Having entered through a slot in the roof, the endless rope was wrapped three times around the driving wheel, 20 feet in diameter, and an associated pulley before entering a chamber housing the tensioning system. This incorporated a wheel mounted on a carriage which was drawn back along rails by a weight suspended in a well. Problems with this mechanism prompted the sinking of a second well – 30 feet further back – two years after the line opened. The rope then entered the sheave room where it encountered the return wheel. Coal for the boiler arrived by barge and was brought from the canalside on a tramway, through a short tunnel which entered the coal store – parallel to the tensioning room – at springing level. The tramway continued forward on cast iron beams, allowing the coal to be dropped into compartments below. Beyond the coal store’s north-east corner was an open- topped pit containing a pair of marine boilers, used to raise steam for the engines at a pressure of just 41⁄2lb/inch2. Perhaps unsurprisingly, this proved insufficient and a second pair was installed in a vacant boiler pit on the opposite side of the railway in 1838. The vaults are symmetrical around a central passageway, but the other half – intended for use by the Great Western Railway – remained largely unused, the GW belatedly choosing to adopt an independent route into Paddington having failed to negotiate suitable leasing arrangements for a shared terminus at Euston. High water mark As trains became longer, to deal with growing traffic levels, the need to divide them for haulage up the incline created an operational bottleneck. And so, in July 1844, rope gave way to banked steam locomotives for outbound journeys, although gravity working continued for services into the capital for another 13 years. Having succumbed to redundancy, the winding equipment at Camden was auctioned in 1847, the engines finding their way to a flax mill and Russian silver mine. Londoners were doubtless glad to see the chimneys dismantled, having contributed briefly to the city’s chronic pollution. In the mid-1850s, a tunnel was driven across the southern end of the vaults to connect the adjacent goods station – where horse power was prevalent – with stables on the opposite side of the railway. No plans have been found detailing the arrangements Stephenson made for draining the vaults – whether a gravity system or continuous pumping – but it’s fair to presume he focussed much attention on the matter, as he had elsewhere. What’s certain, however, is that abandonment brought the problem of flooding, one which has persisted to this day. Typically the depth of water reaches four metres. Tracks A, B, C, D, X and E: if you ever pass through Camden over one of these lines, the vaults will be playing a critical supporting role, with just 1.5 metres between soffit and sleeper. You’ll understand, then, why British Rail instigated a visual examination regime in the late 1980s, involving a complete dewatering every three years. When this was last done, by AMCO Rail in 2014, it took a fortnight to discharge the floodwater into the disused Up Empty Carriage Tunnel which was pushed beneath the vaults in 1922. Within six weeks, the water had returned to its previous level. Checks and balances Whilst visual exams continue to provide reassurance that the vaults’ condition remains fundamentally fair, there is a recognition, from an asset management perspective, that detailed examinations need to be introduced. To that end, a team from Network Rail LNW Civils Special Projects arrived on site in February, its remit being to clear the vaults completely before putting in place permanent lighting and pumps. Benefiting the team is a pre-existing compound 300 metres to the north. From the outset, the vaults were deemed a confined space due to the potential for toxic gas pockets and uncharted wells. Bridgeway Consulting was commissioned to report on the likely risks and implement appropriate safety measures, specifically a rescue team, signing-in point, periodic radio checks, gas monitoring and an extraction fan to deal with plant fumes. All members of the workforce undertook CS1 (confined space awareness) training for self-rescue purposes. Around a dozen men laboured underground at the height of the works, enduring conditions which might charitably be described as “unpleasant”. Three two-inch sump pumps were deployed to remove 8,000 cubic metres of water. This was done slowly – over three weeks – to prevent any damage to the sidewalls caused by a sudden loading imbalance. Thereafter, scaffolders erected a Haki stair tower in the east-side boiler pit to serve as the main manpower access. A second one was installed at the south end of the coal store, creating an exit route to the canal towpath. Left behind after dewatering was silt; lots of it. Working adjacent to the running lines and overhead line equipment, Readypower supplied a long-reach telehandler with electronic boom and slew restrictor to lower a micro-excavator and dumper into the vaults via the boiler pit. Tonne-bags were loaded and lifted out, to be stockpiled thereafter in the compound prior to despatch. In places, the silt was over two metres deep and heavily contaminated. With 600 tonnes removed, what remained was effectively a thick soup, for which the excavator proved unsuitable. Attempts to use a jet-vac resulted in its filters getting clogged with small pieces of detritus, so attention turned to a super-absorbent hydrogel – supplied by Siltbusters – which solidified it sufficiently for digging out as a bulk material. Throughout the vaults, narrow ventilation shafts are apparent in the roof. For the most part, these are capped – buried below the railway – and one of the project’s key objectives was to determine their surface location. This was done by recording GPS coordinates which were then mapped across the railway during Saturday night possessions. Several were found in the Up cess, allowing the concrete capping slabs to be replaced with GRP catchpits. This has helped to moderate the water ingress and bring in some welcome natural light. Interest rekindled Now Grade II* listed, Camden’s winding vaults form part of the area’s rich historical landscape, alongside the portals of Primrose Hill Tunnel, the former horse hospital and Roundhouse. Not surprisingly then, considerable local interest exists in securing the vaults for public use, combining a heritage centre and restaurants with exhibition and performance space. The idea is gaining traction, with all the right people making all the right noises. Not to be underestimated, though, are the huge financial and technical implications. And then there’s HS2. Current plans propose a twin- bore tunnel passing 18 metres below the western edge of the vaults, bringing with it a need to fully understand their layout, including the wells. Also, the intention to create a road-rail access point here requires a determination of the vaults’ loading capacity. To address these issues, an early task, once the silt clearance is concluded, will be to progress a 3D laser scan and full structural survey, the brickwork first having been jet- washed to reveal any defects. High-speed rail will open another chapter in the metamorphic story of Euston station. When its first train departed in 1837, there was no standard time: the capital’s clocks were set 7 minutes 15 seconds ahead of those in Birmingham. Soon, just 49 minutes will separate the two cities, such is the transformational impact railways still have two centuries later. And a fitting accompaniment to HS2’s arrival would be the re- emergence of Camden’s vaults, celebrating a historical role that was no less revolutionary. Written by Graeme Bickerdike. Photography: Four by Three.