The system is actually very clever, It can differentiate between 3 types of vehicles, car size, light goods size, and heavy goods size (I’m not in front of it at the moment (In fact I’m retired!) so can’t get the definitions as stated) but it’s basically on vehicle length. It also can log vehicle numbers & type in each lane, as per hour, day, or week. That’s at EVERY MIDAS pad. that’s why it can tell you that the part of the M60 between J15 (M61 and J18 Simister ) is just as busy at peak times as the busiest part of the M25.
Normal day-time running, you’ve got enough cars etc travelling faster than 50 mph so MIDAS doesn’t trigger unless there are queues forming, but it can however get tricked sometimes when it’s very quiet during the night if a very slow HGV wide load say passes over the MIDAS pads, it can trigger them to set speeds, it then needs an amount of traffic at or just over that posted speed to reset the signals. This doesn’t happen very often, usually with a wide load + ■■■■■■, but it can.
Another point is, Motorways run on Marker-post locations, when a road works are put on (overnight usually) the Foreman of the roadworks crew will pass the marker-posts for the start & end of his roadworks to the RCC, the RCC operator will then set up the system in that area as follows, its called the “Four call procedure”
!) First call, the roadworks foreman gives the markerpost for start & end of the roadworks to the RCC operator, and what lanes he requires closing. The operator will normally ask him if he needs the signals right away or if he’ll call back when ready. (They have been told not to phone until ready for the signals)
The operator then disables the MIDAS pads throughout the area between the marker-posts given, (This stops any MIDAS setting signals because of roadworks vehicles being stopped inside the area) They will set the required lane closures as requested. The RCC op will also set the HDS (Highest Displayable Speed) on all the signals within the marker-posts to at the most 50, or 10 mph less than any mandatory speed limit in the roadworks. In other words, if there is a 50 mph speed limit signed at the roadworks (Common on smart motorway working) the HDS will be set to 40, so if there is an incident within the roadworks, and you would normally set 50’s for an unconfirmed incident, it will only show 40’s, nothing higher.
The roadworks crews will then put up their signage, and the traffic management (cones to you)
2) Once all the traffic management is in place, all signage is out, the rwks foreman called the 2nd time, and the signals are cancelled.
…Whatever the roadworks are for, happens…
3) The work is completed, so the rwks foreman calls again to get the electronic signals reset to whatever lane closures are in place.
(Now this is the bit that sometimes can cause drivers to think that signals have been left on)
The rwks crew remove the cones and traffic management for lane closure, then they have to go forwards to the next junction, turn around, go back to the previous junction, come back up to remove their hard signage for the 1 mile, 800, 600, 400, 200, etc signs that they’d put in place for the closure, On an ‘ordinary’ overnight closure it’s not a problem, because they only put the signage on the N/S of the c/way, so the electronic signs can be cleared of lane closure, possibly being set for speeds whilst the hard signage is removed, but for a roadworks that’s been on for some time, with signage in the central reservation as well. it’s common that signals remain on whilst these are removed, even then knobhead drivers will run into road workers and kill them… I digress!
4) Once all the roadworks are completed, all the traffic management is removed, the rwks foreman calls up, the signals are cleared, the MIDAS pads are reactivated, the HDS is reset back to normal and all is well with the world.
The things that can go wrong with roadworks settings.
They stray out of the declared marker posts, put their closure on before the start marker post given so midas is activated by the roadworks vehicles.
They’ll call for signals and not be in the location, so signals are set for lane closures but no-one there.
They’ll forget to call in the 2nd time and signals are left on whilst the hard signage is doing the job anyway. (Not really a problem, just a waste)
They’ll remove the closure without calling in for signals to be reset, then bugger off as everything is removed, meanwhile the HDS is still set lower, MIDAS is deactivated.
They’ll get the signals set for removing the closure, clear the traffic management, then bugger off, forgetting call number 4. So signals are still set for lane closures, HDS is still set lower, MIDAS is still disabled., until an operator notices that the roadworks has gone over the booked time so calls the rwks foreman to find out he’s at home tucked up in bed!
The odd time that one of these problems occur is usually with a new contractor that’s not completely switched onto the 4 call procedure, if problems are found, they very soon get educated! 95% of the time it works.
Although some areas where roadworks are set are covered by CCTV to a degree, certainly not all are, there are a lot of rwks jobs put on overnight. I worked in the NW RCC, we put an average of 45 roadworks jobs on each night,( 4 calls per job) along with dealing with all the normal stuff, RTC’s, Breakdowns, Debris etc. there were 5 operators (sometimes only 3) on a night shift to deal with it all, with 14 motorways to look after. You just don’t have time or resources to check every job.