It’s the $8 million train station with no trains.

Aggressive predictions that Altamont Corridor Express passenger commuter trains service would come to downtown Manteca’s Grand Central-style transit center at South Main and Moffat  as early as 2018 made four  years ago look less likely with each passing month.

That prediction by ACE Executive Director Stacey Mortensen is predicated on Stanislaus County voters approving a half cent transportation sales tax similar to San Joaquin County’s Measure K.

Stanislaus County voters are expected to vote on a half cent tax plan in November of 2016. Voters in that county rejected similar ballot measures in 2006 and 2008. And while a majority approved the plan, the tax requires a two thirds vote to pass.

Then there is the question whether a sales tax — if it passed — will have enough funds set aside to make service to Modesto and eventually Turlock work. Merced County would also need a similar tax to extend ACE to Merced where it would interconnect with the California High Speed Rail line.

However, if the Stanislaus County sales tax fails again Mortensen earlier this year told Manteca elected officials that the option of extending commuter rail service south through Manteca and ending in Ripon is being considered.

It would cost $161 million to extend ACE train service along the existing Union Pacific Railroad corridor through Manteca and into downtown Modesto as part of the first phase. The project includes 20.3 miles of track to essentially double track the corridor from Lathrop to downtown Modesto. The doubling tracking would cost $40.6 million for construction while the 250 acres of right-of-way required is expected to cost $50 million. Structures — such as bridges — would add another $30 million while a signal system would cost $40.6 million.

Double tracking is essential due to the heavy freight train movement on the UP line. Working on one track would make commute times longer as freight movements would slow down passenger service.

Surveys show potential ridership is strong enough for the option for San Joaquin County to go it alone and make Ripon the southern terminus of ACE service should Stanislaus County fail to step up.

 ACE runs four trains week days  covering the 86  miles from Stockton to San Jose and back. The trip takes two hours and 10 minutes. Just fewer than 1.1 million passengers were carried in 2014.

The Lathrop-Manteca station consistently rates in the top two for boardings switching off with Tracy. The daily ridership in mid-December had 554 bodings at Tracy, 546 at Lathrop-Manteca, 509 at Pleasanton, 272 at Stockton, 227 at Livermore, 189 at Vasco Road, and 187 at Fremont.

Fifty-five percent of the riders and 18.5 percent of the operating budget is from San Joaquin County. The Bay Area, with 45 percent of the ridership, contributes 28 percent of the budget. The fare box accounts for 50.16 percent of the operating budget. It is one of the highest fare box receipts in the country. Typically public transit such as buses and commuter trains secure only 20 percent or so of its operating revenue from fares.

ACE is working toward adding two more trains between San Jose and Stockton as well as upgrading tracks over the Altamont Pass to reduce travel time.

 Should service be extended into Modesto via downtown Manteca and additional trains added on the current route, projections anticipate 2.25 million riders by 2020. Extending service into Merced by 2025 could push ridership to 5.9 million a year.