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Return of the 4DD?

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Return of the 4DD?

Hey gang!!!
Well decades after British Rail dumped the idea after a long 22 year experiment, the 4DD doesn't look as dead as it does now!
Network Rail are now looking at the idea of double decker trains again and a 30 year plan to start upgrading our bridges and tunnels to accomodate them!
More here (Yeah, yeah i know, it's a DM link but i know no shame  Cheesy):
http://www.dailymail.co.uk/news/article-2873797/Double-decker-trains-hit-Britain-s-railways-ease-ove...
So decades after the 4DD was abandoned, sold off to private owners, dismantled and left to rot (only 2 carriages of 8 are now left), it looks as though the 4DD will have a successor!
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Re: Return of the 4DD?

Well, in the US, a lot of the trains they have there are double-deckers, so it's not beyond the realms of reality, it's just the problem of altering the present infrastructure to accommodate them, a lot of bridges can't be raised as the roads need major fettling to make them lest of a hump, so, the only way that could be avoided is if they dug down into the trackbed to drop the tracks down to gain the additional headspace... Smiley
I'm sure the beancounters will look at the cost of a total conversion and think "nah, too pricey, scrap it, again", after they've lined their pockets with consultancy fees and admin charges... Roll eyes
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Re: Return of the 4DD?

OK... nice idea.... get twice as many passengers crammed into the same length of train... double the income per journey.... double the fares to "cover the cost" of the "overheads"...
In this case... "overheads" will be costly....
Signal gantries across the tracks.
Station canopies.... Across the tracks
Bridges of all descriptions... some of which were built at the same time as the original tracks,  ( and to fit the original rollingstock ). even newer built bridges, which would have cost a small fortune to build will need replacing...
Tunnels ... imagine how much it would cost to make them bigger.. ( either head room, or digging down )..
and don`t forget.... while all this work is going on.... there will be the "inevitable" disruption to "normal" services, which could last for years... not just a few months...
Will there be "double decker" station platforms ! ??  or will everyone have to enter and exit by the doors at either end of the carriage?  could be a BIG problem in the rush hour, trying to get twice as many people on/off in time to keep the schedules.... or ... in case of emergency...
Oh, yeah... I forgot... the BIGGEST overhead... the new carriages and locomotive power units to make up these "double decker" trains...
Yeah.. not a cheap option... and will they be really viable?  the only place they would be likely to make money would be on the commuter runs, where the passenger numbers could possibly make them work...  certainly there would not be so many passengers on the long haul routes... London/Manchester    London/Birmingham  London/York  London/Edinburgh London/Glasgow and London to Penzance / Bristol/ South Wales...
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Re: Return of the 4DD?

Thats just the point.. the 4DD didn't need any bridges / tunnels to be rebuilt and that had the lower floor above the bogeys like modern trains today. In other countries the lower floor is down between the bogeys.
The only reason the 4DD was scrapped by BR is because it was taking so long for passengers to get on / off as they literally had one door for 18 passengers per compartment.
If you've ever seen the steps up into the upstairs section, you'll appreciate that it's very narrow (I've been onboard one of the two final rotting specimens that are left - with the owners consent). This means it would have taken a stupid amount of time to have people getting in and out of the upper compartment. The actual idea of the upper deck taking up the luggage space was genius but the sealed compartments instead of a long corridor of steps and easier access to doors was a very stupid mistake.
The drivers cabin isn't much better either, stupidly narrow doorway into the drivers cabin from the luggage room. Credit to BR where it's due though, although they both look an absolute state, they're still standing after 70 odd years - and the undercarriage / chassis is solid on the one i've visited.
The new DD's are going to have to drop the lower floor between the bogies if they want it to work. This will mean no bridges or tunnels will need adjusting but as for doors and passenger loading times, I think the realistic answer is to adjust journey times rather than continue to stick with unrealistic timetables that can't be met. At least then people can't moan the trains are late  Wink
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Re: Return of the 4DD?

Hmm... interesting that you say the coaching stock will have the lower floor between the boagies....
MK4 coaching stock.... As used on the East Coast Main Line... brought into service from 1989 to present day  ( wiki ref http://en.wikipedia.org/wiki/British_Rail_Mark_4 )
shows the height .... From RAIL TO ROOF 3.79 m (12 ft 5 in)   so, assuming the passengers are standing on the bottom deck, ( assume 12 inches above the track ). that reduces the overall height to the roof, to 11ft 5 inches...... assume there will be a "middle floor" construction, to accomodate the upper "saloon".... assume 12 inches (to allow for strength, and services ( heating/power/etc )... reduces the overall height to the roof to 10ft 5 inches... assume the roof is to be insulated, and double skinned, say 5 inches ....
reduces the overall internal height to 10 feet .........................








which means, that passengers will have to be less than 4 ft 9 inches tall, to travel on these trains...  Roll eyes
Because the bridges and tunnels will not need to be re-constructed.... ?  ?  ? 
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Re: Return of the 4DD?

Yes but you've allowed for an extra foot above the rails  Roll eyes
Look at this - the 4DD did the job without even putting anyone down below the usual floor level and that was only 4 inches higher than the mk4!:

So if BR could do that then without utilising the space below the floor level, i'd be pretty sure we could come up with something functional today that does use that space.
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Re: Return of the 4DD?

I've been on DD trains in the Netherlands and that's a very congested country. Trains have lots of stops and I don't remember any problems with people getting off or on.
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Re: Return of the 4DD?

it was the potential need to rework all the tracks that was the reason given for not rolling out maglev systems in this country, yet BR sold the tech to the French and the Japanese and offered it to anyone else with a few bob under their hat as well ...
always trying to do stuff on the cheap in this once great nation, of course they would need to rework some things for a double decker system to be fully operational on all lines but now we have enough extra people straining our infrastructure past failure levels there going to finally find a way to do things that were previously listed under the heading of "not economically viable" .....
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Re: Return of the 4DD?

Quote from: shutter
Because the bridges and tunnels will not need to be re-constructed.... ?  ?  ? 

Actually shutter if you look at some routes, BR years ago to deal with the problem of carriages that were too wide, decided to rip up double tracks through some arches (tunnels / bridges) and put in a single track right down the middle thus increasing the height of the arch. That was really a side effect of their intentions but i don't see why we couldn't do this now to allow for double deckers.
With deckers in use carrying larger numbers of passengers, delays won't be quite as bad and thus single track tunnels won't be such an issue either.
What to do in the future when rail passenger figures are even higher?.. well.. thats that generations problem  Cheesy  Tongue (I learnt that trick from you lot lol). No seriously, victorian tunnels aren't going to last forever anyway so they will all at some point need to be re bored. More and more of the disused ones are collapsing due to lack of maintenance and those in use are ticking away too despite maintenance.
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Re: Return of the 4DD?

Traveled frequently on bi level trains in Sydney

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Re: Return of the 4DD?

Quote from: PeterLoftus
I've been on DD trains in the Netherlands and that's a very congested country. Trains have lots of stops and I don't remember any problems with people getting off or on.

I would suspect that they have realistic timetables too which allow for people to get on and off. In this country it appears that we seem to allow about one minute per station and then the conductor is wanting to get the train rolling again to keep with the timetable.
The reality is that our trains rarely keep to their timetables. Why? because they're unworkable. The journey times need to be lengthened so that they're realistic and THEN the trains won't be late anymore.
Trouble is that it wouldn't go down well with the public would it even though it would stop trains being 'late'.
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Re: Return of the 4DD?

Yes, Indeed I did allow a 12 inch clearance between the rail level and the floor.... there is no way that you can have a coach floor running at rail level, sensors for automatic signalling, and level crossing control will foul the floor at the first opportunity..
Your "project" pic shows a very "primitive" solution, but has one BIG flaw..... passenger comfort.... and of course... how to get the passengers into and out of those "compartments"  a dual level station platform would not work... corridor trains would not work, and slam doors would not be allowed... the present slding "plug" doors would be too complicated to fit to each "compartment" and too expensive.
Modern passengers require a "certain comfort level" unlike the original passengers on B.R. MK1 coaches, who were grateful to get a seat and had to put up with wartime travel restrictions and conditions of the rolling stock...
The 21st century traveller, expects  21st century comfort...
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Re: Return of the 4DD?

Travelled on a DD T.G.V. in France earlier this year and very smooth. Very fast too - 300kph!  Shocked
Went from Lille to Provence. Train ran to timetable and no problems boarding or leaving.
Definitely do it again.  Smiley
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Re: Return of the 4DD?

Quote from: shutter
Your "project" pic shows a very "primitive" solution, but has one BIG flaw.....

By todays standards it has many flaws AND floors  Cheesy
No seriously shutter it was designed some 60 odd years ago - you can't really slate that.
My point was that TODAY we would need to use the space between the bogies. I'm not saying it should run at rail level but at the same time 12 inches is quite a lot really.
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Re: Return of the 4DD?

Even if you could reduce the 12 inch clearance on the actual floor level.... service lines would need to run somewhere, and if you need a gap of ( say ) 6inches for them, that only leaves 6 inches of clearance under the coaches,  Remember these also need to be accessible from underneath the coaches for service and replacement work in the wagon shops...
To accomodate two levels of passengers in comfort, would require coaches to be at least 15 feet high.... add on the safety clearance for tunnels and bridges etc.. you are talking about 16 to 17 feet ground clearance on all coaches... remodelling bridges and tunnels to these sort of levels would be very very expensive....