I spent sometime looking at the Q and A site looking for guidance on having extra blocks on an approach transition.
If my memory serves, I did not think that MwRSF was keen on adding blocks on an approach transition.
We have been of the option that double blockouts in a transition area would not affect the system performance. Transitions don’t deflect much, so the posts shouldn’t twist or fail prematurly, and deeper blockouts would help with vehilce–to-post snag. However, we are skeptical of triple blockouts (24” and up), and have recommended the use of triple blockouts to 1 post location per 50-ft until further evaluation is conducted.
How deep was “SuperBlock” in Des Moines, Iowa?
First off, we did not like “Superblock”. I believe they wanted to use up to 48” of blockout at 3-5 post locations adjacent to the bridge rail.
You do not need to double block an entire system. Double blocks may be used on only 1 or 2 posts were the obstruction is located.