I have a river behind my house in rural Massachusetts that I would
like to be able to cross when I want to.  Depending on the season, the
center section is about 3-4 feet deep and 6 feet wide.  The total
width of the river, including the shallower outer edges is about 25
feet.  Outside of that area, there's a 5-10 foot wide area of muck on
either side.  So, total width of river area including the mucky areas
is about 35-40 feet.  The river floods every few years, becoming
considerably wider and a bit deeper.

We own the property on either side of the river, although our property
plan describes an easement for maintenance by the town, if needed,
although we've never had anyone come by.  We are surrounded by state
land -- we are the only residents who can see this section of river
and our land on the other side.  There are no town wells under the
river or downstream from us -- the river runs out to the ocean ten
miles downstream.

I would ideally employ something that doesn't permanently block the
river for ducks, herons, etc., but the more important considerations
by far are:
-safety
-environmental safety (non-polluting)
-durability
-affordability

I am very physically capable and could employ the help of another
rather physically capable person.  I have a tractor with cart,
wheelbarrows, etc.

I've thought about...
-putting in pilings and plank walkway over them (like a long pier)
-building small docks on either shore and putting a small boat in
-putting in two zip lines between trees on either side

Any new ideas (or thoughts on my ideas) would be greatly appreciated!

Thanks a bunch,
Dave

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Request for Question Clarification by cynthia-ga on 30 Jun 2005 16:51 PDT

Hi gettherefromhere,

In case someone wants to check the county for legalities...

1)  In what city and county do you live in Massachusetts?
2)  What is the name of the river?

~~Cynthia

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Clarification of Question by gettherefromhere-ga on 04 Jul 2005 05:39 PDT

The railroad flatcar sounds like a neat idea, for vehicular traffic in
particular -- thank you for that.  However, I should have been more
clear in stating that my sole use of the crossing method would be for
occasional foot traffic.

I don't want to discourage you, but before you even design any type of
structure, you might want to check with your county extension office
to see if anything is allowable. I have what I consider to be just a
creek behind my house, but the Army Corps of Engineers has
jurisdiction over it, because the whole area is classified as a
wetlands. Good Luck!

There's a really nice layout of a picket bridge on this site:

http://www.machovec.com/rope/bridges.htm

You would have to be a little more limber for this V style rope bridge:

http://www.glenn.cockwell.com/scouting/scouting_rope_bridge.html



Hope this helps a little
Mother911-ga

What a nice project!
My first idea is a suspension bridge, but this would probably require
vehicle access to both sides of the river.  I was contemplating a
single suspension cable supported by A-frame supports on each side,
maybe 20 ft high:  two tapered metal poles set 6 to 9 ft apart at
their bases, meeting at their peak.  (I was thinking of street lamp
poles or the like.)  You would get your physical effort in from
digging and pouring concrete foundations, especially for the anchors
to the cable.
The post foundations wouldn't be so much work, just enough to keep the
posts from sinking, since they would be supported vertically against
each other and by the cable  - and enough to take the strain of cables
carrying the walkway.

The "drop lines" from the cable could be attached before it is raised.
They would be fastened to cables across the river between the posts to
form the support for the walkway.  These would be drawn fairly tight,
and then the drop lines fastened to draw them up, letting the walkway
become narrower at the center as it curves up and down over the river.
Planks to form the walkway and maintain the distance between its
supporting cables.

Too ambitious?  Too expensive?  Pity, but it was fun planning.  :-)

IN a bit of self-justification, let me explain that I was composing my
comment while mother911-ga's was posted.
But I like the confirmation of this type of solution.  :-)
Mayoarin

Irish Lad's comment is pertinent. You really MUST consult the county
about this. In many parts of the country, there is usually no problem
provided you do not damage wetlands or create an erosion problem.

Thank you to all for your enthusiastic input!  In answer to Cynthia's
question, we are in Georgetown, MA (Essex County) and the river is the
Parker River.  On the property plan on file with the town, the river
and immediate surrounding mucky area is indicated as "wetland".  We
are careful stewards of our land and active with organizations that
protect the Parker River Watershed, which encompasses an important
salt marsh.

Assuming the government will let you install a bridge, and that you
want a semi-permanent, low maintanance bridge you can drive a car or
pickup over, AND that you want to save money...buy an old railroad
flatcar and land the ends on a solid surface.  It will last forever...

I like your idea for an elevated walkway. Part of the wetlands
adajacent to me has an elevated walkway constructed of recycled
plastic materials. The 4x4's, 2x4's and planking are all a dark brown.
It looks just like wood, but is totally resistant to rot. This walkway
is completely submerged about two or three times each season from
flooding and it seems to be holding up great. To install it, all that
was needed was a gas powered hole auger and a battery powered drill.

My biggest concern for you would be damage to your structure from
debris during the highest water flow. I have seen whole trees cruising
down the creek on the back of my place.

Good luck on whatever method you choose!