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A question came up regarding our low tension cable guardrail. We are needing to install a grated flume within the cable guardrail run. The flume is 4’ wide, so there’s no way to install it without conflicting with the 4’ post spacing of the cable guardrail. Are we able to omit 1 post or modify the post spacing in order to fit this flume within the run?

A couple of comments regarding your question.

1. The low-tension cable barrier system that you are asking the question about has not been evaluated to MASH at this time. Thus, any discussion on its performance would be based on information from the NCHRP 350 testing of the system.
2. Removal of an entire post spacing may cause some issues. If you recall, that system is designed adjacent to steep slopes. If we remove a post, the stiffness in that region may decline significantly. We had to reduced the post spacing to 4’ to allow the use of that system adjacent to steep slopes.
3. I think a better solution would be to widen the post spacing in one span sufficiently to get past the culvert. That should provide the lease amount of effect on the system stiffness.

Thanks!