How many RRs have built trenches ala the UP (ex-SP) trench going through the inner suburbs of LA, or the one that was built through the downtown of Reno after the UP took over the line? This may seem like a naive question, but isn’t it quite easy for rainwater or other things to build up there? What are the acknowledged advantages and disadvantages of building trenches? Would running a trench, for example, be as risky as having a busy mainline running at street-level (I’m talking about something like Stockton, CA, where the RR actually runs on the street, I believe, as well as not having its own trench?) One that would come to my mind is that it would be quite difficult for RR personnel to get emergency equipment into/out of said trench if a derailment or accident happened in one. Although I don’t know for sure, my hunch is that not too many have been built, b/c I haven’t read or seen about too many around the US…
I think one was built in Lafayette, IN, to get the main off the road through town. They were starting it when I was leaving a “couple (of dozen)” years ago…" It went along the Wabash river, and there was a concern that seasonal flooding would be an issue, but supposedly it was designed for 50 year floods…
There are several hundred U.S. examples of railroads depressed below grade to avoid at-grade crossings with roadways. Look around any major city. Often the railway is partially depressed and the roadway is partially raised.
The only advantage (from a railway’s point of view) of depressing the railway below grade is to avoid grade crossings and the significant maintenance and liability costs they incur. The disadvantages are many. Precipitation is not a major issue so long as the bottom of the trench is above existing storm sewer inverts and above the water table, but in many cases they are not, in which case pumping stations must be constructed, powered, operated, and maintained. Track maintenance is problematic as access can be severely restricted for off-track equipment. Capacity for future expansion is of course seldom provided so some of these depressed grades that seemed like a good idea 40 years ago now are a bete noire (the El Paso trainway, for instance
Thanks for the detailed answer (as per usual), Mr. Hadid. Actually, speaking for the West Coast, I can’t think of any major city where the RR has decided to build a “trench”, except for LA, the one I mentioned. Are you more familiar with the cities than I am? Also, since you admitted that these trenches have high maintenance costs and very few advantages, it would seem strange if more than a few of them were built, wouldn’t it? Wouldn’t it be easier to elevate the entire ROW, and wouldn’t that also decrease the maintenance costs? Wouldn’t RR overpasses be easier and more cost-effective than a trench?
Visit the Official Territory, where railroads have coexisted with densely populated urban environments far longer than in the West. Chicago proper is almost 100% grade separated (the city, not the suburbs).
Bridges are also high capital cost, high maintenance items – you can’t win. Moreover, from a city’s point of view, elevated railroads are eyesores, block access to businesses, subdivide neighborhoods, interfere with traffic patterns, create nooks and crannies for illegal trash dumping and vagrants, and generally devalue the neighborhood.
Yes, generally it’s easier to mitigate noise in a trench as opposed to an elevated track. But either is vastly superior in that regard to at-grade. I’ve not come across sound reduction being a significant criteria in the choice between depressed or elevated as the other factors are generally viewed as much more important.
Good question, to which the answer is “sort of.” The trench walls, which are typically retaining walls with adjacent roadways and structures, have to be engineered to avoid failure, both for its own integrity as well as the foundation integrity of adjoining structures, and every roadway overpass is in effect an elevated structure. It’s not just enough to have structures survive the earthquake without collapse; you also want them to survive without significant damage so that the infrastructure keeps working and (1) its economic ability to generate income does not cease for a long period, and (2) society isn’t burdened with the cost of replacing it.
In many ways the elevated railway structure is cheaper and easier to design for seismic loads.
In both K.C. MO and K.C. KA the railroads that are near the old Union Station elected to build elevated “flyovers” to releive congestion. The problem was not roadways but the need to eleminate diamonds and crossovers at yard approaches.Going up and over reduced intrerferance with existing tracks and traffic.Which was at this point already over capacity. Over was i will assume cheaper and more importantly less disruptive than under. The first one was so succsesful they immediatly began a second at another location nearby.
One fairly minor nit to pick: public funds paid a large portion of the cost of the trench in LA (no, not “Lower Alabama”), the railroads didn’t go it alone. The city(ies) involved had a vested interest in removing all those grade crossings on the separate lines that formerly served the port.
