Transit leaders dream of more than $1 billion in federal taxpayer money flowing into Los Angeles before the prospective 2024 Olympic Games and of local voters approving the fourth transit sales tax increase since 1980. But would the Los Angeles County Metropolitan Transportation Authority be ready to spend the cash?

One bus station at Union Station could offer a few lessons as federal officials and L.A. voters evaluate Metro’s construction record.

The expansion of the Patsaouras Transit Plaza is forecast to be 120 percent over budget and more than three years late — the most troubled of 11 construction projects listed in Metro’s last update. Conceived after a large, unexpected federal grant agreement in 2008, this station has endured miscalculations, surprises and one expensive mistake.

“This was a dream project,” Metro project manager Tim Lindholm said. The federal grant “put us in an unusual situation of setting aside money and budgets for projects we hadn’t designed.”

At an estimated $37.6 million — up from the initial $17 million budget — experts disagree on whether this bus platform will be worth the cost. Officials hope to save about five minutes each way for thousands of commuters walking daily to other buses or trains. Besides inconvenient, the current Silver Line bus stop at Union Station also is dangerous and uncomfortable, officials say.

But when they proposed the station in 2009 to fit with the federal grant, Metro leaders didn’t realize how complicated it would be. Nor did they expect an engineer to “mis-transpose” the location of a subway tunnel on the drawings — an error that could cost taxpayers more than $6 million.

“Usually, the capital funding is scarce, so we study things very thoroughly, and funding eventually becomes available,” said Juan Matute, associate director of the UCLA Lewis Center and the Institute of Transportation Studies. Now the Olympics and an extension of the Measure R sales tax “could lead to a lot of funding being available relatively quickly. It’d be good to have a better understand of costs in advance of that windfall.”

Faster, safer passage

About 3,000 people either board or disembark at the current stop near Alameda Street each weekday, according to data from Metro and Foothill Transit, which also stops there. Passengers have to walk across a 101 Freeway off-ramp or a toll lane on-ramp to wait at a narrow median with two trees, some signs and benches. If riders want to transfer, they have to cross the on-ramp and walk up to 10 minutes through Union Station.

Metro transit planners say they want to improve the experience on one of the agency’s premier rapid bus lines, the Silver Line. The Silver Line connects the South Bay and the San Gabriel Valley to downtown. Today, the bus stop is disconnected from Patsaouras Transit Plaza, Union Station’s main bus hub, which is at capacity.

Metro is planning to build a new covered platform on a busway bridge, about 1,200 feet from the island. It would sit in the middle of the roadway and would connect to Union Station through an elevated pedestrian tunnel. Hinged aluminum panels on the tunnel’s exterior would ripple with the breeze, creating a “wind bridge,” as the agency describes the public art installation.

“Is it a complicated and expensive project?” Lindholm said. “Yes. But it is seriously the only way to solve the problem.”

• PHOTOS: Bus station project at Patsaouras Plaza delayed, over budget

Two pedestrians have been injured near the current bus station since 2010, according to CalTrans data, and officials say it’s dangerous and riders say they feel at risk. Student Maria Florez takes the Silver Line bus to Cal State Los Angeles, and she worries a car will jump a concrete curb and swipe people waiting.

“I would feel safer,” said Florez, 25, who crosses the on-ramp from Union Station after riding the Gold Line from the San Gabriel Valley. “And if it makes it more efficient in the long run, it’s worth it.”

UCLA’s Matute expects the Patsaouras busway station would be well-used because of its central location at Union Station.

“When you save 3,000 people four minutes or five minutes of walking each, it really adds up,” he said. “It does seem to be a project with a whole lot of merit, independent of the cost.”

Costs climbing

But the price tag for the Patsaouras Plaza busway station is still unknown. It climbed steadily as officials hired contractors to design the project, study underground conditions, redesign the project and fix errors.

The initial cost projection of $17 million was low, Lindholm said, because officials didn’t fully understand what they would have to build. Caltrans required Metro to widen the bridge and deepen the foundations.

Pennsylvania-headquartered engineering firm STV was hired in 2009 to create the conceptual drawings. Based on those plans, the first round of construction bids was far over budget — up to $26 million. After geotechnical surveys and downgrading some of the construction materials, STV issued a new set of plans, and Metro sent it out to bid in 2013.

Officials eventually signed a $20 million construction contract with OHL USA, a New York-headquartered construction company, in 2014. OHL, during final surveying, discovered that STV had incorrectly drawn the location of a Red Line subway tunnel. The bridge’s foundation will need to straddle subway tracks and the rights-of-way for possible future subway tracks. That design error could cost another $6 million, according to Metro’s estimate. Metro executives still are negotiating that change-order.

“You hope that everything is being done with a standard of care,” Lindholm said, “but when you go underground, all bets are off.”

After hiring OHL, Metro planned to break ground in April, but now January 2016 is the target. Officials are waiting for Caltrans to approve the revised plans and for clearances from various underground utilities. That has taken longer than expected. Below Union Station is a tangle of phone, sewer, fiber-optic, electrical and other lines. Previous schedules called for the project to be completed in 2010, then in 2014, and it’s now into 2017.

“There’s always the balance, as you build a project — how much money are you going to spend up front investigating?” Lindholm said. “The more you can know early, the better.”

Looking back, he said, “we probably would have done more.”

Meanwhile, STV’s contract was extended, even after its tunnel drawing error was discovered. Its original $789,000 contract has swelled to more than $1.4 million. The latest addition will pay STV to coordinate with OHL and Caltrans. Officials from the company, which is widely used by Metro and other public transit agencies, did not return a call seeking comment.

Engineers sometimes make costly errors when drawing plans, experts say.

“You have so many different players, so much occurring, that information can get misrepresented,” said Lonny Simonian, a construction management professor at California Polytechnic State University San Luis Obispo.

Because the project is set up this way — with one company completing the “advanced conceptual engineering” and another finishing the design and construction — Metro bears responsibility for the error. It approved the drawings before soliciting construction bids.

A dream project

Officials always knew they needed a better Silver Line stop at Union Station, but they never had the funding. Then they got lucky.

After New York withdrew from a federal grant competition, runner-up Metro received $210 million for a broad plan to reduce congestion along the 10 and 110 freeway corridors. The grant was primarily for “ExpressLanes” toll lanes, but it included funding for surrounding roadways and bus lines. Federal money was coming, and Metro had to pitch projects that would qualify.

Normally, Metro would study the conditions at the site and make preliminary engineering plans before finalizing a budget. But they needed to commit to Patsaouras and a sister project on the Silver Line, the El Monte Station, as a condition for the federal funds. Still today, Metro has not projected ridership growth at the Patsaouras station.

At the current rate of 3,000 riders, the $37.6 million project would equate to about $12,500 per rider. The El Monte Station, opened in 2012 for roughly $60 million, cost about $2,700 per rider (at current passenger levels).

“It would be hard to justify $31 million for less than 3,000 people,” said USC professor Genevieve Giuliano, director of METRANS Transportation Center at the Sol Price School of Public Policy. “But it may have a lot of benefits. If we want a transit system that actually works, you have to make those transitions easy and time effective.”

Matute said the costs and benefits are comparable to construction of some light-rail stations.

“I think it’s a good thing that Metro is continuing to pursue the project,” he said. “It’s unfortunate they weren’t able to forecast the cost early on, but it’s not unexpected.”

Metro officials say they plan to carefully approach major construction before any Olympics.

“We are taking advantage of every possible funding opportunity out there to accelerate projects,” spokesman Rick Jager said in an email. “Yes, every step will be taken to ensure that detailed costs studies, environmental reviews and preliminary engineering are complete.”

In September, Metro CEO Phillip Washington wrote letters to the Federal Transit Administration requesting expedited grants — up to $1 billion for the Purple Line subway extension and $77 million for an LAX airport transit center. Both projects have been in planning for years.