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I am wondering if it is possible to modify the railing in one of two ways. Not sure if a zoom is required, but if the answer is maybe and not either yes or no, maybe we can set one up next week?

We are having a conflict with Right of way and these are two options modifying this railing we are considering.  Can we embed the post in concrete (same exact steel tube mounting bracket that we used to attach to the outside of our bridge but embedded in the wing with confining spiral (wing is anticipated to be 12-18 thick).  Or maybe use a deeper embedment (again with the steel mounting bracket but embedded deeper  (say 24 inches  (bracket might be 26.5” instead of 14.5” tall)).

The other option is to modify the attachment to the deck to work with a wingwall system (not a claw connection, see below) and add a block out (see attached) similar to what we would do for the MGS (I understand that the post flange gets narrower, but you a have a bolt hole already, I am just concerned about whether the block out might twist or dislodge or otherwise cause a problem.

Road design is 45mph with posted at the same speed.  Road is basically straight.  Design ADT is 1700 in 2045. 3% trucks. No crashes in the last 5 years.  If one of these 2 option works we will have 24ft wide roadway for 2 lane traffic. We would be  widening the bridge 4ft and are confined by ROW. If we have to try to move the MGS up to the bridge the wingwalls will move out and the bridge will be narrower.

As you note, it is possible to modify the connections such that the steel sockets are embedded in the top of a reinforced concrete wall. Originally with the MGS bridge rail, we discussed options to place sockets in the top surface of RC bridge decks; however, no designs were configured nor tested.

Further, it is possible for the side-mounted systems to anchored to the side of RC walls in lieu of bridge decks as long as the wall can handle the loading conditions.

In general, we have not used blockouts with the weak-post railing systems.

Thanks, and let us know if further information or clarifications are needed.

I agree with my colleague that it is difficult to use blocks on the weak-post systems.  Narrow width flanges limit the use of 5/8” guardrail bolts and the smaller 5/16” bolts used for S3x5.7 posts have never been used to support blockouts…  that could be interesting.

Embedding the socket in a thick headwall could work.  There is a risk of concrete breakout, but if the head wall has significant reinforcement, it should work. 

One more thought from me.  This may be a site in which the top-mounted TxDOT T631 bridge rail could be used.  It is a surface mounted version of the same S3x5.7 weak-post system that we are talking about.  The T631 was successfully crash tested at MASH TL-2 and TL-3 using 75”  and 37.5” post spacing, respectively, while attached to an 8” thick deck.  A thick headwall would be much stronger than an 8” deck, so it should work fine.  Food for thought…  here is a link for more info:

https://www.roadsidepooledfund.org/longitudinal-barrier/txdot-t631-bridge-rail-2/