Subj: Bridge at Sanders
Date: 10/5/00 5:04:53 PM Eastern Daylight Time
From: JRTroup
To: awb@ime.net
CC: Dave.Coffin@state.me.us, doyons@quickconnect.com
CC: johns@tdstelme.net, KBANR1

File: 1916_Sanders_Bridge.jpg (108362 bytes)
DL Time (49333 bps): < 1 minute

Hi Bill,

Attached is my drawing of the Sanders Bridge as it existed at the time of the 1916 Valuation Survey.

According to Dave Wurtz, the original copy of this survey is in the hands of the Phillips Historical Society.

Most of the dimensions here came from Dave's sketch of that original. The original and Dave's sketch give the dimensions in feet and tenths of feet rather than feet and inches. This accounts for the peculiar fractional dimensions on my drawing.

The angles of the wing walls are from field measurements I made on 10/1/2000 (yes, there are pieces of the face/wing wall joints in the rubble pile from which I got the angles for the North abutment). Likewise, I found (again from the rubble) that the walls below the tops of the wing walls are thicker than the 1.9 ft. dimension given for the girder seat on the sketch.

As far as reconstruction is concerned, note that it may be more practical to increase the clear span from 11.9 ft. to 13 ft. This is because the broken and layed-down bottom portion of the old North abutment seems to have pivoted at it's center when it fell, thereby requiring that if we are to rebuild without disturbing the piece in the water, we need the 13 ft. span.

The 2.7 ft (2' 8.4") parapet suggests that the original track was some 14.5 inches higher than we now have (currently 18 inches to the bottom of the rail). I don't think we want to be this high. 2 to 4 inches higher would be fine, actually improving the surface line of the rail. However, as we discussed on 10/1, the abutments were formed, poured and cured one board width at a time and, therefore, are not well bonded between pours. This should make it "easy" to cleave off 7 or 13 inches of the top of the South abutment and recap it to whatever elevation we want.

I would use 4 girders: Two of them on 2 ft. centers under the mainline rails. The other two being spaced further out (2 - 3ft. centers) to support both a gauntlet turnout and vehicular traffic if either is desired at a later date.

I worry about the wing wall as originally built on the river side of the North abutment. I suspect it allowed high water to get behind the abutment and that a following freeze is why we no longer have that abutment in the first place. That raises the question of whether we should try for a longer wing wall at a more acute angle to the roadbed in an effort to keep the fill behind the abutment drier. The negative side of this is that we would have to lose the birch trees in the process.

So, is this enough to get us to a bridge design that will suit our long term purposes, and for which we can get the necessary permits???

Happy Railroading,

Bob Troup