weakness- can't go under too much concrete

The suit’s lens caught Accelerator’s lips moving in a curse.
Shortly thereafter, the sky was covered by thick concrete.
He had entered the tunnel.
Of course, just a tunnel wasn’t enough to completely seal Accelerator’s movements. If so,
he would have been assassinated long ago. The interference was only something that
may happen. That meant his power could end up being weakened by some unknown
amount.
However, if he lost control of his power even for a few seconds while surrounded by
concrete and chasing after someone at over 700 kph, he would be dead. Scraping up
against the wall would be enough to turn him to mincemeat.
He couldn’t continue the chase.

- New Testament Volume 1 Chapter 4 Part 14