The logic is accomplished here: https://github.com/WesleyDRobinson/nextTrain/blob/master/server/app/routes/index.js
Created for a 2 day hackathon at Fullstack, it prompted and took the award of "Most Solopsistic"
This page does one thing. It tells you when the next Manhattan bound L train will depart from Morgan Ave.
Thanks to the MTA Live Data API.
Planned and started to use Twilio API to set up text alerts, but ran out of time--and then moved to SF.