Not long ago, the 23 service plazas along Connecticut’s highways were shabby and out-of-date. Kevin Nursick, a state Department of Transportation spokesman, said they were “dilapidated hellholes. They were dungeons. They were disgusting.”

Then, in 2009, then-Gov. M. Jodi Rell announced plans for a public-private partnership that would pump $150 million in funding into renovations that would make the plazas fit for public respite. But the project’s aftermath has left behind a slew of subcontractors complaining—and at least a few suing—over $5 million in unpaid bills. The DOT has had to intervene in the tangled contractual dispute.