Slow recce executed, I drive again gingerly and take a U-turn. This then is ‘lap’ two of the but to be opened tunnel. I do know the circulation of corners, and I do know the place the development tools is tucked away, so this needs to be enjoyable.

Ahead of me on the down ramp, roughly three and a half kilometres of tunnel that stretches from Priyadarshini Park at Napean Sea Road all the way in which to Marine drive within the centre of Mumbai. On a day with dangerous visitors, you would simply save upwards of twenty minutes. Today, with nobody contained in the tunnel, it’s anyone’s guess.

Mumbai’s coastal street tunnels

To present simply how good the tunnel is, we now have the proper car for the job – the Lamborghini Huracan Evo Spyder. It will get a howling naturally aspirated V10 and a demonic exhaust observe, however the very best bit is that the roof comes off. Time to rattle my eardrums.

As I set off within the route of Marine Drive, with Napean Sea street behind me, the street begins diving down. This is obvious to see initially, with the ocean to my proper and the encompassing infrastructure for reference. Once I descend just a few 100 metres into the tunnel, nevertheless, all references disappear, after which I can’t actually inform how steeply I’m descending.

This tunnel isn’t only a straight, it twists, turns, rises and falls.

The tunnel then begins turning left. And retains turning. What follows is a protracted, tightening 90 diploma nook with an fascinating financial institution angle. Since the development tools has thinned out, I choose Sport on the steering wheel, and this instantly bumps up the quantity of the exhaust. Wowie! The piercing howl is simply mad. No time to benefit from the exhaust now as I begin including increasingly energy. Despite the dusty situations, the low-slung Huracan has a lot grip and poise, it comfortably hooks across the nook; the tremendous weight distribution and the large rubber offering hundreds and a great deal of grip. I do get a little bit of a wiggle as I put my foot down on the exit, however that solely provides to the joy and the drama. One factor’s for certain, this lengthy left is a troublesome nook; so give it some respect.

India’s first undersea tunnels additionally move straight below a number of the nation’s most costly actual property. This is one thing I’m conscious about as we rocket alongside; there’s no manner you would have constructed an elevated street or reduce a path straight by way of right here with out huge disruption and delay.

All ideas of actual property costs quickly dissolve. Even although I put my foot down progressively on the organ pedal like-accelerator, the tunnel begins to blur on the edges in an ideal circle. Whoa! And then the constant and exhausting push within the again blends with the howling exhaust to ship one hell of a journey.

Will Mumbai drivers have the ability to chorus?

The headiest bit, after all, is the sound. It will get so amplified by the tubular form of the tunnel that it seems like I’m driving an overdriven electrical guitar with the distortion pedal flattened. And are you able to think about the wall of sound following the Lambo, and the way it dips and rises with each flex of my proper foot?

There’s no getting away from it, the bark and indignant snarl of the Lambo V10 simply must be one of many all time nice exhaust notes.Very totally different from a V8 or a howling and trumpeting V12, it’s indignant, pressing and stuffed with midrange maintain. And this tunnel is simply making it infinitely louder and higher. 

The lengthy straight lastly goes all the way down to the bottom level. I solely know this as a result of this spot is now acquainted to me. At its deepest level, the tunnel is round 20 metres under imply sea degree; think about that. As we start to climb again up, I get one other lengthy and empty stretch on which I can train the Huracan, and now I’m even tougher on the throttle, the howling exhaust observe thick sufficient to chop with a knife. 

Then up within the distance I see what appears like daylight. I look at my watch; it’s hardly been two minutes. This feels surreal; how I will be in two components of the town at virtually the identical time? Apparently I can. Then the round part, the one reduce out by the tunnel boring machine (TBM) runs out, and we’re again onto the cut-and-cover rectangular part; the on and off ramp of the tunnel. Time to decelerate once more as I come as much as some development tools. We should now be straight under Chowpatty seaside and up forward we rise to fulfill Marine Drive, proper within the coronary heart of the town.

The Tunnel Boring Machine turns across the middle level when it digs and gouges out an ideal circle.

While solely one of many twin tunnels has been accomplished – the southbound one – work on the opposite is progressing quick. Each 11 metre-wide tunnel can have one emergency, and two common lanes. There are 11 cross passages for security between the dual tunnels, and a primary for India is the jet engine-like Saccardo system of air flow. Another India-first are protecting fireproof panels made from calcium silicate; in case of a hearth, there’s additionally a water pumping station each 100 metres. A deep sump and excessive energy pumps additionally assist in pushing rainwater again out, ought to some enter from both finish regardless of the large cross drains and polycarbonate roof.

It feels surreal being in two locations within the metropolis at virtually the identical time.

The largest problem, nevertheless, was stopping the ingestion of sea water whereas the tunnel was being dug below the ocean by the TBM. We requested Dr Cho (see under) and the method he described to us was fascinating. 

Come to consider it, what an formidable mission; by way of a mountain, below the ocean after which again up once more. Make certain you drive by way of the BMC’s engineering marvel the following time you’re on the town. And think about what the whole stretch of the coastal street can be like  and the large chunk of time it would save as soon as it’s absolutely open. And that’s even in case you are not in a Lamborghini.

Q&A with Dr Namkak Cho, Tunnel professional from M/S Yooshin Engg Korea

What was the most important problem with this mission? 

Building it below the ocean, after all. We needed to be cautious to not let sea water in. Because as soon as it begins coming into the tunnel whereas we’re digging it with the Tunnel Boring Machine (TBM), there may be mainly an infinite provide. So what we used is a TBM that excavates in what is known as a closed mode. Here, excessive stress slurry is used to counter pressurise the ocean water that in any other case would have are available, and push it again. Secondly, as we’re constructing the tunnel with segmentary lining, we used cement grouting to fill the gaps within the phase below stress. On prime of this we now have put in water tight gaskets over every phase. 

This tunnel additionally used a brand new age air flow system.

The Saccardo air flow system used right here for the primary time works like a jet engine. It has pairs of inlet and injection nozzles at each ends of the tunnel from the place pressurised air is pushed into the tubular tunnel. Suction through an identical system takes place on the different finish. This permits for a very good circulation of air, which, in case of a hearth, will be actively used to push the smoke out. The circulation of air may also be reversed if wanted.

How is the tunnel safeguarded from flooding?

When it involves ingress of rain water, the essential precept is that water shouldn’t get into the tunnel. This is the rationale each side are coated with a polycarbonate roofing. Any giant quantity of water that tries to get in through the street floor can also be stopped by the big cross drains which might be positioned at each side. However, if some water does get in, we now have giant ‘V’ formed drains that run alongside the perimeters of the size of the tunnel that drain into an enormous sump on the centre. Should water get in anyway, there are a number of giant capability pumps that assist drain the construct up.

Also see: 

Howling by way of the Mumbai Coastal Road Tunnel in a Lamborghini Huracan Video

Driving on Mumbai Trans Harbour Link video