While Level of Service (LOS) criteria is a concept that can be applied to many other transportation facilities and aspects,  among the LOS criteria that have been the subject of much criticism (and perhaps rightfully so especially in the context of safety) are the ones used for intersections. These are associated with delay reduction, which always favors vehicular throughput. The latter means basically, high LOS corresponds to prioritizing car (or motor vehicle) movement while not particularly taking into consideration the safety and movement needs of other road users (not using motor vehicles). Here is an interesting article on this matter:

Boenau, A. (July 9, 2025) “The old traffic math that keeps destroying neighborhoods,” Fast Company, https://www.fastcompany.com/91362348/road-design-traffic-math-destroying-neighborhoods-los [Last accessed: 7/15/2025]

Quoting from the article:

Here are three important questions for experts to ponder:

1. Is slow-moving car traffic ever safer than fast-moving traffic? 
2. Do we have any obligation to provide safe and convenient access for people when they aren’t inside cars?
3. What are the economic downsides of wider, faster streets in the central business district?

When planners and engineers truly wrestle with those questions, they can choose to remain a conformist who ignores the damage of traffic metrics, or become an outlier in the industry and make a positive impact that might be felt for generations to come. Things can get better in the end.

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Again, I must say that rethinking roads and streets should be context sensitive. Still, safety should be the top concern especially for areas that is predominantly residential and/or school. Safety, after all, comes first in the definitions of transportation and traffic engineering.

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