Sacramento International Airport officials said chances were good it would never happen. But it did.
On Dec. 29, three months after the airport's opening, its $30 million automated people mover system broke down. The airport went into emergency mode. For two-plus hours, fliers were funneled on foot across an open-air walkway on the people mover bridge between the new terminal and the jet concourse.
But there was a problem with that solution. The 1,100-foot walkway doesn't meet safety codes for public use, Sacramento County safety officials said. Nobody should have been allowed on it.
Airport executives initially argued that their actions were appropriate, saying they'd do it again if needed. But they changed their tack this month after several executives took a walk of their own on the bridge guided by county inspections chief Thor Lude.
Lude pointed out a handful of safety issues, including a few even he hadn't been aware of.
"That was the 'aha' moment," Lude said.
Airport officials have now agreed to submit a plan to Lude on how to make the walkway safe for limited public use in urgent situations.
"It's in nobody's interest to have this debate go on forever," airport spokeswoman Linda Cutler said. "Let's come together on what we need to do."
Cutler said the airport is hoping for Lude's approval in April. She said it's too early to know what alterations will be needed, and at what cost.
Lude said issues on the bridge include lack of a handrail on the barriers facing the walkway, and several trip hazards, including maintenance hatches and metal plates. To be code-compliant, the ramp also would need to add two level areas, or landings.
The airport may have to regulate pedestrian flow because the path narrows to less than 8 feet, barely room for three people to pass. "You could get pushing and shoving," Lude said.
The December breakdown and subsequent safety debate raise the first significant questions about the design of the generally well-received $1 billion expansion.
The project, called the Big Build, replaced original Terminal B with a new central terminal and a jet concourse building. The two are connected by an automated people mover shuttle. Passengers check their baggage and get boarding passes in the terminal, then shuttle to the concourse building boarding gates.
Some fliers have questioned the two-building design, and, in particular, why the only way to get to the concourse is by people mover.
"They have that walkway right there. Why can't they just open the doors and let us use it?" flier Jeff Raimundo complained during a shuttle backup.
Airport architect Brent Kelley said the two-building concept allowed space for old Terminal B to remain fully open during construction, and should make future expansions easier.
Designers considered a tunnel with rolling sidewalks, but decided an elevated people-mover was more cost-effective in the long term, faster and more pleasant. The people mover employs two shuttle cars on twin guideways, running from the terminal's third floor to the second floor of the concourse building.
Kelley said the walkway on the bridge, clearly visible to shuttle passengers, is meant only for maintenance and emergency access. Designers decided against passenger use because the cost of enclosing it, with heating and air-conditioning, was prohibitive.
He said the bridge's slope and its three-football-field length also make it problematic as a walkway. Designers built it on a slope to allow room underneath for the terminal access road.
During construction, Sacramento airport officials touted the reliability of people movers. Industry reports, reviewed by Sacramento designers, indicate people movers usually run at 99 percent-plus reliability. But even a 1 percent failure rate can lead to headaches. On a day referred to at Denver airport as Black Sunday, the people mover shut down for seven hours, forcing the airport to scramble together a bus fleet to get fliers to the terminals.
San Francisco airport, which has the same people mover system as Sacramento, has deployed bus shuttles numerous times when people movers shut down, including a three-hour event last month.
Peter Muller, president of PRT Consulting, a Colorado-based transportation consultancy, said some airports are designed so people can walk in case of a shutdown, while others figure they can make do with buses if a failure lasts more than a few minutes. He said it's a judgment call.
"People movers are incredibly reliable, but if they break down, they can be quite disruptive to airport operations," Muller said. "It is a matter of weighing the balance."
Sacramento's breakdown came at 7:57 a.m. on a Thursday in peak holiday season. Communications center computers connected to the shuttle went blank. When the system wouldn't reboot, power was automatically shut to the two cars.
Change in plans
Officials previously said if the people mover ever broke down, they'd bus fliers to the concourse building. But that involves its own hassles. Officials calculated it would take 17 minutes to get fliers a few hundred yards to the concourse building, including requiring them to make a two-story trek down a stairwell with carry-ons and submit to a second federal security check. Buses also would have to be shifted away from their primary parking shuttle duty.
So, instead, officials just unlocked the doors to the bridge. Airport workers were stationed every 10 feet on the walkway, keeping fliers away from 5-foot drop-offs on the outside of the railing, and making sure no one could stray into security areas.
An estimated 400 fliers made the five-minute walk that morning, reportedly without incident. Some in wheelchairs were pushed by airport staff.
"We felt this was the fastest, safest, most customer-friendly approach," airport operations chief Lisa Stanton said at the time. "I am hopeful this was a unique, random occurrence."
County documents, however, indicate officials had previously agreed the walkway would be used only as an evacuation area in an emergency, such as a fire, not as a back-and-forth travel route. The December breakdown was an inconvenience, not an emergency, Lude concluded.
Airport officials said the incident prompted them to write a detailed plan for what to do if the people mover breaks down again. That would include using the bridge walkway, if they receive Lude's approval, as well as busing fliers at times, such as in inclement weather.
After all that, it turns out the Dec. 29 outage didn't even have to happen. Airport officials have learned from people mover manufacturer Bombardier that workers could have operated the shuttles manually at slow speed until the system rebooted.
"Had they had those procedures in place, there would not have been an outage," airport official Lance McCasland said.