M20 J3-J5 Smart Motorway - What are these?

Discussion about street lighting, road signs, traffic signals - and all other street furniture - goes here.

Moderator: Site Management Team

Post Reply
4977
New Member
Posts: 2
Joined: Sun Aug 14, 2022 19:29

M20 J3-J5 Smart Motorway - What are these?

Post by 4977 »

Does anyone know what these white, beacon looking things located adjacent to the carriageway are?

Thanks,

4977
9C053FA6-6E30-42E4-9ED1-69E2D9EF422F.jpeg
User avatar
Big L
Deputy Site Manager
Posts: 7517
Joined: Sun Nov 14, 2010 20:36
Location: B5012

Re: M20 J3-J5 Smart Motorway - What are these?

Post by Big L »

Believe those are the stationary vehicle detectors.
Make poetry history.

Did you know there's more to SABRE than just the Forums?
Help with maps using the new online calibrator.
Add your roads knowledge to the SABRE Wiki.
4977
New Member
Posts: 2
Joined: Sun Aug 14, 2022 19:29

Re: M20 J3-J5 Smart Motorway - What are these?

Post by 4977 »

Mystery solved!

There is one pictured here:

https://www.bbc.co.uk/news/uk-england-s ... 935970.amp
User avatar
Conekicker
Member
Posts: 3754
Joined: Sat Dec 10, 2005 22:32
Location: South Yorks

Re: M20 J3-J5 Smart Motorway - What are these?

Post by Conekicker »

I think they're the ones that were exhibited at Traffex recently. Under the dome there's a rapidly rotating head. A moving part. That is present 24/7 in all weather conditions.

Two questions:

1) what is the MTBF?
2) does the unit include a fault reporting system for times when it goes U/S?
Patience is not a virtue - it's a concept invented by the dozy beggars who are unable to think quickly enough.
User avatar
RichardA35
Committee Member
Posts: 5705
Joined: Thu Jul 11, 2002 18:58
Location: Dorset

Re: M20 J3-J5 Smart Motorway - What are these?

Post by RichardA35 »

Conekicker wrote: Mon Aug 15, 2022 12:11 I think they're the ones that were exhibited at Traffex recently. Under the dome there's a rapidly rotating head. A moving part. That is present 24/7 in all weather conditions.

Two questions:

1) what is the MTBF?
2) does the unit include a fault reporting system for times when it goes U/S?
For No 2.
a) Fail to safe and automatically implement a preplanned series of signals to close lane 1 and move traffic into lanes 2-4 until patrolled and confirmed visually (or at a stretch by CCTV) as no obstruction present or
b) just an alarm to inform control?
In other industries only one of these would be considered as "safe" but then they probably wouldn't have only a single instrument doing the job.
User avatar
Conekicker
Member
Posts: 3754
Joined: Sat Dec 10, 2005 22:32
Location: South Yorks

Re: M20 J3-J5 Smart Motorway - What are these?

Post by Conekicker »

RichardA35 wrote: Mon Aug 15, 2022 12:40
Conekicker wrote: Mon Aug 15, 2022 12:11 I think they're the ones that were exhibited at Traffex recently. Under the dome there's a rapidly rotating head. A moving part. That is present 24/7 in all weather conditions.

Two questions:

1) what is the MTBF?
2) does the unit include a fault reporting system for times when it goes U/S?
For No 2.
a) Fail to safe and automatically implement a preplanned series of signals to close lane 1 and move traffic into lanes 2-4 until patrolled and confirmed visually (or at a stretch by CCTV) as no obstruction present or
b) just an alarm to inform control?
In other industries only one of these would be considered as "safe" but then they probably wouldn't have only a single instrument doing the job.
a), surely they wouldn't go for that with a new and unproven device, there'd be the potential for near continuous LBS1 closures a few years down the road as these things inevitably start to go U/S. How long will the bearings on the rotating part last?
b) effectively, given the length of road each unit covers, one failing would be a complete failure for however long that length happens to be (200-400 hundred metres?). 2 or 3 adjacent ones fail and you've the best part of a kilometre with no coverage?

Given that the signalling system is mains powered with no backup supply, presumably this system is the same - no power = no SVD.

Edit, the military are moving from mechanically scanned radars to electronically scanned. I can't help but think that the latter is a more robust system as it has no moving parts and degrades gradually as discrete scan elements fail.
Patience is not a virtue - it's a concept invented by the dozy beggars who are unable to think quickly enough.
User avatar
RichardA35
Committee Member
Posts: 5705
Joined: Thu Jul 11, 2002 18:58
Location: Dorset

Re: M20 J3-J5 Smart Motorway - What are these?

Post by RichardA35 »

It would seem that NH have been pushed into action in the name of safety to bring the risk to the lowest practical, so why wouldn't they plump for the safest, most secure system available or be hauled up in the court of public opinion (again) for putting cost before safety.
Post Reply