Sound Transit 3: Is it the best investment in the future?

SEATTLE -- We continue our in-depth look into Sound Transit 3 -- the $54 billion measure being weighed by voters in King, Pierce and Snohomish counties to expand light rail and other transit services.

Supporters say it is a high-capacity alternative to avoid our growing gridlock.

Opponents say that in 25 years, when the project is finally complete, it will be obsolete -- a dinosaur, they say, as we introduce new technology, like self-driving cars.