I'll start worrying when the freight trains running by my house reduce their crew complement - currently two...
The Docklands Light Railway in east London, UK, has been operating driverless trains for some years. The network is 25 miles long with 45 stations and runs seven days a week from 5.30 am to 12.30 am. In the year 2012 it carried 140 million passengers. There is a driving console and staff are available to take over where necessary but normally all journeys are driverless.