Joe Tegtmeyer delves into the reported cracks for Road Surface Panels of the tunnel that TBC is building at Tesla's Giga Texas factory. Reportedly, the problem is with the Road Surface Panels laid as the floor of the tunnel. They seem to have cracked after they were laid and later all removed.

Again reportedly, the problem seems to stem from the choice of reinforcement material for these Road Surface Panels. TBC, reportedly, chose Fiber Reinforcement instead of traditional steel mesh...

This reminds me of the cracking tunnel segments of a tunnel (can't recall its name or the its exact place) in Turkey which had also used fiber reinforcement ... until also cracks appeared and that the builders had to switch back to steel mesh segments.

Joe Tegtmeyer's pretty interesting analysis is titled "Boring Company Giga Texas Tunnel Road Panel Issues, Mitigations & Probable Solutions".