By kind permission of Network Rail, I was given the chance to go inside the Severn Tunnel and view the electrification works at first hand today.
The whole operation, and that of the works at the nearby Patchway Tunnels, is being masterminded from a temporary headquarters in a series of portable buildings on the edge of Filton airfield.
It was actually my second visit to the tunnel. The first was in 1986 for the centenary and the safety culture has certainly changed since. Back then it was a question of parking at the access point, please don't wear open-toed shoes and that was about it. For today's visit a medical questionnaire needed to be returned 72 hours beforehand followed by the issue of full safety kit on the day and a half hour briefing at Filton before setting off to the access point. There is a strictly enforced 5mph speed limit throughout the compound at Filton and as you'd expect everyone has to sign in. It is not just for security but also as a physical check that workers are fit for duty and are even quizzed on where they are going on departure so travelling time is monitored to prevent fatigue.
I should offer my excuses for any less than perfect shots from inside the tunnel. It is not the easiest place to take photos hand-held without using flash.
We started from the English end and rode into the tunnel on the back of a Road/Rail Vehicle.
It is well known the tunnel suffers from water ingress and although there were occasional drips from the tunnel roof I was surprised how dry the tracks were - even if the walls were a little damp! 50 million litres are pumped everyday from the tunnel into the River Severn (so it can come back in the next day). That's around 20 Olympic swimming pools.
We travelled about two miles into the tunnel - nearly halfway - and caught up with a party working on the new overhead
From the English end the overhead on the down line looked complete from the portal to the midpoint with work progressing well on the up.
As has been discussed before the overhead consists of a solid conductor rail rather than a wire to combat problems with the damp.
You could also see the preparatory work for the overhead to be installed on the up line.
Kitted out in a full orange army outfit meant it actually felt quite pleasant in the tunnel with the lower temperatures and a breeze running through from the Welsh end.
There were four gangs working in the tunnel today. There are three shifts a day seven days a week as work which would otherwise take five years if it was done at night and weekends continues for just under another three weeks.
We reached the point where the tunnel levels out for a short while before climbing to the Welsh end. The two blue lights on the walls indicate the end of the descent for drivers.
It was a fascinating insight into the project which has clearly been meticulously planned, as you would expect, but has also enthused the workforce who without exception were keen to talk about their role and their satisfaction in getting it done safely and on time.
