Sound Transit Three, or ST3, is transit plan for the Puget Sound regions (PSR). It plans to spend 50 billion dollars over 25 years. This would be spent on light rail, buses, commuter rail and a little street car. There are way too many parts to talk about in a short post, so I’ll highlight the general cost effectiveness of ST3 rather than address all the pluses and minuses of every project project.

One of the quirks of ST3 is called subarea equity. Sound transit has split the region into 5 subareas and let it be known that it will spend everything made in a subarea in that subarea. This was important because many voters won’t vote for something they perceive to be taking their money and giving it to someone else.There are downsides to this approach. Some areas have more transit demand than others, but they all spend the same, so some subareas get better value for their investment.

One way to think about how effective a project is is 30 year rider subsidy. After 30 years of use, how much will taxpayers have paid divided by how many riders total have rode the system. This metric can give an approximation of value. If taxpayers are only subsidizing a little per rider, it is probably a decent value. If we are subsidizing a lot per rider, maybe we could find cheaper or more effective options.

The best project in ST3 for subsidy/rider is the Ballard to Downtown Seattle line. It is an expensive and complex project, costing $4,450—$4,762 to build. But this high cost is made up by an estimated 114,000—145,000 daily riders. This makes for a 30 year subsidy of $2.77. This subsidy is only slightly larger than the fare itself. This project not only looks good from a revenue perspective, but it also provides a second line through downtown, giving redundancy to what is currently a system close to capacity.

The worst subsidy/rider is on the Sounder commuter extension to DuPont. Even though this is a relatively cheap project, only costing $304 million, it attracts only 1250 daily riders. This makes for a 30 year subsidy of $30.85. That is about six times the fares paid to ride Sounder. That level of subsidy brings up the question of is this actually a good investment. The answer still may be yes, but it needs to be asked.

The worst project from a total waste perspective is Link from Lynnwood to Everett. This would cost 4.183 billion dollars, but only attract 39k riders. The per rider subsidy would be $12.92. Since Link fare is lower than Sounder fare, the Lynnwood to Everett subsidy is about six times the fare. Light rail is likely the wrong technology to be serving a 15 mile line through very spread out development.

ST3 also has some projects which seem OK. The 145th and SR 522 BRT would cost $387 million and attract 8500 riders. The 30 year per rider subsidy is a mediocre $7.59. This gives a 32% farebox recovery which is comparable to King County Metro’s average farebox recovery of 31%. This is not a clear slam dunk, but it isn’t clearly a bad project.

There are many more projects in ST3. Some of these projects are clearly great deals, like Ballard to Downtown. Other projects are decent, like the 145th and SR 522 BRT. But there are also those projects of questionable worth, like Lynnwood to Everett and DuPont. Bad projects can’t just be excluded because it would mess up subarea equity. Next post I’ll discuss whether ST3 as a whole is worth it and what possible alternatives would look like.