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RE: N-J Barriers

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I’m not sure as to the application you’re interested in, but since you’re looking at a traffic barrier I’d recommend starting with the AASHTO specifications.


You will nee to consult with your client as to the design methodology, i.e. Working Stress Design or Load Factor Design, in which case you would reference the AASHTO Standard Specifications, 17th Edition with Interims; or the LRFD methodology, in which case you would need to use the AASHTO LRFD Bridge Design Specifications, 3rd Edition with Interims.


Also speak with your client as to the prescribed loading, such as HS20, HS20+10%, or HS25. These loads and the appropriate collision load application are identified in the AASHTO Standard Specifications. If your client requires HL-93 loading, then your would be guided by the AASHTO LRFD code. The LRFD code also stipulates various prescribed Performance Levels for barriers (and collision resistance of the bridge decks) based on vehicle types and load conditions. This has to be squared away with your client also. The LRFD barrier/deck collision loading analysis is a bit more rigorous than in the past, but worth the effort. Don’t forget that the bridge deck needs to be able to resist the prescribed loading to the barrier as well.


You do have some latitude with the reinforcing in the barrier so that will be another factor in determining the adequacy of the barrier. Check with your client’s standards or the State DOT standards for your project location, if your client is not a State DOT.


Hope this helps and good luck with the assignment.





Thomas J. Cummings, PE

Manager - Bridge Design Practice

Gannett Fleming Engineers and Architects, P.C.

One Penn Plaza, Suite 2222

250 West 34th Street

New York, NY 10119

P:  (212) 967-9833 Ext. 5244

F:  (212) 268-6684

E:  tcummings(--nospam--at)


From: j.n.sigalas [mailto:sigalasi(--nospam--at)]
Sent: Tuesday, November 21, 2006 7:27 PM
To: seaint(--nospam--at)
Subject: N-J Barriers



I am requested to support by calculations the adequacy of a N-J type safety barrier.

I would appreciate any info regarding code requirements related to design loads,strength and stability

checks etc.