What's Cheaper: an Underpass or an Overpass?

gisa

Routelayer Ordinaire...
Hi All,


I was wondering what is typically cheaper to design and build: an underpass or an overpass. I'm building a route which I'd like to keep somewhat prototypical and while I tend to like the look of overpasses more :cool: somehow I think they cost more than an underpass. I'm curious as to what your thoughts are and how this might be affected by roads/rail that has to go over or under an existing rail/road.

:wave:

Gisa ^^
 
If your talking about an overpass like this, my guess is that it's cheaper because with an underpass you'd have to dig up the gound and the road, lay track, and build a road bridge over it, but I could be wrong...
100_0155.jpg
 
Normally the one that is used in practice cost being the main consideration in any project though flood risk has always to be considered when digging holes in the ground
Regards Bob V
 
I think it is going to be rather difficult to generalize about this since there are so many variables. Railroad grades are quite limited so they will tend to do whatever provides the smoothest and smallest grade, even if it costs a bit more. What is the geology of the area? Are we talking solid granite or swampy muck? That would make anything involving excavation expensive. A railroad bridge has to carry a higher live loading, so the structure will be more expensive as a general rule, but it can also do away with niceties like continuous guard rails and such. On flat ground, such as the midwest or florida you would probably keep the railroad at grade and built the road over since the approaches can be much steeper for cars than railroad approaches. Other factors such as politics may mean putting the railroad right-of-way in a cut to get it "out of sight".
 
Underpass or Overpass

Hi Gisa,

It is usually cheeper to build a bridge tha dig a tunnel, but whether you have a bridge (overpass) for the rail over the road, or a bridge (overpass) for a road over the rail, depends entirely on the terrain. For instance if the railway is in a cutting, even a fairly shallow cutting you would use a road bridge but if the rails are on a bit of an embankment you would use a rail bridge for the road to pass underneath.

Cheers,
Bill69
 
One suggetion might be to find a real life area which is pretty similar to the route you want to build and count the bridges and tunnels. That ought to give you a rough idea for what to do in yourown routes.
 
On dead flat terrain, a road bridge over is most likely (though level crossings are more common in this case). Otherwise, the lie of the land will give you the best clues.

Paul
 
Everything that has already been said not withstanding, you also have to figure out the density of the road traffic and the frequency of the rail traffic.
Traffic engineers would like to replace many level crossings with an under or overpass nowdays, but often won't unless the traffic is so at odds, that it becomes a major safety issue.

Ed
 
Thanks all for your replies!


Now that I think about it, it is a rather difficult question which depends on a lot of variables (it's always silly to post a thread just before you go to bed right? :D ). The area of the route I'm trying to make is in the Great Lakes area of North America and I'm at the point where I'm adding eye candy to the route (like bridges, tracks, sidings, etc...). From my experiences in train travel (mostly going from Montreal to Toronto or taking a commuter train into Toronto) most crossings were indeed level crossings with a few underpasses and a lot more overpasses. I found rural routes used grade crossings/overpasses more while urban routes tended to use a mix of underpasses and overpasses and grade crossings more often. I think that's because space is at a premium and it's perhaps easier to make an underpass in an urban area than an overpass. In the end, I want to make a route that others and myself will enjoy (with lots of low poly eye candy [haha an impossible task perhaps? :D] ) so I will probably make what looks best with some degree of reality...

I'd also like to add the next stage of my question (which I forgot to add). How about rail going over rail? Is it cheaper to go under or over? In that case, I think it would be cheaper to go under but I find the rail overpasses look better somehow. For example, I have a mainline and a massive car plant on it's left. I didn't want the autoracks blocking mainline traffic when they entered (the main line is only double tracked at that point) and even if the entry curve was gentle, the owners of the plant decided after seeing the underpass and overpass look ;) that they'd opt for an overpass as it's in the suburbs and land isn't too expensive and wont cheese off the mainline track users, but you get my drift. ;)

The problem is, I first layed the tracks so the topography doesn't exactly dictate the choice of tracks, but yeah...anyhow, thanks everyone for your input. :) Haha, I might have to do some relaying at this rate (which I find I keep doing the more and more I detail a route...).

:wave:

Gisa ^^
 
How about rail going over rail? Is it cheaper to go under or over?

I submit that it doesn't make any difference which is cheaper.....because one of them will have to go under, and one of them will have to go over.

Ed:confused:
 
It'd probelly be cheaper to build a single track bridge over the main line. If height is an issue take the tallest car you plan on using on your route(cargo inclued) and place it under the bridge and rise or lower one of the tracks from there.
 
I think the lay of the land will be the major determinant not so much costs. If we are talking about level terrain than costs are going to be very similar somebody is going to have to lower or raise and somebody is going to have a bridge. If a railroad going over a highway is approaching on higher ground than the railroad will probably get the bridge.
 
Sure Michael_Evans, that I generally do with each and every bridge. I think the Autoracks are the tallest cars so I use them to get a sense of height. There are some great answers here and I guess as I'm laying the tracks first, I can make the terrain suitable for an overpass or underpass or whatever I wanted but I was just curious and I'm glad this inspired some debate. :cool:

:wave:

Gisa ^^
 
What route are you doing, gisa? Fictional or prototype? Will it be in Canada, USA or both? You mentioned Toronto. There are Toronto layouts, one is the TorontoTrainz one which includes the GO lines to the suburbs, and streetcar tracks, although it has level crossings where there should be bridges (like in downtown Toronto). The other layouts are Toronto subway layouts. I was at Toronto once last year in July as well as Kingston first and Niagara Falls last. We drove up (my mom and her friend drove) from eastern PA. Canada is a bit different than the US. Speeds are in km/h, seeing Maximum 100 km/h signs on highways like the 401 makes you feel like you're on the Autobahn or something even though it translates to about 60-65 mph. In Trainz you can switch between miles and km's at the push of a button. I have a huge layout going from my home to Canada, and I merged the Toronto layout with it and also Niagara Falls. It is incomplete scenery wise, although I have the highways and roads all the way up to Canada, Kingston, and railroad from east of Kingston to the Toronto layout so far. I have PA turnpike, I-81, and the 401 in Ontario. The entire layout except the Toronto section and Niagara Falls were scratchbuilt by me without any DEM, I just built on flat baseboards and used the ruler tool and milesticks to measure distances. It's 300 miles from my home north to the Canadian border where I-81 ends at the 1000 Island bridges. I also made highway exit signs and overhead signs for almost every exit on the highway in PA and NY by reskinning downloaded ones. There's a site with graphics of highway signs on a guide showing every exit I-81 in PA and NY to the border, etc. It took me a while to do and I took a break from it for a while to work on other things, like other Trainz layouts and other games like Roller Coaster Tycoon 3.
 
As has been said you have to build a bridge either way as one has to cross the other. If I had to hazard a guess I would say the railway bridge would cost less only because it would be smaller and have less frills. Of course you must move a lot of dirt in any event.

Cheers

AJ
 
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