Motorway Speed Limit

[CPN]

12 minutes ago, Mjolinor said:

On the subject of asking what method do you think there is to accurately measure speed at all times the car is moving?

The only way I can think of is a Doppler effect sensor underneath the car, probably laser driven but I suppose audio would work but would not be as accurate.

GPS is a quantum leap more accurate than any car speedo... (as long as you are moving of course...)

 

[Trewithy]

Roy124

UK motorway speed limit could be increased to 100mph to 'reduce congestion

Was that report dated the first of April?

[Haliotis]

The most crucial factor is that, at 70 mph (well, for those who obey it) there are still severe accidents on the motorways, when you would expect safety with all vehicles travelling in the same direction.  So, with a speed limit of 100 mph, it would be reasonable to anticipate a significant increase in the accident rate, plus there being more fatalities.

There would be a greater risk due to HGVs being limited to 56 mph, because the closing distance when approaching such vehicles in front would be much more rapid.  Lane 2 would become a very dangerous place.

Increasing the allowed speed for HGVs would not be an option - a 38-tonner pounding along a 56 mph is frightening enough.

The only bright side for the NHS is that a 100 mph limit would reduce pressure on the A&E departments - victims would go straight to the mortuary!!!

[Roy124]

@CPN GPS is probably accurate enough though less so on a winding road.  

[Mjolinor]

Shirley that only works if you have a working speedo in your car. I do not think there is an absolute measure in any of the radar type warning, it just measures the difference between your car and a potential hazardous obstacle in your path.

[Mjolinor]

2 hours ago, CPN said:

GPS is a quantum leap more accurate than any car speedo... (as long as you are moving of course...)

 

GPS is on its last legs and will be dead in a few years. It has been a good few years since the last update and no maintenance is done on it any more. It is not inherently more accurate than any car speedo. The accuracy of it is totally controlled by the US military so no way would UK law ever allow it to be used for anything remotely legal.

There are a good few other navigation systems available and most chipsets support some of the others as well as GPS.

[CPN]

1 hour ago, Roy124 said:

@CPN GPS is probably accurate enough though less so on a winding road.  

As long as your GPS unit and/or phone has a clear view of the satellites, it'll still work well on winding roads...

[CPN]

49 minutes ago, Mjolinor said:

There are a good few other navigation systems available and most chipsets support some of the others as well as GPS.

That's true. Most new modern hi-end smartphones will also do a fix on Galileo or Glonass for example...

edit: I was forgetting about BeiDou and, Galileo (the most accurate apparently) is also being phased out (since 2017) but a newer version is coming...

[Haliotis]

GPS or whatever alternative is chosen, it will tell you where you are, and probably how fast you may be driving.  But it will not consider road/weather conditions, or advise you of how safe your path is compared to other road users - all of which become even more critical to consider as speeds on the roads increase.

[Roy124]

2 hours ago, CPN said:

As long as your GPS unit and/or phone has a clear view of the satellites, it'll still work well on winding roads...

No.  It works out speed by integrating  series of positions.  Radial speed and linear will differ by a small amount but probably close enough for Government work.

@Mjolinor that is why I prefer and usually use SatNav as that can encompass any of the systems.

 

[CPN]

1 minute ago, Roy124 said:

No.  It works out speed by integrating  series of positions.  Radial speed and linear will differ by a small amount but probably close enough for Government work.

We'll have to agree to disagree. I'm coming from a lifetime's experiences and a full technical knowledge of all the systems up there (in the forces and beyond).

[Haliotis]

On BBC News this morning it was reported that the M1 was blocked between junctions 20 and 21 (Leicestershire) by a multi-vehicle crash.  This happened at 06:20 am on a clear dry day - with good visibility and road conditions!!!  

So who could be foolish enough to believe that drivers are capable of such high speeds?  The facts would seem to indicate that whoever set the limit at 70 mph were over optimistic. 

As with all things human, capability varies wildly from driver to driver.  Working on a simple rule of thumb, the capability for an average driver’s career could be said to go from moderate through to very good and then back to hesitant, as experience and age takes affect.

In designing the road network, planners have to devise their layouts to encompass safety for all levels of driver-competence and, even then, they don’t always get it right first time.

[Cyker]

Statistically there are far more crashes at 20 and 30mph than there are at 70mph.

Contrary to what the anti-car groups like to claim, speed has very little to do with the likelihood of having an accident, it only magnifies the consequences - As I keep saying, the problem is not speed but deteriorating driver skill due to lack of enforcement and (controversial opinion) the increase of driver aids reducing driver engagement and attention.

 

It doesn't help that modern road design seems to be far worse than in times past - If anything they are making roads more dangerous; The most dangerous thing in terms of speed is not speed itself, but changes in speed, and modern road design, instead of creating a smooth flow of traffic, seems to be more about forcing cars to make many speed changes for no good reason.

 

On a tangent, one of the reasons LTNs have been such a nightmare here is because they force everyone onto the main roads, and if there are road works or an accident then there is no way to relieve the traffic pressure, and because these roads were never designed to take so much traffic it makes people impatient which is one of the biggest causes of collisions; I've been seeing a noticeable increase in people driving on the wrong side of the road and jumping red lights.

[Mjolinor]

Personally I think the biggest problem is the de-skilling of driving test examiners. Instead of learning to drive, instructors are now forced to teach people to pass a driving test.

It used to be that the examiner applied common sense to the driving they saw on the test and accounted for people being nervous and stressed. That no longer happens and instead they have a stupid sort of points rule to it and new drivers are left with no ability to cope with the unexpected.

Teaching people that there is no need to gear down when slowing and that it is OK to totally rely on the brakes, nightmare waiting to happen.

 

[Haliotis]

Cyker, I fully agree with your views, but I would add my following reservation.  As I have previously stated, the abilities across the whole spectrum of drivers varies quite considerably.  There are many who would firmly believe that they would be just a proficient at 100 mph as they are at 70 mph, when clearly they would not.  Drivers of fast response vehicles (police/fire/ambulance) have to go through rigorous training for this, and not without good reason.

Before motorways were limited to 70 mph, I have driven at 100 mph.  I was a lot younger then but, at that speed, I was aware of my own increased vulnerability.

Now in my (very) late 80s, I still drive on motorways and I regularly touch the 70 limit - mainly to get by strings of slower moving HGVs - but apart from this I am happy to tootle along at 55-60 mph in lane one.

Were the motorway speed limit raised to 100 mph, I would not be happy at being among drivers who erroniously believed themselves to be safe at such a speed.

[Roy124]

@Haliotis about 5 years ago I had the delight of driving on an autobahn and indulged in driving at a ton.

You certainly need to concentrate and plan 'escape manouevres'.  As soon as other traffic, slow movers doing 70, appeared it was prudent to slow down. 

On our crowded roads with slow movers like us pulling out to overtake a truck a car doing a 100 would have problems. 

[Roy124]

3 hours ago, Cyker said:

As I keep saying, the problem is not speed but deteriorating driver skill due to lack of enforcement and (controversial opinion) the increase of driver aids reducing driver engagement and attention.

I find that when I am following a vehicle in lane 2 with 3-bar spacing and ACC some cars seem to think I am going too slow.   The good ones ride my bumper, the bad ones will undertake squeezing into the gap between me in lane 2  and the truck in lane 1.

As soon as they pass they immediately get blocked by the car on front.

They just seem incapable of reading the road. 

 

[Roy124]

PS, I find the same with trucks in lane 1.  They think my safe space is where they should be.

[Haliotis]

Roy, not sure what you mean by, “the good ones ride my bumper”!  At any time, nobody should be riding your bumper, and certainly not on a motorway.   Personally, I detest tailgaters - they give you no room to avoid being shunted from the rear if you yourself are forced to emergency brake. For this reason alone, I always keep a good distance behind the vehicle in front, which benefits me in several ways.  I can see further ahead than the vehicle in front, which gives me more time to react if vehicles ahead have to brake, and I can still exercise a slowing down procedure which gives a following driver ample warning and time to brake normally.

Some drivers get irked by this - they fail to realise that they are still making the same forward progress regardless of the gap.

[CPN]

Totally agree Albert!

[Roy124]

1 hour ago, Haliotis said:

Roy, not sure what you mean by, “the good ones ride my bumper”! 

Joke: both bad one not as bad.

Where I do undertake is under the following circumstances:

I am driving in lane 2 and traffic starts to bunch up.  Lane 1 is empty except for a lorry a quarter mile ahead.   I move in to lane 1 maintaining the original lane  2 speed.  As lane 2 continues to go slower and I catch up with the lorry  I will either remain in lane 1 or move to lane 2 if a gap opens up.  I don't go to lane 1 to deliberately undertake the car ahead.

[Haliotis]

If you happen to get a clear run ahead, it is perfectly legal to be in lane 1 and pass vehicles in lane 2.  The only down side is that you need to keep alert for a driver deciding to pull across from lane 2 into lane 1.  They should of course, check behind them for it being safe to do so, and then indicate their intention when they are sure of it being safe. The only trouble is that some drivers seem to forget that there are others on the roads.

[Roy124]

@Haliotis yes some do some crazy darts.

 

[Mjolinor]

If people passing on the left obeyed the law in that regard I doubt there would be many problems with them doing it. It is illegal to move to a lane further left in order to pass someone, it is only legal to do so if you are in that lane and traveling faster then the lane to your right.

 

[Cyker]

Here's a good one from a few days ago!