I think there is a sign, but it's pretty small (not regular size) and with the trees and parked cars on both sides of the road, it's pretty hard to notice it in time. I was wondering if the restriction sign should be on both sides of the road as they have in most other places?
In the same school area, there are signs on Moss Hall Grove on both sides, so you can easily avoid it and turn right into Thyra Grove (which I did a few days ago).