A very well-written article at the Project for Public Spaces makes the compelling case for why LOS (level of service) is the wrong tool for sizing streets and roads. LOS is a way of measuring congestion.
As the article makes clear, some congestion is not a bad thing:
Asking the simple question, “Do you want congestion reduced at a particular location?” is a question out of context. It’s like asking you whether you want to never be stung by a bee again. Of course, the answer will be yes. But what if I told you that to in order to never suffer a sting again, every plant within a several mile radius would have to be destroyed — and that you could never leave the area of destruction?
You would have a completely different answer, I’m sure.
Plus, it has cartoons!
But seriously, here in this region we’ve been actively looking for better performance metrics than LOS (particularly metrics that account for how many people we can move through a corridor, rather than vehicles).