The Slingshot Effect

Reader Brad writes in with a query:

I wondered if you could indulge me by trying to answer a question that has long puzzled me; I drive mostly on rural roads, and not infrequently must follow a slower car until the opportunity to pass occurs. Often, as I pass I notice the other car speeding up slightly — at least 5–8 mph it seems over its previous speed; almost a magnetic or slingshot effect. I have even noticed that at times I do it myself, involuntarily, as I am being passed! Is this a recognized phenomenon with its own name?

Has anyone else experienced this? One answer may be that the driver being passed has simply lost track of his speed, and being passed suddenly alerts them that they may be driving slowly; speeding up may be a sort of panic response. Another answer is that the sight of being passes awakens some competitive impulse, a version of the “territorial defense” mechanism theorized by Barry Ruback — even if the territory is abstract road space, and the person passing in this case is actually not competing for the same resource, given that they’re in the opposing lane. Or maybe they’re just playing chicken.

In Traffic I note a strange, somewhat related version of this phenomenon, which I call “passive-aggressive passing” — someone bullies you out of the left-lane, you dutifully get over, and they then pull in front of you, and drive slower than they were when they were on your tail. It’s as if all they wanted was to get you to pull over.

But I have no doubt there may be less than noble motives at work in these cases. I myself am guilty of doing something like the following: I will be driving along (in say the middle lane) when I notice someone coming at a high speed on the right side. It seems as if their intent is to cut in front of me, in the small space I have left between myself and the vehicle in front of me. Annoyed by this person’s behavior — the idea that they may pass close to me at a high speed, perhaps forcing me to brake — I have at times slightly accelerated, so that I move closer to the vehicle that is ahead of them in their own lane. The result is that they must hit the brakes, and try something else.

Immature? Perhaps. Or maybe it’s simply pro-social altruistic punishmenthomo reciprocans.

This entry was posted on Tuesday, June 16th, 2009 at 8:10 am and is filed under Traffic Psychology. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

12 Responses to “The Slingshot Effect”

  1. Christopher Monnier Says:

    Or how about, in congested traffic, closing the gap between you and the car in front of you to prevent someone from merging in front of you and stealing your spot in “the good lane”…

    On a related note, inconsistent speed is a huge pet peeve of mine. Besides people basing their speed on the relative speed of other drivers (which occurs in the “rural road” and “left-lane bully” scenarios), I find that people reliably “forget” to travel the normal freeway speed (i.e. at or slightly above the speed limit) when they are traveling uphill. In the Minneapolis area, two places where this routinely happens are on Highway 62 eastbound between Tracy Ave. and Highway 100 and on 35W southbound between the Minnesota River Bridge and Burnsville Parkway.

  2. Todd Scott Says:

    This phenomenon may also be due to aerodynamics. As the passing car goes to the front, the passed car may gain a benefit from drafting. They may gain speed based on the same fuel input.

  3. MikeOnBike Says:

    CM said: “I find that people reliably “forget” to travel the normal freeway speed (i.e. at or slightly above the speed limit) when they are traveling uphill.”

    My 1990 4-cylinder has this “problem”. Large trucks also have this problem. It seems to be the same problem I have bicycling uphill. 😉

  4. Jeff Quinn Says:

    I encounter this ‘slingshot’ effect fairly often, on both sides of the interaction. When I’ve caught myself speeding up while being passed, it’s been because I’ve slipped in speed without realizing it. The passing car makes me more aware of my actual speed rather than perceived speed.

    I also find myself guilty of psychological phenomena similar to some discussed in Traffic: when I speed up while being passed, it’s a natural reaction to an honest mistake. When I’m passing and the other car speeds up, it’s because they’re crummy drivers out to make it hard on me.

  5. Andy Says:

    I have certainly noticed this, and I just had to comment today because this is what creates my FAVORITE driving game. The issue is simply that the driver is not paying attention to driving. In many cases, this is because they are chatting on the cell phone, making routes on their GPS, etc. In the back of their mind they are making sure to stay between the lines (barely), but their speed of travel is often the first thing forgotten.

    So, to remind them that they are driving a huge piece of metal at 50 or 60 mph and not paying attention, I start to pass very slowly, maybe 1mph faster than them. They will start to go a little faster, but just keep staying 1mph more than them. Position yourself so that you are 5-10 feet ahead of them, make sure no other cars are around, and brake hard – almost as if you were stopping. Within a second, they throw down their phone, slam on the brakes, and wonder what the heck happened to make you slow down. Possibly, at this point, they realize that paying attention to the road is a higher priority than discussing with their BFF what color nail polish would look good tonight.

  6. doug Says:

    that bit you mentioned at the end — blocking right-hand passers — is something I did just yesterday on a long drive from northern california to seattle, wa. exactly the same rationale, too — if they want to hot-shot it, they need to get over in the left lanes, where at least that behavior is expected if not welcomed.

    later on, near fort lewis, i watched a soldier pulling moves like that, passing trucks with inches to spare etc., one handed while talking on the phone. he swerved in front of me from the right before i even realized he was there.

    whenever i have to do a long-distance interstate drive, i am so absolutely thrilled to end it alive and unharmed.

  7. Jarrett at Says:

    Do any state driving manuals give the obvious advice, that to minimize the chance of accident the car being passed should maintain speed or even slow down? I always let up on the gas and just coast while being passed, and brake only if it looks like the passer is running out of room.

  8. Michael Says:

    The people who amaze me are the ones who refuse to let me get out of their way. I’ll have just gotten onto a road via an interchange that puts you in the left lane and will have my right turn signal on, looking back, trying to find a gap to get to the right in. The guy tailgating me will *move to the right* and *pass me on the right* *while I’m signaling my intent to move right and get out of his way* and then change lanes left, back in front of me. Boggling. I guess it just isn’t aggressive enough to let someone get out of your way. The first time this happened to me I stopped to check my turn signals at the first opportunity, because they obviously had to be broken, since no one would do that deliberately. Nope, working fine.

  9. aaron Says:

    No, it’s immature, dangerous, and wasteful. Callin’ it like I see it.

    Starting to seem like you like congestion, rather than traffic.

  10. aaron Says:

    I think it’s a little of each on the “inattention and competitiveness” issue. It also can have to do with vehicle design. Passing zones tend to be on downgrades.

  11. Adron Says:

    I rarely drive, I tend to stick to the bus or light rail (in Portland, OR)… but when I do drive my southern tendancies take over…

    I hate driving on public streets/roads because of the incessant slowness of the whole ordeal, so when I pass I seriously pass. Yeah, yeah, yeah, illegality blagh blagh blagh. I stay out of people’s ways and just want the same in return.

    In other ways though I’m probably one of the most careful drivers around, I don’t speed, rarely even approach the speed limit in neighborhood streets. I see people driving around in neighborhoods, and am rarely surprised when I hear some idiot soccor mom on her cell phone just killed the neighbors kid cuz she was blazing through at 30mph in a 20mph, or worse, 10 or 15 mph zone.

    But I digress, the whole passing ordeal is hilarious. The rarity that someone is actually passing me though, I actually pull more to the right and slow down. If they’re wanting to go that fast, I want them blazing that red hot radar beacon in front of me.

    But I do suppose, and have been told many times, I’m very non-standard in my societal behaviors.

  12. aaron Says:

    On the passing, I’m pretty much the same. Get it done. Power transfers are generally most efficient when they’re done quickly. Open the throttle and give the engine some air. The law should be that you must be going at least 5mph faster than the car to your right.

    As for being passed, I don’t move, but I ease off the throttle and let the car slow some. I try not to touch the brake at all, but I at least make sure I don’t speed up.

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Traffic Tom Vanderbilt

How We Drive is the companion blog to Tom Vanderbilt’s New York Times bestselling book, Traffic: Why We Drive the Way We Do (and What It Says About Us), published by Alfred A. Knopf in the U.S. and Canada, Penguin in the U.K, and in languages other than English by a number of other fine publishers worldwide.

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