Dry River Ramble to Suspension Bridge 10/5/08

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Jazzbo

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Waltham, MA Jazzbo & Marty meet Bigfoot on Kenne
I bailed out of a hike to Monroe due to lack of traction equipment so I had to find alternate destinations fast. I’ve always wanted to explore the Dry River Trail, but hesitated on accounts of the Dry River and the condition of its suspension bridge. Since I was in the neighborhood why not take a hike along it just to explore it and see what it’s like. The Dry River is a big river. It’s rocky and full of boulders. The river valley is generally narrow. The valley does have stream terraces resulting from down cutting by the river into valley glacial sediments. The stream terraces are not continuous depending on how close the walls close in. The logging railroad builders tried to locate the tracks on the stream terraces but either tried to cross the river to one on the other side or built the track out on trestles to get to the next terrace.

The Dry River Trail takes several high altitude bypasses to avoid areas where the terraces die out and trail resorts to steep side-hill trail to get by. I suspect these are places where the terrace poops out and has washed out. One bypass entails a 100+ foot elevation gain up the side of the valley. One gets a nice view of Oakes Gulf from one of these.




Here's the bridge. River has steep gradiant here and water runs fast.



The wooden framing of the bridge does indeed look like it’s at the end of its service life. The creosote wood framing looks old and brittle. Must havbe been nice when it was new.



The obvious failure is where one of the suspension ropes has pulled out of one of the cross-members and exhibits a decided sag in this spot. I hope the Forest Service can replace this bridge soon. One writer here has said it was on the list to get done this year, but perhaps the non-stop rains we had this year made that impossible. This would be a complicated project. With budget cuts loooming who knows???



I wonder what their plan is. One might be able to re-use or re-place wooden structure and cables, but I don’t know if they’d be planning to remove and replace the concrete anchors as well. They look sound now, but would they last another 20 years?





Complicated repairs to be done in difficult to access area. The existing bridge design looks fine, but they may want to invest in more permanent anchors so next time bridge fails they only need to replace the super-structure. But that would cost more money. Hummm...

Until the bridge gets fixed I’d hesitate to cross Dry River here unless the water was low and prospects for rain minimal. I declined to cross by rock hop of by wading. Might have attempted wading if I’d had more time or some destination in mind. But even wading looked tricky given somewhat high water with the fast moving water, uneven bottom, and deep holes. I did bushwhack up the north side of the river and quickly came to another terrace with what appeared to be an elevated former rail bed that went on for a while until it and the stream terrace again petered out. I came across this USGS survey marker propped up in a rock pile.



Valley walls got steep again so I decided to bail out and go on to my next destination. The terrace may or may not have picked up again further on. It probably wouldn’t have taken much longer to reach the Mt Clinton Trail by this means.

I did see what looked to be a party of 3-4 people on the other side of the river who had tents set up and were camping. Noise of the river made it impossible to communicate other than by a friendly wave. Maybe they were camping waiting for the river to go down??? ;-)

I took the trail back to the Dry River Campground because it follows the old RR bed and makes for easier travel. It crosses a number of abandoned dry stream channels in outwash fan that are quite interesting from geological point of view.
 
I had the pleasure of meeting some folks from the forest service this weekend, and was imformed that the new bridge is actually all built, off site, and they are just waiting for installation, which they hope will happen this coming year. I guess the hold up has been a contractor issue, not a FS issue.
 
Very Good news!!!

Wow! I wonder where it is. I bet they're going to fly the new bridge in one or two pieces. I'd love to be there when it gets installed. Maybe they intend to use steel beams for span. Like this new bridge I saw recently on Sawyer Pond Trail that was made of steel beams in two pieces. Certainly would cut down on labor costs and last who knows how long.

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Recent PM's from JB about the bridge replacement project inspired me to go to the WMNF projects page where Lo and behold I came across an extensive list of projects and found a description of the bridge replacement in the Decision Memo posted there. I'm cutting and pasting the relevant passage here.

"The existing concrete abutments and cable will be reused as these components have been found to be in good repair by a bridge engineering firm. The other major structural components, including the towers and I-beams will be replaced with weathering steel, which will have a useable life of approximately 100 years and will acquire a brown tone over time to better blend with the natural surroundings. The bridge decking and railing will be wood, similar to that on the existing structure. These materials will provide a balance between useful life and natural appearance. The use of weathering steel will also allow the bridge to be pre-fabricated off site eliminating the need for power tools during assembly.

This decision also includes the transport of new bridge components to the site and removal of existing components with the use of helicopter. ....."

To read the entire document click on link below. Then click on the link "Dry River". There's lots of other interesting stuff to read on this page.

http://www.fs.fed.us/r9/forests/white_mountain/projects/projects/archive.html

Happy trails to one and all!
 
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Very cool stuff there! "At the request of several interested organizations, the Forest Service proposes to construct a multi-purpose bicycle path, approximately nine miles in length, from the Skookumchuck Parking Area to the community of Twin Mountain." Mmm...

Thanks for finding and sharing all this info!
 
Update as of 10/29

Call to Saco District ranger station indicates New Bridge is to be delivered this week. Most likely it will be installed this spring. He didn't say where, but it seems to me they could store it at the DR campground somewhere.
 
Very interesting post Jazzbo! Would be interesting to see it installed but if they land it with a chinook it won't take long. My uncle's with PSNH and when they put in power stanchions its a matter of minutes. Hoist operator sits in the belly of it and can see the color coordinated corners.

Missed a great oppurtunity a few years ago to see a river being bridged with a covered bridge done "old school". Friend of the family did it with an ox team and capstan!;)
 
My uncle's with PSNH and when they put in power stanchions its a matter of minutes. Hoist operator sits in the belly of it and can see the color coordinated corners.

Missed a great oppurtunity a few years ago to see a river being bridged with a covered bridge done "old school". Friend of the family did it with an ox team and capstan!;)

I think it will take more than a couple of minutes. The Decision Memo indicates one reason to utilize the chopper was so it would reduce construction time from 6-8 weeks to 3-4 weeks. Chopper will be coordinated to ferry in new and ferry out old materials. Of course the unpredictable nature of weather and river is a factor.

I'm pleased folks find this thread of interest!
 
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