Repairing the 'M6 of the waterways'
More than 80m underneath Dudley town centre, a major engineering feat is taking place.
In a long and partially dark tunnel, a team of 15 men is working around the clock to repair a 50m section of Netherton tunnel which arches over what has been described as "the M6 of canals".
The two-way canal was built in 1858 to relieve the congestion on the adjacent Dudley tunnel where barges and boats had a wait of several days at times.
It was historically a busy route between the northern and southern Birmingham canal navigations, the Canal & River Trust said.
Cycle to toilet
But, more than 150 years later, the epic Victorian-era engineering work - which stretches for 1.7 miles (2.7km) - is in danger of collapsing unless major repairs are urgently carried out.
However, the logistics of carrying out the £1.5m repairs had to be established first.
A floating platform has been set up underneath the area that needs maintaining which now houses a small digger and other heavy duty equipment.
It was eventually towed into place after being brought in via the other end of the tunnel after the canal narrowed slightly at one point, wedging it solid.
All the other equipment has to be brought in via boat - buckets of liquid concrete to be sprayed onto brickwork, huge bolts to secure the walls, wiring and tools and, crucially, a generator to provide lighting.
Workers use mountain bikes to get out of the complex if they need to use the toilet or when they go for lunch.
Holes have been drilled in the walls and steel tubes slotted in which are then filled with concrete.
'Brickwork very good'
Once the repairs have been made, the tunnel will be reinforced with a new arch to stabilize the centre section.
The project, which started in November after cracks and bulging bricks were recorded in 2011, is expected to be finished before Easter, said engineering manager John Ward.
"We're 80m underneath Dudley town centre and that's pushing down and walls are pushing in and the bed which is very flat is being pushed up," he said.
"We've had to anchor bolts 5-6m (16ft) into the rock to hold the walls in place and concrete is being sprayed on as part of the repairs.
"Surveys have been done to see where the hotspots are. We accept there will be more work to do in the future but, the brickwork is very good considering it's 150-odd years old."
Built using picks and shovels, it took more than two years to complete the tunnel but nine workers lost their lives and 18 others were seriously injured.
Project manager Lawrence Tall said even today the speed at which the canal tunnel was completed could not be beaten or even matched.
"The conditions the men worked in would mean restrictions today, it just wouldn't happen, it would take longer.
"We also don't have the skills any more I don't think.
"Remember, they were used to doing this all the time and the skills were passed on through families and that's not the case now."
He said that in its heyday, the canal would have been "choc full" of boats and horses.
"It would have been really busy - the M6 of the canals back then - which was around the 1850s.
"It was the last to be built during the canal age and built to cope with the demand on the other canal running parallel to this.
"The work the Victorians did here is very good, almost mint condition."
George Ballinger, from the Canal & River Trust, said: "We have been keeping a close eye on Netherton tunnel for some time and have carried out various repairs over the years, the last being in the early 1980s.
"The centre section of tunnel that will be repaired over the weeks ahead has really got us concerned and, ultimately, if we did nothing the tunnel could collapse.
"The works being carried out will help prevent any further movement of the centre section, giving it strength and support for generations to come."