Smart Motorway lanes with different speeds

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JoshBostock01
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Posts: 36
Joined: Wed Apr 08, 2020 22:44

Smart Motorway lanes with different speeds

Post by JoshBostock01 »

So Saturday is the day that I make the journey to Inverkeithing for family committments. This journey involves the M90 south of Halbeath, exiting before the Queensferry Crossing. For whatever reason, the M90 towards the bridge has frequently been rammed towards the bridge for the last few weeks leading to the smart motorway lane controls to be switched to 40.

Today, I was sitting in near stationary traffic when I realised that the inside lane was set to 30, which then turned to 20 while the outside lane was still at 40. Shortly after this I also saw that nobody was in the inside lane ahead and that the police had coned it off due to an accident. It was at that point the next gantry changed to a red X under that lane.

My question is, what would be the legal speed limit here. Are you allowed to have different speed limits for two lanes on the same carriageway. If there were speed cameras there, would they ticket cars going above 20 in the inside lane only.

I'm guessing it was caused by some numpty in the control room scrolling through different displays until they came to the red X which should highlight that Transport Scotland absolutely have no clue how to operate smart motorways. As much as I am 100% in favour of ALR, I personally don't believe that they should be operating a motorway with a hard shoulder that doubles as a bus lane.
Isleworth1961
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Location: South Gloucestershire

Re: Smart Motorway lanes with different speeds

Post by Isleworth1961 »

No, you can't have different speed limits for different lanes. That would cause lane-changing chaos. Obviously, not knowing how they operate the systems, it does sound as if something was faulty.
WHBM
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Location: London

Re: Smart Motorway lanes with different speeds

Post by WHBM »

Makes you wonder how the "absolutely accurate" speeds displayed shown can be used for enforcement when you get discrepancies like this on one gantry.

I've seen different speeds over different lanes as well.
darkcape
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Re: Smart Motorway lanes with different speeds

Post by darkcape »

Most times when I've seen 20mph it has cycled down through other limits first. Must be a quirk of the system.
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AndyB
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Re: Smart Motorway lanes with different speeds

Post by AndyB »

I once saw 30 and 50 on the Westlink for a queue in lane 1 as well. Unenforceable, because you cannot have differential mandatory speed limits unless there is a physical divider between the lanes.

However, you can have differential advisory speed limits - so the lower reaches of the M2 Foreshore in Belfast read 30-30-30-50-50 for most of the day due to the queues to exit towards the Westlink while lanes 4 and 5 to the M3 are grand. Lane 1 to Duncrue Street is absolutely grand, but you will never see a higher advisory speed limit in lane 1 than in lane 2 other than at a diverge when it will be replaced by End.
PhilC
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Location: West Midlands

Re: Smart Motorway lanes with different speeds

Post by PhilC »

Years ago, travelling from the M40 to join the M42 at junction 3A, there was one gantry which showed wildly different limits for the two lanes. From memory it was 20mph i over the left hand lane and 60mph over the right. The previous and subsequent gantries were both blank. It was late at night and there was virtually no traffic so I moved to the right hand lane and then back again to avoid the 20mph sign. I can only presume the display was faulty as there was nothing I could see that would merit a lower limit.
JoshBostock01
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Joined: Wed Apr 08, 2020 22:44

Re: Smart Motorway lanes with different speeds

Post by JoshBostock01 »

Thanks for the replies. I see that it has happened before and is a mistake. Anyway I'm sure it won't be long before a fully laden bus smashes into a car on the hard shoulder/bus lane on that stretch of road due to how badly it's run!
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