I agree with OG; different jurisdictions have different rules. I've seen some places that have a minimum thickness based on trench width and others, like NYC, that have deflection limitations (3/4" in NYC). Also, it's good to check with the AHJ because they may have specific anchoring details.
Thanks I'm in NYC. I was told yesterday by a coworker that NYSDOT doesn't want plates down because there was a really bad motorcycle accident and the cyclist sued.
@jjalex1 - is it just in Region 11 or statewide? I've seen bridge plans for several projects in Regions 8 & 10 that had roadway plates. I also did a bridge project in Region 11 that had a roadway plate detail - just in case.
It's Region 11. Bridgebuster, what is the limiting criteria for deflection? I found the NYC DOT Highway rules August 2016 edition and it says for plating and decking if the deflection is more than 3/4", heavier sections or plates or decking or intermediate supports shall be used.
Of the plate? I've used Roark's before......but a FEA solution is a bit easier for me. The most common mistake I see people make is putting the load in as a point load.....when a pressure load cuts back on the deflection/stress.
Is it based on a single wheel load or maybe tandem or a UDL over the entire plate?
Just the applicable AASHTO service live load (plus impact). (Typically the HS20-44 load.) Most of the time, the geometry of a plate dictates a single wheel.
@jjalex1 - on NYSDOT projects that I've seen with plates, the thickness is specified. Meanwhile, they also have a policy for utility work in State ROW's, which says plates are permitted but nothing more. The NYCDOT Highway Rules only specify the maximum deflection. Attached is a plate "spec" that was used a few years ago on the Belt Parkway in Brooklyn, when the City was doing the Fresh Creek Bridge.
Yep, I've seen that done myself. AASHTO (16th edition, Sect. 3.30) calls out the tire contact area as: "...a rectangle with an area in square inches of 0.01P, and a Length in Direction of Traffic/Width of Tire ratio of 1/2.5, in which P= wheel load in pounds."
You work that out and it comes to a tire pressure of 100 psi...which is about what it typically is.
