Highway Bridges over railroads verses other roads

[roadman65]

http://maps.google.com/?ll=27.818384,-97.637504&spn=0.001217,0.002642&t=h&z=19&layer=c&cbll=27.818384,-97.637504&panoid=Fs_qWQ-Epd-_IvGHG94nOA&cbp=12,104.52,,0,0.55

I was often wondering why the piers for roads over railroad tracks are joined at the bottom?  As you can see the in the above GSV link the contrast between  the standard piers along Business US 77 with connected ones over the adjacent piers supporting the structure over the parallel rail line side by side. I often wondered that as it is almost common in places except here in Florida where normal bridge piers are used.

[Big John]

Those are crash walls for those next to the tracks in case of a derailment, which would create more damage that an errant roadway vehicle.

[roadman65]

Those are crash walls for those next to the tracks in case of a derailment, which would create more damage that an errant roadway vehicle.

Thanks, I was often wondering that.  Even my railfan friends haven't a clue to what they are, but it makes sense.  However, here in Florida you do not see many of these.  I am guessing its not mandated and up to each individual road agency or engineers. 

Even nearby in the same city, there is another line that crosses US 77 that has no crash wall, but the piers are located far from the tracks which might be why, but then again the railroad by federal law has a standard ROW for track expansion, so if that particular line was to be expanded those standard piers would then have to be reenforced.

[cpzilliacus]

Those are crash walls for those next to the tracks in case of a derailment, which would create more damage that an errant roadway vehicle.

Those can be found in some places where the Washington Metrorail tracks are at-grade and go under a highway.

[triplemultiplex]

An errant freight train would make mincemeat out of your typical concrete column.  So yeah, crash barrier.

[D-Dey65]

Thanks, I was often wondering that.  Even my railfan friends haven't a clue to what they are, but it makes sense.  However, here in Florida you do not see many of these.

Ehh, over at US 41 and the CSX Brooksville Subdivision beneath I-275 in Northern Tampa, you have a couple of them on both sides of the piers, but they're not blended in with them like in the links you've got there. Maybe that was something FDOT should've thought of when they were widening I-275.


https://maps.google.com/maps?q=Sound+Exchange&hl=en&ll=28.096061,-82.451792&spn=0.000076,0.027595&fb=1&gl=us&hq=Sound+Exchange&hnear=Spring+Hill,+Hernando,+Florida&t=h&z=15&layer=c&cbll=28.096125,-82.451808&panoid=LTtEJklTMv-3aasJ0Hv2ig&cbp=12,0,,0,0



https://maps.google.com/maps?q=Sound+Exchange&hl=en&ll=28.096704,-82.452006&spn=0.000076,0.027595&fb=1&gl=us&hq=Sound+Exchange&hnear=Spring+Hill,+Hernando,+Florida&t=h&z=15&layer=c&cbll=28.09685,-82.452062&panoid=0_GDG2DdqOjGo8blMeoxmw&cbp=12,91.25,,0,0

I should replace those with pictures.

[Road Hog]

An errant freight train would make mincemeat out of your typical concrete column.  So yeah, crash barrier.

The big gravel-hauling trains that come through my town would pulverize both the crash barrier and the piers if they derailed. Guess it's OK for empty hoppers, though.

[lepidopteran]

On I-75 between Lima and Beaverdam, OH, a N&W rail line parallels the interstate closely (which is why, BTW, US-30 doesn't have a direct interchange.)  Most if not all overpasses on that stretch have a continuous bridge spanning both the highway and the tracks.  The bridge piers on this stretch are typically solid Y-shaped structures, so there are no separate "fingers" to join at the bottom.  But the Blue Lick Rd. exit is different; the space is so tight that even a simple diamond interchange requires a straddle bent.  In the link below, notice how the pier holding up the cross beam has a concrete block on either side for no apparent reason.

http://binged.it/11Djpa4

Note that the ramp also calls for a "vertical" concrete wall at the base; not uncommon on urban freeways, but a little out-of-context in a rural setting.

[Mdcastle]

The added those to I-35W in Bloomington when they made revisions to the corridor to add HOT lanes. In some cases they took out the shoulders in places so I guess semis traveling a few inches from the piers wasn't something they were comfortable with.