How Connect2020 trains might have been more frequent

Dave Honan/Flickr

Back during my first round of gripes about rider-unfriendly choices for the Connect2020 construction delays, I suggested that Sound Transit might have run trains more frequently outside the downtown transit tunnel. At the time, ST said that this would likely result in significant train bunching. After further discussions, they appear to have backed off this objection in favor of other ones, which readers can judge for themselves.

But first, let's show how the right plan would minimize train bunching. While there is (infamously) no fixed schedule, the current operational model for Central Link trains is something like this:

Minute	Event
0	Train cleared to depart Northbound from Sodo
2	Serves Stadium NB (NB platform)
4	Serves Chinatown NB (NB platform)
6	Arrives at Pioneer Square
8 (est)	Leaves Pioneer Square
10	Serves Chinatown SB (NB platform)
12	Serves Stadium SB (NB platform)
14	Arrives Sodo SB, next train cleared to go north from Sodo.

Imagine a second pair of trains, A and B, interleaving as follows. At the start of the cycle, A is loitering just south of Stadium on the SB track, and B is on its way up from Angle Lake.

Minute	Event
0	Train cleared to depart Northbound from Sodo
2	Serves Stadium NB (NB platform)
4	Serves Chinatown NB (NB platform)
5	A departs for Sodo
6	Arrives at Pioneer Square
7	A serves Sodo SB, B serves Sodo NB
8 (est)	Leaves Pioneer Square
9	B arrives at the loitering spot
10	Serves Chinatown SB (NB platform)
12	Serves Stadium SB (NB platform)
14	Arrives Sodo SB, next train cleared to go north from Sodo.

Note that in both directions, this offers headways of about 7 minutes at Sodo and below. In priniciple, one could park trains at the unused track at Stadium and thus extend service to that station; however, ST is using this opportunity to do some repair work at Stadium as well.

I believe a similar pattern would work at Westlake.

One downside is that the turning trains will have to drop everyone at Sodo. While tere is lots of bus service there, ST points out that emptying the train can "introduce rider safety and crowding issues" for those awaiting the next one. Longtime riders recall that Sodo is a traditional dropoff point for trains experiencing a maintenance issue and destined for base. There is risk in making this a routine part of operations, rather than something for urgent situations.

Furthermore, there would be some tough decisions on the fleet. There are probably not enough rail cars to uniformly run 4-car Pioneer Square trains and even two-car Sodo or Westlake trains in the peak. As crowding is not as severe between UW and Westlake, it would make sense for some or all of the Pioneer Square trains in this segment to have 3 cars.

Although not as significant a problem as the lack of real-time information, more frequent trains would have solved a few problems. Westlake is a huge destination in its own right. Moreover, both Westlake and Sodo provide nearly infinite bus transfers at peak to travel further downtown. It's easy to call for smaller safety margins from the sidelines. And yet, much like the Connect2020 bike restrictions, this seems like an overabundance of caution, one that has the disastrous effect of halving frequency on important segments of the line.