They have. Two people were killed in the incident.
Trouble is, you- can spend all you like to make roads safer, but you can never legislate adequately for bad driving. That road is particularly bad in that respect. In the main, two types of driver use that road: the first is the business driver, who needs to use the road to get from Llanrwst or Betws to the coast. The road has a national speed limit, so 60mph is the speed most of them would like to use, but they're often thwarted by the second type of driver: the elderly, non-working driver who has no where to go quickly and thinks everyone rushes about too much.
In fact, a little more thought on the part of both these types of driver, and the road would probably be a much safer place.