Kilsby tunnel work planned in 10 days!

While many companies were forced to shut down during while Coronavirus (COVID-19) was at its peak, the railways kept on running, transporting freight and key workers around the country.

Not only that, engineers also had the chance to catch up with some work that had otherwise been deemed too difficult, as it would disrupt traffic too much.

A prime example is Kilsby tunnel, a 1.4-mile-long tunnel which was built in 1838 and is on the West Coast main line, about five miles southeast of Rugby station, near Daventry.

The drainage system in the tunnel had broken down, a victim of a combination of neglect in the past (as access was difficult) and the heavily limed water that seeped in and clogged up the drains. It also clogged up the ballast, calcifying it into large lumps instead of individual stones and affecting track quality and ride comfort.  As a result, the linespeed had been ‘temporarily’ reduced from 110mph to 70mph.

This reduction in linespeed also delayed Avanti West Coast’s high-speed services between the North and London (and previously Virgin Trains’ services ) – not by much but, when you consider that 292 Avanti trains pass through the tunnel every normal weekday, that adds up to about 82 minutes each day. As the infrastructure owner, causing those delays was costing Network Rail a lot in compensation – around £5 million a year.

So, with a reduced timetable operating due to Covid-19, and those trains that were running only carrying about five per cent of their normal passengers, NOW was a good time to sort out Kilsby tunnel. However, nothing had been planned and major blockades take years to plan, don’t they?

Short notice

Not so! Phone calls between Network Rail and train operators, particularly Avanti West Coast, and to framework contractor the Central Rail Systems Alliance (CRSA – 80% Balfour Beatty, 10% Atkins, 10% TSO), had the whole thing planned in an unprecedented ten days!

Avanti agreed to send all of its passenger trains via Northampton for two weeks, avoiding Kilsby tunnel. This would add about 15 minutes to each journey, but that could be lived with to get the speed restriction through the tunnel lifted.

As part of that planning process, Network Rail, contractors and subcontractors did a walk-through of the tunnel over one weekend, to see how the land lay. By the following weekend, the work had started.

A blockade of the railway was taken, between Hanslope and Hillmorton junction, for two weeks from Sunday 3 May until Saturday 16 May 2020.

Simon Clare, renewals manager at Balfour Beatty for the Central Rail Systems Alliance, explained: “The challenge was to renew the six-foot drainage and the Down and Up main lines in the southern section of the tunnel (around 850 metres in total) and remove the long-term COT (condition of track) speed restriction.”

Despite the short notice, the CRSA mobilised its supply chain. 18 train movements were scheduled, including the Balfour Beatty drain train (twice), an RDT and 15 engineering trains.  Four tampers were deployed, 69 RRV (road-rail vehicle) shifts and over 24,000 staff hours, working round the clock to complete the work. 

“The major issue in the tunnel was removing the existing failed drainage system, although nobody seemed to know exactly what was in there,” Simon Clare continued. “What we found we were removing was large (2 metres in length by 600mm wide by 1 metre deep) re-enforced concrete sections of drain that, in places, had a 30mm concrete pour over the top, making removal even harder.

“In total, the removal of the existing drain took around 56 hours – 26 hours longer than originally planned. However, due to the flexibility of our colleagues and partners in the work, we were able to remove pre-planned 12-hour ‘fire breaks’ in the job through the other three phases to enable the full work scope to be completed on time, accident and incident free.”

In total, CRSA and its contractors installed 3,056 metres of new rail, 2,548 new concrete sleepers, 5,700 tonnes of new ballast, 1,080 tonnes of pea gravel, 745 metres of new drainage pipe, and 13 new catch pits.

As a result, at the end of the two-week blockade, the railway opened up on Sunday 17 June at 60mph. More tamping overnight improved the linespeed to a temporary speed restriction (TSR) of 90mph for Monday morning. Two weeks later, it was back up to the full design speed of 110mph. It was a great result and just showed what could be done if everyone put their mind to it.

“The job was a major achievement for my team, particularly with the extremely short and unprecedented time we had to put this together,” Simon Clare concluded.  “Of course, it wasn’t just our team, the work from the wider Alliance and its partners including SCO (Network Rail Supply Chain Operations – trains and tampers), Atkins (design) and also the planning team (operations delivery managers) and all our wider supply chain meant we were good to go come Saturday 16th.”

Additional maintenance

While the railway was closed from Milton Keynes to Rugby, Network Rail’s maintenance teams took full advantage of their opportunity and carried out 250 other jobs, large and small. These included:

• Replacing and maintaining signalling cabling and equipment;
• 3,450 metres of cable renewals;
• Inspection of nine miles of overhead lines, including nine wire runs;
• Replacing and welding rail;
• Renewals of six switch and crossing units;.
• Installing new railway sleepers;
• Improving 260 metres of trackside drainage;
• Inspecting 170 railway structures;
• Managing 17,000 square metres of overgrown lineside trees and plants;
• Stabilising a previous landslip site at Dodford using 820 tonnes of stone.

The whole exercise was a great success and shows just what the railway can achieve when it makes the effort and thinks ‘outside the box’.

James Dean, Network Rail’s director of the West Coast main line South, said: “Bringing Kilsby tunnel up to modern standards will make a huge difference for passenger and freight trains on the economically important West Coast main line.

“In normal times, it would have been impossible to close this entire section of railway for an upgrade of this scope and scale. I’d like to pay a huge credit to our train operators and industry colleagues for enabling us to carry out this work at short notice and get the railway in the best possible shape as the country recovers from the coronavirus pandemic.”

Gus Dunster, executive director of operations at Avanti West Coast, agreed: “We are pleased to have played an important role in giving Network Rail access to the railway between Rugby and Milton Keynes – a notoriously difficult section to maintain due to the number of trains that use it every day.

“This scale of work would usually take months of careful planning but, working together with industry colleagues, we were able to do this in a matter of days because of our reduced timetable and alliance with Network Rail. At the same time, we were able to protect our vital services for key workers, those making essential journeys and enable works to this treasured landmark to take place.

“It’s a great achievement in unprecedented circumstances and we would like to thank all of those involved for making this happen, and for the patience of everyone who has travelled with us over the last two weeks. The works will deliver a long-term benefit – improving reliability for millions of customers across the West Coast main line.”

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