Thanks in part to a sales tax increase just imposed by Salt Lake County, the Utah Transit Authority is proposing a big 12.7 percent increase in its operating budget next year — going from $403.1 million to $454.2 million. Fares will remain unchanged.

More than a quarter of the total budget will go to pay interest on its $2 billion debt — incurred in recent decades essentially as a mortgage to accelerate building its TRAX and FrontRunner rail systems.

Debt service is UTA’s single-largest expenditure in its spending plan, costing $119.1 million next year. The next biggest expense, at $104.6 million, is for bus operations.

Controversy over UTA’s debt — plus scandals over high executive wages, extensive international travel and sweetheart deals with developers — led the Legislature this year to restructure the agency. A new full-time, three-member commission is slated to replace the current 16-member, part-time UTA board by Nov. 1.

Two of Gov. Gary Herbert’s nominees to that new board — Carleton Christensen and Beth Holbrook — were in the audience Wednesday at a board committee meeting where UTA officials unveiled their budget proposal. Herbert has yet to make the third and final appointment to that new board in a disagreement with Utah County.

Most of UTA’s projected revenue for operations — 68.6 percent — would come from sales tax. Passenger revenue is projected to provide only 11.8 percent next year. Federal grants would provide 14.6 percent — and other revenues (such as from advertising) provide 5 percent.

UTA Interim Executive Director Steve Meyer said the sales tax imposed by Salt Lake County will provide an extra $13.4 million for a half year because of the way the tax hike is structured — but said officials have yet to figure exactly how it will be spent.

That new tax adds 2.5 cents to a $10 purchase (or 0.25 cents per $1), with some money going to UTA and some for local roads.

Voters had killed a similar proposal in 2015. However, new legislation that restructured UTA allowed counties in its district to impose that tax now without voter approval. Salt Lake County opted to do that after cities representing a majority of the county’s population passed resolutions supporting it.

Also helping to boost the UTA budget is that Salt Lake City also is providing an extra $3.9 million to increase service within its city next year.

The new budget includes a 3.5 percent pay hike for UTA workers represented by labor unions. It includes a 3 percent raise for administrators.

It calls for a 7.2 percent increase in funding for bus operations, in part because it projects a 13 percent increase in the cost of fuel. It projects a 6.2 percent increase for commuter rail operations, and a 1.9 percent increase for light rail.

The budget includes no proposed fare hikes. Also, UTA Vice President for Finance Bob Biles said that for the first time in years, it includes no new bus purchases. “We’re making them last longer,” and no new buses are needed immediately. However, UTA is looking at leasing 10 new buses for extra service that Salt Lake City is funding.

The budget increases come as UTA is reporting decreases in its ridership this year — continuing a trend over recent years, in part because low gasoline prices led more people to use cars.

UTA reported that ridership through August was down 3.4 percent compared to 2017, but hoped that popularity of the new Utah Valley Express bus rapid transit system — currently offering free fare because of a federal grant — will boost ridership.

UTA also proposed Wednesday a separate $125.4 million capital budget for new buildings and projects.

Among them are:

• Spending $2.7 million to start relocating the TRAX station at Salt Lake City International Airport, made necessary by construction of a new terminal. TRAX construction, costing a total of $22.9 million, will continue through 2021.

• Spending $2.5 million to finish the new Utah Valley Express line, which opened in August while construction continued.

• Continuing construction to double-track the Sugar House S-Line streetcar.

• Using a $1.2 million earmark from the state to complete environmental and preliminary design work for a bus rapid transit line in south Davis County.

• Finishing final design on a bus rapid transit line from downtown Ogden to Weber State University, with construction expected in 2020 or 2021.