Stupid Motorway. Speed restrictions.

[matacaster]

Uphill stretch of M21 motorway approaching Barnsley turnoff
Traffic approaches bottom m of hill at 60-70mph. Warnings of congestion. Speed limit reduced to 40mph. Result congestion.

There is no congestion, it is a product of traffic moving at 70moh being told to travel at 40 mph, this reducing the throughput, hence congestion. So why the 40mph speed limit? Well, hgvs struggle up the hill and get overtaken by other hgvs going 1 or 2 mph faster. This only one lane for faster traffic, result congestion. Solution - simply have signs stopping hgvs overtaking at all on this uphill stretch. Result, no speed restrictions, just a few lorries slowed down, much better traffic flow.

 

[156421]

Uphill stretch of M21 motorway approaching Barnsley turnoff
Traffic approaches bottom m of hill at 60-70mph. Warnings of congestion. Speed limit reduced to 40mph. Result congestion.

There is no congestion, it is a product of traffic moving at 70moh being told to travel at 40 mph, this reducing the throughput, hence congestion. So why the 40mph speed limit? Well, hgvs struggle up the hill and get overtaken by other hgvs going 1 or 2 mph faster. This only one lane for faster traffic, result congestion. Solution - simply have signs stopping hgvs overtaking at all on this uphill stretch. Result, no speed restrictions, just a few lorries slowed down, much better traffic flow.

or put in a crawler lane

 

[Bletchleyite]

Uphill stretch of M21 motorway approaching Barnsley turnoff
Traffic approaches bottom m of hill at 60-70mph. Warnings of congestion. Speed limit reduced to 40mph. Result congestion.

There is no congestion, it is a product of traffic moving at 70moh being told to travel at 40 mph, this reducing the throughput, hence congestion. So why the 40mph speed limit? Well, hgvs struggle up the hill and get overtaken by other hgvs going 1 or 2 mph faster. This only one lane for faster traffic, result congestion. Solution - simply have signs stopping hgvs overtaking at all on this uphill stretch. Result, no speed restrictions, just a few lorries slowed down, much better traffic flow.

Reducing the limit doesn't reduce throughput, it increases it, because vehicles can be closer together.

 

[bramling]

Reducing the limit doesn't reduce throughput, it increases it, because vehicles can be closer together.

I’m not convinced the theory works in practice, as the standard of driving is too erratic. It might work if everyone gently glided down to the lower speed, but this simply doesn’t happen in practice.

 

[Bletchleyite]

I’m not convinced the theory works in practice, as the standard of driving is too erratic. It might work if everyone gently glided down to the lower speed, but this simply doesn’t happen in practice.

Having used the same bit of the M25 at the same time of day daily before and after a variable speed limit was introduced, it absolutely does work. It's basically the main bit of smart motorways worth keeping.

 

[156421]

Having used the same bit of the M25 at the same time of day daily before and after a variable speed limit was introduced, it absolutely does work. It's basically the main bit of smart motorways worth keeping.

Whilst it may work there (and I my experience also does on M42... the first of the much-maligned "smart motorways") perhaps the specific location described by the OP "Uphill stretch of M21 motorway approaching Barnsley turnoff" is an unique case. However, I'm hard pressed to find much evidence that a M21 exists!!

 

[Mcr Warrior]

Uphill stretch of M21 motorway approaching Barnsley turnoff

@matacaster. You're referring to the M1, presumably?

However, I'm hard pressed to find much evidence that a M21 exists!!

Over in the Republic of Ireland, one day, perhaps? Maybe!

 

[156421]

Over in the Republic of Ireland, one day, perhaps? Maybe?

if the EU funds it

 

[DelW]

However, I'm hard pressed to find much evidence that a M21 exists!!

If it did it, it would surely be in Kent. Though the A21 does get subsumed by motorway for a stretch north of Sevenoaks, it's become a part of the M25.

In passing, when did Cumbrian dialect include use of a scharfes s?

 

[156421]

If it did it, it would surely be in Kent. Though the A21 does get subsumed by motorway for a stretch north of Sevenoaks, it's become a part of the M25.

In passing, when did Cumbrian dialect include use of a scharfes s?

They call it eszett in these parts

 

[DelW]

They call it eszett in these parts

Fair enough IIRC my German teacher used to refer to it as a scharfes s, but in those days it was regarded as old fashioned and its use was discouraged.

But I'm going rather a long way from motorway queues in Barnsley

 

[Bletchleyite]

They call it eszett in these parts

That's because it is a ligature of an S and a Z, if you look at it you can see both letters. A bit like the old English "ae" ligature.

Later spelling reforms meant it moved to represent two Ss.

How did that come up with regard to Cumbrian dialect though?

 

[DelW]

How did that come up with regard to Cumbrian dialect though?

Look at the location of @156421

 

[Bletchleyite]

Look at the location of @156421

Ah

 

[156421]

Usually by the time we've gone this far off topic we'll be told by the mods to start a new thread, or be referred to a similar discussion from 2013 or something.

 

[matacaster]

@matacaster. You're referring to the M1, presumably?


Over in the Republic of Ireland, one day, perhaps? Maybe!

Yep M1, same problem occurs at Sheffield north turnoff (both southbound).

 

[Shaw S Hunter]

Usually by the time we've gone this far off topic we'll be told by the mods to start a new thread, or be referred to a similar discussion from 2013 or something.

The mods can't and don't read every thread. Someone first has to use the report button to alert them to any "irregularity". And ultimately the decision as to whether to take action is solely theirs. Occasionally I'll report a thread for being somewhat off topic only to receive a message that they are happy for the discussion to continue. And that's fine by me. Members making outright demands are soon likely to find themselves under moderation, suspended or even banned. Keep things friendly!