Sunday, November 18, 2012

114 moving violations in one hour

After yet-another close call with a red-light runner at Harvard and Brighton Avenues I decided to spend an hour on this lovely day recording the number of moving violations I could observe at this intersection.

I allowed for folks who had clearly committed to the intersection as the light turned yellow. If anything, this is an under-count of violations, as I was fairly forgiving of various questionable acts. For example, I did not count drivers who entered the intersection to make a left turn and got stuck. I did not count drivers who entered the intersection within a few seconds of the yellow, or who seemed to be unable to stop (and weren't egregiously speeding). I did not count drivers who ended up in the intersection after the light turned red if it was due to another driver's behavior. I looked specifically for intent -- for instance, a change of velocity indicating that the driver was responding to the yellow light and making an explicit decision to violate the law.

I have broadly categorized the violations as follows, in this summary:

  • 114 total moving violations in one hour (12:48 to 13:48)
  • 23 instances of drivers blatantly speeding through the red light, even though they had plenty of time to stop.
  • 63 instances of drivers choosing to slowly roll into the intersection when they could easily have stopped.
  • 28 illegal turns-on-red (No Turn on Red is posted on all directions).

This is a heavily trafficked intersection for people on foot because of all the businesses. I also observed a number of bicyclists who stopped and waited for the red light. I did not see any bicyclist blow through the red light.

Notable violations: a fuel tanker accelerated on Harvard south-bound dangerously and ran the red light. A police officer on a motorbike flagrantly blew through the light going east on Brighton, no lights flashing. A silver hatchback with plates MA 14XZ79 stepped on the gas to get through the red light going west on Brighton, and nearly rammed another vehicle, just stopping short in time. A heavy public works vehicle also ran the red light going south on Harvard.

I noticed (and you can see in the data) that drivers were more likely to roll through the light on Harvard Ave, but much more likely to speed through the red light on Brighton Ave. I suspect this is because traffic moves more slowly on Harvard than on Brighton; the latter functions almost as a 4 lane highway at this point. Also it became apparent that there was a significant difference regarding turn-on-red violations among the different corners: the corners with sidewalk bulb-outs saw fewer turn-on-red violations than the clipped corners. It looks like the clipped corners may actually invite more reckless turning motion.

It's easy to find cases of moving violations here. I counted 114 violations in one hour. There is no justifiable excuse for BPD D-14 to be putting any traffic safety resources they have available towards anything else until they first address the complete lack of enforcement of motor vehicle safety here.


  1. Time the yellow light. How long is it? On that road, engineering standards would dictate a timing of 4.5 seconds and possibly more depending on the outcome of a speed study.

    Driver behavior at traffic lights is remarkably consistent and predictable. You might dislike people who "run" the lights, but drivers must make a split-second decision as to whether to stop. It's the engineers that have time to consider, study, and solve the problem - and they have the tools to do it. If the problem is that prevalent, it's a problem with the signal timing, not with drivers. Research has shown that extending the yellow light by 0.5 to 1.5 seconds permanently decreases the violation rate by ~50% and as much as 90%.

    The Federal Highway Administration has shown cowardice by not incorporating the ITE formula into the MUTCD and making it mandatory. The National Motorists Association's President sent them a letter just last week calling them out on it.

    Also, red light violations are determined by when a vehicle crosses the stop line. If the light is yellow when it crosses the stop sign, it's not a violation even if it turns red while the driver is in the intersection. That's what all-red phases are for - to give those drivers time to clear the intersection. If the signals don't have an all-red phase, they should be re-timed.

    1. Hi there,

      I believe the yellow clearance is 4 seconds, and the red clearance is 2 seconds, which is typical for BTD around here, but I will double-check next time I get out there. Unfortunately, I don't have a schematic of that particular intersection handy.

      I'm not looking to pick on drivers making split-second decisions, as I understand the difficulty posed. That's why I explicitly made it a goal to only look for drivers who had an opportunity to observe the yellow and still made an explicit decision to pass into the intersection when they had a chance to stop. I'm especially concerned with those who did so dangerously, such as that silver hatchback that nearly slammed into another vehicle. At least the slow-moving cars could stop to avoid an accident.

      Also the rate of right-turns on red is fairly high, even though it is marked No Turn On Red. I think the signs could be better placed, but I'm not sure that would change behavior by itself.

      I must say that I think a speed study is the wrong way about this. The problem with Brighton Ave is that drivers go too fast: you can see that there is a distinct difference in the characteristics of the violations along Brighton Ave. That should not be encouraged, instead there should be an overall effort to calm the traffic on Brighton Ave because it is a densely residential and commercial area with a great deal of pedestrians and bicyclists at just about all hours.

    2. The problem is that *all* drivers must make split-second decisions when faced with a yellow light. They have to weigh whether they can stop safely - that means not slamming on the brakes or decelerating extremely rapidly, because even if you can come to a safe stop very quickly, the driver behind you (who may be paying less attention than you) might not be able to. And yes, accelerating may be the safest course of action in some cases. Again, as long as they enter the intersection on yellow they aren't actually violating the law.

      The extreme cases like the silver hatchback are just that - extreme - and can be dealt with by enforcement. The more routine cases are technical violations that can be remedied by proper engineering. Proper traffic engineering incorporates behavioral psychology - determining how motorists, pedestrians, and bicyclists react to certain signs and roadway features - rather than taking a crime-and-punishment approach, which simply does not work and quickly devolves into a revenue source where the incentive becomes to turn all drivers into technical violators ripe for ticketing.

      The purpose of the speed study would be to determine 85th percentile speeds, which is how you determine proper yellow light timing.

      If the rate of red-on-red turns is fairly high, by the way, the issue may be that the sign is unwarranted. Where drivers have good visibility and do not see pedestrian conflicts, they ignore such signage.

    3. Mass RMV manual states that you must stop upon seeing a yellow if it is safe. Again, I was not looking to pick on drivers who had to make split-second decisions, but those who had more than adequate time to observe the yellow and nonetheless still chose to enter the intersection. Many did enter after the red light as well, but I did not think to record those numbers separately, so I will see about that in the future.

      I agree that we should pursue proper engineering of the road over a crime and punishment approach, but I disagree that we should make judgements based on the 85th percentile speed. First of all, that's an arbitrary choice (and always has been, do you know where the number 85 comes from?) Second, it rewards drivers for speeding. Third, the vehicular speed on the road should not be determined by the bad behavior of drivers, but by the need for safety among the many non-vehicular users of the road.

      I'm not sure if you are familiar with this spot, but it is not a highway, it is the center of Allston, which is a heavily populated neighborhood of Boston that was built up in the late 19th and early 20th centuries. The intersection is busy with people on foot at just about all hours. A speed study to raise speed limits and the design speed of the road would be thoroughly inappropriate. Instead, engineering measures should be taken to reduce the design speed of the road so that people do not feel like they need to run the red light.

      As for red-on-red turns, the sign is there for the same reason: visibility is poor, and there are people crossing all the time. I've found myself faced with the grill of an incautious driver's car many times, as they attempt to sneak around the corner and right into me.

    4. The Mass. RMV says a lot of things in their manual that aren't laws, but are instead recommended practices and guidelines. A good example is the solid white line between lanes moving in the same direction. This is used near intersections and during construction, and discourages lane switching, but you can't be cited for it (because sometimes lane-switching is necessary).

      The number 85 was chosen after millions upon millions of dollars were invested in highway safety research by federal and state governments over the past 70 years. In particular there was an explosion of interest and scientific research into the science of speed with NMSL repeal in the 1990's (look up papers by Davey Warren)

      But I'm not talking about changing speed limits or design speed here. A speed study is literally a tally sheet of passing vehicles and their speeds during a time period where they are each choosing their own speeds (off-peak hours, clear visibility and weather, etc). All it would be used for in this case is setting the yellow light timing. I think we can agree that having a properly timed yellow light that minmizes conflicts is beneficial to both pedestrians and drivers.

      With regard to right on red - again, we live in the real world, and you need to factor in drivers' and pedestrians' reactions to signs when you place them. If most drivers are violating the sign, it may be unwarranted. The science shows that drivers notice the context of the neighborhood, the presence of pedestrians, and poor sight distances before they see signs.

      Where unwarranted signs are placed, it can create a divergence between the expectations of pedestrians and those of drivers by giving pedestrians a false sense of security. This actually raises accident rates. You can say "pedestrian safety" 100 times over, but it still doesn't absolve you of the need to examine whether 1) A proposed measure would in fact make pedestrians safer if abided by, and 2) People will react to and abide by the proposed measure in the way you would like them to.

      The point is, it's an engineering judgment, based on sound, peer-reviewed scientific research - not an ad-hoc or political judgment. "Slow Children" and "Children Playing" signs are similarly politically popular but in the real world they get people killed (

    5. Okay, I double-checked the timing today:

      110 seconds total cycle length:
      - 31 seconds Harvard green
      - 4 seconds yellow clearance
      - 2 seconds red clearance
      - 67 seconds Brighton green, of which:
      -- between 6-15 seconds taken from this phase for left-turn exclusive (each direction independently determined)
      -- if pedestrian button actuated then 25 seconds taken from this phase for Barnes dance
      - 4 seconds yellow clearance
      - 2 seconds red clearance

    6. I wish you could cite some research that actually supported the notion of 85th percentile, because I always find circular references. Example: "We chose 85th percentile because everyone chooses 85th percentile." I actually don't think there's any sound, scientific basis for the number 85, and it is just a cultural choice that propagates itself through repetition. I didn't find any papers by Davey Warren of better substance on this matter, either.

      But I'm not terribly interested in that because that work largely applies to freeway and high-speed road traffic. This location here is neither, and the decisions made here should not hinge on the 85th percentile speed of motor vehicles, but must instead depend upon ensuring the safety of all users.

      Ostensibly, what keeps speeds in check is the possibility of collision. In the case of motor vehicle/pedestrian collisions, the motor vehicle operator will suffer much less than the person on foot. Therefore, the incentive on the driver to avoid that kind of accident is lessened -- to the great detriment of the person on foot. Therefore, any changes based solely on the behavior of drivers will necessarily be biased against pedestrians and bicyclists.

      So I agree with you that setting a lower speed limit will not change driver behavior, as the current limit is already routinely flouted. What I observe is that the current arrangement of Brighton Ave encourages much higher speeds than appropriate for the street. I say this from great experience, where I practically need to play "chicken" with drivers just in order to cross the street at a nearby unsignaled crosswalk every day. And MGL states explicitly that drivers are required to stop at unsignaled crosswalks when a person enters, $200 fine, but they largely do not unless you force the issue. I'm not sure if this has ever been enforced, either.

      There is too much speeding on Brighton Ave, it is treated as a racetrack*, and it is not appropriate for the context.

      Now, the reason for No-Right-Turn-on-Red signs at heavy pedestrian intersections is simple, and can be observed just by crossing at any intersection that does permit Right-Turn-on-Red. Watch the driver's eyes as they move up to make the right turn on red. They are focused on the traffic in motion through the green phase. Only at the last moment do most drivers turn and check the crosswalk for the presence of people, at which point the car is typically already in motion. It is well established that Right-Turn-on-Red is dangerous to pedestrians because many drivers have difficulty (unfortunately) with checking two directions at once. To most drivers, they are worried about the possibility of vehicle/vehicle collision because that is a high risk of personal injury. Therefore, they do not worry so much about people in the crosswalk.

      It's something I observe all of the time. At this point, I'm naturally accustomed to reading the eyes of the driver to determine whether or not they are going to notice me. But it's no coincidence that cities like NYC ban Right-Turn-on-Red universally. It's just too dangerous when lots of people are around.

      *random anecdote: one evening I came back home and found a NASCAR-style accident had taken place on Brighton Ave, two cars spun out of control, and one flipped over on its top. The injured had already been evacuated. Naturally, this was never reported in the newspapers, although UHub did pick it up along with my picture that I posted. I have to wonder how many other such accidents have taken place when I was not around.

  2. Some good reading on 85th percentile - it applies to all roads, not just freeways: (the stuff in this about the science of speed limits is an excellent synthesis, but ignore the stuff about "the law" - in my opinion that part's wrong and a bit kooky)

    1. Looks pretty typical. I didn't see any scientific basis for the 85th percentile choice other than "everyone else is doing it." That's nice for establishing a cultural standard, but it doesn't explain much.

      I can definitely agree with this quote: ``Roadway design and environment determine safety and travel speeds, not the number on the sign.''

      But I also noticed a conspicuous absence of any accounting for pedestrian or cyclist safety. There was a great deal of discussion about using the 85th percentile as a balance between speed and accidents from a vehicular perspective, but I didn't see anything balancing that against the needs of other street users. Pedestrians and cyclists aren't considered under the "85th percentile" rule at all, but they have the most to lose from its application.

      Remember, let's bring this back to the concrete case I am talking about: Brighton Ave and Harvard Ave. This is a very heavily used intersection by people on foot. It is a busy business district and surrounded by densely populated census tracts. I'm not sure how much better I can emphasize that. Consider it the most important fact about this intersection.

      Rules of thumb designed to ensure highway safety simply do not make sense in this context.

      Brighton Ave in its current configuration (sans trolley) is hostile to the primary users of the street, and is tilted in favor of over-speeding traffic. It needs to be redesigned to be more appropriate to its context, which is a neighborhood main street, just as that ITE presentation suggests.


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