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Show HN: Elevators

1668 points · 413 comments · Jrh0203

  1. theodorejb · · focus · HN ↗
    The worst situation I've encountered is after a large conference when everyone is leaving the hotel at once. An elevator quickly fills up on the way down, but then wastes time stopping at every subsequent floor with a call, even though no one else can fit inside. At each floor the elevator stops, the doors open, the waiting people see it's already packed, the doors close, and this repeats on the next 15 floors before finally reaching the bottom where everyone gets off. If the algorithm could know an elevator is completely full and only stop at its destination floors rather than every floor along the way with a call, it would be far more efficient.
    1. rz2k · · focus · HN ↗
      There’s also a strategy to jump the line. Say there’s a talk that just took place on the top floor roof deck of a small ~20 floor building. People who don’t want to wait in line with a hundred people, can take the stairs down one level, call the elevator on the way up to enter the car before it is filled, ride it up one level*, and then ride it all the way down to the ground floor.

      To prevent a riot, the building should probably deploy an employee with a fire key to manually operate the elevator.

      * Elevators will answer an up button call while it is going to meet a down call from the top floor, but they will answer that call before filling any new down instructions, so you do have to ride to the top first.

      1. dredmorbius · · focus · HN ↗
        Many buildings permit stairwell entry, but limit stairwell exit for fire code (1st) and security reasons (2nd). You'll want to check to see that you can exit at floor n-1 before attempting this, or you'll be riding the stairs all the way down.
        1. Breza · · focus · HN ↗
          I used to work in a shiny new LEED certified government building here in DC. My office was on the second floor. I had to take a elevator every day because the only stairs were for fire use. So frustrating.
      2. n_plus_1_acc · · focus · HN ↗
        Also works for Buses and Trains. Go one stop the opposite way, then go back. This may take a couple minutes longer, but you'll have a seat for the rest of the journey.
        1. Breza · · focus · HN ↗
          Good tip. Somehow this feels more fair than the elevator example but I can't put my finger on why.
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