Wednesday, February 6, 2008

Smile, You're on Red Light Camera!

I've been hearing a lot about red light cameras recently. With states continuing to pass legislation that allows their use, they seem to be springing up like dandelions across America's cities.

Many argue that the cameras exist as the modern counterpart to the speed trap. But it seems that the cameras are far from a cash cow for the local governments installing them.

Annually in the United States, approximately 800 people are killed in red light running crashes, and half of those are pedestrians or occupants of the car with the green light. In 2002 alone, over 200,000 crashes and 178,000 injuries occurred due to crashes stemming from red light violations. Indeed, red light running is the leading cause of urban crashes in the United States. Many cities are taking a stand.

Washington, DC saw red light running fatalities drop from 16 to 2 within 2 years of their red light camera program's implementation. Across the Potomac, Fairfax County saw a drop of 44% in red light crashes after installing cameras. According to violations of red lights in Virginia Beach tripled after the use of red light cameras was suspended.

A former Georgia Congressman, Bob Barr, editorializes that camera enforcement invades privacy and is just about generating revenue. Of course, his comparison between the succession of the Southern states and red light camera opposition is perhaps a little misplaced, but his point is commonplace. The National Motorists Association makes similar points. Still, drivers who obey the law don't need to fear fines, and ideally red light cameras shouldn't generate any revenue. The point of the camera is to reduce, perhaps to zero, the number of red light violations, so when they are working, revenue decreases.

(On a side note about personal freedoms, one wonders if Mr. Barr, who helped lead the effort to impeach President Clinton, would also be opposed to a camera monitoring when the White House had the red light turned on.)

A study conducted by the Federal Highway Administration (FHWA) found that each intersection fitted with camera enforcement saved approximately $38,000 annually in reduced right-angle crashes. This includes the deduction representing the cost of increased rear-end collisions at intersections with red light cameras.

It seems that a multi-prong strategy is the best solution to reducing crashes. A recent report by the Insurance Institute for by Highway Safety shows that Philadelphia had better results by extending the yellow phase (36% reduction in violations) before implementing cameras one year later (96% reduction). Additionally, intersection redesign could help to save lives and prevent injuries. Proposals include adding protected (left on arrow only) turn phases to signals, installing roundabouts, and prohibiting right turns on red.

The debate will likely rage on for years to come, but red light cameras reduce injury, death, and the costs associated with accidents at intersections. Drivers could make these cameras unnecessary by becoming more responsible motorists. After all, a crash occurs at a red light 23 times each hour on average in the United States.

Have an opinion too? Weigh in!


Anonymous said...

The major fault with a lot of these studies is the assumption that all right angle crashes are the result of red light running. Indeed, in permissive left turn situations, most crashes have nothing to do with red lights.

Regardless, the red light cameras, put in mostly with the best of intentions, are often manipulated by the vendor to increase profits.

That said, let me ask your opinion. On a highway signed 45 mph, what should be the yellow arrow light duration on a protected left turn arrow. The intersection in question has a lagging left turn. Often the bay is empty before the green arrow comes on. The double left turn bay is 480 feet long. I realize you may not have all the factors, but ballpark it.

Matt' said...

Well Mr. Anonymous,

I'm not an engineer (although I was once a nervous wreck from Georgia Tech) so it's not within my skillset to determine the length of a yellow phase.

As stated in the reports I linked to, lengthening yellow phases leads to better results (e.g. fewer crashes and fewer red light violations). In my opinion, red light cameras should not generate revenue at all. Neither should speeding tickets. It would be better if the proceeds of the tickets were donated to a fund for improving intersection design. But, if local governments don't have an incentive, they won't install them.

You seem well-informed, but I want do make sure that all terms are defined. When referring to turning movements there are several different configurations:

This signal housing does not govern turning movement separately from through movements. There are three lights: Red Ball, Yellow Ball, and Green Ball. Left turns can turn anytime when the Green Ball is illuminated, AFTER yielding to oncoming traffic.
( R )
( Y )
( G )

In this configuration, there is a phase of the signal when left turns are given an exclusive (protected) phase. Other times, they must yield as above with a PERMISSIVE signal. There are five lights: Red Ball, Yellow Ball, Yellow Arrow, Green Ball, Green Arrow. They are usually in one of two configurations:
( R ) | ( R )
(L-Y)( Y ) | ( Y )
(L-G)( G ) | ( G )
| (L-Y)
| (L-G)

These signals have an exclusive phase for left turns. Cars are ony permitted to turn when given a GREEN ARROW. Left turning movements and through movements have their own signal heads. There are three lights on each. The Left Turn signal head contains a Red Arrow, Yellow Arrow, and Green Arrow. The Through Head contains a Red Ball, Yellow Ball, and Green Ball.
left thru
(L-R) ( R )
(L-Y) ( Y )
(L-G) ( G )

The light to which you are referring could be either PROTECTED or PROTECTED-PERMISSIVE. I'm not sure which. Since it's at the end of the through cycle (lagging-left), in either case, I would suggest that the YELLOW ARROW be the same duration as the YELLOW BALL for the corresponding through movement.

However, I don't change my support for red light cameras. When the city of Alpharetta, Georgia installed cameras, they expected to catch a lot of people going through without even slowing down. What they actually discovered is that most citations were for people who continued turning after the PROTECTED left turn phase (Advance-Left) went red.

Accoring to a presentation I heard from Atlanta-based PEDS, left turns are the most dangerous movement for pedestrians.

Basically, what I'm saying is that I have no sympathy for anyone who runs a red light.

Matt' said...

Sorry, the formatting messed up the diagram I created for PROTECTED-PERMISSIVE above.

Configuration 1:
( R )
(L-Y)( Y )
(L-G)( G )

Configuration 2:
( R )
( Y )
( G )