The objective evidence shows an increase in rear-end crashes but a reduction in injury and fatal crashes, offering a net overall benefit.

Council et al., 2005 -- https://www.fhwa.dot.gov/publications/research/safety/05048/...

There's a regression to the mean issue at work.

Sometimes an intersection simply has bad luck, draws more accidents than anything about it would cause. Put a camera there, you'll see an "improvement".

One might argue the intersection itself is the problem and should be redesigned, as well as adjoining roadways feeding into the offending intersection.

If it's consistently high something needs fixing. But accidents are random, there will always be some intersections that by pure chance have more accidents. Put cameras on those, presto, cameras "work".

Some intersections having more accidents by pure chance is kind of an oxymoron, imo.

What's an oxymoron about it?

Let's make a hypothetical city with 10 intersections, all absolutely identical. Watch until you have seen 20 accidents. Do you really think there will be exactly 2 accidents per intersection??

Select the intersection that gets the most accidents, declare it dangerous.

Case A: stick a camera on it. Case B: do nothing. Watch another 20 accidents.

In both cases you expect to see fewer accidents at the intersection as the original number was just chance. But if you're trying to prove cameras work...

This states that there are many variables they were not able to control for, such as the yellow light timing, as I previously mentioned. Warning signs were another major factor. There doesn't appear to be enough investigation into the protected left issue.

This is pretty damning, in my opinion. AKA we did some cheap analysis on a small dataset, without confidence or effect size, and just agree with the people running the programs.

"The intent of the multivariate regression analysis was to confirm the direction of the effect, not to establish effects with statistical significance or to assess the size of the effect. To undertake analyses for these purer purposes would have required a substantially larger database, much more precision in the estimate of economic effect at each site, and more accurate specification and measurement of the independent variables. For the purposes of this current investigation, it suffices that both the univariate and multivariate analyses are reasonably in accord with the perceptions that are commonly held by those involved in red-light-camera programs."

> generally because the operators lower the yellow light time to increase fees

I'm skeptical of this claim because the red light camera operators are usually contracted by municipalities. They don't have any direct control over the light cycles.

(Yes, obviously they can be in cahoots with the municipality, but I would be surprised if that was common and not the exception)

Do you have any evidence of this?

Chicago is one publicized example. https://slate.com/news-and-politics/2014/10/chicago-shortens...

I am chosing, perhaps naively, that the Chicago red light cameras are an exception and not common because that whole process was criminal: https://www.justice.gov/usao-ndil/pr/former-redflex-ceo-sent...

That I couldn’t say. It at least provides a model. Most city or county governments have some influence over their traffic engineering or streets staff as far as high level planning concerns.

Neither of you share any references for the objective facts you claim to be stating. At least link an article or a study.

can this not be regulated? yellow light timing must not have changed for the last 12 months before adding cameras

Better to set it using a standard such as 1 second per 10mph of speed limit.

Maybe people should brake on yellow lights.

So the objective evidence indicates that yellow light timing is the most important factor in reducing accidents.

Why are we discussing cameras?