Updated 9/24/11 at 10:00 a.m.

CHICAGO (CBS) — In a letter to Metra riders, the agency’s CEO on Friday called proposed fare increases “jolting” but necessary due to rising costs, lower income and inaction by the previous Metra administration.

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The response comes three days after U.S. Sens. Mark Kirk and Dick Durbin wrote letters to Metra asking for details on the 30 percent fare increase.

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Exactly how that increase effects one way tickets, 10-ride tickets, monthly passes and other fares is “still under discussion,” but some fares will rise more than the average while others less, Alex Clifford said in a letter to riders.

“We know this is jolting; it’s jolting to us, too,” Clifford said.

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But it needs to be done, he says, and you can blame the previous Metra administration.

“No one wants higher fares. But part of the reason we are in such a fix is that the prior Metra administration did not adequately prepare for this day and kicked the problems down the road,” Clifford said.

“Instead of what could and should have been a series of smaller, more moderate fare increases to address the issue, we are forced to propose this major, distasteful one.”

A multitude of factors is leading to the increase, including sales tax proceeds far below what was projected in 2008, as well as the rising cost of diesel fuel. New federal regulations, higher insurance premiums and other rising cost factors are also in the mix, he says.

Clifford says the agency is working with each department to look at ways to reduce costs. To date, the budgeting process has yielded $4.4 million in cuts and savings.

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