Yellow lights shorter in Chicago
- ️Mon Mar 22 2010
The difference may be little more than a snap of the finger, but yellow lights on city traffic signals are shorter than ones in the suburbs. That gap is fast becoming fodder for a new and murky front in the battle over red-light cameras.
Most Chicago yellow lights last three seconds, the bare minimum recommended under federal safety guidelines. In the suburbs, yellows generally stay on for four to four-and-a-half seconds.
Cameras are touted as an effective tool to combat red-light running, but critics claim Chicago’s shorter yellows undermine that premise by making it harder for motorists to stop in time and inflating the volume of tickets.
City officials insist, however, that Chicago’s three-second yellows adhere to sound engineering principles and predate the installation of red-light cameras by decades. And they say the number of red-light-running violations caught on camera is tiny compared with the volume of traffic, proof that yellows in the city are not a trap.
Clouding the dispute have been unsubstantiated charges lobbed by camera opponents accusing the city of slicing yellows significantly below the three-second standard at intersections with cameras. Despite strong evidence to the contrary, the charges have been widely replayed in the media and become a factor in Springfield as lawmakers weigh stiffer controls on the automated devices.
Few traffic control innovations have stirred passions and suspicions more than red-light cameras, which first began to appear in the city in 2003 and in the suburbs three years later.
City and suburban officials insist they have turned to cameras only to improve safety, but there is no question that cameras also mean big money for cash-starved municipal coffers.
Chicago now has 186 intersections monitored by cameras, by far the most of any city in the nation. Last year, the $100 fines generated by those cameras netted the city more than $59 million.
As cameras have flourished, so have questions about their effectiveness in reducing red-light running and accidents.
The Tribune reported last year that state records showed collisions either increasing or holding steady at nearly 60 percent of the city intersections equipped with red-light cameras in 2006 or 2007. City records, by contrast, showed accidents going down more often than not at those intersections.
Yellow lights pose another conundrum in the battle over red-light cameras. If the devices are supposed to combat red-light running, do the city’s shorter yellows undermine that goal? On that, there is plenty of heated disagreement.
There is no universal standard dictating yellow time lengths. Federal guidelines, adopted by Illinois transportation officials, recommend only that yellows be set between three and six seconds. In practice, faster speed limits dictate longer yellows because it takes longer to stop when lights change.
With only a few exceptions, the speed limit on Chicago thoroughfares is 30 mph. Speeds tend to be faster in the suburbs — one reason why yellows last longer there.
A handful of suburbs, however, have installed red-light cameras at intersections where the speed limits are comparable to Chicago or sometimes a little slower — and those yellow lights are longer than in the city as well.
Using a video camera to enhance precision, the Tribune timed signals at nine camera-monitored suburban intersections with speed limits of 30 mph or less, conditions similar to Chicago. At two of those intersections in west suburban Bellwood, the yellows lasted four seconds. The other intersections — in Berwyn, Westchester, Schiller Park, Wauconda and Algonquin — clocked in at about 4.5 seconds for yellows.
But speed limit is just one factor in determining how long yellow lights should be, said Brian Steele, a spokesman for the Chicago Department of Transportation. City streets, for example, tend to be narrower, with buildings abutting the roadways, he said.
“What may have been successful in one community might not be successful in the city,” Steele added.
Indeed, New York, which has speed limits and street conditions similar to Chicago, also sets a three-second standard for yellow lights.
That said, New York builds in another safety factor that often goes beyond Chicago’s. Many communities program traffic signals to have an all-red phase, essentially a brief interlude following a yellow light in which lights are red in all directions.
In New York, the all-red standard is two seconds, while it varies between one and two seconds in Chicago. The Illinois Department of Transportation, which controls the timing on many camera-monitored intersections in the suburbs, sets all-red phases between 1.5 seconds and two seconds.
Steele said the city’s three-second yellow standard has been around for at least a half century. He also said a recent sampling of 14 high ticket-generating intersections found that 99.87 percent of all cars passing through did so without triggering red-light cameras.
Arriving at a common benchmark for yellow lights is difficult because traffic engineering is more of a juggling act between physics and human behavior than it is an exact science. If the speed limit is 55 mph, many people will drive 60 mph. Up the limit to 60 mph, and they’ll go 65 mph.
West suburban Lombard generally sets yellows on its traffic signals at between three and four seconds whether or not a red-light camera is involved. But John Johnson, a village public works supervisor, has upped the time to five or six seconds at accident-prone intersections, including one at East Washington Boulevard and South Westmore-Myers Road.
“We had a couple of accidents that landed vehicles in the front yard of the resident who lives there on the corner,” he said. “No one died, thank God, but ever since I [increased] that time up, I can’t recall another [major] accident.”
In downtown Naperville, with 25 mph speed limits and high-pedestrian traffic, yellow lights are 3.5 seconds, said Andy Hynes, a Naperville project engineer. But he said yellow light times can be as long as 4.5 seconds on higher-speed roads in the suburb, which operates cameras at three intersections.
Camera opponents point to anecdotal evidence that suggests increasing yellows can reduce red-light running. Several Georgia cities last year yanked cameras after a new state law forced yellows to be lengthened and violations plummeted.
Last fall, the suburb of Loma Linda, Calif., east of Los Angeles, increased yellow times from three to four seconds at four camera-monitored intersections and also saw a big falloff in tickets. “If politicians refuse to lengthen yellow lights and still claim red-light cameras are all about safety, then they are liars,” said Rhodes Rigsby, mayor pro tem of the Loma Linda City Council.
Camera foes also say research backs up their claims, citing in particular a study released in 2004 by the Texas Transportation Institute at Texas A&M; University. It concluded that increasing yellow times at select intersections by 0.5 to 1.5 seconds decreased red-light running by about 50 percent.
But James Bonneson, the lead researcher, said in an interview that his findings had been widely misrepresented. He said increasing yellow times would do little to reduce broadside collisions, the most dangerous type of crash associated with red-light running.
Having uniform yellow intervals, like those in Chicago, is more important in promoting safety than the length of the yellows themselves, Bonneson added. “If you increase all the yellows, people would simply adapt,” he explained.
In recent weeks, a group of anti-camera crusaders has gained considerable media attention with claims that Chicago has manipulated signals at several camera-monitored intersections so that yellows fall significantly short of the three-second standard.
But city engineering plans obtained by the Tribune through the Freedom of Information Act show programming instructions dictate three-second yellows at almost all signals tied to cameras. The instructions for the rest of the signals call for four-second yellows.
Using video, the newspaper timed yellow lights at more than 70 city intersections that have generated a large share of camera tickets. All but a handful clocked in with three-second yellows, and the rest were four seconds.
The 186 Chicago intersections monitored by red-light cameras are but a small fraction of the 3,000 city intersections controlled by traffic signals. For each of those intersections, whether they have cameras or not, the signal timing instructions are programmed into an electronic brain locked inside a secure metal cabinet by the side of the road.
At the Tribune’s request, city transportation officials recently opened for inspection the traffic control box at 99th and Halsted streets, the intersection that produces more red-light camera tickets than any other in Chicago.
Inside was a spaghettilike collection of cables and boxes, including a timer with a digital readout that scrolls through light cycles. A “3.0” popped on the screen whenever yellows illuminated on the nearby signals.
Bob Nelson, the general foreman of traffic operations for the city’s Transportation Department, said the cabinets are built with safeguards to prevent tampering.
Signal times can’t be altered without a security code, and only a handful of technicians know what it is, he said. As a backup, Nelson said, the system is also programmed to automatically revert to flashing red lights in all directions if for any reason a yellow cycle drops below 2.8 seconds.
“My family and people’s families drive through these intersections every day,” Nelson said. “It would be morally wrong and criminally negligent if we did something knowingly to get people hurt. We design it to make it as safe as possible.”
Originally Published: March 22, 2010 at 1:00 AM CDT