Bridge vs tunnel?

[Amanita]

Here in Halifax, there's been talk of an eventual third harbour bridge. However, they're also talking about the possibility of a tunnel.

You can guess which I prefer- A suspension bridge across the mouth of the Halifax Harbour would be an amazing sight.

But which do you think is generally better? Bridge or Tunnel?

Like I said, I would choose the bridge. Why? For one thing, a good bridge can be a source of civic pride, an icon. Unless it's epic like the Chunnel, tunnels generally don't get such admiration. Lots of people love to drool and fawn over NYC's bridges, but I don't see so much love for the tunnels.
As Robert Moses once said, "Tunnels are vehicular bathrooms."

Also, for the same cost or in some cases less, a suspension bridge can carry more traffic. When studies for the Verrazano narrows bridge were done, they found that a double decked suspension bridge with 10-12 lanes could be built for the same cost as a two lane tunnel.

As far as I know, not only can the bridge carry more traffic, but if need be, its capacity can be expanded if needed. MacDonald Bridge here in town had a third lane added, George Washington Bridge was designed to have a second deck added when needed, and Verrazano was built with two decks from the get-go, with one being opened to traffic right away. The other deck was opened later when demand increased. And let's not forget 25 April Bridge in Lisbon, Portugal. She was designed as a single deck bridge, with the ability to be upgraded later to carry rail traffic if needed. This was eventually done, with other alterations that increased capacity even more.
Even though nothing ever came of it, there have been studies done concerning double-decking the Golden Gate, even.

Screw me if I'm wrong, but wouldn't a tunnel be harder to upgrade so effectively? Unless you wanted to dig a whole new tunnel, that is.

[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.

[The Chemist]

It really depends on the situation. Here in Shanghai there are a few major bridge crossings of the Huangpu River (all on freeway routes) but all major arterial road crossings of the river are tunnels. This is because the Huangpu is a major shipping artery and requires a lot of clearance below the deck (all bridges have decks at least 40m above water level) which is impractical for use on arterial roads, not to mention extremely expensive. Tunnels are much more practical in this case.

[philvia]

i prefer tunnels in most cases... they dont get any love and typically arent fun to drive through, but i like how they conceal the movements of large volumes of people from one place to the other. One great thing about the hudson river is that you cant see any physical link between jersey city and manhattan, but they coexist perfectly.

however, for smaller bodies of water or less dense areas, a small ornate bridge is more than enough.

[dchan]

Originally Posted by Amanita

Lots of people love to drool and fawn over NYC's bridges, but I don't see so much love for the tunnels.
As Robert Moses once said, "Tunnels are vehicular bathrooms."

These same people would no doubt be cursing the Brooklyn-Battery Bridge had it been built by Moses, since it would have destroyed the views of Lower Manhattan as well as Brooklyn Heights, Red Hook, and other neighborhoods. The point is bridges may be pretty, but unless they're designed in harmony with their environs, they're going to clash with their surroundings.

On the plus side, most bridges I've seen work naturally with their environment.

[Amanita]

Another thing I forgot to mention- terrorism and emergency situations. It's been said that a bomb going off on the deck of a bridge won't do a whole lot of damage- most of the blast goes up and into the air. That's why trucks are banned from the George Washington Bridge's lower deck, and several NYC bridges now have armour on the lower parts of their suspender ropes, where they are most vulnerable.

About working with the environment- can you imagine San Francisco without the Golden Gate?

I think that in some cases like the shanghai situation, tunnels work better. But for a large crossing like the mouth of Halifax Harbour, I'm still all for the bridge. Just as long as we make it beautiful, however. It seems that here in Halifax, the heritage groups get all up in arms over anything new and different.

I feel that the best suspension bridges are the ones which are not just functional, but also show signs that somebody tried for a little something more than pure functionality. Whether it's the art deco lines of the Golden Gate, or the sleek, graceful modern lines of the Verrazano, looks matter too. I feel that the entrance to our harbour deserves something beautiful, something that we can be proud of.

Look at this:
http://www.bridgemeister.com/pic.php?pid=1403
This bridge was only half the size of the ones we have here in Halifax right now, and in a remote part of El Salvador. But still, she was beautiful. A little gem of a bridge. If we ever do seek to span the Halifax Harbour again, I have but one request of the designers. Learn from little Cuscatlan Bridge's example, and make ours beautiful too. Halifax may not be New York or San Francisco. But surely we deserve a new icon to be proud of.

[hammersklavier]

In the situation you're talking about, definitely a bridge.

[ardecila]

I'm fine with a bridge, as long as they do something distinctive, unlike the two-tower cable-stay or truss bridges that seem to be all the rage these days. A true suspension bridge is pretty unusual to build these days, as is an arch bridge.

[hammersklavier]

The irony of that statement is that the true arch bridge is probably the most distinctive type available.

[theWatusi]

If the bridge is going over a body of water where large vessels navigate, the deck has to be high enough to accommodate. This leads to longer approaches on both sides and eats up more valuable real estate than a tunnel might. Also, structures could be built above the tunnel between the portal and the water itself.

So despite the higher cost, tunnels might be preferable in situations where land is scarce (like NYC)

[volguus zildrohar]

I tend to prefer bridges most of the time, particularly in scenic locales if designed correctly. They add another dimension to the landscape for people in the area that can't be appreciated otherwise, even from a tall building.

Tunnels, though, have a special feeling - first you're here and then you're there. It's like a trip through the rabbit hole - what's on the other side?

[tallboy66]

Detroit has a bridge and tunnel to Canada.
The tunnel is much more convenient if you're downtown but the bridge is so much cooler and the view
Plus I always got nervous sitting in traffic under ground and water and seeing the water run down the inside of it and the signs proclaiming fresh air exchange every 30 seconds or something like that.

[Alpha]

A tunnel is a good solution when a river or a strait is crossed on which large ships travel. Ships can be sometimes very high ( 50 metres and more) and realizing a bridge under which such high ships can pass requires long ramps, especially when the bridge should be passed by railways.
For rail connections a tunnel is always better than a suspension bridge as trains can bring such structures into oscillations. As trains can be propelled electrically, there is no larger exhaust problem in longer tunnels today.

A bridge is in most cases cheaper and easier to built than a tunnel. It can be also built wider. If the shores are mountainous, the ramp for a high bridge may be short or even obsolete. On a bridge, there is no exhaust problem as it is in the fresh air. Long tunnels used for car traffic require ventilation.
One disadvantage is however, that a bridge may be not usable at strong winds for empty trucks and other high cars.
Repairing a bridge after a heavy accident may be easier than repairing a flooded underwater tunnel, although I never heard that a tunnel got flooded as result of a disaster ( the only time I heard from such an event, was that a tunnel used for suburb trains in Berlin was blown up at the end of World War II, whereby many people were killed)
However a non-movable bridge brings always a height restriction on waterways.
Passengers and drivers however like more a bridge passage than a tunnel passage, as one sees more: the structure of the bridge and the view from the bridge. From a tunnel you see only the entrance and than the concrete tube!

[triny_groove]

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.


I love bridges. They are beautifull in every way, they are great to see, to drive on and to use as wallpaper! I hate tunnels, when I drive through them I get sick!

[gtbassett]

I was recently thinking about the transportation nightmare that will happen if the Treasure Island redevelopment project goes through. It will basically need an independent roadway between the island and San Francisco, That got me thinking, would they build a tunnel or a bridge? I think it would be tunnel if anything. Treasure island is too small of a space to have a proper ramp up to the height that would be necessary for big ships on their way to Oakland. This is by no means even close to reality, just my speculation of the issue. Anybody who lives in the Bay Area will agree that adding 13,000+ people to Treasure Island would make crossing the Bay Bridge even worse than it already is, which is pretty freaking terrible.

[mrnyc]

manhattanites barely tolerate either of them. they both make too much noise clubbing in the MePa district every night and keep us awake!

[Lecom]

In general, bridges are cheaper to build and impact the city's appearance much more so than tunnels; however, bridges require more ground level infrastructure space for the off ramps, etc.

If Robert Moses had his way, this bridge would've connected Lower Manhattan with Brooklyn instead of the Brooklyn Battery Tunnel, would've been twice as cheap and taken much less time to build. However, its approach ramps would've devastated Downtown's urban fabric and effectively cut off Battery Park from the rest of the city, so a tunnel was chosen instead.


http://secondavenuesagas.com/wp-cont...5/BBBridge.jpg

[SD_Phil]

^A great way to illustrate the advantages of tunnels. Wow that would have been terrible.

[A_Drury]

Tunnels are more expensive but less intrusive and they hide the engineering.

Bridges impose themselves on the surroundings and can become landmarks.

[Lecom]

Bridge and Tunnel Types

By MICHAEL M. GRYNBAUM

Read More: http://www.nytimes.com/2010/12/09/ny...1&ref=nyregion

Take a date to the Brooklyn Bridge for spectacular views and a romantic stroll. Take a drive in the Lincoln Tunnel and prepare for a cramped, crawling trip to New Jersey.
The Queensboro Bridge is the iconic set piece of Woody Allen’s “Manhattan,” perhaps the most romantic portrayal of New York ever set to celluloid. The Holland Tunnel had its Hollywood moment, too: “Daylight,” a Sylvester Stallone disaster film that imagines the thing destroyed by diamond thieves.

Both types of crossings represent humanity’s ingenuity and ambition, engineering wonders that unite Manhattan to the other boroughs and points beyond. And yet the miracles that shepherd thousands of cars at high speeds underwater through New York City do not conjure quite the same devotion as their above-ground, more architecturally pleasing cousins.

“A bridge is in the sky; a bridge has poetry — even the ugliest bridge has a following,” observed Mitchell L. Moss, director of the Rudin Center for Transportation at New York University. “But a tunnel? A tunnel is much more mechanical. A tunnel is all about moving fast. Tunnels are something you get through, not something you experience.”