The Dallas Zoo monorail and rats don’t mix.
The train used to ferry zoo-goers around the grounds has been sidelined since last summer, its third shutdown in as many years.
Among the reasons: aging equipment on the 25-year-old monorail, electrical kinks and rats that repeatedly chewed into power cables.
That’s according to maintenance records NBC 5 obtained from the private, nonprofit corporation that took over management from Dallas in 2009. The city still retains ownership of the zoo.
Now, administrators are working on a $3 million renovation designed to get the monorail running by this summer.
“We're looking at a total rehab and reconditioning of those trains,” said Gregg Hudson, the zoo's president and CEO. “All new electrical, all new pilot system for the electronics, upgrading paint and style. We're also going to be updating the station."
The revamp comes after a series of incidents that knocked out the system, most recently on Aug. 6, 2014, when firefighters pulled 48 people from the box-shaped cars. Officials then blamed the stoppage on a power surge but it was not clear what caused it.
The monorail also stalled on Feb. 23, 2013, after an apparent electrical fault, stranding 93 people temporarily.
A similar malfunction occurred on Sept. 27, 2011, and 30 people were rescued from the elevated track.
Hudson said passengers were not at risk. He ordered the system shuttered after the latest breakdown so officials could come up with a fix-it plan.
"It's a lot like if you've ever had a car — a car with over 100,000 miles on it,” he said. “You've reinvested in it and at some point you have to make a tough decision."
Maintenance records that NBC 5 reviewed provided a summary of some of the issues leading up to the stoppages.
A month before one of the incidents, for example, rats had gnawed on power cords, according to the records.
“Something had chewed the cable,” one notation said on Jan. 22, 2013. “Had to change the entire cable run.”
About a week later, it surfaced again.
“Found very bad problems with rats chewing into two different trains,” the documents said. “Worked late repairing cables.”
Other recurring issues included broken switches and relays. "All these can go out at any given time without notice,” according to Frank Duvall, the zoo's equipment maintenance manager.
Duvall told NBC 5 that problems had grown in recent years, requiring more and more work.
The monorail has taken four million people on the one-mile tour since opening in 1990. But it easily overheated, Duvall said, and routinely was taken out of service on hot afternoons.
The trains ran an average of eight hours a day, according to zoo logs reviewed by NBC 5.
The reconditioned cars will come with welcome additions: air-conditioning and a tug so that if the monorail gets stuck it can be pulled to the station with no rescue necessary.
A zoo spokeswoman said that the project largely will be financed by bank loans, repaid through ticket sales.
Duvall said he is looking forward to the improvements.
"I want to get this back as soon as possible,” he said. “Our guests love this train. It's a great experience. A lot of people have been asking for it."
At a Glance
The Dallas Zoo initially declined to provide NBC 5 with its monorail documents. It argued that train is owned by a private corporation known as Dallas Zoo Management Inc. and not subject to the Texas open records law. NBC 5 contacted the Texas attorney general’s office, which provides guidance on open records disputes, and the zoo later agreed to produce two years of maintenance records but not internal emails.