Sections of downtown Detroit lost power Thursday after high demand during the previous days' 90-degree heat caused parts of the city's aging municipal power system to fail, prompting crews to cut power to city hall and a convention center to prevent the entire system from crashing, officials said.
The spotty outages affected traffic signals, a college campus and a handful of public buildings in and around downtown after three of five lines supplying the municipal system, which serves public buildings, went down over two days.
Karen Dumas, a spokeswoman for Mayor Dave Bing, said officials intentionally cut power to the Coleman Young Municipal Center and Cobo Center so the remaining lines wouldn't overload. She said the initial outages were due to extreme power demand in the last few days for air conditioning and city officials had been warned a brownout could occur.
"Certainly the system is old and we can't deny that. Over the past couple days, usage was higher than normal but we monitor the system and we knew that and we asked our high usage consumers to cut back," she said.
Even though temperatures were only in the upper 70s on Thursday, they had topped 90 degrees Tuesday and Wednesday.
"Heat is the cause," Detroit's chief operating officer, Chris Brown, said of the outages.
Heat also overwhelmed the city's system last July, shutting down power to parts of downtown for two days. City officials estimated power could be restored within a day this time around, between late Thursday and early Friday afternoon.
The outages forced hundreds of people to evacuate the city hall and the Cobo Center, along with the McNamara federal building, the county courthouse, and some Wayne State University and community college buildings. Traffic lights were out in certain areas but working elsewhere. The city's People Mover _ an elevated train with a small route downtown _ lacked power, yet police headquarters was operating normally the Detroit Tigers game went on as planned at Comerica Park.
DTE Energy Co. generates the power used by the Detroit municipal power system and sells it to the city, said DTE spokesman Alejandro Bodipo-Memba. He said the power failure happened in the municipal portion of the network and was not a failure of the supply system.
The outage did not affect most power customers in the city, who are served directly by DTE.
James Hollins of Flint, a contract employee in information technology, said he couldn't get back in the municipal building after leaving for lunch because of the power outage. He said he worried about whether he lost valuable information on his computer at his work station.
As a contract employee, he said, there's "no work, no pay. That's a downer."
The municipal center consists of two towers, a 20-story section that includes county courts and a 14-story section that includes the city's executive and legislative offices.
Wayne State University spokeswoman Francine Wunder said 17 buildings on the campus were without power, and classes were canceled Thursday and Friday.
Associated Press writers Corey Williams, Jeff Karoub and David N. Goodman contributed to this report.