caltrans detail barrier

huangyhg

caltrans detail barrier
hello,
i am designing a barrier type 26 per caltrans detail b11-54. i am building this barrier on top of a new box culvert and wingwalls. on the caltrans detail, there are two barrier types:
1. type 26: on bridge deck
2. type 26a: off bridge deck
i don't know what caltrans means by "off" or "on". can somebody please clarify?
also, i am designing this for a civil engineer who is clueless about construction, as am i. he wants to know if, instead of us (the structural engineers) detailing the barrier, whether we can just call it off as "barrier per caltrans detail b11-54 type xx". i do not feel comfortable doing this. any recommendations? thank you in advance for any help.
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my caltrans standard plans and experience are a little dated, so please bear that in mind.
note that both of these types (type 26 & tppe 26a) are concrete barriers with an adjacent sidewalk.
the type 26 barrier shows the sidewalk on top of a "conc deck or finish grade" and indicates that the dowels at the face of curb and at the back side of the rail are embedded into that concrete.  the barrier is on top of a bridge deck, or possibly in your case, a box culvert with no cover.
the type 26a barrier shows the sidewalk with a thickened edge at the face of curb.  this is to indicate the section of barrier that is placed on top of the wingwall.  the reinforcing bars at the face of curb are completely contained within that thickened edge, while the vertical bars at the back face of barrier extend down into the top of the wingwall (or retaining wall or headwall) stem.
so, if your box culvert has soil cover, i think the type 26a is appropriate, with the back face bars extending down into the culvert headwall.  if it is a box culvert with no cover (direct bearing), i believe you would use the type 26 over the culvert, and a type 26a on the approaches/wingwalls (assuming the caltrans standard u-back wingwall configuration).
i also don't see any issue with referring to the caltrans standard plans for the design details (concrete and reinf.).  caltrans bridge plans do not detail these items separately, but merely call out the standard plans reference.  the standard plans are automatically part of any caltrans plan set.  in fact, if caltrans had done these plans (box culvert and barrier), you would likely see very little of these types of details in the contract plans.  both the box culvert concrete & reinforcing and the barrier concrete & reinforcing would be indicated by referencing the appropriate standard plans (like d81 and b11-54, for example).
if these plans are to be reviewed by caltrans, the b11-54 detail would be very clearly understood by the reviewer.
hope that helps.