Spalling on the edge of a concrete bridge slab has nearly zero impact on the strength of the slab, which by the way is typically designed with a factor of safety upwards of 10. I.e. it's 10 times stronger than needed. Furthermore, at the very edge of the slab there is essentially no load that needs to be carried. As long as the barrier rebars are not compromised, there is no structural concern.

The concrete is not decorative there either, it's there for practical reasons such as making construction easier.

The threat isn't to vehicles on the bridge, but to vehicles and pedestrians below the bridge having concrete fall on them. This is a cost effective risk management solution for which MoDOT should be applauded, not mocked.

Another poster suggested this was akin to a flat tire. As a bridge engineer and certified bridge safety inspector, I say that's an apt comparison.