How does a tunnel NOT fill with water? Are there huge pumps working full-time?

Question

Imagine when it rains. Or if the tunnel is below the water level (of a nearby river or lake, or the sea). How?

Answer 1

When it rains, som ewater does indeed flow down the roadway and into the tunnel.  Tunnels, by their nature, usually are below the grade of teh road leading into them, unless you are talking those that pass straight through a moutain or other obstruction.

Drainage systems are in place in tunnels.  Next time you drive through one take note, you will see storm drain grates along the road just as in a topside road.  Difference is thatthere will be a puming system to bring the water up, out and into a standard storm drain system.

Water from the river a tunnel passes thru doen not require pumps to keep it out.  Tunnels are generally water proof for the most part, and the open ends of the tunnels are above the water level.

Answer 2

The only way water could get in is if the walls or ceiling of the tunnel were leaking.

Rain? how could rain get in?

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edit: "obviously, i'm asking about the drainage system...

drainage pipes fill with water when it rains. why not tunnels (like the chunnel)? its the same.."

It's not the same, obviously.

Well, which are you asking about, drainage systems or a tunnel?

Drainage systems fill with water, because they are designed for it. There are many smaller pipes that take water from many street drains, all funneling water into the larger pipe.

Tunnels are not made to be drainage pipes. Street drains do NOT funnel water into them.  For the last time, how do you think water would get into them? It doesn't.

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Answer 3

A great deal of effort is expended to seal the tunnel walls so that water does not infiltrate.

The small amout that does is routed to sumps which are pumped out.

Answer 4

Hey they got this invention called concrete ever heard of it?

Answer 5

Everything that is possible is done to divert rainwater from entering, but pumps are required also. The pumps are not necessarily huge and they don't necessarily work full time. Water is allowed to accumulate in a sump that is a little lower than the lowest point that needs to be kept dry. When the water rises in the sump, a float switch turns on the pump.

Answer 6

Well obviously they have drainage systems for such things I'm studying Engineering at the moment and I probably wont do anything on tunnels until later on this semester in Highway Engineering.