Kris Kolluri has just been handed what may be the most thankless job in the transportation business: running New Jersey’s much-maligned transit agency.

A former commissioner of New Jersey’s Department of Transportation, Mr. Kolluri had, until recently, managed the project to build a $16 billion rail tunnel under the Hudson River to New York City. On Wednesday, the board of New Jersey Transit confirmed him to serve as the agency’s chief executive.

Handpicked by Gov. Philip D. Murphy, Mr. Kolluri will now have to face the wrath of the agency’s riders, who have just suffered through another hellish summer of breakdowns and protracted delays that stirred unpleasant memories of how unreliable the service was several years ago.

At the height of rush hour on Wednesday, several lines were delayed up to an hour because of a signal problem.

Mr. Kolluri will have just 12 months — the final year of the governor’s final term — to try to make good on Mr. Murphy’s promise to turn the system around.

Rather than making any bold predictions, Mr. Kolluri pledged in an interview on Wednesday to work toward improvements that commuters should appreciate, including keeping stations clean and older trains maintained until they can be replaced.