General Road and Highway Discussion

[danbrotherston]

It is truly amazing how bad our signals are. And I also mean locally within the region.

This is what happens when you only measure one metric, and a pointless one at that...basically, we measure LOS, which is how the signal operates at peak hour for cars only. And there is also only one playbook..."LOS < desired LOS, add lanes or convert to roundabout".

What’s weird is that they don’t even do a good job of optimizing LOS for cars. Look at all those 4-lane roads with no turn lanes (Union, Belmont, Westmount, …). They build lanes that aren’t needed, but omit the turn lanes that are required to get the benefit of the additional lanes (compared with a 2-lane road).

One comment I have about LOS: I think the issue is not with the metric itself, but with how it is used. The idea of grading how well motor traffic is served at an intersection is fine; what’s not fine is the idea that reducing from LOS A to LOS B because of an added bike lane is some sort of disaster that must be averted.

Those roads were built in the 60s and 70s, before our "modern" traffic engineering. I think more lanes do improve LOS, at least in models, but turn lanes improve LOS at a lower cost while also improving safety.

As for LOS itself, not sure what you're suggesting? For one, region actually considers LOS B to be acceptable, but when you say how it is used, do you mean that it rules all? There's an old saying (well, I don't know how old it is) but its something along the lines of you build what you measure. This is highly relevant today (and in my technical job) and it's scary because our level of data collection has allowed hyper optimizations of many things in our society. But suffices to say, if you measure LOS, you will optimize for LOS.

My issues with LOS are basically the following:

1. It ONLY measures cars, not people. I think we all understand this problem.
   
2. It measures peak time congestion, and ignores all other times, which are also important and carry the majority of daily traffic.
   
3. It ignores safety, pollution, noise, induced demand, etc.
   
4. Most serious of all, it measures delay at peak time, and ignores entirely total travel time. Some of the cities with lowest LOS have the highest commute times. It is fundamentally the wrong thing to measure.
   

I suspect the reason we measure and optimize LOS is that it is easy. The issues I raise are much harder to measure for.