Road Guardrail Design, Timber Post 3

[McCarJ]

Where on the internet i can find design standards for road guardrails
I am using 8" x8" timber post spaced 6' on bedrock, how deep should i go for the rock, DO i need concrete foundation or backfill with gravel around the hole, Should i use rock anchors
Thanks in advance

 

[ACtrafficengr]

Is this a public road? If so, use an approved design as per your state's/province's department of transportation. If not, you may want to use a standard design anyway, for the following reasons:

[ul]
[li] Standardized parts will make repair easier[/li]
[li] Less liability should someone be injured in a crash with the rail[/li]
[li]Predesigned details for posts in rock[/li]
[/ul]

I think NYSDOT will drill a hole and backfill around the post with compacted gravel. If the rock is at the surface and sound enough, you might be able to treat it like a retaining wall, with heavy steel bridge rail posts bolted to anchors.

Just remember that eventually, you will have to replace posts, due to crash damage or rot.



"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail." - Wm. Phelps Eno, ca. 1928

"I'm searching for the questions, so my answers will make sense." - Stephen Brust

 

[PEinc]

Nice, AC

 

[bridgebuster]

Hopefully this link still works. It's the FHWA standards for steel-backed timber guard/guide (whatever the case)rail

http://www.efl.fhwa.dot.gov/techdev/steel-backed/sv-main.htm

AC - NYSDOT doesn't have any standards for timber railing. A steel-backed timber median was recently used on a NYSDOT project for historic reasons. The design was a modified version of FHWA.

 

[ACtrafficengr]

Actually, there is an item number for Ironwood (tm) rail. Also, back when I worked for the Department, we spec'd ConnDOT's steel backed timber rail in a job where the Hutch Pkwy becomes the Merritt.

The original poster was talking about timber posts, and said nothing about the rail elements. NYSDOT does have a wood post version of heavy post blocked out W-beam.

"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail." - Wm. Phelps Eno, ca. 1928

"I'm searching for the questions, so my answers will make sense." - Stephen Brust

 

[bridgebuster]

Timber guiderail is a special spec not a standsard one. I couldn't find timber posts in the standard sheets; I was looking in Section 606. Could it be elsewhere?

 

[ACtrafficengr]

There are a few references left in the NYS Highway Design Manual and Standard Spec book, but apparently wood post HPBO W-beam has been dropped as a standard item. It's probably for the best, since unless the soil is highly corrosive, galvanized steel would probably outlast wood posts in a wet state like NY.

In my county, we do have some areas where the soil will eat CMP in only ten years or so, but guiderail posts shouldn't be abraded by running water.

"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail." - Wm. Phelps Eno, ca. 1928

"I'm searching for the questions, so my answers will make sense." - Stephen Brust