Friday, January 27, 2023

1840s Enlarged Erie Canal Aqueduct and Road/Trail/NYC Bridges over Schoharie Creek at Fort Hunter, NY

Canal: (Bridge HunterHAERSatellite)
1910: (Bridge HunterSatellite, northern truss)
1929: (Bridge HunterSatellite, southern truss)


"Built 1839-1841, put into service 1845; six arches demolished 1915; three more have collapsed since." [BridgeHunter-canal] The eastern arches were demolished because they were in the main channel and caused ice jams. I found a date of 1969 for this photo. That date is significant because the three eastern arches have yet to collapse. Obviously, this photo was taken when the river was high because the flood plain is inundated. In the satellite images the flood plain is dry.
4. Looking northeast. - Erie Canal (Enlarged), Schoharie Creek Aqueduct, Spanning Schoharie Creek, Fort Hunter, Montgomery County, NY

This shows that the stone arches carried just the towpath. What carried the "trough" of water? Iron would be bleeding edge in 1840, but would wood be strong enough? Or was it wood beams and iron truss rods?
8. Towpath and trunk bed from southwest shore.

Note the "spur" canal below the canal that used the aqueduct. That is a remnant of the original 1820s canal. It was retained as a feeder canal for the 1940s enlarged canal. A guard lock was added where the remnant of the 1820s canal met the river to keep river flood water out of the canal. The walls of that lock are still preserved. [Photo of a plaque]
1945 Tribes Hill Quad @ 24,000

There is a lift lock a little east of the river where the feeder canal joins the main canal.

When the 1820s canal was built, a dam was built downstream on the Schoharie Creek to form a slack pool which the canal boats used to cross the creek. All they had to build across the creek was a bridge for the towpath. After the 1840s canal was built, they still maintained a diversion dam on the creek to create a pool that fed the feeder canal. [Photo of a plaque]
30. Photocopy: Composite Map of Crossing Site by Daniel J. Mordell from Canal Society of New York State. Bottoming Out: Useful and Interesting Notes Collected for Members of the Canal Society of New York State. Vol. 18-19. Syracuse, 1962.

An arch places a strong lateral force on the pier. Normally, the arches on both sides of a pier balance each other. But since they removed some of the arches, the pier on the end lost its lateral bracing from the other side. So I presume that the arches have been falling like dominoes. This aqueduct has been a popular attraction in the state park. So, as part of a $1.7m rehabilitation, they are going to build a buttress for the end pier.
safe_image for $1.7M project will stabilize Schoharie Crossing aqueduct

While looking for the aqueduct, I noticed that there are two truss bridges just a little upstream of the aqueduct.

Road/Trail/NYC Bridge

The northern truss was a NYC bridge, and...
Nov 2021 Photo by Geoff Hubbs via BridgeHunter-1910, License: Released into public domain

Several photos by a snowmobiler

Trail/Road Bridge

...the southern truss was a road bridge.
Street View, Dec 2021


NYC abandoned their bridge in 1981. So it was available to help handle the traffic on NY-5S when it became the detour for I-90 after I-90's bridge over Schohaire Creek collapsed in 1987. After the I-90 bridge was repaired, traffic returned to the road bridge and the railroad bridge became part of the Gateway Trail - Erie Canal Trail. But the southern truss, already weak, was damaged in 2011 by Hurricane Irene. So the road was moved to the stronger railroad bridge in 2015, and the trail was moved to the weaker road bridge. That is why we now see the trail crossing the road on both sides of the river.

This was taken during the 1987 flood that wiped out the I-90 bridge.
uticaod, Source: New York State Thruway Authority

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