Sounder Bruce (Flickr)
Sounder Bruce (Flickr)

[Update: Facebook commenters pointed out that the behavior I’m advocating for is already legal per Washington Administrative Code 468-510-020, which lifts the “keep right” requirement for the 40-mile stretch of I-5 from Tukwila to Everett, and on I-90 between I-5 and I-405.]

Every June, the National Motorist Association uses its own Lane Courtesy Month to produce a rush of news stories about the scourge of “left lane camping,” or drivers who remain in the left lane despite another motorist wishing to pass. A representative paragraph from Vox: 

That’s because even if you’re driving fast, there’s always someone going faster. If you promptly get back over after passing, that car will be able to pass you, allowing everyone on the road to get to their destinations as quickly as possible. If you don’t, it’ll inevitably lead to buildups of traffic and likely raise the chance of accidents.

That same reporter, in a conversation this year with NPR’s Robert Siegel:

When you’re traveling on the highway, the moment at which you’re most at risk of getting into a crash is when you’re changing lanes. And when you have people going slow in the left lane, as well as the right lane, then people who want to move faster kind of have to zigzag back and forth. They have to change lanes looking over both different shoulders, and it just increases the amount of possible accident scenarios that can happen.

Look at the two statements I bolded above, which to me seem inherently contradictory in urban settings. “There’s always someone going faster” assumes both the right of drivers to create differential speed conditions and your responsibility to yield to their desires. But the Solomon Curve shows one of the most dangerous driving behaviors is deviating from the median speed of traffic, whether slower or faster. So if you’re traveling near the speed limit in the left lane, you should have zero responsibility to move over and are in fact doing a favor for overall safety and flow. The notion of constant lane-switching to appease lead footed drivers is contradicted by the same writer’s second statement, that changing lanes is inherently one of the riskiest behavior. These two are irreconcilable.

On rural highways where there is arguably a legitimate expectation of free flowing traffic at high speeds, sure, keep right except to pass. But in urban areas, left-lane camping is not only justifiable, but can actually help traffic. Consider Seattle, where merging pressure creates daily gridlock already. We have a ton of left-side entrances, and a ton of left-side exits. I would posit that drivers making trips within urban areas should travel at prevailing speeds, should help to minimize differential speeds by other drivers, should minimize total lane changes as much as possible, and should remain in the lane nearest to their entry or exit point.

Consider a trip from Montlake to West Seattle. A driver merges onto SR 520 for a left exit onto I-5, which merges into the left lane of I-5. Most traffic will be merging right to access the central city, with the through lane being the left lane. Such a driver should stay left through Downtown, only merging right for the West Seattle Bridge ramp. Or consider a trip from Northgate to Bellevue. From Northgate Way, this driver should merge left immediately and camp there for the left-side SR 520 exit, rather than waiting until the last minute and blowing up traffic with 5 sudden lane changes.

Urban traffic is all about driving predictably and going with the flow, and the prime directive should be to avoid causing system disruptions either by speeding or by enabling speeding by retaining the dangerous cultural norm and always moving right. No one has a right to speed, speeding kills, and traffic flows better when the river is moving together at a reasonable pace. If left lane camping helps you do these things, you should have every right to do it.

68 Replies to “In Defense of (Some) Left-Lane Camping”

  1. The rules about staying right except to pass break down on urban highways and there are many places where the rules are specifically contravened by markings and signs. The HOV lanes are an extreme example, but there are also exits on the left and there are even several level places where signs indicate that through traffic should stay left to avoid a particularly thorny merge or a place where stalled traffic occurs. All the traffic laws need to be weighed against each other and the particular traffic situation.

    I don’t think it’s so much the case that there are a lot of bad drivers, but more that we all have moments of bad driving. Our bias is to remember the times that we were annoyed by another driver and forget about the far more routine situation of simply coexisting with the other drivers amicably. I do wish we had more continuing education about traffic norms.

    1. Do other cities have many left-side exits? Here they seem to be mostly due to 520 and the express lanes. How many out-of-towners even expect there to be left-side exits?

      1. I could be wrong, but wasn’t the plan initially on interstate highways that there would only be right hand turns?

      1. Do we really have more bad drivers than other places?

        I have heard people in many different places claim that their cities drivers are the worse. I have driven in many different countries and cities and my theory is that increased congestion leads to increased aggression on the roads. I’m not sure how much is tied to our driving “culture”.

        I have also heard the argument that Seattle has a lot of drivers that learned to drive in different countries with different rules.

        If we do have more accidents than other cities, is it fair to blame “immigrants”, bad driving habits, bad highway design, or is it just a byproduct of aggression caused by congestion?

        Good sociology masters thesis idea… I don’t know the answer

      2. Yes we do…

        and it’s all those foreign types…..

        You know…
        the Irish,
        the English….
        the Aussies.
        the Japanese,
        oh, and we can’t forget our friends from India !!

        Rental cars in Ireland have stickers reminding drivers (from the Continent) to “Drive to the Left”

        The Pacific Northwest has as many bad drivers as other places, except it’s such a variation of styles, that it really exposes the fact that probably about 1 our of 5 drivers has some bad habit that annoys the other 4.

        It’s not only lane choice.

        Other entertaining items include:

        Navigating a 4-way stop or roundabout.
        and people seem to behave exactly opposite at either.
        The “Humility Wars” at 4-ways, and the platooning through the roundabouts.

        the “you’re following me too close, I will punish you by going slow,… .oooh I’m going to miss that traffic signal… and then blowing through the ‘orange’ arrow” crowd.
        Texting at said signals and ignoring that it has turned green… for longer than 3 seconds

        those who haven’t figured out that accelerating is also an avoidance maneuver.

        There are a host of others that others could contribute, no doubt.

        We are the Righteous, and … Dooon’t You Forget it !!

      3. I’ve driven in all 50 states, several foreign countries, and lived in different areas of the US. Drivers here aren’t even close to as bad as some other places (while not being as good as those in some others). There are places in the US where the default freeway speeds are either 30 or 90 with no in-between, and whatever lane you want to do it in (hi, Atlanta!). I’ve lived in places where people have no idea that when the power’s out, a signalized intersection should be treated as a four way stop–those are fun intersections to try and cross! The humorist Dave Barry once said that in his city of Miami, the traffic laws are those of whatever your country of origin is.

        It’s like sports fans — every fan thinks the officials from their conference are the worst. It’s because we deal with them, like local drivers, all the time.

  2. The bolded quote statements are not contridictory. Lane changes create great risk. Not letting others pass in the left lane on the freeway, in the general case, increases the total amount of lane changes substantially because someone else will weave (at very high speeds no less). Therefore the safest move for everyone is to keep right except to pass. The second passage refers to your individual safety not everybody’s collective safety. Left lane camping creates negative safety externalities.

    In any case it’s not really a theoretical question but an empirical one (and I’m not sure how conclusive the literature is on this). And clearly the theoretical argument doesn’t apply to heavy traffic, left hand exits/entrances, HOV lanes, or urban roads that aren’t freeways.

    1. I think Zach is right here. Either Driver A moves over one lane to let Drive B pass, and then move back, or Drive B moves over one lane, and then moves back. It’s two lane changes either way. The underlying assumption here was that ‘there was always someone going faster’ in other words, Driver A was the equivalent of Driver B moments before this exchange (he was passing, that’s how he ended up in the left lane). Some significant percentage of drivers always think they’re passing others—that’s why the idea of staying in the right doesn’t pan out in practice.

      1. It’s only two lane changes either way if the slow-poke in the left lane moves right to let the speeder pass – and then moves back.

        If someone is “constant[ly] lane-switching to appease lead footed drivers” as suggested in the original article, perhaps that someone should stay in the #2 (or even the #3) lane?

      2. NoSpin — The statement “constantly lane-switching to appease lead footed drivers” is missing the point. It makes the assumption that this driver A (moving over for driver B), wasn’t in the middle of passing driver C. That statement falsely assumes there are two categories of drivers: fast ones and slow ones. The reality is that it’s a distribution of speeds.

        Think of it this way: *everyone* is passing someone. There’s only one guy, the slowest dude on the road, not passing anyone. So *everyone* needs to get into the passing lane at some point. That’s why the whole thing falls apart.

      3. But camping doesn’t refer to using the left lane while passing. A car driving in the left lane with no car anywhere near it in the lane to the right isn’t passing even if there is a slower car somewhere miles away. The car in the left lane is camping. And it is forcing faster cars to make an unnecessary pass to the right. Of course this only applies in situations where traffic is moving well. In the Seattle case, with congested traffic and exits on both sides of the freeway, generally all lanes are full of cars and everyone is passing or being passed at all times.

      4. @EastsideRider: the issue comes when people have different ideas about what camping means. At high speeds I like to give a couple car lengths of space to the car I just passed before I cut back in front of it. Leadfoot McGee will use that gap to pass me on the right.

      5. @Jeffery. Your example ignores that people can pass multiple cars with one pair of merges. Keep right except to pass, generally, increases the number of cars passed per merge which decreases total merges verses constant weaving.

    2. My argument is not that people should be oblivious and camp out regardless, but that in central cities with heavy traffic more friction can be created by merging than by just staying put at prevailing speeds. If the on ramp deposits me on the left, I’m not going to immediately merge for the sake of people wishing to speed. If I’m traveling at the speed limit or as fast/slow as heavy traffic, I should feel no obligation to merge. I know the law says otherwise, but the law also prohibits the speeding we’re supposed to bend over backwards to accommodate.

      1. Re: merging and changing lanes creating friction which can slow everybody down.
        I think that is partly why a road diet can often create better traffic situations.

      2. The whole stretch of I-5 from I-90 to Mercer is a poorly designed mess with multiple lane merges and on/off ramps on both sides of the road. This area is a perfect example of there being no fast lane, just a bunch of lanes. Infact this whole stretch should be dropped to 30 mph due to all the extreme merging, exiting and constant traffic (like Mercer exit backups) for safety but WSDOT cares more about motorist speed and convenience than safety.

      3. I mean you can have an a freeway in an urban area with free flow traffic and no left lane exits. That’s an fairly common instance, particularly at night if your north of the ship canal or south of I-90. in such an instance the keep right except to pass rule would apply, which means the statements aren’t “inherently” contradictory. I agree, and I think the law agrees, that the instances you generally bring up are cases in which the keep right except to pass rule shouldn’t apply. I also think those cases are not what people are generally talking about when they bring up the keep right except to pass idea.

      4. I’d add that I think that your conclusions based on the Solomon curve are also wrong, in particular your statement: “So if you’re traveling near the speed limit in the left lane, you should have zero responsibility to move over and are in fact doing a favor for overall safety and flow.”

        In freeflow conditions, some people will want to go both faster than others and some people will want to go significantly above the speed limit. If those people are blocked by left lane campers there will be more lane changes with greater speed differentials involved. By sorting cars left to right roughly by speed, there is probably less speed variance in any given merge.

        All that being said it’s really an empirical question and it’s not 100% clear that keep right except to pass actually passes that test. But there’s fairly good theoretical and empirical evidence behind it in the general case.

    3. I personally have no issue with people camping in the left lane when it’s through downtown or when there’s already grid lock. Once cars can’t go above 35 mph, it really makes no difference what highway or freeway it is (WSDOT’s number for when they say the freeway is no longer operating at optimum flow).

      So from that perspective, we shouldn’t be upset that people don’t keep the left lane through I-5 clear once past the ship canal or when you hit the collector distributor going north bound.

      I do not like it when I’m going north and already past Northgate during a reverse commute with light traffic and I see someone sitting in the left lane going 55 mph blocking up cars so they have to dangerously merge in front of me in the next lane over and start zigzagging. This is what is dangerous and this should never be given a pass as a safe thing to do. This is why the law exists and I’ve heard someone who actually used to do this say she did it because her husband was an alcoholic at the time and it was her way of exerting control in her life.

      Don’t let it make you upset, road rage reactions are just as dangerous, just realize that a lot of times the people doing this are either doing it because they have a terrible life situation or they are completely oblivious. Either way, it’s not worth it, let the state patrol handle it and relax. Eventually you’ll reach your destination and this sort of thing is only going to cost you a few minutes at most so just give yourself the extra time and be patient, you live in a major city.

  3. It’s not just a safety issue, it’s about use of limited highway capacity. We can make much more efficient use of road space if everyone actually kept right except to pass. Most of the time, I see the right lane completely empty, and everyone bunching in the left two lanes. And more often than not, someone is camped in the left lane going 55 and passing no one.

    Sure, left exits are an exception, but otherwise keep right except to pass allows traffic of different speeds to sort itself out and use our roads efficiently. It’s also the law. To champion this practice is ridiculous, and I’m sad to see STB encouraging it.

    1. The Seattle slow lane is far left, the Seattle fast lane is often far right. It’s a measure of just how bad Seattle drivers are. We are on average pathetic.

      The law says “keep right except to pass.” Ya, there are some well defined exceptions, but outside of that everyone should keep right except to pass.

      And why is it that nobody in Seattle seems to know that they have a rear view mirror and that they should actually use it on occasion?

      1. Your words to Automotive Engineering’s ear. With demand to replace every computerized camera on every automobile with mirrors and intensive training what they’re for. And windows a driver can see out of every direction.

        Cameras show you what they’re aimed at. Not what screen-contents mean for your next-second life expectancy.

        Driving is a “monkey skill”- car mirror (and hubcap) era term for reflex avoidance of being leopard food. Car horns really should sound like desperate screeching, because high speed traffic is really just fleeing through the trees updated.

        At this very moment somewhere in Africa, a noted scientist is about to discover an iPad made out of a rock, covered with a layer of fossilized monkey fur and leopard drool. Resembling the still wet one the medics will find him holding after his last text message distracted his own attention.

        Blind spots, damn it, shoulder check! Driver’s Ed just got this brand new ’57 Edsel!



      2. “The law says “keep right except to pass.” ”

        The law also says don’t drive faster than the speed limit. If the speed limit is 65 and the passing car wants to go around somebody in the second lane driving 70 then boo-hoo for him, and if he’s blocked by somebody in the left lane driving 65 then double boo-hoo. On two-lane highways there will often be a car or farm equipment in the right lane going less than the speed limit that you’d legitimately want to pass, but that’s unlikely on highways with more than two lanes where everyone except the right lane is going faster than the speed limit anyway.

      3. @Mike Orr,

        No boo-hoo about it. You can be ticketed for impeding the flow of traffic regardless of what speed you are going. If you are going slower than the prevailing traffic then you aren’t “passing” and you must move right. It’s the law.

        Leave speed enforcement to the cops. None of us should take it upon ourselves to enforce the law in one area while violating the law in another.

    2. You can’t actually make more efficient use of highway capacity where it’s limited (i.e. where there’s a risk of flow breakdown) by going faster, beyond some point, because going faster requires greater following distances. I’ve read that some agencies have studied this and find that the best way to maintain flow at high traffic volumes is to limit speed to around 35 MPH. The idea of left-lane camping causing major congestion is a myth among frustrated drivers and certain organizations that cater to them, and deserves to be countered.

      In terms of the best way to drive, however, I basically agree with you. Left-lane camping for long distances (outside of areas with left-lane entrances and exits) is certainly bad in traffic conditions that are common around here off-peak: heavy but flowing. In these conditions camping would cause more lane changes — like it or not, people will drive 75 on I-5 when it’s flowing, and sitting in the left lane won’t change this.

      HOV lanes are an extension of this. Use ’em to access HOV-only entrances and exits, use ’em to pass traffic when it’s backed up, but don’t go out of your way to do several lane changes across faster traffic to get to an HOV lane on the left.

      1. Yes. Driving behavior (left lane, lane changes, following distance) are all second order effects governing traffic flow. The primary variable affecting traffic flow is the density of vehicles. This is why variable priced tolling works.

      2. Reduce i5 speeds to 35 through all of king county.
        It’ll maximize throughput.

        Bonus benefit: Since lanes can now be narrower, due to reduced speeds, take on a left HOV lane to both north and south mainlines.

      3. If I5 is 35mph, we can possibly reduce lane width enough to add PBLs to the fwy without even taking away a car lane so people on bikes can use the preferable-for-bicyclers flat direct routes that the fwys consumed.

    3. If people entering the freeway always gave autos in the rightmost lane the right of way in heavy traffic, the you’d be right. It should always be the responsibility of the merger to drop back behind a car going essentially the same speed if it overlaps at all when the acceleration lane separation point ceases. But far too often — at the last second — jerks will “gun it” and squeeze in, knowing that the car behind is always “at fault” in a following situation.

      Those sorts of moment by moment stresses are why people don’t drive in the right lane.

  4. The term “left lane camping” carries the implication that driving at the speed limit in any lane, anywhere, is either dangerous or violating someone else’s rights. Attitude behind that needs to be corrected by a court order to the State drivers’ license bureau.

    Thanks, Zach, for the note of common sense about different settings, rural and urban. Though this isn’t about city lines, but what makes traffic move safest and best. Rule of thumb should be that a speed limit 45 mph and under means what it says.

    The longer I’ve been driving between Olympia and Seattle, the more I’ve been shopping for a camera system giving me a real-time readout through all my windows and on my speedometer. Would be good to show a legislative committee what it’s like to be tail-gated ten miles over the 60 mph limit in the right lane.

    Especially with committee-members’ names displayed alongside the license plate five feet behind my back bumper at in the right lane at 80.

    From Seattle south, I get the sense that in driver education, “following distance” counts as panic-inducing trigger words for politically-correct French sissies who’ve got espresso machines by the tape deck. Like the villain in “Taladega Nights.”

    Importance of actually knowing how to drive a car is worth a month’s postings. Because everywhere in this country, exact analogy is understanding of democratic government (yeah, in the form of a republic too.) An absolutely critical skill that everybody is assumed to, well, just, you know, pick up. Results on display this whole year, with a lifetime of real consequences to start in exactly a month.

    Nobody should be allowed our of middle school without knowing how to chair a committee. Learned from kindergarten on, with last half hour reserved for government-operating training, by State law. Age of adulthood, including voting, should be same as age you can be tried as an adult.

    And every license issue or renewal decided by a yearly road test with a highway patrol instructor. Who’s got the authority to put your fee to either a driver’s license or a yearly transit pass to be accepted nationwide. Death and insurance rates should plummet.

    Though downside is that the only transit seats available will be on BR (streamlined bus parked in whatever lane) T.

    Mark Dublin

  5. The Solomon Curve reference is interesting, because the wikipedia article doesn’t even mention what I had read was the modern interpretation of what’s going on (don’t have the reference at my finger tips).

    Basically, the Solomon Curve most applies to highways (not freeways). There are huge speed differentials as cars enter and exit the highway, which cause crashes. Apparently, lots of these crashes disappear one you add turn lanes and pockets, allowing entering and exiting vehicles to change speeds not on the highway itself..

  6. This assumes everyone’s speedometers are calibrated to ‘atomic clock’ accuracy.

    They aren’t. Even roadside ‘slow down’ radar signs are amusing because I regularly drive past two, which read ~5mph difference with my vehicle reading the exact same speed. (one ~2 above, the other ~2 below).

    There are days when I might need the illusion for greater speed (it really doesn’t make that much difference in reality), and having the left lane to pass someone whose situational awareness seems to be lacking is best done if there is some predictability to the situation.

    Just as the rules for approaching a 4 way stop (or roundabout) are that whoever is there first goes first, or if everyone arrives simultaneously, the one to the right goes first, create that predictability.

    That’s how things stay moving.

    Two things that RIGHT lane camping (i.e. left lane only to pass), solves is that on the days where I wish to ‘kick back’ (I actually got out of the house on time), the right lane will be the more comfortable place to be, in general, reducing the scope of my visual input.. and

    as someone who wishes to merge onto a freeway, I can pretty much assume I’m going to be dealing with someone who will be driving at a slower speed, and not be passing someone else on the right, and in the merge lane.

    Will we next be defending the people who merge without looking in their mirrors?

    1. Well, at least don’t get “Found in the wreck with your fingers on the keyboard, and Seattle Transit Blog on your screen!” CTOFS (Cautionary Transit Oriented Folk Songs) are a regrettable casualty of safety regulations whose incidental side effects save thousands of lives.

      But some years ago, I met a Seattle architect by the name of Grant Jones, with an interesting resume item. He believed that the principles of US highway design chiefly reflected the high-speed military logistics of the original National Defense Highway system- before the program went into the trough of Gas-Hog-Barrel sprawl.

      But he also calculated that it was possible to design a highway specifically for enjoyable and efficient automobile travel. Including grades and curves that needed no mechanical mechanism to regulate speed and spacing.

      Since I resent having to use my car for reason but enjoyment, including combined with other purposes- reason for my Thurston County Sounder (for starters) fixation- I’d gladly pay both tolls and taxes for a shift of our whole highway system as Mr. Jones recommends. Check it out.


  7. Hear, hear. Most of the “get out of my left lane” talk comes from people who think it’s their natural right to drive 80 in a 60, forcing everyone else to weave in and out to accommodate them. My desire to get out of your way when I am already going over the limit is pretty damn low.

    The real hazard on WA multi-lane highways is that every car on them is traveling a slightly different speed. It is not uncommon to find yourself in a pack of people going every speed between 45 and 85. It is also extremely common to find yourself with cars passing you, or falling behind, very slowly, on both sides.

    “Following distance” is a joke in WA driving. If you leave the recommended following distance, someone will ALWAYS pull into it. Every single time.

    1. That’s fine, you just drop back again. You’re losing maybe a couple seconds to your destination any time this happens, and probably less than that.

  8. I chuckle at the attitude that a lot of left-hand lane hoggers seems to have: “You’re breaking the law by speeding so I’m going to break the law by sitting in the left-hand lane and block you.”

    1. Speeding is far more dangerous to life and property, and if by traveling at the speed limit (or the safe limit) helps keep others from doing speeding, then that’s a net win. Speeders simply shouldn’t have the right or expectation of passing, that’s all I’m arguing. The road shouldn’t be ruled by others’ impatience and reckless disregard.

      1. You seem to be assuming that if you are in the left hand lane when others want to pass you, that those behind you will calmly follow you at an appropriate distance, smiling, thanking you for letting them know the speed at which you think they should be driving. Personally, I’d rather move out of the way than have an line of angry tail-gaters a few feet from my rear bumper.

      2. What data do you have that shows that speeding is less dangerous than weaving to the right into slower traffic in order to get around an unnecessary obstruction?

        There is a reason that slower traffic is supposed to keep right. It is because speed differential and unnesessary lane changes are both dangerous and reduce safety.

        What you are advocating for would reduce safety. Go drive on the autobahn sometime. If you survive you might understand.

      3. Not true. It’s speed differential, not actual speed. Else, wouldn’t the Autobahn be the most dangerous highway in the world? It’s not … partly because they strictly follow “drive right / pass left”.

        Posted highway speed limits have very little to do with the actual safe driving speed on those roads. 55 mph speed limit was introduced to encourage fuel efficiency, not safety. Most highways are designed for higher speeds than the posted limits.

        This is very much a cultural issue. In Michigan (or lots of other places in the US), the idea that people will only drive the posted speed limit would be ridiculous. Police almost never ticket speeding under normal circumstances unless the driver is at a “dangerous” speed (10+ over posted limit) or otherwise behaving in a dangerous manner.

      4. Replace “less” with “more”. There is no data that shows that moderate speeding is more dangerous than forced and unnecessary lane changes into slower moving traffic.

      5. @Matt M,

        I know a Seattleite who once took a road trip to Los Angeles. She was left lane camping because she claimed she was going the speed limit and could use any lane. About 60 miles outside of LA she got a ticket for impeding the flow of traffic. She was of course incensed at this “violation of her rights.”

        After the formalities were complete she got back on the freeway and got right back in the left lane. Her friends explained it to her but she wouldn’t listen. 30 miles outside of LA she got a second ticket for impeding g the flow of traffic.

        We need more of that in Seattle.

      6. We need more traffic tickets issued in Seattle, period. Blocking intersections? Driving in bus lanes? Parking in traffic lanes? We need enough tickets issued that people can be sure violators will be ticketed.

  9. Not quite. This is a more complicated issue than people think it is. The key to speed differentials is to do it in a predictable way (i.e. slower traffic keep right). At lower densities (up to about 8% occupancy, 60+ mph) a speed differential enforced by “keep right except to pass” reduces platooning because drivers won’t bunch up right up against each other. This increases the overall spacing of vehicles and leads to more stable overall traffic flow. More spacing between vehicles also means more safety. And because lane changes are done in a predictable way, it is much safer than people weaving back and forth.

    On the other hand, left lane camping causes platooning of vehicles, with sections of high density and then low density directly downstream. While you get higher measured throughput because vehicles are closer together, flow also starts to become unstable. When you have platoons of traffic reaching critical density (occupancy 13% to 15%, speed of about 45 – 50 mph depending on location), any merging or additional lane change will cause flow breakdown, which leads to congestion and also increases the risk of collisions.

    The key is to maintain lane discipline to a point where it is no longer reasonable (too much traffic or about 10-11% occupancy). Up to this point, it will reduce platooning and delay flow breakdown. Beyond that, then it’s reasonable to implement speed harmonization where everyone drives at the same speed (11% to 15% occupancy) so all lanes are utilized equally at maximum throughput (about 1800 vehicles per hour at 45 mph). The next stage (16% occupancy and beyond, speeds below 40 mph, significant drop in throughput) is flow breakdown and there’s not much to be done after that.

    *Occupancy values depend on location and roadway geometry

    1. Great comment, thank you. I should have been clearer that my argument is limited to urban areas in which 11-15%+ and sub-50 mph speeds are the norm. In free flowing environments, I think the standard “keep right” advice applies.

  10. My own excellent instructors told us to think of entering moving traffic as edging a boat out into a main channel, with traffic flow for current, and other cars as other shipping already underway.

    Any lane I plan to spend several miles in, I try to smoothly position my car with a space cushion same lane distance from both my “leader” and my “follower.” Constantly adjusting my speed to theirs.

    On the open road, especially the Interstates, my “artic” training seems to work to the satisfaction of my fellow motorists, the police, and my brake linings and fuel mileage.

    Private and public motoring, absolute worst problem is a widespread attitude among both civilian and too many on-duty transit drivers that only difference between them and the Mel Gibson CDL-holder was how far a rotting tank-truck could go after throwing its trolleypoles.

    Ignoring firm possibility that the pre-Apocalypse Australian outback had charging slots for buses with paint jobs like (add your own informal Australian working class description of that color scheme).

    High school driver training should seriously train every class as a professional road rally team, in a sport stressing control and timing over plain acceleration. Practice that in normal driving also reaches the bathroom faster. With fewer incidents causing same result as late bathroom arrival.

    And students constantly reminded that it’s up to them whether cost of mandatory flame-suits is going to get added to their course fees.


  11. If you want to see how well “keep right to pass” works, travel to Germany and drive on their freeways / autobahns. Even in urban areas they don’t end up with the same congestion we have with all else being equal (number of cars, speed limit, etc).

    “So if you’re traveling near the speed limit in the left lane, you should have zero responsibility to move over and are in fact doing a favor for overall safety and flow. ”

    I wholeheartedly disagree. If there is an empty lane to your right, you should merge right. Period.

    Going the speed limit can be dangerous. If traffic is flowing 10 above (regardless of the reasons or legality), then going the speed limit is a hazard. In no way should you be in the fast lane in this situation.

    This editorial talks about left-lane campers, but we must NOT forgot those who camp in the middle lane when the right lane if empty or they are not gaining on traffic in the right lane. Those are often more dangerous. I’m sure we’ve ALL experienced the sudden jerk of the steering wheel as someone is merging right from the left lane and someone left from the right lane. All because someone is sitting in the middle lane when they should be in the right lane. No argument, that’s how you improve flow and safety.

  12. Drivers are different. Less experienced driver changing lanes at speed is arguably more risky than when more experienced drivers do that. So I would suggest that be polite, but be also aware of your driving skills.

    A different issue that encourages me to stay in the middle lanes (but not left lanes) is when I don’t know where to turn, or which lane I have to take at junction/exit.

  13. Washington State Law: Keep Right except to pass. It’s a pretty simple concept. I just wish it was enforced.
    Stay right unless you are passing. In the city, in the country, anywhere there is more than one lane! End of discussion.

  14. People like to gripe about Washington’s overly courteous drivers being less safe, but we have the lowest fatality rate outside of New England, and 50% lower than states like Michigan upheld as examples by others on this thread. Absolute speed and differential speed both matter greatly to safety. In urban areas where traffic exceeds a certain level, policy already dictates that we manage the lanes for uniform speed (such as I-5 between Boeing Access Road and I-90), and in such cases all lanes should be equal. I find it surprising how much resistance there is to the idea that speed limits – limits– should be obeyed.

    1. Zach, compared to the highways I remember in Michigan, and have driven more recently in California, WSDOT just doesn’t have a feel for highway design. In LA- which really surprised me for its ease of driving, I knew five miles ahead of an exit which lane I needed to be in.

      Here, have frequently had to pass my exit, turn around, and try to learn my approach for next time. When I drove for Metro, I spent a lot of my own time in addition to paid qualification driving next shake-up’s routes repeatedly.

      I’ll cut our engineers some slack for same reason I’m patient with transit construction and cost. The more important a destination is, the worse the terrain and the more convoluted the waterways. And the harder to design a freeway ramp and its approaches.

      So I don’t think the average driver here has over-dramatic manners or other character flaws. Though I do think that career-long intensified vehicle-operating training (as opposed to printed rules and regs, which really aren’t the problem anyway) would save time and fuel nationwide, and take a big load off insurance and emergency rooms.

      Without very much capital expense, and very little legislation.


    2. Have you ever driven in New England? Speed limits aren’t even a suggestion. The standard there is for the left lane to move at ~80-85 and the right lane to move somewhere between 65 and 70. This is even in congested urban areas, and somehow they manage to make it work (it’s because they’re actually paying some attention compared to the complete obliviousness seen in Washington). Drivers aren’t the best at keeping right there compared to some other places but it’s still worlds better than Washington.

  15. I agree Zach. I think in general if you are in the left lane, and passing cars on your right, then you are OK. You don’t have to pass them going very fast, either. As long as you are going past them at a steady pace (one or two MPH faster) you are correct in being in that left lane.

    Your other example is true as well. It is hard to blame someone for getting over into the exit lane too early. The whole reason the left lane rule makes sense is because it isn’t the exit lane. Those who are using the freeway for a very long trip (e. g. Seattle to Chicago) should be able to use the fast lane and avoid those who are making shorter (slower trips). So don’t blame the folks that get in that left lane too early — blame the people who designed the freeway that way.

    Of course it makes sense to adjust the rule of thumb to conditions as well as area. Moses Lake is different than Lynnwood. If you are traveling along the freeway and there are very few people, then you shouldn’t be in the left lane for very long. But if you are in moderate to heavy traffic, then staying in the left lane (while slowly passing cars) is just fine.

    Oh, one last thing. While driving too slow in the left lane is a judgement call, it is rare that the opposite is ever OK. You should never pass on the right, as it is inherently dangerous. Come up behind someone, flash your lights, and otherwise make it known that you want the other guy out of the way, but don’t pass the guy on the right. Otherwise you can easily create a situation where the guy in the left lane wants to change lanes, but sees a stream of cars coming up on his right.

  16. There are two comments above that I think make a lot of sense. The comment by Jason and the comment by GK about middle lane campers. When I go from the Eastside to Seattle, there are two places I always camp in the left lane. On SR-520 at the I-405 interchange, and on I-90 at the I-405 interchange. Both of those areas have variable speed limits and the left lane is usually posted at a higher speed (not that anyone observes it unless the traffic is already slower). The right lanes are full of folks moving at different speeds and doing risky merges.

  17. How about ST3 “provisional” like this: “Zipper Truck” left-most lane so buses can go faster than present freeway speed limit both directions.

    Remaining lanes, beginning at entry to most congested areas, post sign over each lane announcing which one to be in for which exit or destination.

    By now, should be enough “App”- age for every motorist to have this information real-time, in addition to signs. Goal should be more slower and smoother than sporadically faster and much rougher.

    Anybody whose schedule would require left lane passing now, buses across the barrier could be moving fifty or sixty. Board-able at stops far outside the congested area. Hate term “behavior modify”, but should be good test to see who really needs to be in those regular lanes and who doesn’t.

    Best thing about the “zipper” is that as light rail gets built out, barriers can get “zipped up.” Provided people haven’t gotten to like them.


  18. If our medium distance infrastructure relied more on high speed rail, we could get places faster by having no idea what this article is going on about

    1. I think we’re all discussing how to get the best use out of the transportation infrastructure we already have while we’re building the high speed rail system most of us agree we need.

      Though it’s strange nobody has suggested just clearing our freeways of everything but transit and emergency vehicles during the times we know they’ll be working at about a sixth of their design speed. We’ll have to buy a lot of buses and build a lot of parking at boarding places.

      But considering time, fresh air and personal freedom being wasted by present situation, could pencil out and also get some votes. Good start: maybe the business community would pay for one transit only lane per direction for Christmas time shopping day region-wide, just to see what would happen.

      Or at least connecting Downtown Seattle with either Southcenter, Bellevue Square, or Alderwood? Look at it this way. Any heavy-traffic day, we’d get a lot worse blockage, stopping both cars and transit, with one fender-bender. Or spilled fish-truck.

      We could also call it a National Security drill- which could be the only use of taxpayers’ money deserving that name in fifteen years. And put every opponent in the position of being accused of helping ISIS. Who in addition to all the other God-awful things they do, sell a lot of oil.

      Mark Dublin

      1. I think an important thing to note here (haven’t read all of the comments so forgive me if someone else pointed out already) is that just because some people are speeding more than they otherwise were, does not mean the freeway is functioning “better” (where better means moving more people/hour). The whole left lane camping while speeding thing is all based on this assumption and it just doesn’t hold up. Higher speeds mean more space between cars (or more collisions if you don’t – which brings throughput to a halt) and more lane changes also impacts throughput.

        This is governing by cranky Seattle Times commenter. Which unfortunately is how most of our politics work in this country, especially in the Puget Sound region. This is how we ended up with 35,000 people killed/year on our roads and millions of injuries.

  19. Sound Transit should have their Fare Enforcers hand out fines for bad escalator behavior.

  20. This article should have been a lot shorter:

    1. When freeway is below capacity, use left lane to pass only.

    2. When freeway is at or above capacity, use left lane to utilize full freeway capacity as designed.

    3. If there is an instance where driving in the left lane while freeway is below capacity is safer (Mercer exit; SR-520 exit), then by all means change lanes sooner than later and drive in the left lane to make your exit. Use common sense here (AKA don’t lane change 5 miles prior to the exit, keep it to 1 to 2 miles).

    Driving (especially freeway driving) is already unsafe, you can’t really make human bodies flying at 60 mph ‘safe’. Encouraging people to break laws to prevent other people from breaking laws is not some magic wand that will magically make freeway driving safer. I would argue that left lane camping is more dangerous than someone going 5 to 10 over. And if people speeding on the freeway makes you uneasy, I would recommend sticking to city streets.

  21. It’s keep right except to pass, not keep right except to speed for your entire trip. I’m fine with keeping right, but I’m not ok with doing it to give criminals a lane to themselves.

    We have a *toxic* driving culture in this country that kills tens of thousands every year. There’s a side of me that thinks the “keep right” laws just encourage the false sense of entitlement criminals have to speed and act aggressively.

    1. But you have not been appointed traffic lane enforcer cop. It’s not your job to regulate traffic. It’s up to police to enforce speed law.

      1. Agreed, with the addition that it’s the responsibility of any user of the roadway to obey the speed laws to begin with. It’s not a good thing that we have to waste our money paying cops to babysit the freeways because we can’t keep ourselves from acting out behind the wheel.

        I mean, I get that you can’t change human behavior. But what I hear when I’m told to move right is: “Move over. People who don’t care about your safety or the law think it’s really important to act out their aggression right here, right now.” That we’d ask law abiding, safe drivers to change their behavior to appease criminals makes no big picture sense.

  22. There’s a perception bias that left lane camping is safe. While causing unnecessary congestion by slowing down traffic causes accidents, the people at the front of the line aren’t the ones involved in those accidents.
    There’s also a difference in safety to which way a lane change is happening. Shifting to a left lane is safer because the driver has the mirror closer and peripheral vision. Changing to the right lane has blind spots, but the greater situational awareness makes changing right after a pass safer through greater situational awareness.
    When roads are congested, lane usage doesn’t have much impact. On wide open rural roads, people are pretty good about lane discipline. It’s times of light congestion that a little courtesy and lane discipline would keep the roads moving smoothly.

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