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We’d like your expertise on an issue we may be facing at SCDOT.  Easi-set has FHWA approval for the J-J hook connected F-shape portable barrier, however when we prepared our Standard Drawings for these a few years ago Easi-set provided us with details for a jersey shape barrier as that was the more common shape their plants produced in SC/NC at the time.  We didn’t notice that details for a different wall were provided and now seek to verify that the jersey shape with J-J hook connections is suitable by MASH.

I’ve attached the eligibility letters which all seem to be explicit for the F-shape.  I’ve also attached the jersey shape detail as well as how we’ve shown that in our Standard Drawings.

Is it feasible for you to determine if the jersey shape would function similarly to the F-shape?  This would be for each of the free-standing, bolted (concrete), and pinned (asphalt) conditions.

We appreciate any insight we can get on this.  Please let me know if you need additional information or if you’d like to discuss by phone.

Thanks,

Joey

While I can't comment directly on the performance of the JJ-hooks barriers as a proprietary systems, I can make some general comments that may assist in your decision making.

In general, the performance of NJ and F-shape barriers would be considered similar. Both are similar in shape and height with the exception of the 3" taller lower barrier toe on the NJ shape. Computer modeling and crash testing has indicated that the toe and lower slope of NJ and F-shape barriers can promote increased vehicle climb and instability. However, full-scale testing of NJ shapes has not indicated failures due to the increased tow height. Thus, we would typically consider the general shape of the NJ barrier acceptable.

The second factor that comes into play when changing the barrier configuration for a PCB connection is the structural capacity of the barrier segment. For the barrier segments we are discussing here, the original, F-shape JJ-hook barrier tested to MASH had a reinforced F-shape with a 9" wide top. The NJ shape barrier proposed has appears to have similar reinforcement, but is only 9" wide at the top. Both barriers appear to use the same connection hooks and anchorage for the hooks.

We typically recommend that if one is changing the shape for a new connection with full-scale crash testing, that the new barrier segment have equal or greater structural capacity. In this case that may require additional reinforcement in the NJ shape segment to account for the narrower upper section.

We have conducted testing of anchored NJ shape PCBs for NYDOT and NJDOT where the top section of the barrier had significant structural damage that affected test outcomes when the barrier was anchored. That would seem to further reinforce the need for increasing the structural capacity of the NJ barrier with JJ-hooks if you plan to use it moving forward to be more consistent with the tested F-shape segments.

Hopefully those comments help you out. If you have further questions, please let me know.

Thanks!