One-Way Pairs: the Bad and the Ugly

One of Jane Jacobs’ prescient observations about bus service in The Death and Life is that one-way pairs, as practiced on the avenues in Manhattan, are bad for riders. Her argument was that one-way pairs require people to walk too long to the bus line, and this cancels out any gains in speed. (This is truer today, when signal priority is an option, than it was fifty years ago.) Jarrett Walker has formalized this in two posts using station radius as an argument; the issue is that passengers need to be within a short walking distance of both halves of the line, and this reduces coverage.

However, not all one-way pairs are created equal. An underrated reason to keep bus services on one line is simplicity: it’s easier to remember that a route follows one street than that it follows two, and also service to specific destinations can become easier. Taking a cue from proper rapid transit, ITDP’s magnum opus BRT standard treats it as a given that buses should run in the median of a street and only even lists one-way pairs as an option on very narrow streets, and even then as an inferior one. The argument revolves around service identity.

In particular, one-way pairs that preserve a semblance of service identity and simplicity are not as bad as one-way pairs that do not. For the original walk-distance reason, it’s also better to have the one-way pair closer together. Jarrett specifically praises Portland’s light rail one-way pair, located a short block apart, as an example of a good couplet. Manhattan’s one-way pairs are located a long block apart, so the walking distance is worse.

But even Manhattan’s one-way pairs are at least coherent. The First/Second Avenue bus follows First and Second Avenues for the entire length of the avenues; south of Houston, it follows Allen, the continuation of First. This is the advantage of the grid. In Providence, things are not as nice, though still somewhat coherent, if one remembers, for example, that Angell and Waterman Streets form a one-way pair (they’re treated as such for car travel, too, so anyone in the neighborhood would know, though people from outside would not).

In contrast, this is how Tel Aviv’s one-way pairs work. They’re getting worse amidst the various bus reform. The post is in Hebrew, but look at the map at the bottom of bus #5, the city’s busiest (and most frequently bombed back in the 1990s and early 2000s). The travesty is that none of those streets on which the line runs in one direction only is even one-way. East of Ibn Gabirol, the street hosting lines 25, 26, and 189 on the map, the streets are wide and two-way. The reason for the complication is lack of left turns. In order to make car traffic flow a little more smoothly, Tel Aviv has completely eviscerated its bus service.

In principle, Tel Aviv has infrastructure for consistent one-way pairs when necessary and regular two-way service elsewhere. For example, Dizengoff and Ben Yehuda, the two north-south streets hosting buses to the west, function as such for cars. They both have contraflow lanes for buses, allowing buses to use them as two-way streets; some do (for example, #5 on Dizengoff), while others still go one-way (for examples, #9 and #55). Likewise, Jabotinsky, the east-west street feeding into the big circuit, is one-way and narrow west of Ibn Gabirol, and could be a one-way pair with Arlozorov to its south; but Arlozorov is kept two-way, and so #66 is two-way, and #22 uses the two as a one-way pair. (By the way, those are fan-made maps; the official maps don’t use color to distinguish routes, and are thus completely unusable.)

The results of the mess coming from ending any service coherence are predictable. Israeli car ownership, low by first-world standards, is rising rapidly, and the social justice and affordable housing protesters are now complaining about high fuel prices. None of them is anti-transit on principle, and all who I confront tell me they’d ride transit if it were usable. I live without a car in a city with worse transit than Tel Aviv, but to me car ownership is not aspirational. When the only transit people know in their country is unusable, people this generation will get cars. The next bus reform will then take into account more left turn restrictions coming from the need to accommodate more vehicles. The next generation of people will grow up with the expectation of even worse bus service and not conceive of any alternative to automobility.


  1. Zmapper

    One way streets tend to be overlooked by the urbanist circles, but the inclusion of one way streets allows for more pedestrian centered activity nodes to be created without disrupting traffic too much. In Denver, try to think how much harder politically it would have been to create the 16th Street Mall if 15th and 17th weren’t one way with the ability to handle large numbers of autos and buses efficiently.

    High speeds kill people, not average speeds. Because of the simpler traffic signal phasing, traffic lights can be timed to keep traffic in packs moving at 25-30mph, allowing people to travel at a high average speed but a relatively low top speed. Denver frequently uses dummy lights every couple of blocks, the idea being to keep traffic in a tighter, more controlled pack. With traffic in tight packs, it becomes much easier to cross the street.

    One unique thing Denver does in the newer areas is to split a two way street apart at major intersections, so it looks like the intersection of 4 one way streets from above. Instead of a 4-phase signal timing with separate lights for left turning traffic, the East-West street gets the light and then the North-South street gets the light. Using this example, an Eastbound driver on MLK wishing to travel north on Central Park would wait until the East-West phase, then make a left turn at the same time all other MLK traffic is moving. The driver would then wait between the Eastbound and Westbound “streets” until Central Park traffic would receive a green light.

    The ideal main street in my mind would be a central bus and ped only street as the focal point, flanked by two one way streets a block apart on each side of the street. For a pedestrian crossing the area, instead of having to wait a long time to cross potentially nine lanes of high speed traffic, with turning conflicts abound, they cross a three lane street, then two bus lanes, then another three lane street. People in cars get where they want to go at a reasonable rate of speed, people walking get to cross arterials more resembling streets than highways.

    On a side note, I feel compelled to mention this disaster of a one way street. Yes, a one way street with a bidirectional mainline freight railroad right down the middle.

    • Alon Levy

      The problem is that in Tel Aviv, there are almost never these alternative streets. The city was built on a Garden City grid: there’s a network of arterials, forming a grid in the northern part of the city and a more irregular network in its southern part, but it’s not too dense. There are 250-500 meters between successive arterials in the Old North. The other streets can’t be used to go all the way through; most were designed to be quiet residential streets and thus are not through-streets, and the few that are are NIMBY-prone. Try to route through-traffic there and your popularity will immediately sink below that of Mahmoud Abbas and just above that of Ehud Barak.

      The four-way intersections you talk about are a good option, and exist partially in Manhattan. The major intersections involving Upper Broadway, for example 96th, work this way for cars turning left. It slows down cars somewhat (say, 22.5 seconds, i.e. half a phase – they need to wait 45 seconds at the intersection, but would be delayed half that if the intersection had four-phase, auto-oriented signaling), but pedestrians can cross without waiting too long. This could be the main solution on the divided arterials in Tel Aviv, which predominate in most of North Tel Aviv, excepting the oldest parts, south of the river and west of Ibn Gabirol.

    • Nathanael

      “On a side note, I feel compelled to mention this disaster of a one way street. Yes, a one way street with a bidirectional mainline freight railroad right down the middle.”

      Oh, Fort Collins! Yes, I have family there. When you mentioned this I knew where you were thinking of immediately.

      The City has proposed a plan to build a passenger train station on that street, separate the track from the street by “depaving” the middle section, and using the remaining lanes for local access (rather than as a thoroughfare). It would work, but the popular justification for it is the train station, and first they have to figure out how to get someone to agree to run a train from Denver to Fort Collins.

      • Zmapper

        Mason Street will become two way in a few months in order to accommodate the Mason Corridor busway, so enjoy it while it lasts. Because they never built the connection to College at the north end, it is rather useless as a one way street and would function better as a two way street.

        I recall CDOT had plans to build a train station for commuter rail in 2075(!) between Lapote and Maple, though the single track will remain in its current location and service will only be hourly.

        Priority number one should be to get the tracks off Mason somehow, through the use of a viaduct or a tunnel. Visually, a tunnel would be the best alternative, though ventilation and construction cost would mean that a tunnel likely won’t work. A viaduct above Mason would be the cheapest, but the most visually disruptive alternative. Looking a 1/2 block east, the alleyway between Mason and College starts to look attractive, though it would require the relocation of about 10 or so businesses. I don’t think that any of the buildings right in the path are on the historic list, though most of the buildings in the way appear to be post-war single story structures.

        Space should be preserved for a four track station with two island platforms; this will provide enough track space to allow for a frequent Denver-Fort Collins service, service continuing up towards Cheyenne, and a track for a potential Amtrak or Intercity service to stop at.

        In order to make it less visually obstructive, a brickwork arching design that matches the surrounding architecture would be the best solution. Whatever they do, don’t propose a bland concrete and steel structure; it won’t survive NIMBY attacks longer than 30 minutes.

        A sketch of it in Google Maps is here:

        Finally, I don’t see how RTD will be able to build commuter rail up to Longmont, much less a future extension up further north. They have shot themselves in the foot so much and treated the area north of 72nd Ave like crap that a sales tax increase likely won’t pass. Northern residents don’t expect a train anytime soon, and the Southern residents already have their train, so why would any group vote for a tax increase?

        • ant6n

          If ventilation is an issue, a tunnel could be left open to the top. For example if there exists a single track in the median of a roadway now, one could built a 2-track tunnel just below that, and leave a strip open where the single track used to be. Building plenty of crossovers, and it should be fine.
          I’ve seen something like this for a u-bahn/stadtbahn station or something somewhere, but I don’t remeber exactly.

        • Nathanael

          The road is wide enough to keep the track on the surface and still have viable road traffic on either side.

          Nobody thinks Fort Collins – Denver will support better than hourly service, so grade separation doesn’t seem necessary even in the medium term…

          As for funding, Fort Collins / Cheyenne service would definitely be funded from totally separately sources than RTD. Sources which don’t exist right now.

          • Zmapper

            The issue isn’t through traffic, which can proceed while the train is moving, it is cross traffic. I have waited enough for 120-car coal trains destined for Wyoming to crawl their way through town that the tracks need to move somewhere. The estimate for moving the tracks east of town was I believe over 1.4 Billion. Even at low Colorado construction costs, 1.4 Billion is a ton of money to spend on a single city. My guess is a tunnel or viaduct/ earthen embankment stretching the entire town could be done for under $400 Million, which provides the benefit of having grade separated tracks for less than the cost of moving the railroad out of town.

            Nobody thinks FtC-Denver could support more than hourly service? Ask the local rail advocacy groups, they think that more trains could be needed.

            From what I have heard, Wyoming is flush with money at this point that they are willing to pay for a good chunk of the line up to Cheyenne. It is important to remember that Fort Collins is twice the size of Cheyenne, and the greater Denver area much, much larger than Cheyenne, so it is in their best interest economically to be well-connected to Colorado. Wyoming has even done a preliminary study (though it assumes FRA compliant diesel push-pull trains and no track geometry improvements). The study is here:

          • Adirondacker12800

            Nobody thinks Fort Collins – Denver will support better than hourly service,

            I’m sure they could fill a car an hour. Metro Fort Collins has a population of 271,927
            Metro Cheyenne has a population of 91,738. Fort Collins is 60-ish miles from Denver and Cheyenne is 45 from Fort Collins. Unless they spend a lot of money, it’s going to be slower than driving. Make it faster than driving and they might be able to fill up two cars. and you’d still be sending a mostly empty train between Cheyenne and Fort Collins.

            Look at it this way. Cheyenne is far away from Fort Collins as Ithaca is from Binghamton. Very roughly the same size. And there’s a nice wide flat straight Interstate between the two. How often do you get the urge to go to Binghamton? Or people in Binghamton get the urge to go to Ithaca?

            Or look at it another way, Fort Collins is metro Lancaster PA and Denver is Philadelphia. The Keystones run once an hour-ish and in fiscal year 2011 Lancaster had 539,338 boardings and alightings. Or roughly 1,500 a day. It’s easier to park in Denver than it is in in Philadelphia. The road between Fort Collins and Denver isn’t the PA Turnpike. There’s nothing like New York or Baltimore beyond Denver. A car an hour might be stretching it.

          • Zmapper


            Fort Collins – Denver also serves Loveland, Longmont, Boulder, Westminster, and
            Thornton. Not even counting Denver proper, nearly a million people live between Denver and Cheyenne. The downtowns of all the cities, with the notable exception of Boulder, all line up right along the railroad. Jarrett Walker of Human Transit likes to talk about lines being the ideal transit geometry. Well here you go, a million people lined up within about 3 miles of an existing railroad.

            Close to 5,000 people commute between Fort Collins and the Denver metro area, and 5,000 commute the other way. Commuters travel every way at rush hour, there is no real “peak flow” in any direction. The commute patterns make it ideal for transit, as you have bidirectional travel demand 18 hours a day. If you can’t fill a 4-car FLIRT EMU or like vehicle running every 15 minutes a day, you aren’t trying hard enough.

            Cheyenne is more difficult, partially because of the distance and prevalence of acre-plus ranches up there, but a few factors could make passenger rail competitive. Downtown Cheyenne is rather dense compared to like cities, and vacancy rates are low. Cheyenne never did experience the suburban shopping area push as much as other cities did. Warren Air Force base is right next to Downtown Cheyenne, which means that a bus shuttle to the rail station could be competitive.

            The other thing you have to consider is weather, particularly snow and wind. During the Winter it feels like I-25 is closed more often than it is open! People veering off the highway and rollovers are common all year round. If a crash shuts down the highway, the nearest detour that isn’t a one-lane barely dirt road is US-85, all they way over by Greeley. The concern here isn’t travel time, but reliability. Will you reliably be able to get home from your job at the Cheyenne hospital or the Air Force base, or will you be stranded up in Cheyenne, forced to find a motel room?

            Service map is here:

          • Adirondacker12800

            Sigh. I was being charitable comparing Denver to Philadephia. The whole Front Range Urban Corridor, the name WIkipedia gives it, is 200 miles long and has less population than metro Philadelphia.

            If there are 10,000 people rushing to and fro to work, you’d be really really lucky to get 20 percent of them. Or 4000 trips. Here’s what 20,000 trips looks like.


            And here’s what the Census has to say about commuting


            When the weather is so bad it closes down the Interstate it’s bad enough to shut down the shuttle bus to the station and makes the drive from the station to home nearly impossible. Keep in mind that Pennsylvania has weather too.

          • Nathanael

            “How often do you get the urge to go to Binghamton? Or people in Binghamton get the urge to go to Ithaca? ”

            Personally, about 6 times a year due to necessary appointments, but I know off the top of my head three people who do so three times a week due to club meetings.

            I don’t actually think Ft. Collins-Denver will support even hourly service, but that was a “top possible” number.

          • Nathanael

            “The issue isn’t through traffic, which can proceed while the train is moving, it is cross traffic. I have waited enough for 120-car coal trains destined for Wyoming to crawl their way through town that the tracks need to move somewhere. ”

            So the problem is the freight traffic? The *passenger* trains will be short and fast enough that they won’t block traffic.

            There was a large scheme planned for rural “coal line” bypasses in eastern Colorado.

            Barring that, one could put all the freight trains to take the riverside corridor (grade separated) and put the passenger trains downtown.

            Of course, that would require further cooperation between archenemies BNSF and UP, and would specifically mean UP allowing more BNSF trains on its line without overcharging BNSF. This won’t happen. If the network were nationalized a la British Rail, it could be done easily.

          • Nathanael

            The thing is, Ft Collins – Denver *could* almost certainly support clockface hourly service in the mornings, evenings, and midday. (Not necessarily at night, which is why I said hourly was a maximum.) This is a pretty standard level of service for intercity service in many countries, and would probably be sufficient to get a large ridership. It would probably start out filling one car an hour, but soon it would be up to two, and then as people’s patterns change, perhaps three or more. Over a distance as long as Ft. Collins to Denver, turn-up-and-go frequencies aren’t going to be necessary to get the ridership.

            But no funding for anything, so sigh.

    • Adirondacker12800

      ….an Eastbound driver on MLK wishing ….

      At least they don’t have to worry about there being any pedestrians. Why didn’t they go for a full cloverleaf? Or a SPUI?

        • Adirondacker12800

          I’ve been in Fort Collins, decades ago, but I’ve been in Fort Collins, Of course it has pedestrians, it’s over run with college students. Look at the satellite image, there isn’t going to be any pedestrians out there until cars and bicycles are banned, leaving everyone to shoe leather.

  2. dan reed!

    Philadelphia has a strong one-way pair in Chestnut and Walnut streets, which run east-west across Center City and West Philadelphia and form the spine of its main shopping district. They’re one block apart (with a smaller street/alley, Sansom Street, running between) and run to the edges of the city, which allows for really legible bus service like the 21. Though the streets are narrow (maybe 28 feet curb to curb), they allow traffic to move smoothly at low speeds while being very nice for walking (not always biking, unfortunately).

  3. EngineerScotty

    One thing that Jarrett mentions frequently is that contraflow couplets (permitting busses and trains to board toward the center of the couplet, assuming vehicles that have doors on the same side as traffic moves–on the right in the US and Israel) work better that ordinary couplets. Portland’s Transit Mall is an example. (The other major light-rail couplet in Portland, Yamhill/Morrision is not contraflow, but trains travel in the left lane on these streets and board on the left, so it has the same effect).

    Portland has a few bad examples, though; the most notorious of which is probably the 15 bus, which travels on Salmon and Washington streets–five blocks apart–through downtown.

  4. Pingback: Asymmetric Mode Choice | Pedestrian Observations
  5. Keep Houston Houston

    How frackin’ easy is it to just put in a 50′ left turn bay and put up a sign that says BUSES ONLY? You could even have it signalized so that the bus triggers it every 6/10/15 minutes while it’s green the rest of the time.

    I’m a huge fan of eliminating left turns on arterials but if the logic says a bus route should turn left, make a damn exception.

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