Canadian Railroads > The Big Bridge at Davis Mill

I was in the Grand Falls, NB area last week for a few days (likely the last visit for a while, since the "Atlantic Bubble" has now burst), and photographed several of the large trestles on CN's NTR main line through western New Brunswick.  In fact, looking on Google Earth I discovered two more that I wasn't aware even existed, one just east of Grand Falls (and easily accessible), and another between New Denmark and Blue Bell that is hidden in the woods, even though it is quite near Rt. 108. 

I photographed the big one at Davis Mill all three days I was up there, first close to sunset on the 17th.  I could hear 305 approaching from Plaster Rock, but 10 minutes before the train got there, the sun dipped below the horizon.  Trust me, the empty trestle at sunset looks better than the train crossing it, taken at ISO 1600!

The next day (see the recent post regarding the BC Rail unit on 121), after waiting for the DPU to cross the New Denmark trestle, the head end was already across the Davis Mills bridge by the time I got there.  I was hoping the 20 mph permanent speed restriction would slow them down enough, but it was not to be.  And to add insult to injury, the bridge was shaded by a cloud by the time the DPU got there, so this view when it was in sunlight will have to do.

On the 19th, 121 was only a couple hours late, but that put the sun almost right behind them.  This view from the west end of the trestle, even without a train, turned out to be the most interesting of the lot.  The mileboard for Ennishore siding can be seen part way across the bridge.  All the other bridges seem to be a deck girder design, unlike this one which has the girders extending above the railhead.

GTD

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.   .   .   nice, I wonder why they have not put welded rail on that last bridge?
JB

Spectacular bridge. Is the painted portion a recent replacement or they just didn't paint the middle?
Brian N.

I think like a lot of long bridges, painting is more or less a job that is never done. There was painting in progress when I photographed it in 1994.  Most photos I've seen that show most or all of the structure show a portion in progress or in fresh paint.

Keep in mind that CN doesn't do this so it looks good for those of us behind the camera.  It's all about corrosion prevention.

The following is from my book "Seven Days in September 1994", and is based on my internet and print research:

"My primary objective this day was the bridge in New Denmark, NB. I’ve seen this location referred to as Salmon River Trestle, Salmon River Bridge, Salmon River Viaduct, and Little Salmon River Viaduct. It irked me a bit, as I didn’t want to seem like I didn’t do my research and refer to it by the wrong name.

After a bit of searching, I found the Canadian National Railways Atlantic Region Campbellton and Edmundston Divisions Employee Timetable of April 26, 1953. The timetable refers to it as the Little Salmon River Viaduct, that’s as official as it gets.

Time Table 95 of April 30, 1989 makes no mention of the structure save for the permanent speed restrictions of 25 MPH for Railiners (Budd RDCs) and 20 MPH for freight and passenger trains from MP 172.5 to MP 173.7. I was five years too late to catch Railiner 626 or 628 eastbound out of Edmundston.

Some statistics for this massive structure that’s the second longest of its type in Canada:
completed: 1910, length: 3920, feet spans: 51, height: 195 feet, cost: $815,070.87 (including sub- and superstructure), steel: 13,991,310 lbs. (just under 7000 tons)."

3rdswitch Wrote:
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> .   .   .   nice, I wonder why they have not put welded rail on that last bridge?

For one thing you won't have as hard a time dealing with the stress caused by the rail's thermal expansion:

"Any piece of steel when heated tends to expand. For a mile length of rail steel, that expansion can be substantial. The amount of expansion depends on the rise in temperature, and the coefficient of thermal expansion. For most rail steels, the coefficient of expansion is roughly .0000065 of its length per degree (F) of temperature rise. That may not seem like much, until you figure that there are 63,360 inches in a mile of rail steel. Thus, a rise in temperature from 10 degrees F to 110 degrees F can cause a one mile strand of rail to grow by 41 inches"

So for this bridge that would be a ~ 30 inch rail growth.  Bolted rail would simply allow the gaps to close at each joint.  For a 20 mile an hour bridge speed would welded rail be worth the cost?

The bridge itself surely has expansion joints.  Depending on the bridge design, you may be able to handle the rail expansion using Conley Joints, but again for a 20 MPH bridge is it worth the cost?

http://www.cmi-promex.com/category/image-galleries/curved-rail-expansion-joints

Quote from:

http://interfacejournal.com/archives/644

Brian

 

There is an expansion joint just off the bridge at the end shown.  There may be one at the other end too, but it's a lot harder to get to, and I've never been there.

It's interesting about the confusion over names.  This bridge has frequently been called the "New Denmark" bridge, but there is a different bridge in New Denmark (photographed with the BC Rail heritage unit the other day).  The group of homes and farms at the west end of the bridge is Davis Mill.  The river flowing under it seems to be called "Salmon River" (no "little"), both locally and on maps, although like Nova Scotia, there is likely a Salmon River in every county of New Brunswick.

GTD

The one with the stack train, top notch, even without any engines!

Andy

Ahhh, lean something new every day....Now I know why the Japanese use jointed rail on their bridges.
The Japanese also make use of a lot of "Slip Joints" when using welded rail.

Dave