In Baltimore a replacement bridge for US 1 that crosses over the West end of the CSX Mt. Clare Yard is now reported to only clear the top of rail by 22 feet 10 1/5 inches instead of 23 feet.
I thought I had read somewhere that new and newly rebuilt bridges were required to have 25 feet of clearance over the top of the rail. When the I-70 bridges over CSX’s Frederick Branch were rebuilt - visually the new bridges appeared to be at least four feet higher than the bridges they replaced.
Minimum vertical clearance in Maryland is 22’-0" by statute (COMAR 09.12.91.04 - last changed 2/14/86) Lateral vs. Vertical clearances may be getting confused here.
If the original design was agreed to at 23 feet, I hope the highway bubbas have to pay for the undercutter to get things back to the agreed-to height. That inch and a half may be enough to stop a high load from getting anywhere out of port and destroys all the recent efforts to expand clearances on the east coast. I suspect that the 23 feet distance was more of a system rule with 6" of cushion built into into it going back to the 1958 model laws.
The scandal may be that the engineer or contractor “blew it” during construction and thought that it was no big deal. Either raising the bridge or lowering the track has big con$equence$ when you add in the approach run-offs. The State of Delaware had a bigger cluster-fluff with their 415 freeway over CR/NS about a dozen years ago at Newcastle/Bear. (in that case the bridge deck was raised and the highway approaches were run-off several thousand feet. Not cheap.)
Not uncommon for highway engineers to get caught guessing at horizontal and vertical clearances. If a distance was agreed-to before construction, stick to it!
(The surveyor in me starts asking questions in terms of asking what caught the error?, was there any recent track surfacing playing into this?, was this engineers acting badly and designing down to the absolute mininimum distance without any cushion, datum shifts and so on…? So much for keeping the attorneys underemployed.)
Cutting corners just bit somebody.
Perry: there is more at play here than just the height of a railcar. Non-railroaders shoot themselves in the foot over this constantly. It’s not only bridges, wireline utilities are even worse… and they never seem to learn [banghead][banghead][banghead]
Ah, yes. The infamous Parkway bridge in Liverpool, NY, comes to mind.
Can’t lower the road - it’s all but floating now as it’s built alongside Onondaga Lake and on a former canal bed.
Raising the bridge will involve raising a lot of railroad, which will have practical limits as there are crossings nearby and the line joins the CSX Chicago Line not far away.
After a recent spate of over-height collisions with the bridge, there is talk of actually bringing money to the table. It is estimated the cost will be well into the millions.
I remember nominal clearance for ‘domestic’ doublestacks (stacked 8’6") as being 23 feet.
But that’s static clearance, and a train is anything but static when it gets to the neighborhood of an overhead clearance. Ride excursions and side-to-side roll can both cause ‘incidence’. The folks who came up with the Union Pacific Arrowedge found out something else about vertical clearances and aerodynamic lift… but then again, actual engineers should have known better.
The only ‘solution’ that preserves strict grade separation is to raise the road approaches, on post and beam is there is inadequate room or time to make a properly-settled and graded embankment for the approaches, and provide an appropriate clearance span and protection rails/fences.
Of course anything like this ought to be built not to stack clearances, but stack clearances plus catenary electrification – and that should be the rule for any improvement, infrastructure project, wireline or cable crossing, etc. (in the absence of coherent adoption of hybrid dual-mode-lite).
At least in theory, the problem might be addressed by constructing a protected grade crossing only for traffic that doesn’t clear the bridge – perhaps one with mandatory protected access as in the UK. That might be especially appropriate if the route is an important connector and there are no reasonable alternate routes nearby. Has anyone done a traffic count of high vehicles, or a survey of how many vehicles per day would use the crossing if it were not restricted height?
I have seen projects both in Louisiana and California that use active trash pumping to remove stormwater or flood egress from a depressed-clearance crossing “pit”. The cost to install and maintain such a thing would be no more than an equivalent sewer lift station, and arguably with the provision of sufficient sealed vaults very few events would require active pumping to keep the road open.
In this case, it’s the highway that has the clearance problem. The clearance is shown as 10’ 6", although it’s actually 11’ 9". Getting to a 14’ clearance would involve raising the railroad bridge ~3’…
There are alternate routes in place. The problem is overheight (for that road) vehicles that ignore the numerous warnings and drivers blindly following their GPS. There are even overheight sensors coupled with warning systems.
The bridge in question is here: 43.09066 -76.19340
I’m sure vendors of Commercial Grade GPS have already done this. The inventigations of trucks that have struck the bridge almost always reveal they were using consumer/ free phone GPS apps.
The thing that stops them, as at the infamous 11’8" or whatever it was bridge, is a portal frame a few feet from the bridge girders with a large, heavy steel beam arranged at clearance height – the idiots hit that instead of the bridge, and stop before they cause structural damage. Note that this doesn’t nominally require approach regrading at all: clearance is clearance above grade at the point of contact.
The other is the height sensors reasonably far out on the approaches, the first of them deployed in advance of the turns that should be taken to alternate routes with clearance, that detect sequential approach of an overheight vehicle and sound the loud alarms, strobes, police alerts, etc. that let even the dumbest driver understand that They Will Not Fit. That includes no-turn light-up signs and camera observation, which gives advance warning to local enforcement should a driver just keep going wrong.
What I was saying is that, if there is no effective alternate ‘truck route’, provide a bypass that doesn’t involve significant reverse moves by vehicles that can’t turn around to let them cross the railroad at controlled grade. That moves the ‘high-centering’ transitions sufficiently away from the track foul zone that even long combinations would be stuck with the head or tail end well off the tracks… some of the earthwork expense might be avoided by using an otherwise-suboptimally-safe extreme skew crossing to achieve the necessary control height in the approach and departure grading.
The problem with such devices, according to NYS DOT, is that this is a relatively high speed (55 MPH), four lane road. They are concerned that a truck striking such devices at speed could potentially cause them to become dislodged and airborne, striking another vehicle or bicyclist who were in the wrong place at the wrong time.
“portal frame” = Sacrificial Beam … and those don’t always work. Determined stupidity can be a scary thing.
Eisenhower/Johnson tunnel on Interstate 70 on the continental divide has all the advanced warning in the world (including stop lights) and it still has the scars from some pretty big fails.
In all fairness, there are drivers out there who are aware of clearance restrictions. Many years back at a different job, we received a call from a driver asking for an alternate route since she knew of an overpass that wouldn’t clear her truck on the regular route. I was able to provide one for her that worked.
The barriers that I’m referring to are lengths of 1/4" chain hanging vertically. They can’t become dislodged. It’s simply there to give an audible warning that there is a problem and much better than striking the bridge or a solid beam. It’s like the one below but it’s all chain.
