So I was riding home, heading west going towards a fairly small intersection (for those in Denver, Yale and South University), and had a red light. I was the only vehicle going west, and moving about 20mph or more. Just before I begin to slow to stop at the light, I see the vehicles on the north/south (University) come to a stop, and two vehicles traveling east proceed through the intersection (i.e., the eastbound light was green). My light was still red, so I assumed that there was a left-turn signal for the opposite side, and that my through signal would change any second. At this point, I was thinking that I would hit the intersection with perfect timing. However, the signal for westbound traffic NEVER TURNED GREEN, as it normally would either before or after a left turn signal on the opposite side. Making the silly assumption that I was effectively clear, though the light was red, I went through the intersection, and nearly collided with two lanes of southbound traffic, which now had the green. Fortunately, those people managed to avoid hitting me, and I gave them an "I'm sorry" wave as I moved through.
Now, before you start blasting me, I know that red means stop, and I obey this rule far more scrupulously than most of the cyclists I see on the road, and I truly regret the idiotic way I rode this afternoon. Also, this little experience has taught me more than any forum chastizing will, so please refrain.
My problem is that, based upon my experiences as both a driver and cyclist, I had every reason to believe that the light for westbound traffic would turn green, if even for two seconds, as part of the normal cycle. This assumption would be no different for motorized traffic. If this is not reasonable, how can I tell which intersections are going to do this? Has anyone else had this experience? (seeking to dull the pain of stupidity)
I try to be as predictable as possible, is it too much to ask that traffic signals be predictable as well?
The BikeForums Team
-adv-
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I've had that happen severl times here in town, where I'm the only one at a light and there's not any cars on my side of the light. I guess it's from the bike not being enough to trigger the light sensors. I just go through when it's clear when that happens.
More weird - a couple of times I've gotten a green light, when the intersecting lane still has a green light too! I just go by common sense and forget the light colors anymore.
Bikepacker67
If I wait a full cycle, I just wait til oncoming traffic has a green, then just watch for oncoming right turners and proceed thru the intersection.
Left turns are a bit more tricky at a faulty light. Usually I do the same as above, inching out into the int until the oncoming traffic passes thru, then make my left.
Of course it helps that I'm always loudly dressed.
Bekologist
Ah, the nuances of traffic signal sprinting depend partly on being able to read the lights, and getting to know the signals on a route can be a big aid in sprints to beat the traffic.
the city sometimes changes intersection timing. sometimes the direction that gets primary left turns changes as well, making predictability of lights uncertain
.a few other things i've noticed...
I'm finding more and more traffic signals that have 4-5 car lengths of sensors that are sensitive enough to pick up a rolling bicycle...a lot of late night lights will signal for me if i roll the wire cuts in the pavement.
by tagging the "T" that may be painted atop the sensor with your bottom bracket, you can get sensors to give you right of way off a stop, even if cars approach from your opposing direction at a 4-way light.
got to love the sensors. but you can't trust the traffic signals to work the same way every time. emergency vehicles have transmitters that signal greens at some intersections, so watch out for those doggies.
you can usually get a good run due to a nearby fire station, or emergency fire/rescue vehicle after it has gone by.
In unrealated traffic safety issues, today i ran a red, ringing drawbridge signal with downed gates because there was traffic stopped on the span -i knew i could clear the deck before they would. rode across easy as pie.
UmneyDurak
Just a stupid sensor in the road.
thequickfix
The sensor thing seems to be a big problem; I usually can't trigger them on my own, and I have to wait for someone to come along in a car to do it. In a few instances, I have even circled around a car that has pulled up behind me (when I am the first in the lane) in order to have them pull forward and over the sensor.
The thing about this particular situation though, is it seems that, even if there is no traffic waiting on the westbound side of the intersection, a brief westbound green would seem to be a necessary part of the east/west street cycle. If this did, in fact, depend upon the sensor, I may never have been able to turn the light, no matter how many light cycles occured!
chipcom
You actually make a good point - lights are not predictable. I know the behavior of every light on my commute and the only common behavior is that there is no common behavior. It's like some evil traffic engineer senses when I got the behavior of a light down and changes it, just to screw with lil ole me some more.
I have one light that acts exactly like the one you mention - if there is no traffic in the through lane I just ride up on the sidewalk and push the ped button - of course once I do usually a car pulls up and I have an awkward time getting back on the road, but oh well, the good <your diety here> would not get his/her daily laugh if he/she didn't have me to screw with.
DataJunkie
I believe these particular lights are programmed to be a tad more intelligent.
Instead of auto cycling through the entire sequence it notices that the sensors are not triggered and skips that cycle.
I have this same problem with numerous lights in the denver metro area. Specifically, dahlia and hampden.
If no cars are around I have to trigger the walk button. bleh!
At times I have to take a longer break. Fortunately, I usually need a break at dahlia and hampden due to the hill.
Now if we could figure out how to trip these sensors 100% of the time.......
Or the traffic engineers could.....FIX them!
ItsJustMe
I've seen lights that skip the green on lanes that have no cars sensed in the lane.
If it doesn't trigger for a bike, it's defective; report it to the DOT and get it adjusted.
genec
I've seen lights that skip the green on lanes that have no cars sensed in the lane.
If it doesn't trigger for a bike, it's defective; report it to the DOT and get it adjusted.
Nice thinking, but what if you ride a carbon fiber bike?
LCI_Brian
Check this out for advise, although this only works when you can see the loops or reasonably guess where they are located:
I look for the automotive grease spot... first I want to avoid it, second, it indicates about where the mass of the engine usually is... and just to the right, about a foot and slightly forward less than a foot, is the sweet spot for the sensor.
Seems to work anyway.
TYB069
I've seen lights that skip the green on lanes that have no cars sensed in the lane.
If it doesn't trigger for a bike, it's defective; report it to the DOT and get it adjusted.
According to my traffic engineer buddies, the sensor is programed to pick up what cars are made of: steel. Even if you ride a steel frame bike, there may not be enough steel to pick up the signal. My guess is that if the sensor doesn't work, the DOT will have already heard about it due the mile long line of cars that have been sitting there for the last few hours. Anyway, if it doesn't signal, push the walk button on the light pole. That should trigger at least a walk signal if not a full on green light.
genec
According to my traffic engineer buddies, the sensor is programed to pick up what cars are made of: steel. Even if you ride a steel frame bike, there may not be enough steel to pick up the signal. My guess is that if the sensor doesn't work, the DOT will have already heard about it due the mile long line of cars that have been sitting there for the last few hours. Anyway, if it doesn't signal, push the walk button on the light pole. That should trigger at least a walk signal if not a full on green light.
No walk signal in my area has a button in the left turn lane.
Helmet Head
Nice thinking, but what if you ride a carbon fiber bike?
Doesn't matter, unless your rims are carbon fiber too. Check out the paper LCI_Brian posted.
"Also note that the wheels of the bike are the most effective bike parts for detection. Even a bike with a non-metallic frame may be detected if the rims are conductive."
genec
Doesn't matter, unless your rims are carbon fiber too. Check out the paper LCI_Brian posted.
"Also note that the wheels of the bike are the most effective bike parts for detection. Even a bike with a non-metallic frame may be detected if the rims are conductive."
Saw the part that said: " It is possible for an inductive loop sensor to detect any conductive material such as aluminum, steel, or titanium."
If that is the case, there are a ton of intersections in San Diego that need work.
The thing that irratates me about this situation is that we have to do the "inspections" for the street crew. If they can adjust these things to work right ultimately, why not do it right to begin with?.
BTW as an aside... I know there are lights in my area that I have reported, and the street crew have responded to me, and yet they still don't work. Go figure.
noisebeam
I've triggered (as an experiment) several inductive sensors with nothing more than a front aluminum wheel, no bike attached.
Al
Helmet Head
I've triggered (as an experiment) several inductive sensors with nothing more than a front aluminum wheel, no bike attached.
You're such a geek, Al.
(I mean that as a compliment).
webist
We have a light in our town at the busiest intersection which I call the smart light. Even in the middle of the night, it will give the green to the lane with traffic. All one has to do is wait through the yellow signal for the dominant (default) green lanes and one gets the green. I don't know if it senses bicycles because I never use that intersection on the bike. I'm not avoiding it, my normal routes just don't call for its use.
TYB069
No walk signal in my area has a button in the left turn lane.
Yeah, that could be a problem...
TYB069
We have a light in our town at the busiest intersection which I call the smart light. Even in the middle of the night, it will give the green to the lane with traffic. All one has to do is wait through the yellow signal for the dominant (default) green lanes and one gets the green. I don't know if it senses bicycles because I never use that intersection on the bike. I'm not avoiding it, my normal routes just don't call for its use.
Thats how actuated intersections are supposed to work in theory. Often, there is a minimum green time, say 30 seconds. Occasionally, you find one like that switches without delay.
genec
I've triggered (as an experiment) several inductive sensors with nothing more than a front aluminum wheel, no bike attached.
Al
Meaning you found well tuned ones. I have some close to my house that I can't trigger with a heavy Huffy.
JLauren
Ah, for the good 'ol days when traffic lights were operated by a timer. Once you found the rythm you could go through a whole string of lights without having to stop. Nowadays, now that everything is "smart", everything thing has become much more unpredict NO CARRIER
sbhikes
Sometimes they change the pattern or timing of the lights. Perhaps yours changed because of time of year. School's out, right? You have to keep track of the macro timings as well as the micro ones. I know that around here with so many colleges and a university, the school year has a direct and major influence on the timing of traffic signals.
chennai
I've seen lights that skip the green on lanes that have no cars sensed in the lane.
If it doesn't trigger for a bike, it's defective; report it to the DOT and get it adjusted.
That's just way it should work in a bike friendly place. That's not the way it works in Denver. Denver has a policy against adjusting sensors for bikes, unless the sensor is actually installed in a bike lane (a very rare situation.) Even being on a city-designated bike route is not enough.
thequickfix
Perhaps yours changed because of time of year. School's out, right?
That's an interesting observation. The particular intersection I referred to is just south of DU.
Thanks for all of the info regarding "smart" intersections- I had never previously seen a traffic signal operate the way this one did. Now I know.
I guess I will have to work on triggering the sensors. Lately, I have been riding mostly at night, which is a trade off between lack of traffic to deal with and lack of traffic to change the signals. Sometimes, I will even ride in tight circles over the sensors to try to find the "sweet spot". Is this technique even feasible?
noisebeam
Meaning you found well tuned ones.
There are also many that don't work with my steel bike. The point is that they can work for just a front wheel if properly tuned, which is motivation to call to get them set up right.
Al
noisebeam
Sometimes they change the pattern or timing of the lights. Perhaps yours changed because of time of year.
Round here they not only change with time of year, but with time of day and weekday vs. weekend.
I know some lights I can make before 7am, but after they cycle changes so I can't, similar cases on the way home at different times of day.
Another issue with triggering lights, is not actually triggering them, but knowing that you did. Some work on both timing and triggers, so a set time must elapse between x-street green signals. One may trigger a light and then have to wait 2-3min if you had just arrived at the light at a yellow. It would be a nice feature to have an indicator that the light has been triggered, like an LED on each corner light post.
Al
San Rensho
This is why I NEVER RELY ON and occasionally disobey stop lights. When I approach a light, even if I have the green, I assume that cross traffic will proceed through their red and have a contingency plan for an out in case they do. On more than one I occassion, I have had to do so.
By the same token, if I approach a red and I can proceed without interfering with traffic or pedestrians at all,I do so.
genec
There are also many that don't work with my steel bike. The point is that they can work for just a front wheel if properly tuned, which is motivation to call to get them set up right.
Al
I have; they responded; lights still don't work; I run them.
Actually in the case I am thinking of, they work on one side of the cross street, but not the other.
But bottom line, if bikes can use any road anywhere, why do we have to demand that lights get "tuned?" Why can't all lights be adjusted at the time of installation, rather than requiring a post process complaint?
noisebeam
IBut bottom line, if bikes can use any road anywhere, why do we have to demand that lights get "tuned?" Why can't all lights be adjusted at the time of installation, rather than requiring a post process complaint?
Maybe they were installed correctly, but have since changed. Added asphault, changed controlled parts during maint.
This is an areas to advocate for, for improved installation and maintenance guidelines. Not eve advocate, but even work with local DOT or city.
Maybe xDOT trucks can carry a dummy front wheel to use as a tester? ;)
Al
genec
Maybe xDOT trucks can carry a dummy front wheel to use as a tester? ;)
Al
Calibrated of course to NBS standards for Wheel, bike.
sbhikes
Yes, I've seen the ones that differ on time of day and day of week, too. You end up developing spidey sense on all the signals in town.
nova
I've seen lights that skip the green on lanes that have no cars sensed in the lane.
If it doesn't trigger for a bike, it's defective; report it to the DOT and get it adjusted.
Good luck on that. Road by me and close to chip (jhonson rd.) that lite doesnt seem to belong to any one. Ive called odot on it 3 or 4 times city of norton twice and barberton 3 times. None of them seem to know whos responsability it is to fix/tweak that sensor. Its realy iritating as its one of the roads i need to ride to get to a few locations. Never fun to try and signal the driver behind you that he needs to get up behind or beside you other wise the light will never change.
As for carbon bikes all bikes have some metal in them and its more metal than is in common road litter. So these signals should be able to sense your bike regardless of material imo. If they dont they aare faulty.
noisebeam
This is an article from todays paper about traffic management systems.
Casey Newton
The Arizona Republic
Jun. 14, 2006 12:00 AM
Beleaguered Valley commuters have angels on their shoulders.
Technologies known as intelligent transportation systems, or ITS, are watching out for motorists, alerting them to danger and even reducing their commute times.
On half of the state's freeways and some surface streets, the new technologies are quietly changing the way we get around.
• On city streets across the Valley, engineers use remote cameras to adjust the timing of traffic signals, flushing out clogged intersections and improving traffic flow.
• On the freeways, the Arizona Department of Transportation's extensive monitoring network enables motorists to get traffic information in real time and change routes accordingly.
As much as new technologies have aided commuters, transportation officials say they are only the beginning.
As residents wait for Valley streets and highways to be widened, transportation agencies are using the new technologies to maximize the use of existing roads.
"You cannot build yourself out of congestion anymore," said Nicolaas Swart, ITS guru for the Maricopa County Department of Transportation. "You have to make the best use of the infrastructure that you have. And that's where ITS comes in. It optimizes the road space that you have."
Traffic-management centers are open in Phoenix, Mesa, Chandler, Glendale, Scottsdale and Tempe. ADOT, Maricopa County and Valley Metro operate centers, as well.
Valley agencies have spent nearly $45 million on the technologies since 2000, according to the county. In the next 20 years, they will spend an additional $200 million.
That's less than 1 percent of the county's 20-year, $25.8 billion regional transportation plan.
But engineers say ITS will have a huge impact on improving traffic.
Repairing the commute
"It's real-time repair of congestion," said Bruce Dressel, an ITS analyst for Scottsdale.
From a chilly office in downtown Scottsdale, Dressel and two colleagues monitor 43 intersections across the city.
When cars begin stacking up at Scottsdale's most reliably crowded intersection, Frank Lloyd Wright Boulevard and Loop 101, Dressel punches a few buttons on his keyboard.
Moments later, the intersection is nearly empty.
Most Scottsdale intersections run on a two-minute cycle, and every light turns green once during that period. By giving the more crowded lanes a few extra seconds of "green time," Dressel eliminates the bottleneck. Cars in other directions get slightly less green time but still make it through the intersection in one cycle.
Scottsdale used to alter 30 signals each month, sending a technician out to the intersection to begin a process that could take three days.
Today, the process is done remotely and takes seconds. Since the installation of 31 new cameras earlier this year, Scottsdale has made an average of 230 changes a month.
"That's why I love my job," said Dan Edwards, who operates Scottsdale's ITS system. "It feels so good to be in a spot where I have a direct impact on traffic. . . . I'm still kind of in awe of it."
The degree to which cities can manipulate traffic on their streets often depends on how many cameras they have installed.
Engineers are reluctant to meddle with traffic signals unless they are certain it won't create a bottleneck somewhere else. If they don't have live video of other nearby intersections, they can't gauge the impact of their work.
"Any time you make a change, there is an impact on intersections upstream and downstream, including those where we lack the ability to mitigate the impact by remote control," said Debbie Burdette, principal traffic engineer for Glendale.
Know before you go
Unfortunately for commuters, ADOT can't simply adjust traffic signals to eliminate gridlock on the freeways.
But the agency can help steer motorists around the worst trouble spots, and ITS technologies are making it happen.
At ADOT's Traffic Operations Center in Phoenix, engineers observe the state's entire transportation system on giant video screens. When a wreck happens or a road closes, ADOT alerts a wide network of traffic information companies, public agencies and, if necessary, emergency responders.
That's good news for people like Ernest Valenzuela, an apartment maintenance worker who commutes 80 miles round trip each day.
Before he heads home to south Scottsdale from his job at Interstate 17 and the Carefree Highway, Valenzuela dials 511 to check road conditions.
"It's helped me immensely," said Valenzuela, 48, who alters his route based on what 511 tells him. "I've told a lot of people about it: 'You've got to call this number. They're more accurate than the news.' "
Operated by ADOT, 511 and its companion Web site, az511.com, are attracting a growing number of users. Since its inception in 2001, the system has received 2.4 million phone calls for real-time information, rising to 66,000 per month nowfrom 7,400 calls per month its first year.
"I find it very helpful," said Hector Mejia, 16, of Surprise. "There was a really bad accident on the 101 once. I called 511, and they told me about it."
Mejia avoided the freeway.
"It was perfect," he said.
The growing use of new technologies on the roadways is the product of an effort that launched in 1996 when the Federal Highway Administration awarded the Phoenix area a $7.5 million grant to lay the groundwork for ITS.
"When you have a population explosion like we've experienced in the Valley, especially in the last five years, the ability to communicate to motorists becomes even more imperative," said Diane D'Angelo, an ADOT spokeswoman.
ADOT's primary goal is to collect real-time information about traffic conditions and distribute it to drivers as efficiently as possible, whether by phone, freeway sign, airport kiosk, Web site or text message.
Not all strategies have succeeded completely. For example, ADOT estimates that only 20 percent to 25 percent of drivers change routes based on information from variable message signs on freeways.
Despite progress on ITS, transportation officials say Arizona has miles to go.
Only about half of the state's freeways are under camera surveillance, with large sections of Loop 101, U.S. 60 and others still lacking instruments.
The Valley's network of major roadways lags further behind, with only about 5 percent of the region's arterial roads outfitted with ITS technology, said Faisal Saleem, president of ITS Arizona.
The road ahead
Proposition 400, the half-cent sales tax to support transportation that Maricopa County voters passed in 2004, will provide about $50 million to install the systems on regional corridors.
One project under way is creating a so-called smart corridor on West Bell Road, where as many as 70,000 motorists travel daily between Loop 101 and Loop 303.
"Motorists will notice better synchronization of signals," said Saleem, who is the ITS coordinator for Maricopa County. "Also, there will be some dynamic message signs on the arterial, so they would get travel information on that."
The project's first phase, between Loop 101 and Grand Avenue, is under construction.
Although installing cameras and sensors on city streets can provide "the most bang for the buck," Saleem said, most of the money budgeted for ITS off the freeways has been reserved for the most heavily trafficked roads.
Cities that want to add ITS to less-crowded streets typically have to pay for it themselves, and few have.
Tim Wolfe, assistant state engineer for ADOT, speaks of a near future when intersections will sense when a car is going to run a red light. Eventually, ITS will be able to alert other cars to the danger and even stop them from entering the intersection.
Until then, Wolfe said the technologies have proved effective in managing the transportation network.
"Technology is helping us to do some very short-term things that improve congestion and incident management," he said. "The possibilities are just amazing."
Al