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Network Rail has finally twigged that while SSI has the drawback of being British it has two unique selling point – it works and doesn't cost the earth
For this column the British Rail Research developed Solid State Interlocking(SSI) is up there with the Pandrol clip, the Mk3 coach and the APTIS ticketing machine. In other words, heritage kit so far ahead of the game when it was launched that replacement is very difficult. Cost effective replacement is very difficult indeed
Of course after April 1994, the view in Railtrack was that SSI was yesterday's technology and that those still making the kit were dead in the water. But 10 years on it looks as though Network Rail will be ordering the latest versions of SSI. And that's before Westinghouse and Alstom unleash their new generation CBIs which feature SSI software ported across onto modern safety crucial processors.
For this news I am indebted to Network Rail Chief Executive John Armitt who told the Annual Dinner of the Institution of Railway Signal Engineers on 25 April that SSI was now the competition which CBIs had to beat. And on the CBI approval front there is good news, not so good news and bad news. Cost effectiveness is something else.
Let me be equally clear that at today's estimates we cannot afford CBI. The benefits are not yet clear, delivery so far has been poor. If the whole signalling community cannot find solutions for CBI in the UK at SSI prices, we will ask the question ‘why go that route'? John Armitt 25 April 2003 |
So, the good news is that my chums at Atkins finally got acceptance through for the Ansaldo ACC CBI and Stage A of Manchester South was at last commissioned over the weekend of 29-31 March. More of this in a future issue.
Not so good is the news from Siemens on the Dorset Coast resignalling. Back in mid-February I was invited down to see the installation and was told that a 52 hour possession had been booked for 10-12 May for the final commissioning.
However, this was dependent on the Application Safety Case, the final submission for the SIMIS-W interlocking, going through Infrastructure System Review Panel (ISRP) on 14 April. A week before the visit the ISRP had granted cross-acceptance for SIMIS-W, the VICOS operating system and the AzSM(E) axle counters.
This meant was that vital safety was cleared, leaving the adaptation of the software to UK signalling principals. It is this ‘cultural' transfer that has caused much of the delay to the various CBIs.
I was out of the country on 14 April, so when I got back I checked with Siemens for news of how they had got on and the news was that while some safety case submissions had been made and accepted, some had not been completed in time. So the not so good news is that Siemens is currently putting together a revised schedule with Railtrack and reviewing possible possession dates.
Seeing SIMIS-W installed on site was a real eye opener. In particular, all the trackside kit is hardwired back to the containerised interlocking though multi core cables.
In contrast, SSI talks to trackside modules through data links. I recall that in a paper to the IRSE in 1996 Railtrack's then Engineering Director claimed that one of the ‘considerable benefits' of SSI was the replacement of multi-core cables by trackside data links. This provided ‘significant first cost saving and continued benefit in cable testing and repair'.
So what did Railtrack do under the same Director? Give Siemens a contract for a pilot CBI which relied on – er, multi-core cables. As Informed Sources First Law states, never assume railways are rational organisations.
SIMIS-W is a derivative of the SIMIS C developed in the early 1980s – contemporaneous with SSI. Its primary role was signalling complex layouts at large stations, As a result SIMIS-W is ideal for ‘short and fat' schemes. Currently Siemens is engaged on a pre-feasibility study for resignalling 2km of Glasgow Central – an ideal application.
This optimisation for ‘short and fat' explains the hardwiring back to the interlocking – which comes ready wired and tested in a containerised housing ready for connecting to all those multi-core cables. Of course, Network Rail insisted on the pre-tested kit being re-tested again on site.
Hardwiring also means that you can drive point machines and signal heads directly by ac power supply switched in the interlocking cubicle. Once again, a handy feature in ‘short and fat' schemes.
But UK signalling uses dc power. At Bournemouth this means having interface cubicles, with more wiring, transformers and circuit boards, at lineside locations. You can see a good example of this at the country end of Bournemouth station.
Another aspect of hard wiring, as opposed to data links, is the physical constraint imposed by a maximum cable run of 6.5km. As a result SIMIS-W requires an interlocking cubicle every 13km, which on a long and thin scheme makes serving a small number of automatic signals expensive.
Of course, the hard-wiring vs data link argument is not one sided. Data links don't like lightning strikes, one of which nearly wrecked that famous 3hr 29min London-Edinburgh record run on the ECML in another life. And the bits and bytes can occasionally get confused – especially if a Pendolino is cranking on the megawatts.
But Dorset coast, or as one wit remarked apropos its truncation from the 50 route miles between Brockenhurst and Weymouth to the 16 miles of New Milton to Branksome, Bournemouth sea front, was still an eccentric choice for a SIMIS-W pilot.
Still, JFDI, as the safety case team at Siemens mutter through gritted teeth. And at least they know where they are going.
Which brings us to the bad news. Back in August 2001 I was invited to unveil Bombardier's first operational Ebilock CBI which was running in shadow mode on the third of the pilot schemes at Horsham (photo Modern Railways September 2001).
Talk about the curse of Modern Railways. Nearly two years on and according to informed sources Horsham commissioning is still up to a year away. And, of course the plans to use Ebilock for Thameslink 2000 were dropped before the project ran into the Transport & Works Act treacle.
In his speech John Armitt identified West Anglia route Modernisation (WARM) as a success. He also said that recovering confidence in the railways would require ‘a willingness to be open to different but tried and successful ideas'. Could SSI and IECC be making a comeback?