When planning the project in 2000, the tentative opening was planned for 2007, but that was clearly too optimistic even if everything had been done properly. The attempt to actually open in 2012 was quite serious, and transfer from TXL was supposed to be just weeks away after the final acceptance round (which then failed spectacularly).
To corroborate its seriousness, I actually had a ticket issued to BER in 2012 that was changed to TXL about a month before the flight.
I was actually scheduled to fly home out of BER in 2012. I don't know how much lead time the airline actually had, but I only found out a few weeks before that my flight changed to TXL.
yes, currently it is 1096 days too late. and counting.
Washington, DC has been working on relaunching trolley car service since 2004. I think it was originally scheduled to be completely in 2008. It's still not open for service and there's a small but vocal number of people who think we should just pull the plug on even bothering. Infrastructure is hard, I guess.