Light working, watch for cop?
January 5, 2010 6:21 PM   Subscribe

Why do cops direct traffic when the lights are working?

I moved to NYC about a year and a half ago and I've been noticing cops out there directing traffic when the traffic gets heavy but there are no accidents and the lights are working perfectly. Why?

My observation is that if the lights are working properly, a cop isn't going to speed up the flow of traffic. As a pedestrian, I just ignore the cops and walk when I have a walk signal (I do cut down on my jaywalking when they are around, but I doubt this is the reason for their pressence). Cynically, I think this is make work for the cops, the justify their pressence and hours. But I also suspect I'm missing something here.
posted by Hactar to Law & Government (23 answers total) 2 users marked this as a favorite
Context >> Stock Video
posted by SirStan at 6:35 PM on January 5, 2010

Best answer: I suggest you pay a little more attention to the cops before crossing in future. I often see officers wave cars on even though the light has turned red -- either directly through the intersection or to make a turn that they were prevented from making when they had the light by the volume of pedestrian traffic. At certain intersections at certain times, they can be very useful in improving the flow of traffic beyond what would be accomplished by just obeying the lights.
posted by Dolukhanova at 6:36 PM on January 5, 2010

Best answer: I'm in LA, but there are a couple of intersections near my house that have cops directing traffic during the morning rush hour. (The lights are working.) I'm pretty sure it's so that everyone does what they're supposed to do -- the ones who make the left turn *after* the light turns red but get stuck in the intersection, or the ones who think they can make it across an intersection before the light turns red but can't, are the ones who screw everything up for everybody, cause gridlock, and make the whole scene turn to shit whether the lights are working or not. So, I definitely do not see it as something the cops do to justify their hours. I actually think it's something helpful that my city does for me.
posted by BlahLaLa at 6:37 PM on January 5, 2010

These are just guesses, but here's what I always figured (and I have often wished for a cop at certain intersections, for these reasons):

1. Some intersections don't have a left-turn lane (especially in NYC), or a left-turn signal, so it becomes impossible to turn left, lanes get backed up, people get stuck in the middle of the intersection, etc.
2. To stop people from "blocking the box".
3. To stop people from running red lights.
posted by equalpants at 6:39 PM on January 5, 2010

IANATE (I Am Not A Traffic Engineer), though I do spend a semi-ridiculous amount of time driving.

I see this a fair amount in L.A. Even if traffic lights are working in terms of literally functioning, it doesn't always mean that they're working in terms of adequately accounting for traffic demands under irregular circumstances. If there's a baseball game, for example, the whole area around the stadium is going to be a mess because there will be extra-heavy traffic converging on one specific point. The regular timing of traffic lights won't account for the demands of an X% increase in the number of cars trying to make a left turn to get into the stadium, for example, so a traffic cop needs to do it.

In the cases where there's not a specific event causing a disruption in the normal flow of traffic (i.e., it's just heavy evening traffic), the work of traffic cops helps avoid gridlock, so that traffic is at still kept moving, even if it happens to be moving slowly.
posted by scody at 6:40 PM on January 5, 2010

BlahLaLa has it right. Drivers might be tempted to think they can make the light, only because of traffic, be stuck in the middle of an intersection thereby blocking cross traffic. They are there to make sure that doesn't happen.

Plus in New York they aren't cops probably, but Traffic agents (oldsters still call them brownies for the brown uniforms they wore back in the 70s.) The video SirStan linked to shows, in fact, a traffic agent.
posted by xetere at 6:42 PM on January 5, 2010

Best answer: Today at 34th & 8th, there was an officer directing traffic, and I saw him stop several people from making turns (it is restricted there during certain hours). People who make turns at no-turn intersections during busy times really can jam up traffic, since the cars that want to turn have to wait for pedestrians (holding up cars behind them), and they often end up blocking the box.
posted by AlisonM at 6:46 PM on January 5, 2010

Also, as a NYC driver, I can say they really do help make things run smoother. Things on the road can turn into a colossal shitshow quickly, and they help to avoid that/clear things up quickly if that does happen.
posted by AlisonM at 6:50 PM on January 5, 2010

I've seen this in Philadelphia on the UPenn campus. (For those who know Philly: usually at the intersection of Walnut with 34th, 36th, or 38th.) I always joke that it's because UPenn undergrads never learned how to cross the street.
posted by madcaptenor at 6:52 PM on January 5, 2010

Response by poster: Thanks everyone. Since I gave my parents my car when I moved to NYC, I haven't been looking at the streets from a driver's point of view. This makes sense. Like I said, I was missing something.
posted by Hactar at 7:04 PM on January 5, 2010

This all makes so much sense, it makes me wonder: Why don't the cops turn off the traffic signals when they're out there, so drivers and pedestrians will know to look for someone directing traffic?
posted by DrGail at 7:26 PM on January 5, 2010

I would think that it's because the lights are still on a timer that is coordinated with the surrounding blocks, so the timing is still important. The officers are there to make sure that things run smoothly, and people don't break the rules (which is what really screws up traffic).
posted by AlisonM at 7:44 PM on January 5, 2010

in NYC they are mostly there to keep people from blocking the box which is the main source of gridlock.
posted by any major dude at 7:44 PM on January 5, 2010

There are cops directing traffic at both ends of the street where my work is located. It's a U-shaped street that intersects with exactly one majorish street - one entrance has a light, the other doesn't. The right lane of said majorish street backs way up with people trying to get onto the tollway, and without the cops directing traffic it's very difficult to get out of the office park and onto the majorish street.
posted by SisterHavana at 7:47 PM on January 5, 2010

I used to work close to an intersection in Ft. Lauderdale where cops trained to direct traffic. Weekly, like clockwork, there was a group there taking turns directing.
posted by 6:1 at 7:53 PM on January 5, 2010

Best answer: There's the whole bit about "blocking the box" where enough people (frustrated) inch over the line (at green....then yellow....and into the red light) where they block the traffic of the cross traffic.

And once people are that gets only worse...and take a quick look at what happens when it gets back - you get gridlock
posted by filmgeek at 9:29 PM on January 5, 2010

AlisonM: "Also, as a NYC driver, I can say they really do help make things run smoother. Things on the road can turn into a colossal shitshow quickly, and they help to avoid that/clear things up quickly if that does happen."

My experience is exactly the opposite. I think they screw things up. In NYC during rush hours every corner or significant intersection has its own personality. The regular drivers get used to that and know the ins and outs as well as what to expect in terms of timing and making turns, etc. I find that when the cops show up, they so alter the norm that it breaks down. I have waited two or three lights when there is a human directing traffic when I otherwise would have been through in one or two cycles.

I always assumed it was some sort of city welfare/work program to keep these folks employed so I accepted their ineptitude.
posted by JohnnyGunn at 9:40 PM on January 5, 2010

They have these in Chicago too, particularly weekday rush hours, not necessarily all day. Michigan Avenue in particular has some tricky circulation issues with left-turn lanes and a heavy bias toward turning west. If they didn't have the traffic cops out there there would most definitely be gridlock. The problems I have seen are mainly from people being confused about what the cop is trying to get them to do.

I don't know what it was like in the 70s -- you used to actually hear about bad gridlock days on the national news then. Perhaps everyone went anarchic every-car-for-itself and deliberately blocked intersections because everyone else was doing it and you needed to force your way across. But what I've seen in NYC and Chicago in latter days is more hesitation mistakes -- "Do I go? Do I stop? Do I -- OH SHIT I'M IN THE INTERSECTION AND THE LIGHT CHANGED AND HERE COMES CROSS TRAFFIC."
posted by dhartung at 11:30 PM on January 5, 2010

Traffic lights are timed for average conditions, sometimes there is a back up on one street more than another. A cop can be sent out to 'pull' the traffic against the light and get things moving again.
posted by InkaLomax at 4:44 AM on January 6, 2010

The traffic cops make traffic worse and better at the same time. Sure, they can prevent gridlock in certain intersections, but overall they tend to make things worse, because they'll work and manage their intersection so that it's flowing well, but because they can hold traffic in one or more directions stopped at slightly different timings than the light, that whole avenue can get backed up as that intersection is slightly out of sync with the programmed timing of the lights.
posted by andrewraff at 10:44 AM on January 6, 2010

Please allow me to add this delightful ray of light to the thread from Philadelphia, PA:
Officer Johnson
posted by Geckwoistmeinauto at 3:16 PM on January 6, 2010

I know I'm on the opposite side of the planet, so my input may not be that relevant, but ... here in Melbourne, Australia, we often have cops directing traffic in peak hour at intersections with fully functional traffic lights. I'm quite sure it's done as a training exercise. The cops out on the road look young (20-ish), and there'll be a couple of older cops on the sidelines watching on.

I'm pretty sure that, here at least, it's part of "Being A Cop, 101" training.
posted by Diag at 3:36 AM on January 7, 2010

They can also stop people from double parking or loading/unloading passengers in the middle of the street, which can often really clog things up in New York, typically with delivery vehicles and cabs. Holding up pedestrians trying to cross the street to clear a queue of drivers trying to make turns is another valuable part of this, at least when it's done right.
posted by zachlipton at 2:42 PM on July 13, 2010

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