables each driver to see oncoming traffic relevant to him. The next driver in the queue behind the dog sniffer should ALWAYS leave a space for the relevant dog to pass in front of him. People who don't do that are stupid.

Subject: RE: BS: U.K. Traffic flow question
From: Raedwulf
Date: 26 Jun 11 - 06:46 PM

May I offer you all a link?

http://www.amazon.co.uk/Traffic-drive-what-says-about/dp/0141027398/ref=sr_1_1?s=books&ie=UTF8&qid=1309128231&sr=1-1

Buy it, borrow it from your library. Whichever way you get your hands on it, read it. Then think about traffic. It's a very interesting read... ;-)

Subject: RE: BS: U.K. Traffic flow question
From: McGrath of Harlow
Date: 27 Jun 11 - 12:07 PM

Dog sniffing? Sounds a pretty unsavoury practice.
...............................

Roll on the day they have some kind of tachometer device in cars that will record when drivers go too close to the car in front for the speed they are travelling at, and forward the information to the licensing authorities.

Subject: RE: BS: U.K. Traffic flow question
From: Richard Bridge
Date: 27 Jun 11 - 01:02 PM

Or a cannon to remove silly people who are getting in the way and preventing the free flow of traffic.

Subject: RE: BS: U.K. Traffic flow question
From: Don(Wyziwyg)T
Date: 27 Jun 11 - 01:07 PM

Absolutely MGoH!

Driving on M-Ways I always find I have to keep dropping back all the time, because every time I leave a gap more than five car lengths, four other drivers shoehorn their cars into it and I don't relish a game of skittles at seventy mph.

Don T.

Subject: RE: BS: U.K. Traffic flow question
From: Don(Wyziwyg)T
Date: 27 Jun 11 - 01:13 PM

An acquaintance of mine, who drives an unmarked police car on the M25, assures me that the day is coming when somebody braking for the Dartford Crossing Tollbooths will be hit from behind and the resulting multiple nose to tail shunt will travel right round the 126 miles to the other side of the booths.

This, he maintains, will be a Godsend, as the authorities can then tarmac over the lot and build a sensible road on top.

Don T.

Subject: RE: BS: U.K. Traffic flow question
From: McGrath of Harlow
Date: 27 Jun 11 - 02:44 PM

So what is "dog sniffing"?

Subject: RE: BS: U.K. Traffic flow question
From: Richard Bridge
Date: 27 Jun 11 - 03:00 PM

Two cars at a cross-roads approach head on (in the UK). Both want to turn right. The correct way to do it is for each to pass behind the other, so the offsides (driver sides) of the cars are closest. This does somewhat resemble the introductory routine of two dogs.

Subject: RE: BS: U.K. Traffic flow question
From: Penny S.
Date: 27 Jun 11 - 04:54 PM

And some junctions have lines to make cars pass nearside to nearside. But where there are no lines, you just have to use telepathy to work out which tactic the opposing car is going to use. And some look proper peeved if you get far enough ahead of their thought processes to do the right thing.

At Dartford, the powers that be will persistently argue that the toll booths have nothing whatever to do with the jams. And hence, that there is no need to end the tolls as promised, which should have been done some years back.

Penny