I'm a big fan of behind-the-scenes tours. Factory tours big and small, how it works, and inside-view opportunities are just too good to pass up. There's always some kind of unexpected technology, or problem that I never knew about and that someone managed to solve. Even small tours, like the three minute "how marshmallows are made" at Jet Puff was fascinating. (Unfortunately, they stopped
offering the tour in 1999 and closed
the factory in 2001; glad I got to see it!)
Earlier this month, the Fort Collins Traffic Operations department offered a behind-the-scenes look at how they manage the city's traffic. The 90 minute talk included examples of how they time the lights, what those "push to cross" buttons really do, and some of the big problems that they have to deal with (trains!). Some of the highlights that got my attention:
- Timing. The intersections on the major roads are all timed in sync. This permits traffic to flow while hitting few red lights. This reduces traffic congestion, lower fuel consumption, and reduces air pollution since fewer cars are idling. Timing the lights for one direction is easy. Timing it for both directions is hard. And adding in a new traffic light can throw everything off!
- Crosswalks. The button to cross doesn't change the light. Instead, it tells the light to stay green longer when it does change, so people have time to cross the road. If you don't press the button, then the light stays green just long enough for cars to get through -- not for a human to walk. Moreover, because the pedestrian altered the light timing, it may have repercussions for miles up the road (if this is at a timed light intersection). However, pressing the button does not do anything to make the light change to "WALK" faster.
- Short Left. We have a couple of intersections where there's a short left. That is, the left turn signal barely stays green long enough for 1-2 cars to get through a busy intersection. This solution came about from thinking about global pollution. Which causes less pollution: 3 cars idling as they wait for a left turn, or 20 cars idling while 3 cars make a left turn? The solution is simple: minimize the left-turn duration so that high volume cross traffic doesn't idle very long.
- Blinking Yellow Arrow. Fort Collins is getting more blinking yellow left arrow signals. Turns out, this is a national thing. Intersections with green left-turn arrows used to switch to a solid green to indicate "go when clear". But too many people thought that green meant go, so it caused accidents. The new solution is to use a solid green arrow for right of way and a yellow flashing arrow to mean yield to oncoming traffic. As the presenter put it, people don't know what a blinking yellow arrow means, but they know it isn't green, so they yield before going.
- Signs. The Fort Collins traffic department is responsible for maintaining all of the traffic and street signs in the city. There's about 80,000 signs! Street names, speed limits, directions, etc. That's about one sign for every two people in the city!
If you drive around Fort Collins, you are bound to see a huge number of cameras. Almost every intersections has directional bullet cameras above the traffic lights. The major intersections also have 360-degree cameras so the traffic department can look around.
Older traffic technology used induction coils in the ground to detect when a car was waiting. These had a few problems. First, the car had to be waiting over the induction coil for the car's metal to trigger the "car waiting to cross" sensor.
Second, the waiting vehicle had to have mass to trigger the induction sensor. Bikes and pedestrians didn't have the mass, so the sensor wouldn't see you waiting.
Finally, trucks were a problem. The cab of the truck would trigger the sensor. The rear of the truck's trailer (with the tires) would also trigger the sensor. But the middle of the truck's trailer was too far off the ground to trigger the sensor. As a result, a slow truck would look to the sensors like a single car turning. The truck would get through the intersection, but the line of cars behind it would either run a red light or have to wait another traffic cycle for the light to change again.
The solution? Use cameras! The cameras watch the lanes and "see" when there is a vehicle, bike, or pedestrian waiting. It turns out that these are more accurate than induction coils. Like most cities, different intersections come under construction each year. As they revamp the intersections, they are removing the induction coils and installing cameras.
At the control center for the city, they can actually display every intersection's camera. Green arrows appear on the screen when a car, bike, or pedestrian is "seen".
Big Little Brother
One person (not me) asked if they were recording all of this video. The short answer is "no". And they had two really good reasons:
- Privacy. If they don't record it then they don't have to worry about privacy issues.
- Storage. Recording video takes a ton of storage. That means higher maintenance costs. You need an expensive system for recording, hard drives are expensive, and administrative staff is expensive! Not storing video is cheaper.
So let's say there's an accident at an intersection. The traffic department can immediately see the aftermath -- sensors and cameras feed into an automated system that alerts to slow traffic and congestion. However, there's no recording of the accident itself.
The traffic department also emphasized that they do not feed traffic sensor information to the local police department. There are a few intersections in town with explicit red-light cameras. But the other cameras will not turn you in if you are speeding or driving recklessly. (Having seen the cameras and video feeds
, I don't think they have the resolution to capture a license plate. So they couldn't turn you in even if they wanted to.)
Go with the flow
Fort Collins also has systems for measuring traffic flow. For example, they can use the cameras to automatically count cars that pass through an intersection and measure wait times at traffic lights.
The traffic department also uses simulators, where they can estimate the impact of new lights timings, construction, weather, and even new lanes. Combined with the cameras (for counting cars), they can use this to determine how accurate their simulators are. (Really impressive!)
Beyond the cameras, the city is testing out other measurement methods. At many of the major intersections are bluetooth monitors. Every bluetooth device beacons an id. (The id is typically distinct, but not unique enough for tracking.) These bluetooth sensors hear your device's id as you drive though an intersection. When you appear at another intersection, they can approximate speed and traffic flow. Every smartphone with bluetooth enabled, every car with hands-free phone access, every bluetooth headset... they all permit the city to monitor the traffic flow.
Of course, I had another thought... What if I had a dozen friends go to a dozen intersections and all transmit the same bluetooth id? (The guy at the city department of transportation gave me a look and said, "Please don't.")
On news reports and podcasts, I keep hearing the same things. The Internet of Things is coming
. The Internet of Things is facing adoption challenges
. The Internet of Things will...
Guess what: The Internet of Things is already here. And it's been here for decades. Your car, your phone, and your headset are all IoT devices. The traffic lights and road sensors and crosswalks are all part of the IoT. Cameras watch you and make automatic adjustments so you can safely walk across the road. And you may have thought your hands-free driving system was just a convenience for you, but it also allows the city to optimize the traffic patterns so you -- and every car around you -- can get to your destination faster and produce less pollution globally.
Finally, I'd like to thank the Fort Collins Traffic Operations
for this great behind-the-scenes view (and the cookies). This was way better than anything on TV.