Rt 7 Bridge, Day 3

Rt 7 Bridge--Completed

August 3rd, 2013

With an experienced crew of 8 bridge builders we wrapped up the project today.

Pete and Christine start planking on the south end

We arrived on site to find the timbers as we had left them spanning the stream.  We attached them to the sills and began to install the blocking and deck planks.  Because the beams were slightly warped, we used a bar clamp to align them as we inserted the blocking in the space between the beams. 

Dave and Steve start on the north

This blocking serves several functions:  it helps share the load among all three timbers,  maintains equal space between them and most importantly, because the beams are relatively narrow for their depth, keeps them from twisting under load. 
The careful layout and installation of joist hangers on previous project days paid off, as we had little trouble inserting the blocking.

Kneeling on temporary planking, Pete and Dave drive the "golden spike" in the middle of the span

The bridge seems strong enough

While the blocking and planks were being installed, four 6x6 posts were set into the ground, two at each end of the bridge.  These are intended to keep the bridge mostly in place should it ever be floated off the ground by flood waters.  This area sees water up to two feet above the trail--particularly in the spring.   When this happens, hikers are routed onto adjacent roads until the water subsides, usually in a day or two.
Our greatest concern would be to find the bridge had been floated so far out of location that one end dropped into the stream--the thing is so heavy we would not likely be able to pull it back into place w/o heavy equipment.

Bob and Don attach railing posts

Adding railings to the bridge completed this phase of the project. 
While most AT bridges in Mass don't have railings, for this long span and deep ravine, railings seemed like an appropriate measure.

Our first official customers.  Two Northbound thruhikers

The final phase was the demolition and removal of the old bridge.  Using a rock bar, we were able to easily pry the planks from the the 8x8 timbers.

Steve removes nails from the old bridge planks

Timbers were unbolted from their posts on the north end and using the comealong--with some effort--we were able to drag them over to the south bank.  The timbers were cut in half for transport back to the tool shed.

Don operates the comealong to drag the old timbers ashore

We then cut up the portions that were not rotting, and will use them for bog bridge base timbers on a project happening later in the month.

From identifying the problems with the old bridge (rotting support beams and a widening stream bank), to completion this past week took almost two years.   Along the way, we were early users of ATC's new bridge policy, applied for and received approvals from the Sheffield Conservation Commission and the National Park Service, and paid for about half the materials through an LL Bean Grants to Clubs program.  Total cost for this project was about $2000.  Volunteer hours for construction totaled 138.  Planning hours are harder to figure, but are probably around 100.  During construction, we had the pleasure of working with staff from ATC's New England Regional Office and the Mass Department of Conservation and Recreation's AT Ridgerunners.  Special thanks to Bruno's Dog House for letting us use their hose to wash off with poison ivy soap after each day of construction.

Open for business.  Note the posts at the ends to reduce the tendency for the bridge to float away

Looking Northbound

Rt 7 Bridge--Day 2

July 30, 2013

Today was about getting the previously assembled beams across the stream and fastened in place. 

Sill work, beams in background

Dave and Jim setting sills

We finished up the sills for the bridge to rest on and on the beams, laid out and attached the joist hangers for the internal bracing.

Denis finishes up sill bearing plates.

One at a time, each 500lb beam was then slid from the assembly area and pivoted to align with the sills before being sent across the stream. 

Dragging a beam into position for launching.

This was probably the most difficult part of the day, as the ground was not particularly even, and the 36ft pieces were heavy and cumbersome.  Next time, we'll bring some rollers to ease this process.

To keep the beams upright and horizontal on their way to the far bank, we installed a piece of 1/4" wire rope across the stream to carry the front end.  This wire was 75 ft long, attached to a tree on the south side, and to a post we installed in the corn field as the anchor on the north side.   To support the 250lb end of the beam in the center of such a long span, this wire needed to be very tight.  We used two 1/2" diameter turnbuckles to tension the wire until the post began to shift slightly in the ground.  A bracket was attached to the front of the beam to hold a pulley that traveled along the wire.

Beam #1

Beam #2 starts the journey

With most of the team lifting and pushing from the north side, the beam was slid over the sill and out over the stream. 

As the beam approached the south bank, two people lifted and pulled the beam up and over the sill.

Once all three beams were across, they were set in their final locations and screwed to the sills with timber screws.

First beam landed

All 3 beams in place and ready for planks

On our next (and hopefully final) day on the project, we'll work our way out along the three beams installing blocking and deck planks as we go.  Then a railing will be set in place and the old bridge taken apart and removed from the site.

Footbridge near Rt 7 (Sheffield)

Day 1 (July 27th)

One of 3 truckloads headed to the site.

Before today, we had made several trips to the job site to ferry materials from the Tool Shed on Mt Greylock to a location near the job site.  For the largest pieces, we used the power wheelbarrow to carry many at a time.

A full load for the wheelbarrow

Despite a hot, wet summer we had nice weather for the first day of construction.  Our first tasks were to set the sills that the bridge would be resting on and to assemble the various pieces of lumber needed to create the three large timbers necessary to span the banks of the stream.  How big are they you ask?  They need to span a 28ft wide ravine with enough left over to rest securely on the banks--36ft in total.  In addition, they need to be strong enough to carry a reasonable number of hikers.  Using data from the US Forest Service, we found beams 4" wide and 14" deep would be required.

Early in the planning stages (over a year ago) we looked into the possibility of purchasing timbers of this size.  While they could be ordered, the logistics of transporting something this long and heavy (600lbs) to the job site were more than we could support.  So the plan is to laminate plywood and 12ft long 2x14's together at the site set them onto the sills with a bit of rigging.

Today we got the sills started by using a water level (a clear plastic tube filled with water) to make sure the sills on both sides were at the same elevation, we did not want the bridge to be sloped. 

Dave and Jesse use the water level to set the sill height

While the south end of the bridge could be set on sills dug directly into the bank, the north side  required about 10" of excavation to provide a level bearing surface.

North sill is set deeper into the ground

While one team installed the sills, the other began on the beams.  Because we had no workbench available, these would be assembled on the ground next to the trail.  Fortunately,  the AT crosses into a farm field at this location and there was relatively flat open ground to work on.  We laid out the first layer of 2x14's and blocked them up so they sat flat and straight along a taught string we set for that purpose. 

Don and Christine use a string to lay out the beam pieces.

After spreading a liberal amount of construction adhesive, 14" wide pieces of 3/4" plywood were screwed to the 2x14's.  Then another application of adhesive, and the outer later of 2x14's were screwed into place. 

Adhesive is applied

The lengths of all the pieces were arranged so that butt joints were always overlapped by two other pieces.  Finally, at each joint, bolts were installed to reinforce these locations. 

All joints reinforced with bolts.

While theoretically, this should work, we won't be completely certain until everything is in place.  We'll know more after the next project day.

Rock Steps at Kay Wood Shelter--July 2nd, and 9th 2013

On the blue-blazed side trail to Kay Wood Shelter, we have a short section that due to the available terrain, goes directly down hill for about 30 feet before leveling out at the shelter area.

Because it is straight down the "fall line"--directly down hill, the route water takes when flowing over the ground--and due to use (it's the lowest spot along the slope) this short segment collects a fair amount of water and allows it to run quickly.  The combination of volume and speed of water is a guarantee of erosion, creating a nice little gully, that of course hikers want to avoid, which means they walk along side of it, widening the trail and creating another site for more erosion.

The best way to address this issue, is not to let it happen in the first place.  Trails should cross slopes at an angle climbing/descending more gently.  Ideally, 12% is the maximum desired grade for foot trails to prevent water from getting up enough speed to start washing material off the trail.  For some perspective, an interstate highway specification is for no more than a 7% grade.  Another way to think of grade is the amount of "up" you need to cover in a given distance of horizontal travel.  12% is about 1" of up in 8" of travel.  A 20 foot section of trail at 12% would have a rise of about 28 inches.  This is noticeably steep for a hiker, but hikers and trail managers in New England consider this kind of slope a luxury.  Through tradition, or because of limited available land or geology, or just Yankee stubbornness, a 12% trail is pretty rare around here.

So, you have a steep trail and it is subject to erosion, what can you do?  First off is to find ways to get the water off of the trail at frequent intervals so it doesn't build up speed.  Waterbars are the most often used means--channels cut accross the trail, strengthened by rock or timbers--that sluice the water sideways off the treadway and into the woods.  Unless they get clogged with leaves, dirt, or rocks.  Or the rocks that strengthen them are not large enough or set poorly.  Or hikers walk around the ends pounding down the dirt and providing a new route for water to continue down the trail.  As a Maintainer, you can address the first of these shortcomings.  As a Trail Builder, you can address the second.  The third?  Well, that's up to Hikers.  There are vastly more of them than there are of the other two groups.  Just suck it up and go straight over the water bars--don't walk around them...

So, I've got that off my chest, let's talk about rock steps.  When you have no choice but to go stratight down (or up) and the slope is steep, steps are the only answer--and one of last resort.  Steps take a long time to build.  If you want them to last, build from rock--it never rots.  But, you need to have a source of rock that is suitably sized (big), shaped (has at least one flat side, preferrably two or more) and close to the work site.  You need to be able to set this rock deep into the soil and against other rocks so they will never move again.  This takes time and some skills that are best imparted by working with an experienced crew leader.  Surprisingly, you don't need to be a body builder to work with rock--even big ones.  Learning how to use simple tools and (occasionally, but rarely) a modest amount of basic rigging, regular people can move really heavy things pretty much right where they are needed--very slowly.  There is a level of craftwork that needs to be done, but you learn it by doing it.  The work is hard but honest, in the sense that you are dealing with elemental materials and forces.  The satisfaction is high, there's something to look at after a hard day (or days) in the woods.  This thing you have helped to create has an immediate practical value--and if built right, you can show it to your grandchildren.

OK, on with the project.  We had 8 of us at the trail head on Tuesday morning.  A large crew by our standards--and most welcome.  A short hike on a humid morning brought us to the shelter and project site.

We gathered around the blown out section and discussed our options--either by installing new steps directly into the existing gully, or creating the steps on an undisturbed slope immediately adjacent.  Keeping the trail's footprint small by staying in the gully had some appeal, but the exposed bedrock and likelyhood of continuing water problems favored starting fresh, and we were also able to take advantage of a slightly more favorable slope.

Mining crew at work while Don clears a downed trees

For this project, the rock "mining" was pretty simple.  Just up hill was an even steeper slope/cliff, that had produced what looked like a lot of reasonably sized and shaped pieces that would be easy to transport to their new home.

Some rocks are easier to get to than others.

 A good rule of thumb, "if it isn't too heavy to pick up, it's too small".  We wanted the largest rocks that we could find that were still possible to move.  Of course, to be truely useful, the best rocks have a couple of nice flat surfaces.  Soon, what seemed at first to be an abundance of material, was quickly winnowed down into a few really nice, workable rocks, and a bunch of lesser candidates--which we were going to use anyway.

Once pried out of the hillside where they had been sitting since the glacier left,  the next step is to get the rocks down to where they would be set to create a step.  Given the small work site, we did not want to just send boulders down the hill willy-nilly.  Being a bowling pin is not a good thing.

Anita and Jim coax a rock down the hill

Using a combination of rock bars and pick-mattock, rocks were coaxed/slid/flipped down the hill close to their ultimate location.

To create the most stable stair, each rock should rest on its neighbors below (and in some cases to the sides).   Putting the front edge of the next step onto the back edge of the step below works with gravity to keep everything together.  Simply excavating holes in the soil and dropping rocks in usually results in the rocks creeping downwards or being squeezed out of their position by frost and/or water flow.

Once the bottom rock is set, the slope behind it is excavated to receive the back of the next step.  The art of this process is gauging the size and profile of the excavation to match the incoming rock, and finding the best way to mate the surfaces where the rocks contact each other.

Step number two is landed by Silvia, Dave and Jim.

 More often than not, given our relative inexperience, we had to try several different orientations of the rock to get the best fit, while maintaining a reasonable height of step and level walking surface. 

Don, Jim and Denis coax step number three into place.

If the walking surface of the stair are rounded, slanted or look slippery, hikers will often bypass the steps, continuing the erosion process and widening the trail even further.

Day 1 has 8 steps in place.  4-6 more to go.

To help keep hikers on "the straight and narrow", the sides of the stairs are lined with vertical slabs and the earth on either side of the steps will be covered with "scree" rocks--loosely piled rocks that deter hikers from walking alongside the stairs, increasing the opportunity for more erosion.

Denis and Don install the last few steps

 On Day 2, we landed 6 more steps and installed the vertical slabs and scree rocks.  A few more steps than we had originally planned, but the actual number of steps needed to cover an area depends not only on the slope of the land, but the thickness of the rocks.  Our steps on this project varied from 4" to 8" in height.  At the top of the run, we installed a water bar to direct runoff away from the staircase.

The scree rock is stacked alongside the stairs to reduce walk around.

Work Complete!

Bog Bridging Gone Wild--June 22, 2013

More Bog Bridging 

 Today's project was to get a large load of bog bridge materials to a work site that was pretty remote (for Massachusetts).  It is a good mile and a half in from the road, and the AT passes over some pretty rocky terrain on the way.  We also had over 75 pieces of lumber to deliver to this distant location.

In previous posts, I've gone into some detail about the why's and wherefore's of installing bog bridges, so the topic of this post is about Transportation.  This particular work site is so far into the woods that we were definitely considering harvesting some nearby trees to use for materials.  However, scouting around we found only a few that were suitable.  They needed to be Hemlock (moderately rot resistant and straight of trunk), have a diameter 12" but not more than 18" (larger would be too heavy to move), and provide enough length for the 200ft or so of trail that needed work.  They also had to be reasonably close to the worksite and have enough room to fell them without hanging up in other trees.  While we did find a few possible candidates, using them would mean that 10 years from now, we'd be in the same situation--but without any suitable trees.

The other issue was that processing (felling, debarking, splitting, transporting, notching and installing) native trees requires a measure of experienced crew power, and we would have needed to devote several project days to this effort--did we really have enough time this season to devote to this one project?

Instead, we decided to use our usual rough-sawn Tamarack lumber and  offer the project to any interested service groups.  Most service groups can put a fairly large number of people into the field on a given day.  While most are not particularly skilled in trail work, they are eager to assist, and enjoy a day outdoors--even if it means carrying pieces of wood and nailing them together in a mud hole.

However, even the most enthusiastic group would find the required 75 3-mile round trips daunting, so we looked for a way to reduce the distance from the materials cache to the worksite.

Our first idea was to make use of a power line right of way that crosses the AT 3/4 mile from the project site.  Scouting this access revealed a cliff between the road and the AT that we would not be able to get the materials over.  However, a few years ago, the local snowmobile club had cut a trail through the woods that bypassed the cliff so they could ride (illegally) on the power line.

Don, Steve and Silvia on the power line

This turned out to be the best approach, so we organized a work party to schlepp the goods to the AT, where the BSA troop will pick them up for a 10 minute walk to the jobsite.

 We decided to use a power wheelbarrow to transport several pieces of wood at once.  This is essentially a motorized, track driven bin that has a pretty light footprint and can travel over forest duff and occasional wet areas little damage to the ground.  It can carry about 400lbs at a time, up some pretty impressive slopes.  It is however, very slow and does not handle rocky or uneven surfaces very well.

Don returning with an empty wheelbarrow

The 3/4 miles of power line travel on existing twin track was not without it's challenges.  After about 3 weeks of rain, the lower areas of the vehicle track are pretty wet.  Muddy water hides two 18" deep trenches left by power company maintenance vehicles.  Stay centered to keep the wheelbarrow from sliding into them.

Climbing a steep slope with a load of planks

 Once in the woods, we followed the old snowmobile trail up the hill to the AT.  We typically have a spotter in front to point out rocks or other obstructions to the operator.  The wheelbarrow has very short ground clearance, and can get high-centered on protruding rocks, or if canted too far to the side, will turn over under the wide, heavy loads we placed on it.

After 6 round trips we got all of the pieces to the staging area near the AT where the scouts will hand-carry them about 1/4 mile further to the work area and install them later this month.

Last load to the drop off point.

In late July, Scouts from BSA Troop 1 in Pittsfield transported and installed all of the materials on the AT.

A Hardened Patio for South Wilcox

The new South Wilcox shelter built in 2007 has the usual patio out front under the shelter overhang.  The patio was constructed by building up a rock retaining wall and filling the interior with rocks and mineral soil to create a level area that the picnic table could sit on, under cover of the shelter overhang.  In a project earlier this year we moved the privy at this site, (which had not been moved for 10 years by the way!) and made repairs to the rock retaining wall around the patio. 

So today our project team of Don and I started out with buckets of mineral soil from the pit behind the shelter to level the patio.  We used a long board found under the shelter as a screed to flatten and level the area.  The leveling was done by eye as yours truly forgot to bring along a level!  I would guess we put down a dozen or so buckets of mineral soil to accomplish this part of the job.  Then we mixed buckets of mineral soil with concrete (we had previously lugged in a 94# bag of cement!) in a ratio of 3 to 1 and spread the mix about 1/2" to 1" thick over the whole area.  Lastly it was time to sprinkle water over the whole area and watch the cement set.  Well actually we decided to have lunch! 

Here's what it looks like all done:

We put boards around the patio and posted a sign on the shelter center post asking hikers not to step on the patio until Friday and to feel free to put the picnic table back on the patio at that time.  Hopefully the cement will have set by then.

The idea of this whole effort is to reduce the amount of dirt that gets into the shelter from hiker foot traffic by providing a relatively hard dirt free surface in this area.  It should also make for a surface that is less likely to get uneven and erode.  There is a bit more rock work that could be done to strengthen the corner opposite the stairs but all in all we have a much improved patio. 

We have a number of open project days on our schedule this year.  If this effort at South Wilcox is successful, we may try to make the same improvement at the Noepel shelter later this year.  Anyone got some good ideas on how to lug 94#'s of cement up to Noepel?

6/4/13 Timber Steps at Furnace Hill Road

Today we addressed a long-standing problem on the Trail just south of Furnace Hill Rd, in Cheshire.  The trail crosses a deep drainage dip, probably created when the land was logged off in the mid-1900's.  At the bottom of this ditch we built a simple bridge about 5 years ago, but the 12ft climb back up through soft soils has been the site of a number of solutions over the past years, none of which were very satisfactory.

For this attempt, we decided to use large timbers to provide durable steps up this steep slope.  Many years ago, a trail volunteer salvaged some 6x10 timbers from a bridge being demolished in Pittsfield.  For a long time they have sat in the pile of materials adjacent to our toolshed waiting for the appropriate project.

We cut several of the timbers into 5 ft lengths and pulled out all of the old nails that were still embedded in the wood from its previous life.  Being treated with preservative, these chunks were really heavy, probably over 100lbs each.  Fortunately, the project was close to the road and we had a good crew on hand to tote these beasts up the hill.

Once on site, we demolished was was left of a rotting stair made from native logs, and a few of the undersized rock steps that were sliding down the hill.

Clearing out the former steps

Don and Dave started to excavate trenches to insert the new timbers in the lower section, while Denis started on the top two steps.  Sim started on a large drainage dip up hill from the stairs, so water draining down the trail will be diverted, reducing the erosion of the bank that supports the steps.

Setting the timbers

Figuring out at what height and distance to set the timbers was the tricky part, the slope of the hillside varies, and the steps needed to conform to it so to keep a reasonably regular interval for hikers.

Don drives rebar to pin the steps

Denis places rock to secure the timbers

The steps were pinned to the soil with re-bar stakes, but the stakes alone will not be enough to resist the weight of the backfill dirt and hiker traffic, so rocks are set at the ends of the timbers to help stabilize them.  The timbers are also installed leaning back slightly into the hillside.

 Once secured, the gaps between the timbers are filled in with mineral soil harvested from a "borrow pit" dug out of sight of the trail.  Mineral soil is the dirt that is below the soft 'living' layer that supports most of the plant life in the woods.  Mineral soil doesn't contain any roots or vegetation, so it packs down well, and won't shrink over time.  The borrow pit is then filled in with brush and branches to as not to be a hazard to people who are off-trail.



So, you may be saying, "these timbers don't look very natural, why didn't you use rocks, or logs harvested from a nearby tree or two?"  Rocks certainly would have been a longer lasting and more natural looking material, but large enough rocks were not available in this location.  To survive, rocks for steps must be very large, so most of their bulk can be buried in the soil, otherwise they won't stay in place.  The smaller rocks at this location just did not have what it takes.  Locally harvested logs were previously installed and lasted only a few seasons in this damp location.  The treated bridge timbers will last longer, and being close to the road and within sight of neighborhood houses, we did not feel we were diminishing the trail experience for hikers.  Another alternative, building side-hill trail that would switchback up the slope with no structures, was not possible in this location either.  We would need approximately 75 feet of footpath to climb this slope, and AT lands here are very narrow--we would have been well onto the neighbor's property.  So here we are with timbers.

An important final element to the project was the construction of a large drainage dip just uphill from the stairs.  No matter what materials or type of construction we installed, if large quantities of water pour over the steps in heavy rains, nothing will stay in place for long.  The drain will divert water coming down the hill away from the steps.  The local maintainer will need to make sure debris does not collect in the drain--if it is overwhelmed, we'll eventually loose the stairs too.

Just as we were wrapping up, we had our first customer, an NB thruhiker, who seemed to have no difficulty traversing our work.  Apologies for the shovel handle in the picture, my photoshop skills aren't up to removing it.


Cosmo