Fence on Pedestrian Bridge - need railing?

[Ben29]

I have a client that wants to provide a fence for a pedestrian bridge. My job is to provide calculations proving that the fence works as designed. The fence is providing a complete enclosure of the bridge because a METRO train runs above this pedestrian bridge. I was told to follow the 1997 AASHTO Guide Specifications for Design of Pedestrian Bridges. This guide does not mention anything about railings or fence. So I am referencing AASHTO LRFD Bridge Design Specifications Section 13.8.2 which gives design live loads for railings and fence.

So here is my question: If I have a complete fence enclosure over the entire bridge walkway, do I need railings? I can't find anything in the code that tells me that I DO NOT need railings. This is just a pedestrian bridge. There is no vehicular traffic on this bridge.

I have attached (2) drawings. One drawing is a section through the enclosed fence. The other drawing shows an elevation of the fence. In the elevation, you can see how they have railings beyond the fence enclosure.

 

[Ron]

If the fence can handle a 200 lbf lateral load or a 50 plf load in any direction, you would not need a railing.

 

[jayrod12]

Agreed with Ron.

 

[BUGGAR]

Is ADA an issue?

 

[Lomarandil]

I don't know where this requirement would come from (foggy memory), but might you still need a continuous handrail at the correct height?

 

[chicopee]

Somebody may need to use these railings as handrails, so yeah, BUGGAR has a point.

 

[racookpe1978]

Most people will feel more comfortable WITH a handrail at 36 inch above ground.

(But with that much steel wrapped all around me, in a long enclosed tube of bare steel and fencing, I'D feel like I were in cattle chute headed to the boxcars for a concentration camp! )

 

[bridgebuster]

Never thought of it that way but you have a good point.

 

[racookpe1978]

That style is at least a little more "open" ... A more circular arch - one that curves out a bit more, would be more attractive. Too damn bad we can no longer trust people to just walk in the open over a highway.

 

[bridgebuster]

you still have some trusting souls here

 

[thaidavid40]

I happened to notice on the framing isometric view of the top horizontal chain-link arms that the slots in the cap plates are aligned on the same axes as those on the posts. Wouldn't one set of slots - say the ones on the post's cap plate - need to be turned 90 degrees, to cross with those on the arm's plate? That would allow for the greatest amount of field adjustment and fit-up at erection time.
Just a quick observation,
Dave

Thaidavid

 

[ACtrafficengr]

Shoot.

The county I work for bought a disused rail right of way. The state DOT made us put up hooligan fencing on an overpass over a state highway. I never thought about whether it would meet handrail loading, and apparently the state permit engineer didn't either.

 

[Jourdan730]

I talked with some of my academic advisers and engineering specialist and there is some haziness about the hand rails. We as a group feel that there is a requirement to have the hand rails for those citizens with disabilities. Now, the circumstances are different based on the actual purpose of the bridge, but this isn't a concrete fact so please take into consideration looking more into more specialized handbooks and or manuals to pinpoint our information about the hand rails. I hope this help.