This $69 million project is only 5 years old. It already has cracks.

Sacramento's $69 million passenger train platforms at the downtown depot are just five years old, but they are already falling apart.

Hundreds of cracks have formed on the two concrete platforms, allowing water to seep into passenger tunnels. The city, which owns the site, is likely facing repairs that could cost in the millions of dollars and cause disruptions for train passenger for an extended period.

But the city doesn't want to pay. It has filed a lawsuit against three of its private construction partners, accusing each of negligence. In the suit, the city says the concrete starting cracking even before workers had finished building it.

One of those contractors, Granite Construction, counters that city officials were themselves negligent and should be on the hook for paying a share of whatever the repair costs turn out to be.

A jury trial to untangle the mess has been set for October in Sacramento Superior Court. The city and private construction companies meanwhile have agreed to mediation in June in an attempt to come to an agreement on shared responsibility.

City officials and attorneys declined comment on the problem, including what it will take to fix it and whether there is any safety risk for train passengers.

The platforms are located a few hundred feet north of the historic Amtrak depot at 4th and I streets, which is now called the Sacramento Valley Station. Constructed over a two-year period, 2011 to 2013, the platforms are designed to handle more than one million train travelers a year on the three main services that run through the site, the Capitol Corridor and Joaquin regional trains, and the longer distances Amtrak routes.

The city appears to have determined in 2014 that the concrete on the platforms was failing. It demanded the contractors fix it at their expense. Those contractors refused, prompting a 2015 city lawsuit that now involves a half-dozen players.

The platforms remain in full daily use. But extensive interlacing cracking is evident on the concrete, especially in areas above the pedestrian tunnels. Some cracking and water stains are visible as well in the tunnels below.

Evidence at the site indicates the city recently bored holes into the platform at several points - called "destructive testing" - to look inside the platforms to determine the scope of the problem.

Mikael Anderson, a licensed engineer and chair of the Sacramento State University Department of Construction Management, visited the site at The Bee's request to offer a cursory assessment based on visual inspection of the concrete.

The cracking does not appear to pose an immediate threat to train users, he said, although he said that assessment may change when the station is at a higher capacity of users and trains. A full determination would require studying core samples of the concrete and reviewing the engineering and design drawings and documents.

He noted there are only a few cracks visible in the tunnels, compared with many cracks on the platform surface above. That suggests the cracking may be mainly confined thus far to a "topping" or surface slab that likely was poured over a deeper structural slab.

A repair job might involve breaking out and replacing portions of that surface slab, which, on visual review, may be 10 inches deep.

Anderson said the cracking could be caused by the locomotives that run in and out of the station a few feet away. Braking locomotives create both vertical and lateral vibration in the concrete.

"I think the train has a lot to do with this," he said. Asked if that should have been accounted for in the engineering designs, Anderson said, "From an engineering standpoint, the vibrations are hard to quantify."

The three major players in the drama include large companies with years of state and national project experience.

The general contractor, Granite Construction, is a Northern California company that does frequent business in Sacramento, including work on the Golden 1 Center arena a few blocks away immediately after doing this project.

Vali Cooper, a Bay Area-based construction manager, has overseen rail and highway projects around the state.

TranSystems of Missouri, the company that designed the platforms, has worked nationally on high-speed rail projects and facility designs at some large airports.

The city contends that project designer and engineer TranSystems was negligent and careless and "failed to prepare the plans ... in accordance with ... professional standards of care."

In particular, the city claimed that TranSystems failed to recommend waterproofing material between the platforms and the tunnels below. "It knew or should have known that its design would result in water intrusion ... to the ... tunnels."

TranSystems did not respond to Bee requests for comment.

The city contends that contractor Granite Construction was negligent as well, and that it put reinforcing steel in the wrong places and didn't cut the concrete's "joint control grooves" the proper depth. The city also alleges Granite failed to flag problems with the concrete mix.

Granite responded in court documents saying that if there is a problem here, the city itself is negligent and should be required to shoulder its share of any repair costs.

The city also sued project manager Vali Cooper, saying it failed to properly monitor Granite's work.

Neither Vali Cooper nor TranSystems responded to Bee requests for comment.

The city initially published an estimated cost of $44 million for the project prior to construction. But the city's court filings note dozens of change orders were requested by contractors and approved by the city during construction. The city on its website now lists the project at $69 million.

The project involved moving the passenger and freight rail tracks a few hundred feet to the north, away from the train station. That involved building new tracks, as well as the platforms, the tunnels, ramps, staircases, and a covered path from the depot to the tunnel. The project also included a separate pedestrian-bicycle tunnel and other infrastructure and mechanical works.

The project was controversial. Historic preservationists and rail riders complained it forced people to walk several hundred farther from the depot in heat and rain to get to the trains, including forcing them to walking down and up long ramps. Amtrak has been running golf cart service to and from the platforms for people who have difficulty walking that distance.

City officials said the track move was important, however, in order to help turn the Sacramento Valley Station and the surrounding 30 acres into a modern, multimodal regional transportation facility.

The moving of the tracks also notably allowed room to build two bridges to extend 6th and 7th streets into the previously landlocked northern 200 acres of the old downtown Southern Pacific railyard, to allow for future development there.