The Sound Transit Board on Thursday kicked off a public involvement campaign to decide what mass transit projects should be studied as the final candidates for a Sound Transit 3 (ST3) ballot measure.

Community members throughout the fast-growing Puget Sound region can engage on ST3 priorities via an online survey, a new interactive website, public meetings and social media.

“Continued expansion of our successful transit system through ST3 is critical to keeping our people and our economy moving,” said Sound Transit Chair and King County Executive Dow Constantine in a media release. “It’s a pivotal time at Sound Transit, and we invite our riders to be a part of it.”

The board is seeking input on a draft list of projects to be considered possible candidates for the ST3 measure. After collecting input on the Draft Priority Projects List, the board will identify a final list of projects to be studied this fall. The results of those studies will support further narrowing by the board to shape a draft ST3 measure for public input in early 2016.

Potential projects emphasized so far by the board and earlier public input include but are not limited to building light rail extensions to Everett, Tacoma, downtown Redmond, Ballard and West Seattle, as well as bus rapid transit on I-405 and improving ST Express bus and Sounder commuter rail services and facilities.

An interactive ST3 website that went live Thursday – soundtransit3.org – offers a chance to learn more about regional transit benefits, explore potential projects, and take a survey through July 8.

Six public meetings around the region begin June 16:

Seattle: June 16, Union Station, 401 S. Jackson St.

Everett: June 18, Everett Station, 3201 Smith Ave.

Redmond: June 23, Redmond Marriot, 7401 164th Ave. N.E.

Tacoma: June 24, Greater Tacoma Convention & Trade Center, 1500 Broadway

Seattle (daytime): 11:30 a.m.-1:30 p.m. June 25, Union Station, 401 S. Jackson St.

Federal Way: June 25, King County Aquatic Center, 650 S.W. Campus Dr.

Except the June 25 daytime meeting in Seattle, all of the meetings will run from 5:30 to 7:30 p.m., with presentations at 6 p.m.

For the ST3 measure to be considered by voters in November 2016, the state Legislature must first grant the region additional local revenue authority. Members of the Sound Transit Board are seeking $15 billion in new revenue authority and have emphasized it is critical for the Legislature to act on this and a statewide package of transportation investments before the current special session ends.

“The Puget Sound’s expected 30-percent population growth by 2040 will be equivalent to adding the populations of Tacoma, Seattle and Bellevue combined to our already congested transportation network,” said Sound Transit Board Vice Chair and Tacoma Mayor Marilyn Strickland. “Before the Legislature adjourns we need the authority to meet the public’s strong demand for expanding our transportation system with more congestion-free travel options.”

The Sound Transit District is home to 50 cities and more than 40 percent of Washington’s population.

“Our region is home to 70 percent of our state’s economic activity and 97 percent of its congestion. Between 2010 and 2014 alone, congestion delays on I-5 nearly doubled,” said Sound Transit Board Vice Chair and Everett City Councilmember Paul Roberts. “Expanding light rail will protect our economy by ensuring businesses want to locate and expand here. It will also help us control carbon emissions and pollution to our air and water.”

Over the past 14 years Sound Transit has developed a strong track record delivering mass transit investments. The University Link light rail extension, with new stations on Seattle’s Capitol Hill and at Husky Stadium, is on track to open in early 2016, six to nine months early and approximately $150 million under budget.

In 2016 Sound Transit is also on schedule for an early opening of an extension of Link one stop further south from the airport, to Angle Lake. In 2021 light rail service is scheduled to open to Northgate.

By 2023 Sound Transit is on track to extend service further north to Lynnwood, south to Kent/Des Moines and east to Redmond’s Overlake area. The extensions are expected to increase overall weekday ridership to more than 350,000 by 2030.

To complete an online survey, go to soundtransit3.org.