Big US cities could be squeezed by unfunded public pensions as they and counties face a $574 billion funding gap, a study to be released on Tuesday shows. The gap at the municipal level would be in addition to $3,000 billion in unfunded liabilities already estimated for state-run pensions, according to research from the Kellogg School of Management at Northwestern University and the University of Rochester. “What is yet to be seen is how this burden will be distributed between state and local governments and whether the federal government will be called upon for bail-outs,” said Joshua Rauh of the Kellogg School.