Inside Thanet tunnel's construction works

Earlier this month it was reported the tunnel would have to stay partially closed until the end of October.   Finn Macdiarmid reports.

Transcript

00:00The infamous A299's tunnel contraflow system is going to be lifted this month, after being

00:05extended to the end of October, which the public weren't pleased with.

00:09The engineers and officials tell us they can reopen the tunnel fully once the fans are

00:13refurbished.

00:14In June it closed the London bound side around the clock, forcing cars through a single lane

00:18each and putting a 40mph restriction on the tunnel after an issue with the jet fans was

00:22discovered during an inspection.

00:25The original plan to replace the fans was said to take three months, but after realising

00:29this would need an entire reconstruction and redesign, meaning the contraflow would

00:33last up to 12 months, they then decided to refurbish the existing fans, leading to the

00:37end date of October.

00:39There are not many places that you can get fans, you can't walk into a DIY store, these

00:44are incredibly large bits of equipment, the decision was then made actually, having looked

00:50at it, having got the consultants in and seeing what could be done, if we were to get a brand

00:53new set of kit in, up to modern regulations, that would involve having the contraflow in

00:58place for a significantly longer amount of period, perhaps 18 months, perhaps longer,

01:03whereas the decision was made actually by a lot of the hard work of the crews here and

01:07the team.

01:08Now there's 32 fans in total in this tunnel, 16 either side, and they take 17,500 watts

01:15to power.

01:16That's roughly equivalent to the daily power it takes for an average household in the UK.

01:21So getting them replaced or refurbished is no small feat.

01:24The fans are two metres long, and they're there primarily for safety, able to push smoke

01:29out in the event of a fire, and on a day-to-day basis, they keep the air clear.

01:33While the tunnels have more fans than they actually need, it's part of their many safety

01:37practices they comply with.

01:38So whilst there are 16 fans in both bores, so there's 32 overall, we can operate the

01:45tunnel safely and meet that best practice with 14.

01:48That means that if we do have a failure, we don't have to shut the road, we don't have

01:52to put the contraflow on, we can operate the spare fans, so to speak, to achieve the

01:57same end and move the air, move the smoke, and allow access.

02:01While the tunnel used to be at the national speed limit of 70, evidence has come to show

02:05that won't be safe, leading them to keep the 40mph limit even after the contraflow

02:10is finished.

02:11The efforts of the engineers aren't all just to keep up, however.

02:15They have their sights set on installing a new ventilation system that can last the next

02:1825 years, and they say the refurbished fans will give them the time to properly implement

02:23this change.

02:24Finn McDermid for KMTV in Chestfield.