The city threw itself a party on Saturday, March 19, the day Seattle's newest light rail stations opened.

There were street fairs on the surface—at the new Capitol Hill and University of Washington light rail stations—and what felt like an amusement-park ride underground. Crowds stood anxiously in line on Capitol Hill, funneled down full escalators, and packed themselves into trains. Wide-eyed toddlers—kids who will never know their city without mass transit—watched tunnel walls whoosh past outside the train windows. "We're here!" one excited mom told her kids when the train pulled into University of Washington Station.

The message of opening day—build rail and Seattleites will ride it—is borne out in ridership numbers. At this time last month, about 35,000 people were using light rail on a normal weekday. The Monday after the new stations opened, the first regular workday, the number jumped to 47,000 people. On Tuesday, to 57,000.

According to Sound Transit, the agency that builds light rail, new rail lines to Ballard, West Seattle, and Seattle's suburbs could attract 525,000 riders every weekday. A line between downtown and Ballard would attract as many as 133,000 people a day. It would be revolutionary.

But new lines will be built only if voters approve a new light rail tax package. Advocates and elected leaders are hoping that will happen this fall. Sound Transit's board recently released its plan for that tax package, known as Sound Transit 3. The plan is still in draft form, and a final board vote is expected in June. Here's what you need to know:


IT'S GOING TO COST A LOT

Fifty billion dollars. Some of that money will come from existing taxes, some from new taxes, and some from the Feds.

Since its creation in the 1990s, Sound Transit has been going to voters to fund each new phase of light rail construction. This time, they're going big. Over the course of the next 25 years, Sound Transit proposes collecting $27.6 billion in new property taxes, sales taxes, and motor vehicle excise taxes (sometimes called car-tab taxes). That would be combined with existing taxes, bonds, and expected federal money for the $50 billion total. The various new taxes would shake out on average to about $400 more per year over the next 25 years for the average household in the region, according to Sound Transit.

Passing the package, the largest in Sound Transit's history, will be a fight—and it could get ugly. The measure will come before voters a year after a nearly $1 billion city transportation levy drew criticism for being too expensive and just a few months after an August vote on a housing levy that will be double the size of the last housing levy. In an editorial accompanied by an illustration of a light rail train running on a track made of dollar signs, the Seattle Times editorial board is already calling ST3 a "breathtaking investment."

But the payoff for going big would be dramatic.


IT'S GOING TO DOUBLE THE AMOUNT OF LIGHT RAIL IN PUGET SOUND

Today, Sound Transit operates about 19 miles of light rail. When the projects already funded and under way are done, that'll grow to around 50 miles. All of the projects in Sound Transit 3 would expand that to 108 miles total, about the same size as San Francisco's BART system.

The agency is currently in the process of planning and building light rail north to Shoreline and Lynnwood, east to Bellevue, and south to Angle Lake. ST3 would extend some of those lines, taking rail farther north to Everett, farther east to Redmond and Issaquah, and farther south to Tacoma. Within Seattle, the plan would build two new lines to Ballard and West Seattle, and would add a station on the existing line at Graham Street in South Seattle. The package would start planning work on lines between Ballard and the University of Washington and from West Seattle to Burien, but wouldn't fund full construction of those lines. Voters would have to approve the construction at some point in the future.


THAT'S A LOT OF STUFF FOR THE SUBURBS

While Ballard and West Seattle are two of Seattle's transportation choke points, this plan is decidedly suburban. There are a few reasons for this. Most importantly, the entire region votes on the taxes that fund the rail built by Sound Transit and pays those taxes, so the agency has a policy of funding projects across the region at a scale that's roughly equal to how much money each part of the region is paying into the system. This is both a matter of agency policy and a political calculation to get the suburbs to vote yes on transit packages.

Additionally, Seattle has gotten most of the light rail that's already been built, even though the whole region has been paying for it. In the suburbs, "there's a feeling of it's our turn," says Shefali Ranganathan, director of Transportation Choices Coalition, the advocacy group that will run the campaign for ST3. With people already being pushed into outlying areas because of Seattle's rising rents and the suburbs expected to experience significant growth, all of this rail to the burbs will meet a serious need—just not a Seattle-centric need. (Seattle had a chance to build its own rail system within the city. RIP, monorail.)


IT'S GOING TO TAKE A LONG TIME

The timelines of ST3 are maddening—even for voters normally happy to shell out for rail.

While the agency will continue building projects already under way, the first ST3 rail project wouldn't be done until 2028. Rail wouldn't open in West Seattle until 2033 and in Ballard until 2038. The new station at Graham Street would come online in 2036. (That's 17 years between the recent opening of a station on Capitol Hill and the expected opening of a station at the West Seattle Junction.) Thirteen years passed between voter approval of the first Sound Transit tax measure and the opening of the line between downtown and the airport. Another seven years passed between the start of that line and the new stations in Capitol Hill and at University of Washington.

Seattle mayor Ed Murray, a member of the board that drew up the ST3 plan, said "The timelines give me pause." Transit advocates took to Twitter to complain that light rail wouldn't serve some of Seattle's fastest growing neighborhoods until their kids or grandkids are adults.

According to Sound Transit, those timelines are due to both financing constrictions and construction challenges. The most basic limitation: It takes a while to collect enough taxes to pay for such expensive construction. The agency also faces complex limits on how much it can bond or borrow at once. Construction, too, is complicated. According to Sound Transit's estimates, planning and designing routes and studying possible environmental effects can take as long as 12 years per line. Construction can take another five years or more. The agency then spends another six months to a year testing the new routes before opening them. This whole process will be especially complicated, the agency says, for the route to Ballard, which will snake through a new downtown tunnel and stop at Denny Way, South Lake Union, Lower Queen Anne, Smith Cove, and Interbay before reaching Ballard. Building under downtown, through an already built-out environment, and over the ship canal will add time and cost to the project. Few rail projects can be done more quickly than 15 years, and Sound Transit is saying Ballard will take 22.

Transit advocates are calling for shortening these timelines—e-mail your thoughts to emailtheboard@soundtransit.org—but significant change is unlikely.

"We have no easy sound bite for the public," TCC's Ranganathan says. "At the end of day, we're not going to shrink that timeline by 10 years. It would be impossible to do that unless we actually had the cash... It's just a function of how the revenue comes in."


STILL, THIS MUST HAPPEN

Make no mistake: ST3 is not enough. Seattle's choked streets and lack of transit make up an environmental and equity crisis. This region is pathetically behind in developing the kind of mass transit other cities have relied on for years—the kind of transit that makes it easier for people to live without cars, the kind of transit that makes it easier for poor and working-class people to live in a region where housing costs are high. But we are here because previous generations failed to act. Growth and displacement will continue. Sound Transit's design of this package, and our eventual vote, will determine how prepared we are to respond.

"If you think traffic is bad now, think about this: Over the next 25 years, a million more people will join us in this region," county executive and Sound Transit Board chair Dow Constantine said in his state of the county speech on March 28. "Growth is not a problem. Failing to get out in front of that growth is."