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TL-2 permanent concrete barrier

Question
State WI
Description Text

Could you review these drawings? My concerns are:

Can the footing be used with or without soil behind it?

Where is the LON point on the sloped end treatment?

What rate should the sloped end treatment be flared away fromt he roadway?

I know that the curb near the slope end treatment needs to be removed.

Keywords
  • Permanent Concrete Barriers
Other Keywords none
Date April 25, 2012
Attachment SE TL2.pdf


Response
Response

Can the footing be used with or without soil behind it?

I am assuming that "footing" refers to the 8" slab you have underneath the barrier, and that "soil behind it" refers to the soil fill on the backside of the rail which brings the groundline to the same height as the top of the slab on the front of the barrier.

For the barrier itself, this soil backfill is unnecessary.  Remember, this TL-2 barrier was tested as a bridge rail.  Thus, it was assumed that there was no fill behind the barrier at all.

For the end treatment, the soil backfill is necessary.  Note, all testing of this end treatment was conducted with the system attached to a flat / level surface.  If the ground surface on the backside of the barrier were significantly lower, roll would be introduced to the vehicle as it was impacting the upstream end of the system and the vehicle may become unstable (rollover)

Where is the LON point on the sloped end treatment?

The Length of Need for the low profile barrier system was defined as the joint location (or connection point) between the 20" high barrier and the sloped end treatment.

What rate should the sloped end treatment be flared away from the roadway?

TTI originally designed and tested this end treatment without flaring the system at all " it remained parallel to the roadway and inline with the barrier.  As such, the drawings included in chapter 8 of MwRSF's report no. TRP-03-109-02 "Development of a low-profile bridge rail for test level 2 applications" also illustrated a parallel end treatment.  The end treatment was never evaluated as a flared system.

 

Additionally, the height of your end treatment at its far upstream end is 6".  This height should be limited to a maximum of 4" (as was tested by TTI and recommended in the MwRSF report noted in the previous paragraph)

Date April 25, 2012


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