Occupational hazard I suppose, but lately I seem to be having traffic thoughts wherever I go, times when I feel like I really need an operations engineer on hand to answer burning questions of perhaps little consequence.
To wit, I’ve been boarding a lot of planes lately and have been curious about the boarding process. Certain seat parameters are announced, a bunch of people rush up to the agent, they are scanned through, and then there’s that stretch of gloriously empty boarding tunnel you go bounding down — until the moment, usually when you round the curve, that you hit the back of a queue. So you set your bag down, until the person ahead moves, then you creep up, then you wait, etc. It often gets me to wondering: Would it be any more efficient to allow people through the initial bottleneck any more slowly, so they could magically walk uninterruptedly to their seat? How much time is wasted in these shuffling stop and go steps? Would it be better to stagger arrivals so that there’s less chance for a queue to form? Or would the queue just form somewhere else? I know many people have thought long and hard about the best way to “plane” passengers, but not sure if this particular quirk has come up.
These thoughts came up again when reading an interesting post I missed the first time around over at Khoi Vihn’s Subtraction. It concerned the author’s interest in the new “destination-based dispatching” elevator system at his place of work. DDB, as I’ll call it, is the new new thing in the elevator biz; basically, instead of putting people onto an elevator and having them choose their appropriate destination, it has people choose their destination and then puts them on an appropriate elevator.
In any case, Khoi Vinh rounded up an elevator expert to talk these things over. One thing that came up was an idea that I touch lightly upon in the book: The comparisons of elevator traffic to vehicular traffic. (in the case of Traffic it’s an engineer with LA DOT comparing the problem of synchronizing traffic signals to elevator flow). But in this case, Vinh makes another analogy: “For instance, there are four basic modes of traffic: balanced mode, in which up and down calls are evenly distributed throughout the building; up-peak mode, in which most traffic wants to go up (mornings, usually); down-peak mode, in which most traffic heads downwards (close of business, usually); and lobby-peak mode, in which the majority of the traffic goes from the lobby upwards.”
In essence, “vertical transportation engineers,” as elevator types are known, have a very similar job to “horizontal transportation engineer,” at least in terms of managing peak-hour flows. Shortly after everyone in a place like Shanghai has fought through the traffic and gotten to their job at a tall office tower, they then face new traffic troubles (which have even included calls for “traffic cop” style monitors). Of course, elevator types have an edge, as I can’t imagine how “destination-based dispatching” could really be made to work in the vehicular traffic world (perhaps if DOTs manipulated routing and real-time traffic data?).
Another problem similar to traffic is the idea that some waits seem worse than others. As the engineer tells Vinh, “destination-based dispatching changes the name of the game — because the technical problem to solve is [no longer] minimizing people’s hall call wait time, but rather their total elevator involvement time.” DDB plays a bit of psychological havoc because while people’s total trip may be shorter, they may spend longer in the lobby, watching others board first, wreaking havoc with their sense of social justice. Ramp-meters in traffic have the same rough effect (even though their better for the long-term trip in most cases).
Still, it’s a fascinating world, extolled in places like Elevator World magazine. There, we learn such things as the fact that lunchtime elevator traffic, in one building study, accounted for 12% of building population (almost seems low, no?). As in car traffic, there’s all sorts of clever counting devices too, from photos of “lobby counts” to “traffic analyzers” that “record the time every landing and car call is made and cleared.” As in car traffic some have even suggested “flex time” arrangements would help alleviate morning up-peak flows.
For more on this, do see, if you haven’t already, Nick Paumgarten’s piece on elevators in the New Yorker, which I have to say is the piece that’s brought me the most pleasure in that magazine all year.
This entry was posted on Monday, September 8th, 2008 at 4:33 pm and is filed under Traffic Wonkery, Uncategorized. 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.