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It’s been quite amusing to see the way the anti Hs2 campaign’s suffered a bout of collective amnesia now that the Telegraph has latched onto the idea of double-deck trains.

Amnesia because this has been done to death before. It didn’t stop Hs2 then and it won’t stop Hs2 now.

The Telegraph (behind the curve as usual) has suddenly discovered a report that was discussed in the rail press way back in April. Here’s the Tel’s report from November 16th – and here’s the original report from Rail Technology Magazine way back on April 16th (seven months earlier!)

Needless to say, the anti Hs2 mob have got all excited about this and grasped onto it like a drowning man holds onto a lifebelt. In doing so they’ve studiously ignored all the pesky technical, engineering & economic questions that real-world folks have tried to address for years – not to mention the circles that would need to be squared.

Now, ignoring the fact the Tel’s report is based on a design house study that hasn’t come up with anything yet (far less than a workable train design), let’s have a look at some of the questions the anti Hs2 mob ignore but sensible people are bound to ask.

How can double-deck trains fit in the UK?

The simple answer is – they can’t as things stand. The UK loading gauge on most routes simply precludes their use.  But this is not just the height of trains we’re talking about – it’s the length of the vehicles too. Let’s delve into a bit of history. When our Victorian network was built the railways ran short (30ft long) 4-wheel coaches. In fact, these were still being built right up to the end of the Victorian era. What this meant was the railways could get away with some tightly curved platforms and tracks as the coaches could fit around them.

DG07795. 455837.Clapham Jn. 4.10.06.

The picture above shows Clapham Junction now with a train of 19.83m long class 455 vehicles in platforms with a pretty fierce reverse curve. Fancy trying to fit longer vehicles in here without the horrendous rebuilding costs & disruption to the UK’s busiest station that would entail?

Gradually (to improve comfort & with the invention of the bogie) coaches got longer & some doubled in size to reach 60-62 foot long. The issue with this is (and always was) the overhang of the coaches on curves which governs how tight platforms & other infrastructure can be. For many years British Rail standardised on coaches that were 57 ft 0 in (17.37 m) or 63 ft 6 in (19.35 m). Eventually the Intercity fleet standardised on 23m long vehicles whilst commuter and local services used 20m long vehicles as the maximum that could fit many tight platforms.

Why does this matter to double deck trains? Simple – because of the amount of room taken up by stairwells. Here’s a few examples.

DG124463. Interior. DPZ push-pull set. Innotrans 2012. Berlin. Germany. 19.9.12

DG124472. Interior. DPZ push-pull set. Innotrans 2012. Berlin. Germany. 19.9.12

FDG06906. 8652. Stairs. Amsterdam. Holland. 1.5.08

There’s no benefit on capacity of a double-deck 20m vehicle as the stairwells at either end take up so much room it cancels out the seats provided on the upper deck. A 23m vehicle will give you around 12-13% extra capacity. It’s only when you get into longer vehicle lengths that DD coaches make sense. But here’s the rub – those longer coaches won’t fit on much of the network. Not only that, but they would even be restricted on some lines they could because of the curvature on certain station platforms or tight curves where they’d foul adjacent lines. For example. SouthWest trains use 23m long Class 444s – but these are banned from platforms 1-4 at Waterloo, thus reducing the flexibility of the railway.

Oh, and don’t even ask how much headroom you might have on the top deck. Even in Europe this can be quite tight. With the UK’s restricted loading gauge you’d be lucky to be able to stand upright if you were above 5’6″- hardly good when the average height is 5’9″ & will only increase over the next few decades!

So, what seems a simple idea proves to be increasingly complex when you look at the details – something the anti hs2 mob never do anyway. Put simply, the capacity to be gained from double-deck trains doesn’t make up for either the cost of adapting the network to make them fit or the reduction in operational flexibility (and thus track capacity). What you gain on the swings you lose on the roundabouts.

You could add 12-13% capacity to coaches at great expense, but reduce the overall capacity of the railway and find your gain is even less. But how much time does that 13% buy you? At the current rate of growth it’s less than a couple of years on some routes. At best it might be a decade on others. But at what cost? In 2005 Stagecoach carried out a study into running DD trains & found just the short bit between Waterloo and Clapham Junction would have cost almost £1 billion to convert for full-scale double deck trains (The Times, June 2005)

Then what?

This is a serious ‘alternative’ to Hs2? Of course not. Hs2 is designed to take intercity trains off the classic network. DD trains don’t add any capacity to our lines, they simply allow a few more folks to get on existing services. besides, would you want to travel long-distance in one of these cramped vehicles?

It’s time the anti Hs2 mob stopped grasping at silly straws.