Bridge vs tunnel?

[Lecom]

Originally Posted by HooverDam

Ill take bridges in the situation you're talking about. For pedestrians hover I prefer tunnels. Here in Phoenix we have this small tunnel:



for pedestrians thats at a midblock point connecting to shopping areas on either side of a busy street that pedestrians used to try to cross w/ out a crosswalk, which was dangerous. Ped bridges often have to have huge ramps, really high stair cases to clear the height of traffic and because of that don't get used that much.

So long post short: For pedestrians, in small spaces: tunnels. To cross rivers or harbors: bridges.

Mosaics in underground pedestrian passages in Rostov-na-Donu, Russia, made during the Soviet times

[MolsonExport]

I hate tunnels, I GET SICK EVERY TIME I CROSS one, and , i love bridges. They vare beautifull in every single way. It's lovely to pass though them, it's lovely to see them, and they are really good as wallpapers. Plus, the bridge is much safer than a tunnel.

Most people pass through tunnels and cross bridges, but you seem to do things differently.

[yarabundi]

Originally Posted by HooverDam

Ill take bridges in the situation you're talking about. For pedestrians hover I prefer tunnels. Here in Phoenix we have this small tunnel:



for pedestrians thats at a midblock point connecting to shopping areas on either side of a busy street that pedestrians used to try to cross w/ out a crosswalk, which was dangerous. Ped bridges often have to have huge ramps, really high stair cases to clear the height of traffic and because of that don't get used that much.

So long post short: For pedestrians, in small spaces: tunnels. To cross rivers or harbors: bridges.

We have 15km of these pedestrian underground tunnels connecting more than 60 buildings in downtown Montréal -including universities, public libraries, dozen of office towers, hotels, shopping malls, trains stations, bus stations as well as Montréal's convention Center and even the Mecca of hockey namely the Bell Center. In most cases, these tunnels are providing commercial spaces for retails store -so there are about 1,500 retails stores connected to these tunnels or along these tunnels.

So, in any downtown core, I really thing that they are more convenient than pedestrian overpasses, less intrusive (they are no eyesore). Hundreds of thousands people used them every day in Montréal.

[M II A II R II K]

Those old school skywalk pedestrian bridges between skyscrapers would have been cool.

[M II A II R II K]

There's the case of the Confederation Bridge connecting to PEI. The supports have to be specifically designed to cause slabs of ice to break up as they move through them. A tunnel would have avoided it but if a way to make a bridge work over a long and cold distance it may very well work out cheaper.

There are also new experimental options like tube tunnels immersed in the water that are tethered to the bottom that could work out to be a feasible option since it wouldn't involve digging through too much dirt.

[Roadcruiser1]

Here is my idea why, and which one is better

Tunnels

Pros
-Requires less demolishing to make room for the approaches to the portals.
-Won't interrupt shipping traffic.
-Won't leave a giant mark over a waterway.
-Requires a massive amount of engineering creating more jobs.
-Won't be interrupted by weather related problems.

Cons
-Traveling in a tunnel won't provide good views.
-The price per mile for a tunnel is staggeringly expensive.
-The massive amount of engineering would require more money for labor.
-If possible it could disturb underwater life during construction.
-If it was imploded with a big enough explosion water could get in killing everyone.

Bridges

Pros
-Cheap labor, and cheap construction cost.
-Provides excellent views.
-Can be modified to handle rail traffic. Vehicle tunnels can't.
-Massive landmark.
-Can carry pedestrian, and bike traffic unlike a vehicle tunnel.

Cons
-Could be very ugly looking creating a giant scar.
-Approaches can be steep requiring demolishing of multiple properties.
-Takes up a lot of land.
-Blocks ship traffic.
-Affected by weather related conditions.

If it were me though I would still go with bridges, because bridges like suspension bridges are often extremely beautiful.

[IMADreamer]

Aside from the obvious stuff stated over and over I've always preferred bridges. I like how they become signatures of towns and cities and in places like St. Louis where you are crossing the river and you've got the Arch, stadium, and other buildings right there it's pretty cool and you get a nice long look at it. On my trip to NYC we took the tunnel in from NJ and you just kind of arrive in a mass of buildings in Manhattan and that's it. Very uneventful.

I will say also that St. Louis is missing a huge oppertunity for a signature bridge with the new I70 bridge. The original design was something fantastic, the final design is just a run of the mill cable stayed bridge. blah.

As a car guy I do enjoy a nice tunnel for a quick blast through a few gears with the windows down. There is no better sound then a good sounding engine in a tunnel.