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Morgan Wick

If I read the article correctly, which was more of a feature article than a news article, the change hasn't been enacted into law yet...


Another issue with LOS was the school-like grading system, with A being least congestion and (IIRC) F being most. The problem is that having an A or B expressways isn’t good—it means you’ve overbuilt, paid for more capacity than you need. Expressways really should be C’s or D’s—full. Of course, most people don’t read LOS level D as “Hmm, it looks like our infrastructure is being used—good thing we didn’t build more.” They read it as, “That’s awful, we want A-grade expressways.”


I have one nit to pick with the City Lab article: They seem too quick to move to VMT as the new metric, which would not capture the hyper-local impacts that an intersection delay analysis captures.

For purposes of scoring a project's overall impact, totally in agreement that VMT is the way to go. But as you take a project like this into design, it is still important to examine the impact of a transit investment on the surrounding street network - which includes both cars and buses. Many car trips will be diverted in the short run (not every trip can be replaced) and the impact of these trips on nearby intersection is studied through the delay analysis that produces LOS. Not every mitigation to additional intersection delay is a street widening - in many cases we can retime the signal to mitigate the new traffic patterns.

The confusing language around LOS needs to go, but a similar metric should be maintained for this type of localized analysis.


Yeah, I don't think that VMT is really a good replacement for LOS, especially for the local impacts mentioned above. What about passenger-weighted LOS, where the delays are measured not in vehicle-minutes but in person-minutes? Then speeding up a bus with 40 people by 1 minute wins over delaying 20 cars by 1 minute.


Re: Betamagellan.wordpress.com | 07/09/2014 at 01:21

I've heard said that the goal for rural/highway/flow-first/roads should be LOS A and the goal for urban/street/place-first/places should be LOS F. i.e. Designing for "what were you thinking of bringing a car into a city?!"


Just a hypothetical question: If we had priced roadways, would congestion still be viewed as a plus, or it is possible that congestion and price are a reasonable tradeoff? Because we won't get pricing if there isn't some value to travelers.

Congestion has the virtue of being income agnostic - nobody's exempt. To compensate, what happens if the rich decide to move to the city and price the poor out? That seems to be what's happening in my area, though I'm sure many factors are involved. Poorer families are increasingly found in car-dependent distant suburbs, where they can afford the rent but face astronomical costs to get around both financially and in terms of time from their day.

With priced roadways, the rich would have an upper hand on mobility, affording to travel farther. Would that help alleviate displacement of the poor?

I don't know the answer, but it has always seemed wrong to me that the best transportation answer is massive inefficiency. Congested highways carry only a fraction of the throughput of uncongested ones, while dumping pollutants from idling cars and killing more people in accidents. There's no end state on the horizon where congestion results in game-changing mode shifts; gentrification and stalled infrastructure investment are much more prominent on the horizon. Just pain to the bad people who keep finding it rational to drive.

Can't we think of a better strategy that has a chance of changing the game before our grandchildren have grown up and died? Personally I think most of the big environmental paradigm shifts have come from changes that add value rather. Insulating your house reduces your cost, but also keeps you cozy. Cleaning up sewage is good for the lake, but also gives you a beautiful place to recreate. But for transportation the only prescription seems to be to make things worse and worse and hope at some point it will be bad enough to spur a radical change we haven't thought up yet.

BTW, I agree, LOS is a ridiculous relic of the freeway planning days before anyone realized that people would move as the result of new accessibility and make longer and more frequent car trips as a result. That was a long time ago; time to move on.

Andre Lot

LOS is a useful tool for designing, planning and managing controlled-access freeways and expressways, which serve different purposes than local streets.

The problem is not the metric per se, but the context in which it is used.

Any metric that one picks up will have some shortfalls. A project that kills most activity on a given small area and displace most residents will severely reduce VMT ot PMT. Tearing up all high speed transportation links (airports, fast trains, highways, all paved roads) would obviously slash them as well, while throwing us back to 1820.

LOS is particularly useful for non-urban freeways, sectors where medium and long distance traffic dominate and bypasses, where free flow is important and no transit project can, within reason and without radically changing lifestyles and spatial organization, reduce the demand for road traffic.


How come we can't have a "transit level of service", with transit systems where riders experience long wait times (whether due to infrequent service, crowded vehicles, or both) getting an F, and insist that infrastructure projects not worsen this metric?


The concern here is that without LOS, cities will not have to provide any information at all about the effect of their actions (especially road diets. Granted that LOS is a very problematic measure, at least it conveys something about conditions on the roadway.

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