SEATTLE — A new survey has convinced Sound Transit officials they’re on the right track with ideas for adding light-rail and bus service in years to come.

That includes stretching Link light rail north to Everett and adding rapid bus service to Lynnwood from the I-405 corridor.

Nearly 25,000 people filled out the questionnaire available online from June 4 through July 8. Some 70 local governments and interest groups wrote letters.

“It’s safe to say we got a very robust response from our partners and from the public,” said Ric Ilgenfritz, Sound Transit’s executive director of planning, environmental and project development.

Ilgenfritz and other staff revealed the survey results during the Sound Transit board meeting Thursday.

Of the respondents, 78 percent supported the projects list, they reported. Overriding concerns were worsening congestion and the time it takes to commute.

People also wanted to know more about costs of the future improvements and how to pay for them.

Building out the light-rail spine to Everett, Tacoma and Redmond were top concerns — as has been the case since voters first approved light-rail plans nearly 20 years ago. The survey also showed high interest in building new rail segments to Ballard and West Seattle.

Ilgenfritz told the board that the survey demonstrates that agency’s original ideas are “certainly not perfect, but a good, solid start to the planning process.”

The non-scientific feedback should help the agency draw up a $15 billion expansion plan known as Sound Transit 3, or ST3 for short.

Voters likely will be asked to approve the plan, and the taxes to pay for it, in November 2016. State lawmakers, during the legislative session that ended this month, granted permission to put the package on the ballot.

Paying for the proposal would require increases in sales tax, property tax and car-tab fees.

The light rail additions aren’t likely to get built until sometime in the 2030s, if the schedule holds.

The Sound Transit board expects to vote in August on which projects to formalize. People should have another chance to weigh in on the proposals early next year. The board plans to finalize the ballot proposal by mid-2016 for that fall’s ballot.

Leaders in Everett and Snohomish County have made a strong push for a light-rail route that would serve Paine Field and Everett Station, then continue north to the area around Everett Community College and Providence Regional Medical Center Everett.

People from the northern end of Sound Transit’s service area participated less in the online survey than those in Seattle, the Eastside or the south end. A meeting in Everett held as part of the public outreach about ST3, however, was the best attended of the six held throughout Sound Transit’s service area in Snohomish, King and Pierce counties, agency spokesman Geoff Patrick said.

Light rail is expected to reach Lynnwood in 2023. Earlier this month, the Federal Transit Administration completed environmental approvals of the 8.5-mile addition from Northgate to Lynnwood. That keeps construction on target to begin in 2018.

The new segment would include stops at the Mountlake Terrace Transit Center, Northeast 185th Street in Shoreline and 145th street in Seattle. It’s predicted to carry 63,000 to 74,000 riders each weekday by 2035, with a Lynnwood-to-Seattle trip taking an average of 28 minutes.

More info on the 2016 ballot proposal: www.soundtransit3.org.

Noah Haglund: 425-339-3465; nhaglund@heraldnet.com. Twitter: @NWhaglund.