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I have a question about whether a MASH-compliant barrier curb with a chain link on top needs to be retested to ensure it is crashworthy. The last sentence of Section 5.9.3 of the NJDOT Roadway Design Manual seems to indicate that only the chain link posts on top of the MASH TL-3 NJ Barrier curb or MASH TL-5 F Shape Barrier curb within the clear zone must be made breakaway (i.e., with breakaway couplings). Please advise.

There would be concerns about placement of chain link fences on top of barriers. MwRSF and the pooled fund developed guidance for the Zone of Intrusion (ZOI) under NCHRP 350. This guidance was recently updated in NCHRP 22-34. The ZOI is an area that structural components of a vehicle may extend past the top of a permanent barrier and contact hazards.

Chain link fences attached to bridge rails are subject to two major concerns. If the fence is located within the Zone of Intrusion (ZOI), which is the area behind the traffic-side face of the barrier into which a vehicle may protrude during impact, it must not produce excessive occupant compartment deformations, vehicle snag, nor occupant risk due to stiff beam and post members. Additionally, there is concern that vehicle impacts involving the fence, especially impacts with heavy truck vehicles analogous to MASH TL-4 or higher, may have the potential to disengage components or sections of existing fence designs.

In terms of Chain link fences, the most recent work was done at TTI. See below

https://static.tti.tamu.edu/tti.tamu.edu/documents/0-7082-R1-Vol2.pdf

https://www.roadsidepooledfund.org/wp-content/uploads/2024/06/TRNo.-617741-01-Final.pdf

https://www.roadsidepooledfund.org/wp-content/uploads/2022/04/TRNo613131-03-1-2-FINAL.pdf

Thanks!