On the Expo and Millennium lines, you'll never wait more than 8 minutes for a train. On the combined portions of these lines, which connect some of the densest centers in greater Vancouver, you'll never wait more than 4 minutes -- not even at 7:00 AM on Sunday or 11:45 PM on a Tuesday. In a year of living in Vancouver and riding Skytrain every day, I never waited more than 5 minutes.If WMATA undertook a similar policy, it's hard to overstate the benefits to the region. More frequent trains would mean that the system could handle more riders. More people would use the Metro, because the expected wait times and crowdedness would both fall. Perhaps the labor cost savings would even allow the Metro to stay open later. Many of these additional riders will spend money in the local economy that they otherwise wouldn't have.
The lack of a driver is the key to those extreme frequencies. When you have a driver on every vehicle, the labor cost is the dominant cost of operations. So when you have to cut service, as many North American agencies are doing this year, you end up cutting frequencies, starting with late night and weekend. Many North American light rail systems are dropping below even a 15-minute frequency in the evening, making themselves increasingly useless for the spontaneous trips that are essential to freedom in urban life.
Of course, such a plan might not be feasible in the D.C. region, for any number of reasons. But I suspect that a study thereof would never be conducted, as it puts in jeopardy the jobs of the current train operators. Additionally, the fatal Red Line crash last June, in which the train operator hit the brakes to no avail, wouldn't help convince people that driverless trains will be safe. However, the D.C. area may be paying quite a high price to keep these people employed, if it means limiting the hours and frequency of Metro trains.