Marston Mat Mudway

Marston Mats, aka perforated steel planking (PSP), were developed by the U.S. before World War II. The idea was to quickly build temporary runways and landing strips. They were first used at Camp Mackall airfield near Marston, North Carolina, in the U.S.

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A Curtiss P-40 Warhawk on a Marston Mat runway at Milne Bay, Papua New Guinea in September, 1942. – public domain

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I honestly don’t remember where or when I acquired four of these heavy metal planks, probably saw them advertised somewhere. I know I didn’t pay much for them. The idea at the time was to see about using them for my bridge deck. I wasn’t able to acquire any more at the time, so opted for the wood deck you see in the photos. One of these days I’ll replace that deck with something metal. I like that the perforations would let air flow through so the bridge would not be as vulnerable to high wind gusts.

Meanwhile during our rainy season, areas where we like to walk get more than a little muddy. The small creeks flood and send water everywhere. I’m always digging ditches to try to control the flow somewhat, but this particular area is low, so it’s always a mucky mess.

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So I installed some 2×10 planks I had as well as the four Marston Mats. Nothing much to it, other than first setting out short cross members for everything to rest on. While you could just toss the planks into the mud, raising them up a bit makes them more effective, and you can get them level to some extent. I screwed down the wooden planks, but the mats were heavy enough to be stable without reinforcement.

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When finished with the project, we noticed that Jeep the dog appreciated the wooden planks, but not so much the mats. He proved the point that the Marston Mats would not be the best material for a bridge, assuming you want to allow your four legged friends to come across with you. We’ll be watching for other options.

Thanks for stopping by! Be sure to check out our suspension bridge book. Here is the link:

Building a Small Cable Suspension Bridge with the Cable Locking System

Images, diagrams, and text copyright 2013-2016 by Marvin Denmark unless otherwise noted. Please do not copy and post my content anywhere without my permission. Thank you.

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A Simple Swamp Bridge

We continue to expand the trail system on our property in the Great Northwet, and that’s not a spelling error. Here in western Oregon many areas that are passable in summer become higher-than-boots water in winter. One spot we have is a small wetland that is fed by a stream that runs year-round, just not as torrential during the dry months. I decided it would be a good place to put a small stump-and-plank bridge so that we could connect two trails we like to use.
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I had some 20 inch diameter cedar posts that would work well for the bases. Planted in water and being cedar, they would not rot anytime soon. I cut them with a chain saw and then the fun part began – digging holes in deep mud, in water. Even in summer, it is a very boggy area. My goal was to dig until I hit more solid ground, but of course the sludge would just pour back into the hole as I shoveled. I dammed up in front of each hole as I dug to divert some of the water, and that helped. Mostly it just took persistence and a bit of mind over matter.
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I set the posts 10 feet apart for my 2×10 planks. If you use something smaller for planks, it is probably best to space the posts closer together. I cut the planks so that they centered on the posts and screwed them down. Then I used metal strapping to tie them together. I could add another deck using smaller dimension lumber to really beef it up, which I’ve done for other bridges on the property (more on them later!), but after walking across this bridge every day for several months now, it seems to be all we need for such a short span – about 40 feet. I might punch some metal posts on each end and the center and add a rope railing for balance. In any case, it’s not a bridge for the non-sober!
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Thanks for stopping by! Be sure to check out our suspension bridge book. Here is the link:

Building a Small Cable Suspension Bridge with the Cable Locking System

Images, diagrams, and text copyright 2013-2014 by Marvin Denmark unless otherwise noted. Please do not copy and post my content anywhere without my permission. Thank you.