Dozens of large digital billboards could sprout alongside local expressways next year under Mayor Rahm Emanuel's plan to raise more than $150 million in advertising revenue through a 20-year deal with a private partnership that would put up the signs on city property.

Under the proposal, a partnership created by East Coast billboard giant Interstate Outdoor Advertising and French firm JCDecaux would install 34 digital signs on municipal property bordering the Kennedy, Dan Ryan and other city expressways, according to Lois Scott, the city's chief financial officer. The exact locations have not been disclosed pending the plan's unveiling to City Council members next week.

The deal would guarantee the city $154 million, Scott said. The city will get at least $15 million a year in 2013 and 2014, but the guaranteed income would drop to as little as $6 million a year for each of the remaining years, according to Emanuel spokeswoman Kathleen Strand. In some of those remaining years, the city will receive more than $6 million to reach the $154 million guarantee, she said.

The city's take each year will be based on a share of gross advertising revenues generated by the signs and could be considerably higher, Scott said.

Both of the firms have political ties to City Hall.

Executives with Interstate donated $10,000 to Emanuel's campaign for mayor, half coming from CEO Drew Katz, a frequent donor to Democrats, according to state and federal records. Katz has donated $175,000 in contributions over the years to federal candidates, records show, including $3,000 to Emanuel when he was in Congress and many thousands more to the Democratic Congressional Campaign Committee when Emanuel was running it.

Interstate's Chicago lobbyist is Neal & Leroy, the firm headed by Langdon Neal, who is chairman of the Chicago Board of Election Commissioners.

JCDecaux is no stranger to Chicago. The French company won a contract criticized as a sweetheart deal under former Mayor Richard Daley in 2001 to put up bus shelters around the city. Neal was an attorney representing JCDecaux on that contract.

The proposed deal is the biggest piece of an Emanuel plan to help balance the 2013 budget with $18 million from "municipal marketing" initiatives, and the latest example of Chicago government partnering with a private firm to raise cash.

The city also plans to increase advertising on the sides of 375 downtown garbage cans, and soon will announce a corporate sponsor for the blue bin recycling program that the mayor hopes to expand to all households, Scott said.

Gone is a controversial proposal first floated by Daley to put advertising on iconic downtown bridge houses. "That's off the table," Scott said. But a municipal marketing advisory council convened by Emanuel will continue to consider other ways to raise ad revenue.

Emanuel first floated his idea of municipal marketing as part of his 2012 budget, when he projected raising $25 million by advertising on everything from buildings to the city's website. Those plans didn't get off the ground.

City Council approval is needed for the billboard deal, and Strand said the administration hopes the digital signs will begin going up in late 2013. The billboards will range from around 14 feet by 48 feet to about 20 feet by 60 feet, she said.

Scott said the proposal is in keeping with the mayor's pledge that Chicago won't be overrun with tacky billboards.

"We have about 1,300 billboards in Chicago, and this will add another 34," Scott said. "At the same time we add these billboards, the city will be more aggressively going after the illegal billboards around the city."

Emanuel's administration agreed to the deal in consultation with his advisory council. Lee Bey, a former Sun-Times architecture columnist who sat on the council, said he was satisfied the billboards won't mar the city's look or get jammed in next to significant buildings. But he also said he doesn't know exactly where they will be built to rise above the expressways.

"We'll deal with that on a case-by-case basis," Bey said.

The billboards will have a certain amount of time dedicated to messages from the city for events such as the Taste of Chicago, Scott said. Cigarette ads and political advocacy will not be allowed, she said. And if there is an event like the NATO summit or some kind of emergency, the city will have the power to take over the message boards to transmit traffic alerts or other information, she said.

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