Slippery bridges

[MissJean]

Slippery when wet!
What is best?
Prob ripping it out and building a new one, but I don't have the time or energy at the moment, so...

I have heard that a strip of roof shingle on each board is good. What is the best way to fasten them down? Galvanized roofing nails in the corners, or, maybe long staples?

Wouldn't a shingle cause the wood to trap water & thus rot faster tho?

I have also heard of putting down a lenght of chicken wire or that really heavy duty screening stuff (I forget the name). That would not trap water, but, if it wore through and the wire poked up, it could be a flat hazard.

What do ya'll think.

[S2RT]

groove the boards in the direction of travel with skilsaw ~ 1/4"d x 3/4" apart.

[splat]

Cover it with Chicken wire. works quite well.

[errollthin]

Hey I think I rode that today. Slid right off, problem seems to be always in shade. Epoxy paint with grit embedded.

[MikeT]

Gritty paint: Expensive, paint generally doesn't adhere well to pressure treated, especially the PT that is wax coated, and the grit wears off requiring recoat every few seasons, which is even more difficult on well used filthy, slimy algae covered bridge.

Roof shingles/roll roofing: Easily vandalized, will accelerate rot

Wire screening/Roof shingles/roll roofing: Roofing nails and staples will be difficult to get flush into hard pine PT. Protruding nails, staples, and broken wires bad for tires, worse for feet (not all hikers wear solid footwear), really bad for dog paws.

Grooving: Not practical with circular saw because batteries won't last and not always practical to bring portable generator to bridge site, and pre-grooving lumber offsite adds considerably to logistics. Could do with chain saw if you watch out for nails. In any case, cutting enough grooves in anything but a very small area will be tedious and time-consuming.

All of the above are workable in specific isolated cases (ie several broken bones/yr at the bend in one bridge), but in my opinion generally not worth it in a volunteer environment.

What do I do?
1. Use rock armoring or crushed stone instead of wood bridges where possible.
2. Make all bridges comfortably wide, 30 inches or 3 feet, 2 feet minimum, to give people some safety margin, confining narrow bridges strictly to difficult (diamond or double diamond) trails.
3. Make bridges very level (better than 3%) in the lateral direction (perpendicular to direction of travel). Sideways slides are what cause bad falls and longitudinal traction is provided by lateral decking, which I also recommend.
4. Tell people to be careful on bridges. The woods are an inherently dangerous place.

Future:
Rough cut lumber, but yards don't stock it and it is relatively expensive to have custom milled.
Recycled plastic, can be bought with grippy woodgrain embossed texture, but relatively expensive and comes in bendy 5/4 thickness.

[MissJean]

Thank you every one for your input.

Out of curiosity, I looked up trail rating on the IMBA site and the trails with the bridges in question would be a hard blue square or an easy black diamond. How'bout a blue diamond. ;)


Sideways slides are what cause bad falls and longitudinal traction is provided by lateral decking, .

Very true. I have a faint scar on my calf from just such a fall.


Rough cut lumber, but
yards don't stock it and it is relatively expensive to have custom milled.
.

As the bridges are being replaced, we are using rough cut lumber. (lesson learned!) There is a yard in Milford NH that has it. Everything else, even oak, gets too slick too fast.

I think just for a temp fix, until the fall when there will be more time, I'll do the chicken wire thing. There are very few, if any walkers, on those trails.

[S2RT]

Jean - Are these slick feaures at Yudicky?
S

[mcstumpy]

I know that bridge on Fireline with the 1/4 turn in it kills me every single time i try to get over it. wet or not...
I think I like it wet better than dry because I just fall off sooner!

[MissJean]

Jean - Are these slick feaures at Yudicky?
S

Yes.

[dirtrider2]

Mike T, sounds like pre-grooving the wood before you take it into the woods could answer some of the concerns you brought up. But I don't know how possible it would be to bring wood into this location. Someone mentioned grooving parallel to the course of travel. I don't think that'll work for traction or drainage. I think it'd be better to make a diamond pattern in the wood.

Dave Mitchell

[S2RT]

And it's a lot easier to "pre-score" with access to a radial arm saw.

[Tim]

Slippery when wet!
that really heavy duty screening stuff (I forget the name).


I think you mean "hardware cloth" - about 1/2" mesh galvanized screening? It's probably a bit tougher than chicken wire, but more expensive.

Tim

[C.P.]

I can (and have) put grooves by scoring bridge tops with a chainsaw...this method does come with certain qualifications though;)

[radair]

Here's an idea. Bring a cordless drill and a bag of 1" galvanized raised head hex wood screws and put them in strategic areas (maybe just the edges so you don't have to ride on them if it is dry). Easy, simple, and should last as long as the bridge.
I don't think that's a good idea, especially if they're only on the edges. Fall on those and it would be like falling on a giant rasp.

Scoring with a chain saw or cordless circular saw is the best route, IMO. Hardware cloth would work well, but requires constant maintenance so you don't get wires sticking up.

[Slappy]

Scoring with a chain saw or cordless circular saw is the best route, IMO.

Agree. Tried and true.

Wet washers and/or rounded screw heads will do zero to enhance traction. Sharp hex heads scattered along the edges will leave you with an unpredictable deck surface - slickery in spots, sharp and grabby in others, hell to fall on. There's enough opportunity to get hurt out there already w/o us adding more.

[Slappy]

A chainsaw's really not all that tough to deal with. Scoring a bridge on an established trail would probably be one of the cleanest and easiest projects you could use one for actually. A cordless circ saw would be even easier, just bring a couple batteries, set the depth how you want it and go to town. Gotta be far better than putting in hundreds of screws I'd think. (Figure on a 10' bridge, even if you only installed a single line of screws at each edge, spaced 2" apart, you'd be looking at 120. This approach accomplishes even less than simply screwing a length of strapping or something similar to the edges btw.)

[S2RT]

Even the washers will be slippy when wet, then they rust, then U fall and instead of a few splinters, U get rusty scuff marks. Those'll leave a nice mark...

Gotta stick with scoring, especially if you (bad word coming) PLAN your structure, and precut + score the decking B4 you get to the site. Gotta be able to find someone w/radial arm saw that can just pi$$ through the deck prefab.

BTW there is just such a "longitudinally scored" feature in Lowell Dracut in a seasonally muddy, shady spot. 2nd season, plenty of traffic, NO mold or moss, grooves are still clean. AND..... no slips ;)

[MissJean]

especially if you (bad word coming) PLAN your structure,
;)

Oh, them's fightin' words!

The main structure in question is the "Tobin" bridge on Barbwire. Made with oak decking & PT under structure.

The "plan" was followed ,to a point, but then the trial day boss had to check on other things & decking was put too close together so the water runs down the whole thing, rather than inbetween the slats, thus adding to the problem. (Live & learn, be very detailed when explaining things) And the sun never hits it.

The other structure in question on Fireball was built by someone before "plans" were invented. ;) When it is fixed, it will be fixed to the same high standard that was used when it's sister structure was fixed. That baby is not at all slippery.

[S2RT]

Oh, them's fightin' words!

The main structure in question is the "Tobin" bridge on Barbwire. Made with oak decking & PT under structure.

The "plan" was followed ,to a point, but then the trial day boss had to check on other things & decking was put too close together so the water runs down the whole thing, rather than inbetween the slats, thus adding to the problem. (Live & learn, be very detailed when explaining things) And the sun never hits it.

The other structure in question on Fireball was built by someone before "plans" were invented. ;) When it is fixed, it will be fixed to the same high standard that was used when it's sister structure was fixed. That baby is not at all slippery.

Problem #1 Material: ~1-1.5L 10% Bleach in a spray bottle; 1 floor brush (the kind Grandma used to use); Slappy's battery powered skilsaw; hammer & wood chisel; beer.

1. Groove the deck longitudinally (I like that word;)).
2. Create gaps between the deck boards (carefully w/skilsaw, hammer & chisel).
3. Mist w/bleach solution + scrub the deck till free of slimy stuff.
4. Rinse deck with beer.
5. Ride it.

[MissJean]

Problem #1 Material: ~1-1.5L 10% Bleach in a spray bottle; 1 floor brush (the kind Grandma used to use); Slappy's battery powered skilsaw; hammer & wood chisel; beer.

1. Groove the deck longitudinally (I like that word;)).
2. Create gaps between the deck boards (carefully w/skilsaw, hammer & chisel).
3. Mist w/bleach solution + scrub the deck till free of slimy stuff.
4. Rinse deck with beer.
5. Ride it.

Sounds like a plan! Have at it. :)