Delays and schedule changes can make the underground commute frustrating for New York straphangers.

Thankfully, a new iPhone app may mean those daily pains are a thing of the past.

Alex Bell, a graduate student at Columbia University, developed SubwayArrival, a free app that uses crowd-sourced data to track the trains live. Users can predict when the train will arrive at the nearest station, saving them a long wait on the platform.

Unlike other apps that rely on published schedules, Bell said SubwayArrival can still provide accurate data when delays occur—something that might save the MTA millions in infrastructure costs.