8 votes

BM - Sulphite Railroad Covered Bridge 29-07-09


Bridge in 2010

Photo taken by James Walsh

License: Creative Commons Attribution-NonCommercial (CC BY-NC)


View this photo on Flickr

BH Photo #273452


The existing structure replaced a framed trestle bridge erected here in 1891 or 1892 by the Franklin and Tilton Railroad. This unusual bridge, built by the Bridge and Building Department of the Boston and Maine Railroad in 1896, appears to be the only deck-covered railroad bridge left in the United States. It was named Sulphite because of the large amounts of sulfur transported over the rail lines for use by the giant pulp and paper mills not far from the bridge. It is also known as the Upside Down Covered Bridge because the railroad track crosses over the top of the structure rather than running through its center. Service over the line was suspended in 1973. The bridge sides are boarded over with 7/8" siding and the ends are closed. There was a fire inside the bridge on October 27, 1980 that is believed to have been arson. Replacement costs could run as high as $500,000. The Sulphite Bridge is listed on the National Register of Historic Places.


Pratt deck truss bridge over Winnipesautee River on Former Boston & Maine Railroad (Franklin & Tilton Railroad)
Franklin, Merrimack County, New Hampshire
Closed to all traffic
Future prospects
To be fixed and preserved
Built 1896 as Covered Pratt Deck Truss, Abandoned 1976, Outer wood burned off by vandals in 1980
- Boston & Maine Railroad (BM)
- Franklin & Tilton Railroad
Covered Wooden Pratt Deck Truss
Length of largest span: 65.0 ft.
Total length: 225.0 ft.
Posted to the National Register of Historic Places on June 11, 1975
Also called
BM - Upside-Down Covered Bridge
BM - Winnipesautee River Bridge
Upside-Down Covered Bridge
Railroad Bridge
Sulphite Covered Bridge
Approximate latitude, longitude
+43.44490, -71.63524   (decimal degrees)
43°26'42" N, 71°38'07" W   (degrees°minutes'seconds")
Approximate UTM coordinates
19/286757/4813595 (zone/easting/northing)
Quadrangle map:
Inventory numbers
NRHP 75000130 (National Register of Historic Places reference number)
BH 50592 (Bridgehunter.com ID)

Update Log 

  • January 24, 2021: New photos from Josh Schmid
  • December 26, 2015: New photos from Mike Garland
  • June 11, 2015: New photos from Royce and Bobette Haley
  • May 17, 2015: Updated by Luke: Name change via Royce's forum post.
  • February 14, 2014: Added by Jack Schmidt
  • January 26, 2014: New photo from Luke Harden
  • August 10, 2012: Updated by Daniel Hopkins: Added category "Railroad"
  • December 18, 2011: Updated by J.P.: Added category "Boston & Maine Railroad"
  • December 18, 2011: Photos imported by James Baughn


  • J.P. - wildcatjon2000 [at] gmail [dot] com
  • HAER NH-36 - Sulphite Railroad Bridge, Former Boston & Maine Railroad (originally Tilton & Franklin Railroad) spanning Winnipesautee River, Franklin, Merrimack County, NH
  • Luke
  • Jack Schmidt - jjturtle [at] earthlink [dot] net
  • Royce and Bobette Haley - roycehaley111 [at] yahoo [dot] com
  • Mike Garland - Rapier342 [at] comcast [dot] net
  • Josh Schmid


Sulphite Railroad Covered Bridge 29-07-09
Posted December 29, 2015, by george oakley (georgeoakley49 [at] yahoo [dot] com)

Thanks luke.I thought you would say that.I saw a deck cover in some of the pictures underneath the rails and ties.Is this from when it was a covered bridge?

Sulphite Railroad Covered Bridge 29-07-09
Posted December 28, 2015, by Luke

It was suspected to be arson: https://www.nh.gov/nhdhr/bridges/p103.html

Sulphite Railroad Covered Bridge 29-07-09
Posted December 28, 2015, by george oakley (georgeoakley49 [at] yahoo [dot] com)

Thanks guys for all of your responses on the bridge and especially the rail being bent.Was the fire on this bridge naturally caused by a lightning strike or was it arson?Because if it was either it could cause the rail to actually warp because I worked in the metals industry and do know at very high heat steel will do that.I just never expected to see pictures like that.

Sulphite Railroad Covered Bridge 29-07-09
Posted December 28, 2015, by Chester Gehman (gehmanc2000 [at] yahoo [dot] com)

The rails are bent due to the fire in all probability. Railroaders call this a "sun kink"--in the summertime heat, rails will expand lengthwise, and with no room to expand will cause a bend in the rail. This is an extreme example of such a kink--the fire was pretty hot. Looking closely at photo #6 we can see that spikes and tie plates are missing--pulled out when the rails bent. Remaining spikes are loose. The wheels of a train could never negotiate a bend in the rails like this without derailment.

Sulphite Railroad Covered Bridge 29-07-09
Posted December 27, 2015, by Royce Haley

I am by no means an expert but I have visited that bridge a couple of times and I don't think the bends in those rails were cause by the fire. There doesn't appear to be a sign of fire, severe heat or soot on the top of the ties or rails. The rails are to neatly bent to be an accident. And I doubt the fire moved the spikes over on the ties to correspond with the curves. As well no other parts of the rails over the bridge are bent.


P.S. as stated earlier in the thread this is a duplicate page. I saw a duplicate page alert in the forum last year for this bridge as well.

Sulphite Railroad Covered Bridge 29-07-09
Posted December 27, 2015, by Will Truax (Bridgewright [at] gmail [dot] com)

The cladding was lost to a fire in 1980, the heat from that event also kinked the rails.

Sulphite Railroad Covered Bridge 29-07-09
Posted December 27, 2015, by george oaakley (georgeoakley49 [at] yahoo [dot] com)

I have a couple of questions on this bridge.First,i noticed it is described as a covered bridge which by looking at the pictures it is not.Second in pictures of the bridge the railroad track is bent.doesn't look like normal track.What i'm wondering is how that track got bent like that.Any answers would be greatly appreciated.

Sulphite Railroad Covered Bridge 29-07-09
Posted December 26, 2015, by Ian Martin

This entry is a duplicate of this one: http://bridgehunter.com/nh/merrimack/bh50592/

Sulphite Railroad Bridge
Posted December 18, 2011, by Tony Dillon (spansaver [at] hotmail [dot] com)

I have known about the "Upside Down Covered Bridge" since I was a kid. I knew it had been burned many years back but was pleasantly surprised to find out it is still standing. And even better to hear it is going to be put into use and preserved!

Sulphite Railroad Bridge
Posted December 18, 2011, by J.P.

I found this bridge today by accident, but anyways, this bridge is the only upside down covered bridge left in the united states. The bridge was burnt and lost its original wood covering, but still stands with the truss intact. there are plans to refurbish and open it on a trail. I'm not sure how to upload haer stuff, so I have posted the haer link on here.