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Ever wonder what the heck the city is thinking about when it programs its traffic lights? One frustrated reader did and sent us the following question, which we forwarded to Santa Rosa’s traffic engineer, Rob Sprinkle, for a response, which is below:

The question: As a Santa Rosa driver, I’m amazed and frustrated by the traffic lights in town. They seem designed to impede traffic, not facilitate it. In most cities, if you are driving on a major thoroughfare, going the speed limit, you make a number of lights and then all the lights turn red at once and the cross street lights all turn green. In Santa Rosa, it’s possible and frequent to miss two, three, four lights in a row on major streets like College Avenue, Fulton Road, Guerneville Road. Is there something about the lights in Santa Rosa I don’t know? Is there something the traffic engineers don’t know? Could you investigate? Robert D.

The answer: It is hard to explain how each signal in the city is timed and why, but I will share some of the challenges we have and hopefully help explain why signals operate the way they do.

At each intersection there is a traffic signal controller (computer) with instructions programmed on how to operate. The instructions (I will list just a few here) tell the controller whether to work in conjunction with other traffic signal controllers, if so, at what times during the day; how long the yellows must be; how long the pedestrian crossing times need to be; whether there are left turn arrows that need activation, and a host of other parameters.

Typically a controller uses detectors as inputs in order to determine if a pedestrian would like to cross or if vehicles and bikes are waiting to proceed at the signal. The pedestrian uses the buttons on the poles to input the detection, and either in-ground loops or camera detectors are used for vehicle and bike detections. One of the challenges we have is stuck detectors. A stuck detector tells the controller that there is a car, or it may “think” there is a car, waiting on a specific approach. If the detector is broken, or if a pedestrian button is broken, then the signal will continue to “think” there is a car or pedestrian waiting and will default back to that approach in the absence of any other detections. These issues are often difficult to track down as they can be intermittent but do cause unnecessary delay.

That aside, the majority of arterial corridors do have coordinated signal timing plans throughout various times of day. Our older systems use the actual time of day to set a group of signals into a synchronization plan to help move traffic more efficiently on a corridor. Even so, depending on when and where vehicles enter the system and whether it is peak commute times, delays may be experienced. We often do get inquiries regarding signal operations or malfunctions and it is often due to a malfunctioning detector. Another issue that occurs is when a signal transitions from one timing plan to another timing plan; the controller can short cycle and not give the same amount of time to an approach that it had in the previous cycle. The controller is doing this to try to get into step or sync with the other signals in the system.

Another system the City has been installing is an adaptive traffic control system. This system uses the detectors to determine how busy a signal, or group of signals, is and automatically adjusts the cycle length of that group to best utilize the time in the cycle. College Avenue between North Dutton Avenue and Brookwood Avenue has seen a 49% reduction in stops and a 33% decrease in travel time from end to end along this corridor compared to the non-adaptive traffic control system. Similarly, Guerneville Road/Steele Lane has seen an increase in efficiency following the implementation of the adaptive traffic control system.

This is just a quick explanation of some of the issues related to signal timing. It is much more involved and complicated than discussed above but I hope this helps explain some of the issues.

The city continually reviews the signal timing and operations throughout the city in order to achieve the greatest safety and efficiency.

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Comments

29 Comments

  1. ER

    College Avenue traffic lights seem to be set to the speed limit, 35 mph. If you get in sync, you can hit most of them green except for Humboldt. I seem to get the red at Humboldt regardless of the direction I’m going.

    The lights at Brookwood and 2nd, 3rd, 4th, etc, are better than they used to be years ago although I have come to a stop on one of the numbered streets and a car that wasn’t there when I stopped and is approaching on Brookwood from a couple of blocks away will usually have the green light when it gets to where I’m stopped. This seems to happen in the late evening. I’ve even had this happen on Sonoma Avenue and Brookwood. I was recently stopped on red on Sonoma, no one around, and a couple of cars approaching from both directions on Brookwood got the green and I was still on red.

    I’ve seen the short cycle problem happen at Sonoma Avenue and Santa Rosa Avenue. One green cycle for Sonoma Avenue will let 5 or 6 cars through. The next cycle will let 2 cars through. This happens when there is a lineup of cars on Sonoma Avenue, so causes frustration.

    July 13th, 2010 12:36 pm

  2. Gary Lipking

    The Colgan Ave. signal at Petaluma Hill Rd. headed east on Colgan is maddening. Stays red far too long in the mornings.

    July 13th, 2010 12:36 pm

  3. Mary

    I have sat at the corner of Sebastopol Rd and Dutton Ave for as long as 20 minutes trying to turn left on to Sebastopol Rd from Dutton. The signals for east and west bound traffic as well as north and south bound traffic changes numerous times befor the left turn signal changes. This has happened three times in the recent months but does not happen everytime

    July 13th, 2010 1:24 pm

  4. Sharon

    I drive down Guerneville every am around 6 am and end up sitting at every light. Don’t see how you can say that Guerneville has increased when I waste more time and gas to sit for no one. The left turn lane from Gureneville to Coffey takes up to 3 min to change every time when there is NO ONE coming the other direction.

    July 13th, 2010 2:05 pm

  5. kyle

    the obvious solution is to ride your bike. That’s what the city council had to promise to get bankrolled last election.

    July 13th, 2010 3:07 pm

  6. Joe

    Try turning left on to West 3rd from Fulton going east. Sometimes it doesn’t even change. And how come the going left west goes first before the straight traffic and going east it turns after the straight traffic. Maybe instead of just relying on broken monitors try physically going out at these times and monitor whats really happening.

    July 13th, 2010 3:18 pm

  7. Kathie Rutherford

    Downtown Santa Rosa – E Street from Sonoma Avenue to 5th Street. The yellow lights are extremely short. For example, if you come up to the cross walk in your car and the light has just turned yellow, it is red by the time you get to the middle of the intersection. Because of this, and the fact that most people anticipate a longer yellow light, cars are in the middle of the intersection constantly when the light is red. And, yes, the timing on this street is also bad, the lights only click for you early on Saturday or Sunday morning when you don’t have to be at work.

    Speaking of traffic lights, it would be appreciated if the police would talk to or tag the people that are walking against the light. Now that it is summer, kids are in downtown and walk wherever and whenever they please. I realize that the law states that pedistrians have the right of way, but they push it to the limit by blantantly stepping out against the light or in front of cars. It would be great if the police would get a handle on this so it happens less often.

    Thank you

    July 13th, 2010 3:56 pm

  8. paul

    Santa Rosa traffic is run by and for city employees. There is no other logical explanation for the weirdness of the signalling. Stopping all traffic flow along Guerneville rd for one car with a full signal cycle is absurd. This type of problem exists all over the city. Most cities hardly take gas consumption/economy into their design. With some real programming extreme changes in gas consumption are possible. If it were possible to increase national ga efficiency by 2 or 3%, it would be major national news.

    That is exactly possible in most cities, but they hardly take their roles seriously. Thi is also true in rural areas that use speed traps and bs speed limits, rolling stop tickets, full ycle waits for left turns, (and on and on), where local fuel economy takes a back seat to traffic infraction income.

    So that it is clear, neither city nor county nor sate gov’ts put fuel economy at thehead of their traffic designs, and they are directly responsible for 5 to 10% of gas waste, maybe even more

    July 13th, 2010 4:30 pm

  9. red

    hybrid cars have proven that unnecessary stops are a major form of fuel waste. Poor signalling in both city and rural areas directly conflict with all the hoopla about fuel economy. At seldom used signals, flashing reds and yellows are more economical than stopping whole signal flows, all the cars stopping for one. This is also true late at night. In rural settings, yeild and yellow signals would lessen full stops from highway speeds, a huge hit on fuel economy.

    If the nation took all this seriously and programmed signals and placement of full stops for 7/24, the nation could see a huge drop in fuel waste without doing anything to cars.

    Ideas like allowing rolling stops scare cops but constitute huge boosts to fuel economy.

    But all these entitie won’t do diddle as they get too much from traffic citations. Gov’t won’t touch this issue as it finances itself with infraction fees for less than dangerous driving infractions.

    July 13th, 2010 4:45 pm

  10. seth

    Going east on 4th st. crossing farmers ln. in the afternoon is the worst. but for the most part they do a pretty good job with the signals. cry babies

    July 13th, 2010 5:35 pm

  11. Robert Tanner

    I have studied traffic signal operations for nearly 25 years. I have to confess I find the operations in Santa Rosa to be the WORST I’ve ever seen.
    I’m beginning to think the city is being overwhelmed with the cost of such a complex signal timing system. They keep promising to have more ‘Intelligent Traffic System’ components installed, but what good is it when the city can hardly keep what they already have going?
    Now they’re talking about using a portion of that proposed 10% added tax on car registration to try to fix signals. I opposed such expense at the recent SCTA meeting this Monday. I felt that we spend too much money on fancy traffic lights that encourage driving.
    The city needs to admit that signals are a huge expense and if not well operated, can be a huge liability to a city. I, for one, do not go to Santa Rosa for business, if I can avoid it. I waste too much gas waiting for red lights. I also have had far too many ‘Near Death Experiences’ from red light runners, drivers either distracted or impatient.
    The city is going to have to bite the bullet and make serious changes:
    1) Go back to All Way Stop Signs at some smaller intersections. This will encourage more walking and bicycling.
    2) If room is available, install 100 foot or larger roundabouts. These bigger roundabouts are not to be confused with the little ones on the Humboldt Bike Blvd.
    3) If signals REALLY are needed, use more Protective-Permissive Left Turn Signals. The FHWA has created a new ‘Flashing Yellow Arrow’ Left Turn light that is easier for drivers to interpret. This signal is on its way to being fully approved for California.
    Transportation generates 60% of the Greenhouse Gases in this County! The City of Santa Rosa Absolutely HAS to do its part to reduce these gases by giving up its attempt to cater to drivers with fancy signals.
    REMEMBER: Signals favor motor vehicles; Stop Signs and Roundabouts favor pedestrians and bicyclists. We want to favor pedestrian and bicycle travel, don’t we?
    Are you listening, Santa Rosa?

    July 13th, 2010 8:16 pm

  12. hv

    The lights on Santa Rosa Ave at Toys R Us/Cost Plus is a waste in the AM. I’m through there every day and have stopped for those lights and there is absolutely NO ONE turning out from the stores – they’re CLOSED!! Why those lights run at 7am with no one around like it does at noon when it is busy is a pure waste. There are a few more intersections like that!

    July 13th, 2010 8:52 pm

  13. Anon

    Ever since this blog has started I have been more and more involved on the Press Democrat website. I find it just so informative and interesting. Way to go Roadwarrior.

    July 13th, 2010 11:54 pm

  14. RD

    Going east on Bicentennial off the 101 I frequently catch the light at Ventura in front of Kaiser, and then again at Mendocino, then again at De Vera Way (Home Depot/Albertsons). Three lights in less than 1/4 mile! Why can’t these be timed to cycle together? It takes nearly 5 minutes to get through them all. It’s frustrating and a complete waste of time and gas.

    On B Street from 6th to 1st in front of the mall I catch all the lights 90% of the time. Five full light cycles. I could walk faster. Stupid stupid stupid.

    If we are going to conquer our out of control use of energy we have to look at problems like this that are hugely wasteful. It’s going to be the small things that add up that will help us win the battle.

    July 14th, 2010 7:51 am

  15. JR

    What drives me nuts is trying to turn left onto College from Cleveland. The left turn lane has about 5 or more cars, on average, waiting to turn yet the signal is only green for about 5 seconds!

    August 7th, 2010 9:39 am

  16. KC

    OY! What about a lot of the smaller cross-streets that pass through Farmer’s? I’ve found the timing is directly connected to the signal at Hwy 12 and Hoen Frontage. When the Highway traffic gets a green, no matter the time of day, all of the cross-street traffic gets shut off for 4-5 minutes. Maddening.

    August 18th, 2010 9:24 am

  17. Ray Marshall

    My job involves driving a truck daily around Santa Rosa. I am on the streets, covering many miles. Overall, the traffic light system stinks. It is either outdated, or the traffic engineers need to get out of the office and on the streets more and do some major tweeking of the signal lights. Many signal lights change on timers and not to traffic flows. I can name dozens of intersections where you waste gas and time waiting for phantom traffic.

    October 15th, 2010 5:46 pm

  18. ben

    who do i report this to if the traffic lights do not work?

    December 13th, 2010 9:35 pm

  19. T-raff

    2 words.

    Traffic circles.

    Anyone unable to deal with how to use a roundabout properly should loose their licence for 6 months.

    January 4th, 2011 4:20 pm

  20. KT

    I’ve been watching the intersection at County Center Drive and Steele Lane for over ten years as I live nearby. Never in all my years of driving have I seen a worse intersection for signal sequencing!

    When the city decided to allow In-N-Out to open here, they PROMISED they would install (or activate) sensors at the intersection, but no positive change has occurred.

    Traffic from the JC at the noon hour and after classes, both afternoon and evening, is congested beyond any reasonable amount and traffic accidents are a constant source of noise and annoyance, not to mention imminent danger to drivers and pedestrians using the intersection. Drivers coming from Illinois Avenue run the stop sign as it crosses Armory at an alarming rate trying to make the fickle light at Steele Lane knowing that if they miss it, they are likely in for a long wait for it to cycle again.

    The city should be sued for creating an unsafe environment for drivers. Perhaps then they will address the situation they know exists here. When they promised to initiate better signal response to get the planning commission to okay the In-N-Out, and then didn’t follow up on that promise, they made a conscious decision to disregard the safety of the citizens of Santa Rosa and all those who drive here, thereby opening themselves up to a lawsuit. Anyone involved in an accident at this intersection should include the city in any actions brought in a lawsuit, then maybe they will understand that they are responsible for making traffic flow not only safely, but in a manner consistent with expectations of drivers.

    Rather than focusing on wringing every spare cent they can out of the taxpaying homeowners who live here and shoppers who still come to Santa Rosa by upping parking violation fines and buying Robo-Traffic-Cop cars to cite more parked vehicles in the already over-burdened downtown parking situation, they should spend a little on a traffic engineer who has some semblance of competence and lose the idiot who is obviously not doing his current job correctly.

    Santa Rosa is run by people who either have no clue as to what they are supposed to be doing, or simply don’t care. Either way, the city should be made to pay for their laziness and incompetence!

    March 8th, 2011 1:33 pm

  21. Cait Woodbury

    I f I read the traffic engineer’s report correctly, it sounds as if each intersection is essentially handled as an individual event, dependent on sensors and other factors. I didn’t read anything in his report to indicate that traffic lights in SR are coordinated with each other. Maybe I missed something. It also sounds as if the repairs and upkeep of these systems is beyond the capacity of the city to manage. And it sounds like a hodgepodge of old and new systems.
    I know SR probably can’t afford to tear it all out in one fell swoop and put in an entirely new system, especially with the current budget crisis, but let’s hope to see some serious analysis of what needs to be done. Roundabouts and traffic circles can be tremendously efficient if designed properly. Of course, the big problem will be training SR drivers to use them correctly. Apparently many local drivers can’t even be taught to stop at red lights, so I don’t hold much hope for them learning how to enter a roundabout.

    March 30th, 2011 7:16 am

  22. David B

    Rohnert Park Expressway!!! The worst. Either way. Lakeville and Golf Course as well.

    April 4th, 2011 7:27 pm

  23. Mark B.

    It is nice to know other people have HAD IT with the signals which seem to impede traffic. I come to an intersection, and as I approach, my light is green, and I see some poor motorist waiting for it to change on the cross street, and it is not until I get to JUST the right spot to cause me to stop hurriedly, that it turns red and the other car goes. Then, it is my turn…. I wait and wait, flash my lights, back up over the sensors,(i’ve had passengers get out and push the pedestrian button and hop back in) and then i see it- salvation! Another car on the cross street is approaching way down yonder. When it gets to JuST the right spot, The light changes for us both. It seems that the plan is to trap folks and the signal is hopes that they become frustrated enough to run the red and possilbly get caught. Funny thing is that when I tried running it, it seems to “panic” and gives me the green as I break the law. Northbound SR Ave, Petaluma hill rd. It will stop you for no one, and then take forever to change. I just drive straight through it, it is an insult to my being to do what is obviously wrong- waste my time and expensive gas. Don’t punish the night shift people who are already targeted by police simply because the sun is not shining. —Mark in the Dark

    May 28th, 2011 12:42 am

  24. peter

    Yeah, the light on college and cleveland really fries me, im trying to get to my jazzercise class and i always get stuck! Dont they know a man needs to exercise his calves once a week?????

    September 1st, 2011 4:20 pm

  25. Maggie

    I drive home coming from Country Club Dr. R.P. to Sonoma Ave. every evening about 1015 PM, try to avoid driving on that very UNSAFE 101 NB SECTION (what were they thinking building a stupid, unsafe ramp like that one?), enter Santa Rosa Ave. to be more safe…Well, the traffic at that time is minimal compared to the horrendous traffic aT 2 PM, but I have yet to understand the traffic light system…I sit at more red lights with NO/ZERO TRAFFIC coming, I sit by the red light by LES SCHWAB, NOT OPEN AT THAT TIME, and wait, and wait for any traffic to come, for the lights to change…..Re. the traffic light by In’n'out on Steele Ln…what the heck??? Try making a left turn so one can go back to Mendocino Ave…..NOT HAPPENING….FORGET IT…If one is lucky and gets across the street and tries to make a right turn then…well, not happening because traffic trying to get on 101 SB is blocking the road….IT IS FRUSTRATING..

    March 31st, 2012 11:12 am

  26. Fern

    What I notice is the lack of sensors at Santa Rosa traffic lights. Too many signals remain red while the “green direction” has no cars at all and still we wait and wait at the red light. Then off in the distance you see a car approaching the green light which will turn red just in time to stop that car so they must wait. It truly seems like that is the master plan.

    June 9th, 2012 8:21 pm

  27. tejaswini

    what is the solution for problem that occurs when there is no traffic still someone is waiting for traffic signal

    July 21st, 2012 6:10 am

  28. Me

    No matter what streets you drive on in Santa Rosa, u hit red lights over and over. I come home late at nite, no one on the road. I get a green, drive the speed limit to the next light 2 blocks up, bam RED again…this happens over and over. In any other city the lights turn green as hit them with no traffic. Bad traffic planning and and its bad on your car and frustrating to the driver. Fix the prob city planners!

    January 28th, 2013 5:54 am

  29. RPierce

    I would like to know why they put in an un-needed traffic signal on Fountaingrove Pkwy? In turn, they messed up the light at Altruria. I have to wait 3 minutes EVERY day when there is no one coming on Fountaingrove. I finally get a green light and then get stopped at the new light, which is not needed and, like other have said here, impedes traffic, does not facilitate it.

    August 22nd, 2013 3:14 pm

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