San Francisco’s new $2.2 billion Transbay Transit Center has only been open a month, and already the visitor walkway that encircles the rooftop park is crumbling.

“No one is happy about it,” Transbay center spokeswoman Christine Falvey said.

Dozens of spots along the half-mile path have become the walking equivalent of potholes.

Since it opened on Aug. 11, tens of thousands of visitors have crossed the center’s $1 million mosaic floor and ridden the elevators and escalators up to the three-block-long park, which cost just over $32 million to build.

And while a certain amount of wear and tear or even patch-up maintenance was to be expected, no one predicted the walkway, which costs $673,000, would start falling apart so quickly.

“A lot of the divots are by the elevators and escalators where there is heavy foot traffic, but regardless, this should not be happening,” Falvey said.

The walkway — which affords visitors panoramic views of the surrounding city streets as well as access to the various attractions and botanical displays at the 5.4-acre park — is made of decomposed granite rather than asphalt.

And while permeable, decomposed granite pathways have been used successfully in parks around the country, the mix here has failed to hold up even under normal foot traffic.

Falvey said the short-term plan is to patch up the walkway’s eroded sections as needed.

A long-term fix has yet to be worked out.

“They don’t know what the problem is right now,” Falvey said.

The good news is that the walkway is under warranty. The bad news is that the crumbling path is the latest glitch in a long-running saga of problems and setbacks for the massive transit center.

Conceived 17 years ago as the “Grand Central station of the West,” the Transbay center was designed as a hub for bus and trains — but rail service remains a distant hope, leaving much of the space empty.

What’s more, the building wound up costing $800 million more than expected.

“It may someday be the Grand Central station of the West if we get the trains,” Supervisor Aaron Peskin said. “But until then we have the greatest public works debacle since the pyramids.”

Poll spin: New polling shows a majority of San Francisco voters favor taxing corporations to pay for new homeless services, but they may balk at the costs.

At issue is Proposition C, which would tax large businesses and corporations to raise $300 million a year to house the homeless.

The money would be on top of the $300 million the city already spends.

A “No on Prop. C” campaign poll of 800 likely November voters by EMC Research showed the measure winning 56 percent to 42 percent. Only 3 percent of those surveyed were undecided.

But when voters were told that Prop. C would be the single largest tax increase in San Francisco history and that it would house about 4,000 people over five years at a “cost of nearly a half-million dollars per homeless person,” support dropped 10 points — to 47 percent.

Prop. C was placed on the ballot by a coalition of homeless and housing advocates — among them the Coalition on Homelessness, the Affordable Housing Alliance, the Glide Foundation and the San Francisco Tenants Union.

The groups see the measure as a chance to finally solve the city’s homeless problem by essentially doubling the current spending.

Now Playing:

San Francisco Tenants Union Executive Director Deepa Varma said while the price may be high, cities around the world are finding that “providing housing is cheaper and a better solution.”

The San Francisco Chamber of Commerce and the San Francisco Committee on Jobs are opposed. They argue that the affected businesses already pay about 40 percent of the city’s taxes and that sticking them with another $300 million a year would drive many out of the city.

Prop. C opponents have signed on a small army of consultants, including Whitehurst Mosher Campaigns, 50+1 Strategies and Riff City. They plan to spend upward of $2 million over the next six weeks to try and hammer home the message that the city needs greater accountability for the more than $300 million a year it already spends on homeless-related services.

Tower talk: As officials continue to investigate what caused a window to crack on the 36th floor of the sinking Millennium Tower over the Labor Day weekend, it’s interesting to note that a forensic architecture crew conducted “destructive testing” in the same unit earlier this year.

Rachel Miller, a lawyer for the Millennium Homeowners Association, which is investigating the window problem, said engineers looking into the building’s potential fire safety defects had cut into a wall beneath the window but don’t believe their work contributed to the window cracking.

While the cause of the cracking is still being investigated, Miller said the association’s own initial reports indicate it is “an isolated incident” and not related to the building’s more serious sinking and tilting problems.

As with everything going on with the building, however, the window episode appears cursed by bad luck.

Over the weekend, a drone that was sent up to photograph the window lost its GPS tracking connection and struck the neighboring Salesforce Tower before crashing to the ground.

The only reason the drone was sent up was because the Millennium’s window washing crane, which hangs over the roof, was itself on the fritz and will be for at least another five weeks because Millennium’s management can’t get a replacement part. That means replacing the cracked window is also on hold.

And on it goes.

San Francisco Chronicle columnists Phillip Matier and Andrew Ross appear Sundays, Mondays and Wednesdays. Matier can be seen on the KPIX TV morning and evening news. He can also be heard on KCBS radio Monday through Friday at 7:50 a.m. and 5:50 p.m. Got a tip? Call (415) 777-8815, or email matierandross@sfchronicle.com. Twitter: @matierandross