What are the exact gradients (also known as grades) and horizontal lengths of vertical curves for all major mid-level or high-level (defined by me as having a clearance below of 48 feet or greater) railroad bridges that go up and over (usually in terrain that is rolling hills or flatter), including the approaches?
All I know is that the Hell Gate Bridge (between Manhattan, NY and Queens, NY) has a grade of +1.218% maximum (1.2% typical) on the North approach, -0.76% maximum (-0.72% typical) on the South Approach, with a vertical curve across its 978-foot main span with entering and exiting grades of +0.4% and -0.4%, respectively.
Likewise, the Eads Bridge (between St. Louis, MO and E. St. Louis, IL; which does not carry mainline trains anymore) has a grade of +1.153% on the west approach (St. Louis freight tunnels), +0.65% at the west abutment bridge, vertical curve between the centers of the major side spans, -0.65% at the east abutment bridge, and -1.5% on the east approach.
For full-resolution image, search the Library of Congress.
For the San Francisco-Oakland Bay Bridge (formerly carried interurbans), the former East Span (demolished 2014-2018) has a constant grade of +2.74% on the skyway and 2 east deck trusses, vertical curve across the center deck truss’ 509-foot span, +1.3% on the west 2 deck trusses and cantilever east anchor span, vertical curve across the cantilever 1400-foot main span, and -1.3% on the cantilever west anchor span. The Yerba Buena Island Tunnel has a grade of +2.5% and the West Span has a vertical curve of 6370 feet with entering (east side) and exiting (west side) gr
Pretty sure the grade at the east end of the original Bay Bridge was more than 2.74% – 4% sounds a good guess.
The eastward climb to the Benicia Bridge is 1% maximum – averages around 0.95%. Westward climb on the old westward track is 0.4 to 0.45%; on the old eastward track the SP chart shows 1.95% for 3500 feet.
What are the exact gradients (also known as grades) and horizontal lengths of vertical curves for all major mid-level or high-level (defined by me as having a clearance below of 48 feet or greater) railroad bridges that go up and over (usually in terrain that is rolling hills or flatter), including the approaches?
So, what are the values for the other high-level railroad bridges, such as the MacArthur Bridge (between St. Louis, MO and E. St. Louis, IL), Delair Bridge, Benicia-Martinez Bridge (1930 span, center among 3 parallel bridges), Frisco Bridge (formerly known as Memphis Bridge), Harahan Bridge, CSX Susquehanna River Bridge, PRR Susquehanna River Bridge, C&O Railroad Bridge (completed 1889, demolished 1970), C&O Railroad Bridge (completed 1929), Huey P. Long - O.K. Allen Bridge (Baton Rouge, not New Orleans), Salmon Bay Bridge (clearance below of 50 feet at low tide), Cairo Ohio River Bridge, Vicksburg Railroad Cantilever Bridge, K&I Bridge (Louisville, KY), 14th St RR Bridge (Louisville, KY), Big Four Bridge (Louisville, KY; does not carry RR anymore), PATH (under FRA jurisdiction) Lift Bridge (clearance below unknown), Poughkeepsie Bridge (does not carry RR anymore), Queensboro Bridge (formerly carried rapid transit trains and streetcars/trolleys), Quebec Bridge (in Canada, not in U.S.), other high-level railway bridges located outside of the U.S., etcetera? Diagrams and/or links to ones would be most helpful.
What are the exact gradients (also known as grades) and horizontal lengths of vertical curves for all major mid-level or high-level (defined by me as having a clearance below of 48 feet or greater) railroad bridges that go up and over (usually in terrain that is rolling hills or flatter), including the approaches?
So, what are the values for the other high-level railroad bridges, such as the MacArthur Bridge (between St. Louis, MO and E. St. Louis, IL), Delair Bridge, Benicia-Martinez Bridge (1930 span, center among 3 parallel bridges), Frisco Bridge (formerly known as Memphis Bridge), Harahan Bridge, CSX Susquehanna River Bridge, PRR Susquehanna River Bridge, C&O Railroad Bridge (completed 1889, demolished 1970), C&O Railroad Bridge (completed 1929), Huey P. Long - O.K. Allen Bridge (Baton Rouge, not New Orleans), Salmon Bay Bridge (clearance below of 50 feet at low tide), Cairo Ohio River Bridge, Vicksburg Railroad Cantilever Bridge, K&I Bridge (Louisville, KY), 14th St RR Bridge (Louisville, KY), Big Four Bridge (Louisville, KY; does not carry RR anymore), PATH (under FRA jurisdiction) Lift Bridge (clearance below unknown), Poughkeepsie Bridge (does not carry RR anymore), Queensboro Bridge (formerly carried rapid transit trains and streetcars/trolleys), Quebec Bridge (in Canada, not in U.S.), other high-level railway bridges located outside of the U.S., etcetera? Diagrams and/or links to ones would be most helpful.
Legend has it (IIRC) that the 2% rule of thumb for maximum grade dates back to the B&O, as that was the maximum grade used then the old road was built.
Nonetheless, it’s usually the case that the grades on a line aren’t considered exceptional until they rise above that 2% number.
B&O adopted 2.2% as their maximum grade between Cumberland and Wheeling , and when newer roads wanted Fed funding or license to develop their own ROW and go into business, the Fed mandated 2.2%. It was because B&O was doing well with the equipment they used over their grades, and the Fed wanted to ensure similar success. The UP, for example, was required to make their ruling grades no worse than 2.2%. My source is Vance, J.E., The North American Railraod, Johns Hopkins, 1995.
No one knows what the requirement actually was – the law probably wasn’t written carefully enough. Good a guess as any: the grade wasn’t supposed to exceed 116 feet per mile, so it could exceed 2.2% as long as the grade didn’t average more than 2.2% for any mile. And that’s uncompensated – the “ruling grade” on Donner Pass and Tehachapi is around 2.35% compensated.
Next question: since SP’s original line to Oregon was/is 3% plus, did SP not get land grants for it? Did it get no land for any of the line, or just for the steep part?
Railroads constructed in the late 18th century through the mountains of Colorado, New Mexico, Arizona, and California (of which I am familiar) were constrained by the need for water, by the construction tools available for blasting and by those devices for moving the materials. There were many locations where grades of 3% plus were necessary, Raton Pass between MP 648 and MP 652 for example. They just built it and then modified it later when the ‘state of the art’ changed. And it is still being modified today.
There are no ‘maximum’ limits. Each situation dictates what will be necessary given the conditions prevailing, ie, type of traffic, governmental constraints like avoidance from endangered ‘whatever they wish to protect’, and others. Each situation is given substantial review before a plan is established.
I’ll check, but has to be close to level. No need for one end to be higher than the other. (Edit: the UP chart says the NW end of the bridge is 7 feet higher than the SE end. Wonder if it’s true.)
As for typical grades on modifications – why would anything be typical? When Santa Fe double-tracked across the Mojave Desert around 1923 the new downgrade track from Ash Hill had a couple miles of 2.2-2.3%, while the original 1880s line was 1.4%.
It makes sense that the northern end of the bridge is higher, because there is a hill there, and construction costs are always preferrable to be minimized, so they did that to minimize the excavation of the hill in order to maximize the value with the money. The Benicia-Martinez Bridge (1930) has a length (run) of 5620 feet, so an exactly 7-foot rise would mean it has a grade of 0.125%.
I’m guessing a lower bridge would have been cheaper, even if it needed more excavation, which it likely wouldn’t. They probably needed the bridge to be at least X feet above the water and the approach was set by that. No other reason to climb the hills at all.
(Turns out the westward approach does include 2000 feet of 0.5%.)
A lower bridge would have required many times more excavation because the north end is a steep hill, basically a bluff. Immediately to the east of it is a marsh, which is even less suitable for laying tracks for heavy coal trains because of extremely soft soil condition, quicksand in fact.