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People see red at Don't Walk on a green light
Mar 05, 2007 04:30 AM
Jack Lakey
Staff Reporter
A clash of competing interests plays out at Toronto intersections every time someone crosses the street with the blessing of a pedestrian signal.
When people use crosswalks to get to the other side, there's often a button on a nearby post that activates the "walk" signal – the familiar white figure in full stride.
Push button – change light. What could be simpler?
But there's a lot more taken into account with every signal change than most people realize.
An intersection's traffic volume and flow, vehicle emission restrictions, span of time needed for a walker to cross, the buildup of vehicles at the lights and the presence of transit routes are just some of the variables.
Savvy pedestrians won't be surprised to learn their ease of movement often takes a back seat to the car.
"Everything we do with traffic signals is a compromise," says Bruce Zvaniga, who's in charge of them in Toronto.
Our recent story about the seemingly conflicting signals at the intersection of Islington Ave. and Titan Rd. caused a flurry of emails and calls from people making similar complaints about other corners across and beyond the GTA.
Our story dealt with a reader's concern that pedestrians crossing Islington at Titan often faced the red "don't walk" sign while cars moving in the same direction had a green light.
If the button was pushed just as the light turned green, it often caused the red hand to continue to flash, stranding prudent pedestrians at the curb for the rest of the green and then the red before getting the go-ahead from the pedestrian signal.
That's exactly how it's supposed to work, Zvaniga said. Unlike intersections where the walk signal and traffic lights are synchronized, the pedestrian signals at Islington and Titan – as is true at about one-third of the city's intersections – can only be activated by pushing the button, he said.
Thus pedestrians who arrive at the corner just as the light turns green are deliberately held up until the next green appears, said Zvaniga, calling this a "car-centric" measure to cater to the high traffic volume on Islington.
It was a sore point in the calls and emails; people found it maddening to have to wait for two cycles of lights to get a walk signal.
Some didn't realize they had to push the button to order to activate the signal; others said people end up crossing against the red hand, sometimes causing near-misses with turning vehicles.
In the parlance of traffic engineering, Islington at Titan has a "semi-actuated signal operation," meaning the busier street stays on green until a waiting vehicle is detected at the arterial street or a pedestrian shows up and pushes the button. It's all in aid of co-ordinating traffic signals across the grid, Zvaniga explained.
"We need to know when the side street is going to see a red and the main street traffic will see a green" in order to co-ordinate traffic signals further north and south along Islington and keep the main bulk of traffic moving.
The semi-actuated system, which is used in cities all over North America, was introduced here in 1983, as a method for reducing idling times at intersections and curbing exhaust emissions, back in the days when concerns over global warming were barely a twinkle in the eye of environmentalists.
Metro Council set a goal of reducing fuel consumption by 100 million litres annually, and one way to do it was to reduce idling times at intersections, he explained.
Back then, most signals worked on a "fixed time" basis, in which lights changed automatically after a set period of time, regardless of the number of cars or pedestrians waiting at the red light.
There are still lots of fixed time signals today, said Zvaniga, noting that they're cheaper to operate and work well where two equally busy streets intersect.
If used at an intersection such as Islington and Titan, however, cars on Islington would often get backed up for virtually non-existent traffic from the side street, he said.
As it is, pedestrians are given 18 seconds to cross Islington before the traffic lights change to yellow. The walk signal shows for seven seconds and the flashing hand for the next 11 seconds.
But if just one vehicle is waiting on Titan to turn north or south onto Islington, the control equipment is set to provide a green light of just seven seconds. That's not nearly for enough time for a person to walk across, which is why the pedestrian signal must be activated, Zvaniga said.
Another two seconds of green is allotted for each extra vehicle waiting on Titan, up to six. The tally is done by electro-magnetic sensors in the road.
City transportation officials are well aware that many people don't like semi-actuated lights. They've heard as much from city council's pedestrian committee, said Zvaniga.
More pedestrian-friendly systems, such as cameras or sidewalk sensors to detect the presence of people waiting to cross and activate the signal, have been considered but aren't the answer, he said.
Infra-red sensing equipment shows more promise, but needs to be improved before the city would consider using it, and that could be several years away, he said.
People see red at Don't Walk on a green light
Mar 05, 2007 04:30 AM
Jack Lakey
Staff Reporter
A clash of competing interests plays out at Toronto intersections every time someone crosses the street with the blessing of a pedestrian signal.
When people use crosswalks to get to the other side, there's often a button on a nearby post that activates the "walk" signal – the familiar white figure in full stride.
Push button – change light. What could be simpler?
But there's a lot more taken into account with every signal change than most people realize.
An intersection's traffic volume and flow, vehicle emission restrictions, span of time needed for a walker to cross, the buildup of vehicles at the lights and the presence of transit routes are just some of the variables.
Savvy pedestrians won't be surprised to learn their ease of movement often takes a back seat to the car.
"Everything we do with traffic signals is a compromise," says Bruce Zvaniga, who's in charge of them in Toronto.
Our recent story about the seemingly conflicting signals at the intersection of Islington Ave. and Titan Rd. caused a flurry of emails and calls from people making similar complaints about other corners across and beyond the GTA.
Our story dealt with a reader's concern that pedestrians crossing Islington at Titan often faced the red "don't walk" sign while cars moving in the same direction had a green light.
If the button was pushed just as the light turned green, it often caused the red hand to continue to flash, stranding prudent pedestrians at the curb for the rest of the green and then the red before getting the go-ahead from the pedestrian signal.
That's exactly how it's supposed to work, Zvaniga said. Unlike intersections where the walk signal and traffic lights are synchronized, the pedestrian signals at Islington and Titan – as is true at about one-third of the city's intersections – can only be activated by pushing the button, he said.
Thus pedestrians who arrive at the corner just as the light turns green are deliberately held up until the next green appears, said Zvaniga, calling this a "car-centric" measure to cater to the high traffic volume on Islington.
It was a sore point in the calls and emails; people found it maddening to have to wait for two cycles of lights to get a walk signal.
Some didn't realize they had to push the button to order to activate the signal; others said people end up crossing against the red hand, sometimes causing near-misses with turning vehicles.
In the parlance of traffic engineering, Islington at Titan has a "semi-actuated signal operation," meaning the busier street stays on green until a waiting vehicle is detected at the arterial street or a pedestrian shows up and pushes the button. It's all in aid of co-ordinating traffic signals across the grid, Zvaniga explained.
"We need to know when the side street is going to see a red and the main street traffic will see a green" in order to co-ordinate traffic signals further north and south along Islington and keep the main bulk of traffic moving.
The semi-actuated system, which is used in cities all over North America, was introduced here in 1983, as a method for reducing idling times at intersections and curbing exhaust emissions, back in the days when concerns over global warming were barely a twinkle in the eye of environmentalists.
Metro Council set a goal of reducing fuel consumption by 100 million litres annually, and one way to do it was to reduce idling times at intersections, he explained.
Back then, most signals worked on a "fixed time" basis, in which lights changed automatically after a set period of time, regardless of the number of cars or pedestrians waiting at the red light.
There are still lots of fixed time signals today, said Zvaniga, noting that they're cheaper to operate and work well where two equally busy streets intersect.
If used at an intersection such as Islington and Titan, however, cars on Islington would often get backed up for virtually non-existent traffic from the side street, he said.
As it is, pedestrians are given 18 seconds to cross Islington before the traffic lights change to yellow. The walk signal shows for seven seconds and the flashing hand for the next 11 seconds.
But if just one vehicle is waiting on Titan to turn north or south onto Islington, the control equipment is set to provide a green light of just seven seconds. That's not nearly for enough time for a person to walk across, which is why the pedestrian signal must be activated, Zvaniga said.
Another two seconds of green is allotted for each extra vehicle waiting on Titan, up to six. The tally is done by electro-magnetic sensors in the road.
City transportation officials are well aware that many people don't like semi-actuated lights. They've heard as much from city council's pedestrian committee, said Zvaniga.
More pedestrian-friendly systems, such as cameras or sidewalk sensors to detect the presence of people waiting to cross and activate the signal, have been considered but aren't the answer, he said.
Infra-red sensing equipment shows more promise, but needs to be improved before the city would consider using it, and that could be several years away, he said.