I am aware that there must be some sort of connection between Burscough Bridge box and Sandhills because the BB1 and BB2 signals show on the map on Open Train Times. Beyond there are semaphores at Parbold which has no electronic connection to anywhere. Real time trains always shows no report.Burscough Bridge works TCB to Sandhills - it's not an absolute block section.
As in the train is now entering Staffordshire? Would this system have had to have been changed on the creation of the Metropolitan counties in 1974? Additional blocks would have been needed for the West Midlands, Greater Manchester and Merseyside.when they were rebuilding the WCML for electrification in the 60's, it was said (in jest) trains were signalled county to county rather than block to block!
If Network Rail is repeatedly paying out for delays then that must improve the business case for resignalling mustn’t it?Cost of opening an extra signal box vs. resignalling vs. paying out if the cause is determined to be Network Rail…
Guess which wins…
So yes, the length is determined by the planned / required line capacity.
I believe it’s called ETCS. Correct me if I’m wrong but does ETCS work by determining what a train’s stopping distance will be at the speed it’s travelling at and marking that distance immediately in front of it as occupied, without defined blocks, hence moving block? I can’t help thinking that instead of the European interoperability of obsolete 25 year old GSM technology, we should be developing a new British signalling system fit for the 21st century.At the risk of kicking the hornets nest here - With modern technology surely there's a better solution?
The short answer would be “enough”. What is the most common/average length of blocks across the network. There must be a certain level which is sufficient for most lines. 7 mile or longer sections are edge cases and should really be eliminated due to their instability. Other edge cases include running 24tph on Thameslink.How much resilliance do you factor in, where do you stop, at what point does the cost outweigh the benefits?
A very good point.Thats a business decision, surely. A massive delay because of a long section means the railway suffers reputational loss. How you calculate the value of that I dont know.
Again, completely ridiculous. That equals the one on the Bentham line.Are there any single track sections longer than that? Some on the Far North line look to be close to 20 miles.
I am aware of the fundamentals of railway signalling. I am not suggesting that it is safe for a train to proceed into an occupied block under any circumstances.Yes it is unsafe as allowing another train into an absolute block section contravenes the fundamental rule of absolute block: one train in one section at one time!
Where the signals are placed though is a different question and there quite possibly are better places for signals to assist with keeping the passenger service running. There is always the option of adding intermediate block signals to sub divide a section, but the cost of that would have to be weighed against the cost of delays/or benefits that splitting the section can bring in purely financial terms.
While it IS safe to proceed if the next train IS actually 7 miles away, of course all signalling only exists because without it, it is not KNOWN if the train IS 7 miles away or 7 feet away (the ML148 signal is on a curve surrounded by trees). The issue of frequency is that inability to differentiate between 7 miles and 7 feet is insufficient for most purposes.Do you know the previous train is 7 miles away, or do you suspect it is based on what normally happens? That's how absolute block works - you don't send the next train into the section until the previous one has left. The signallers have no visibility on what's going on until the train reaches them. You resignal if you need more visibility and/or increased frequency.
I am confused by Far North line frequencies. As far as I can tell, I don’t believe it’s possible to use the Far North line to visit Thurso/Wick/John O’Groats in a day from anywhere out of Glasgow/Edinburgh/Aberdeen/Inverness and then return that same evening, necessitating at least an overnight stay at the northernmost tip of Great Britain.It is nowadays ! (Or at least was pre-Covid). The Far North Line service is more intense now than ever, with as well as the four Wick/Thurso through trains, various short workings. It got to the stage that if the afternoon northbound Wick was late, it would be held for around an hour to avoid delaying the afternoon southbound Wick, because if the latter was late, its crossings with other trains, conflict with the Kyle line trains, and turnround times would wreck the Far North and Kyle line timetable for the rest of the day; Whereas the northbound caused no such issues.
That is quite clearly another example of where the level of resiliency is insufficient even for the current service. Should modern resignalling projects not also include provision for future frequency increases?Pre Covid trains crossed there every morning.
Sometimes even resignalling isn't the answer. When Nantwich - Shrewsbury was resignalled in 2013, it went from Absolute Block to TCB controlled from Cardiff - but the old AB sections were replicated, meaning there is still a near 10 mile section between Prees and Wrenbury which limits how close the local service can follow the fast, and adds to delays when trains are running late.
There was a box half way along that section at Whitchurch, but it closed a few years before resignalling, and the opportunity to replace it wasn't taken up.
I was thinking about that. That probably explains why the 2tph to Southport run within 15-20 minutes of each other, the minimum permissible by the long sections, but leaving a spare path for a sandite/de-icer MPV in winter in the spare 40-45 minutes.The Southport line has another long absolute block section from Parbold to just before Wigan sidings. Unless both are resignalled, the train wll just end up waiting at Parbold anyway.
The long block sections can cause problems at peak times, when 3 trains an hour use the line as one delay causes a knock on, add in the railhead treatment train that often runs in the afternoon peak during leaffall and delays can mount, whether or not it's worth the cost of resignalling, I'm not sure.
Interestingly, if the Burscough Curves are to reopen, Southport to Burscough Bridge is going to need to be resignalled to allow about 8tph, including resiliency/railhead treatment and be integrated with the Ormskirk to Preston line which currently lacks any signalling equipment at all. The resignalling could be done out of the budget for that project as a whole.