HI guys,
Well, the Hood has explained the UK timetabling thing quite well. Fundamentally, travelling on a Sunday in the UK (and sometimes Saturday) puts you at risk of timetable changes, and it's good practice to check close to the date. The reason's simple: traditionally, Sundays have less travel demand so major changes inconvenience the least people, and they are generally paying lower fares so put up with it. Not always true nowadays, but you get the idea.
Now, to the doors.
The 'Slam Door' was, I understand, invented in the late 1800s - and became the required solution in the UK. Basically, the door will always latch closed if shut firmly (i.e slammed !). It is therefore impossible for the passenger to fall out by leaning on the door. Prior to this, the door had a non-sprung handle that could be left open or closed. It was also deemed unacceptable that a passenger could accidentally pull a handle inside the train and inadvertently open the door. The simple and robust Victorian solution to this was to only have a handle on the outside, and to provide 'droplight' windows on every door. You have to deliberately lean out to open the door - it can't be an accident (but stupidity is still possible: the Victorians thought that it was reasonable if you die by being stupid...). Originally, the windows had a leather strap to support the window (the strap had holes over a peg, like a belt on your trousers). Later, British Railways developed the droplight used on the BR Mk1, Mk2, and Mk3 vehicles.
The 1973 HST design has the Mk3 carriage design, complete with droplight windows and air-conditioning (the only major change was a 3-phase electrical system, making it incompatible with normal loco-haulage but more efficient especially in transmission loss and for electric motors such as on the air-conditioning).
Incidentally, the Mk3 was the first 'monocoque' carriage: incredibly strong in end-on collision; see the Colwich crash in the late 1980s, a 110mph head-on collision where the only fatalities were one driver and those in the Mk1 buffet cars.
I recall (from an article I read) that when BREL sold Mk3 carriages to Ireland in the late 1970s/early 1980s, the Irish wanted power doors. So BREL developed a hydraulic closer that operated the hinged door without handles. It was clever, because the closer initially operated at very low force (so you could remove your fingers from the door gap, being warned by the pain before they became trapped!), but eventually latched the door closed. But BR never retrofitted this to stock.
In the 1990s, there were a spate of people falling out of train doors at speed (some due to faulty slam locks, some due to idiocy opening the door!), and central locking above a low speed was implemented throughout the UK fleet. Interestingly, the BREL power door closer was never implemented even as a retrofit in the UK.
Since the 1980s, new UK stock has been built with power doors as the default, almost always sliding (often 'plug' types). This is safer but there is a lot more to go wrong, and there was a big scare when one type of stock developed a nasty habit of opening the doors at speed on crowded trains!!
The Severn Valley Railway (a heritage steam line) still operates a GWR carriage with twist handle doors. Platform staff and the Guard have to make a special check to ensure they're safely shut. Even so, I have observed the door hanging open in the past as it went by the trackside gang I was in (so we of course phoned the signalman & he had the train stopped for inspection!).
It is interesting that only a year ago, China railways ordered something silly like 5000 or more slam door lock mechanisms urgently - from a metalwork company in Hull in the UK [we buy unrelated parts from them, and we had to wait slightly longer because the lock job had a tight deadline]. So China is still fitting slam door locks to new build rail vehicles - probably because it's a robust and simple design, if a little confusing for people who haven't experienced it before.
I guess that is all you want to know about slam doors, probably a lot more, but maybe interesting to some folks here.
Disclaimer: I don't work on the UK's railways & never have directly, I just remember a lot of engineering-type stuff! This is what i understand, others may be able to correct me!.
TTFN,
Merry
