Re: Speed limiters

Yes, that's how it works in the normal cruise control mode.

Yes, that's correct. It allows me to let off the gas, or even brake, when approaching a tight corner.

Yes, as an alternative to pressing the button to turn it off, of course. I assume it is intended as a safety or emergency feature. Imagine you are starting to overtake and forgot that you have the limiter engaged. Maybe you will slightly panic and not think to press the button or maybe not be able to find the button quickly enough. You can just "floor it" and off it goes instantly.

Yes, in normal cruise control mode, that's how mine also works. Mine will even engage the friction brakes if the speed is much over the set speed.

I don't doubt that it will happen in the future. Laws are governed mostly by politics and bureaucracy, and only very little by science.

Sounds like a terrible idea to me. Keeping a very low speed is actually quite difficult, and requires some attention. I'd rather spend that attention on the traffic situation around me.

This was the guy they all used:

No more SMs are being built, thank goodness. The irony down here using the M27 is that it took years to convert most of it to a smart motorway, and only a year later they're replacing the barrier over two miles. The result is that for most of 6+ years it has been a 2-lane motorway!

No "white van man" tailgating and doing 90+ up your way? ;-)

On 7/7/24 9:00 AM, Don Y wrote: <....>

Many adaptive cruise control systems (but not all!) have full authority down to zero-speed; they control the brakes as well as the throttle.

This is separate from any collision avoidance functions.

Some adaptive cruise control systems (on for example older Audi and Nissan vehicles) disengage at speeds around 10-15mph and just leave the car rolling without any control. If you did not takeover they could collide with anything in front.

kw

The main reason I'm against them _as currently implemented_ in e.g. Rhode Island is because a large fraction of the proceeds goes to some private corporation and the rest is used to make landlords happy:

"“If we generate half a million, 1million,whatever it is that we generate,that′s 1 million I don’t have to raise on the backs of property owners," DaSilva said."

Just bilking the poor to feed the well-to-do's pockets.

If there were some sliding scale that automatically dinged a millionaire $17,000 every time they did 55 through a school zone then no I'm not opposed to that, "they were successful because they were smart" so learn to drive, idiot.

Don't worry. If it spread too far eventually automatic law enforcement would start making life difficult for "real people" vs. the impoverished and itinerant so I don't really see it happening, in concept at least it's too fair.

In theory the smart motorways are monitored along their length by cameras and control rooms. Each lane has a tick or a red cross above it to indicate if it is in use or not available. At peak times all lanes are run live which leaves no room for error whatsoever.

Emergency vehicles have to fight their way through traffic if something happens (as opposed to going down the non-running lane hard shoulder).

There were a few of those in the UK. One in Manchester London Road 4 lanes under flow control depending on the time of day. 3 in for morning rush hour and 3 out in the evening they were notorious for head on crashes. Picture from the late 1970's:

UK motorways have strict central reservation barriers which are being reinforced to heavy weight solid cast concrete with tensile steel inside to stop the larger HGVs going straight through them.

That is the point of "smart" motorways. There is no hard shoulder to pull off onto - it is a live lane just like all the others. You can't always control where you breakdown either. There are refuges from time to time but far too far apart to be any use.

In my student days we got stuck immediately behind a vehicle in the outside lane (long before mobile phones). What happened next was very interesting. A pair of heavies saw what had happened from a distance behind us and created a rolling road block. When they had stopped all the traffic we got out and pushed the dead car onto the hard shoulder and then got back in our car and continued our journey. It was touch and go whether someone would pile into us when we had to stop like that.

Same in the UK. Highways agency vehicles have damn big flashing please don't hit me signs with an arrow that can be erected behind them.

There is a lot more of that work at the moment because of the crisis with smart/dumb motorways. They are dumb as hell when the smarts that are supposed to keep them safe are not working!

Opposite sense in the UK, but we do have a few free for all junctions on urban motorways where traffic is injected and must leave from the outside (fastest) lane. A recipe for high speed collisions.

They could be a useful if they were properly maintained and drivers understood them. Unfortunately neither condition is met in the UK.

There are also variable speed limit motorways and roads equipped with the latest average speed camera technology. That is also part of smart.

It's all software anyway, but yes, that's essentially true. I adjust the speed with the same buttons, and engage and disengage them with the same button.

In a sense, the two modes do the exact opposite: The cruise control maintains a minimum speed, but allows you to go faster, while the limiter holds a maximum speed, and allows you to go slower.

Mine does that. It will first beep loudly, and if I don't fix the situation myself, it will (or should; I have not tested it) apply brakes.

Mine does that too. It is very useful. My previous car had cruise control, but not adaptive. Those are essentially useful only when you are alone on the road.

AFAIAA there aren't any down here, not even the M25. Are there some up north or in the Midlands?

From what I remember from many years ago, in Toronto there were "Expressway"(?) lanes as the extreme two outside lanes of the highway through Toronto. There was was limited entry and access to those lanes, as they were intended for keeping up the speed of through traffic. In effect you had a central barrier and another almost continuous barrier on the nearside.

My recent cars automatically increase engine RPM by changing gear to maximize engine braking, in addition to using brakes if necessary.

Some people find that disturbing to have the engine spinning at

kw

A few years after I learned to drive (in 1972!) I was in England's Lake District which has some long and pretty steep hills. Coming down one in my manually-geared car I decided I could save petrol by turning the engine off and leaving the car in second gear, using the aid of engine braking to save heavy use of the brakes. What I'd forgotten is that the fuel pump wasn't electric, but was driven off the engine shaft. So as the engine braking was rotating the shaft all the way down, at the end of the run not only hadn't I saved any fuel but I'd flooded the cylinders as well and the engine wouldn't restart until all the excess fuel had been expelled!

You were lucky—if you’d bump started it successfully, you’d have blown the exhaust right off the car.

Turning off the ignition for a few seconds inside a tunnel was a popular stunt BITD—made a lovely bang. ;)

Cheers

Phil Hobbs

Central motorway A167(M) in Newcastle is one of the worst. The two road decks are stacked one on top of the other and the run ins and outs are placed wherever they could fit them. The odd one requires near suicidal driving to get from the far right lane injection to the left lane exit for the city centre. I pity any non-local drivers encountering it.

This Google maps image shows the top deck you can see exits to left and right (and there is a lane injection from the right two). It is inclined to jump onto the bottom deck when you try to move the viewpoint.

The underdeck is even more scary you get a fast lane injection shortly after going under the roadway which on a sunny day is already very dark.

Google "Central Motorway" "Newcastle" if the link I doesn't work...

Most of the junctions on the underdeck are normal handedness, but the majority of the junctions on the top deck are fast lane entry/exit.

That is crazily weird! I wouldn't like to attempt it without being shown it as a passenger first.

Streetview can't seem to handle moving forward from the start. The first few steps are ok, then it jumps to the underdeck.

I wonder if it was all designed by a non-driver!

I can assure you *that* doesn't happen when you drive along it. But is is probably one of the most dangerous UK motorways I know of.

Quite possibly. Newcastle is infamous for doing crazy things to traffic flow. Right now they are simultaneously upgrading the Great North Road A1(M) *and* repainting the famous Tyne Bridge at the same time. Taking out the two most important East coast road routes north simultaneously.

The Tyne Tunnel (toll) is the only other decent alternative crossing to avoid getting snarled up in miles long traffic queues.

That shouldn't have happened - the float needle valve in the carburetor should cut off any flow from the fuel pump.

The fuel pump typically operated off a cam on the camshaft. It was spring operated so that if the flow is restricted by the float valve it would reduce the stroke of the fuel pump - potentially down to zero.

With modern cars going downhill it is non-obvious whether it is better to put the car into neutral to cause the engine to go to idle where it stays consuming some fuel or leave it in gear such that engine goes into fuel-cutoff but adds some braking resistance.

kw

On 7/8/24 14:46, Jeff Layman wrote: [...]

In France, there are quite a few intersections that seem to have been designed under the influence of some potent drugs. I call them 'nouilles'.

Jeroen Belleman

When the engine is not running and not spinning over, there is no suction on the carb and you are correct that once the bowl fills to the point that the buoyancy of the float applies enough force to the needle valve there will be no fuel flow. However, in this case the car with manual transmission and clutch out is in gear and moving so the the engine is continuously spinning over, causing air to flow through the carb and sucking fuel through at least the idle circuits and most likely also through the main jet circuits. This continues until the engine stops spinning. Do it for a few seconds and you can get a bit of raw fuel into the exhaust manifold which then ignites from the hot exhaust when you turn the key back on and engine start running again. It also rinses off a bit of the oil on the cylinder wall and rings so you don't want to keep doing it or you eventually cause some wear, and also get raw fuel flowing past the rings into the oil pan. Do it for a few seconds and you get a little explosion and bang out of the tailpipe. Do it for many seconds with an old, wimpy, rusty exhaust system and you can get a big bang and literally split an exhaust pipe or blow the muffler off the pipe. Do it for even longer and you flood everything with so much fuel that it is so rich the engine won't restart when you turn the key back on, and you have to change the oil and wait for everything to dry out. Ahh, the fond memories of teenagerhood :-).

Belgium was worse. In parts of Brussels you can find priorite a droite roundabouts within spitting distance of normal ones. They were gradually phasing out the priorite a droite rule when I lived there.

Priorite a droite and roundabouts really doesn't work at all - traffic on the roundabout must give way to traffic entering from the right!

You are quite lucky that the steering lock didn't engage.

In later cars with servo assisted brakes you also lose their effectiveness if the engine isn't running to produce the vacuum.

No. In normal conditions it is standard motorway 70mph limit and 3 running lanes one hard shoulder. When it gets busy the speed limit drops to 60 (then 50) and the hard shoulder becomes a running lane.

In that latter mode a cross in a lane indicates an obstruction in that live lane so you have better slow down and/or get out of it.

UK drivers are mostly quite good about opening a path for emergency vehicles. What they don't do well is zip merging.

Nothing like that here or if there is then it is cryptographic. Where I live the PM (previous) moves about quite a lot and it is done by 16x police motorcycle outriders going ahead and escort vehicles followed by a bunch of heavies.

The drivers freezing is silly places problem is common in the UK too.

We don't have enough real estate for that. Motorways where the opposing lanes are more than 10' apart can be counted on the fingers of one hand.

UK the advice is to get out of the car and stay behind the crash barrier. Cars on the hard shoulder get hit with monotonous regularity.

Similar but no flares. HGV's will protect a serious crash site though I've only been in one major incident as the first car to stop without hitting anything and was then protected by the HGV behind me.

It was reported as 3 HGVs and a car. But it was actually a single car that clipped the central reservation 2 or 3 times and then swept across the live lanes totalling a couple of cars as it went. The HGV driver behind me had a QD dashcam with higher viewpoint which was used in evidence.

It is reckoned that for every hour of stationary traffic queue on a UK motorway there will be one serious rear end shunt (in addition to the original incident that caused the queue). Sometimes rubberneckers on the other carriageway cause a separate incident.