Civil engineers need to design around people. This is a hint for this week’s Micro Softy.  At the Dallas-Fort Worth (DFW) airport, the train Skylink seamlessly transports you from terminal to terminal. Trains depart every 2 minutes, with a maximum travel time of 9 minutes between the farthest points, making it highly efficient. The train operates from Level 3. An up escalator takes you there.  Here is something interesting. There is a single escalator that takes you up to the Skylink train. There are two down escalators for those exiting the train. That’s this week’s Micro Softy. Why are there two down escalators but only a single up escalator for Skylink?   See next week’s Micro Softy for the obvious answer.  Solution to Micro Softy 73: Necklace Cutting   Here’s last week’s Micro Softy concerning a girl named Sally with money flow problems.   Sally needs to pay her rent daily for 30 days using individual gold beads from a 31-bead necklace. However, each time she cuts the necklace to separate beads, she must pay a jeweler to reconnect it. To minimize these jeweler fees, she must find a strategy that allows her to give the landlord exactly one bead per day using the fewest possible cuts. …