NEARLY FOUR MONTHS after the reopening of the Sumner Tunnel, the MBTA is still waiting to be reimbursed by the Massachusetts Department of Transportation for its efforts to mitigate the traffic impact caused by the two-month closure.

The T upgraded service on the Blue Line and made it free. The transit authority also lowered commuter rail fares to North Station from as far north as Salem and Swampscott from $8.75 to $2.40. Ferry service from East Boston was offered for free and new service from Lynn was offered for $2.40 a trip.

In all, sources say, the MBTA spent an estimated $7 million trying to mitigate the traffic impact of the tunnel closure, which will take place again next year as MassDOT completes the tunnel work.

State transportation officials have handled the issue of mitigation costs awkwardly. Transit advocates have suggested the cost of mitigation efforts should be rolled into the cost of the overall project. But state transportation officials have acted like they don’t know what to do.

Back in June, before the tunnel closure, officials initially had no comment when asked whether the MBTA would be reimbursed for the lost revenue. But later that day MassDOT issued a statement saying “mitigation is a necessary cost of the project” and added: “Full costs and cost-sharing options for mitigation services are currently being finalized across both 2023 and 2024.”

Nearly six months later, the awkward dance continues. ”The MBTA and MassDOT are in ongoing discussions regarding the financial needs of the MBTA,” an MBTA spokeswoman said in a statement on Monday.

One source at the T said no one at MassDOT has said the T won’t be reimbursed for its mitigation efforts but at the same time officials have done nothing to address the issue.

While the tunnel closure wasn’t the traffic disaster everyone feared, it also wasn’t a triumph for transit. An estimated 40,000 cars travel through the tunnel on a typical weekday. After the shutdown began in July, officials estimate roughly three-quarters of the cars used a different route – the Ted Williams Tunnel, the Tobin Bridge, or other roads.

The MBTA estimates the drivers of 3,900 cars, nearly 10 percent of the total, shifted to public transit, while 5,500 cars just stopped commuting because their owners were either working remotely or on a summer vacation.

The T estimates trips on the Blue Line increased 7 percent on weekdays during the shutdown. Trips increased 4 percent on the Orange Line (where fares were not reduced), 17 percent on the commuter rail, 3 percent on bus, 2 percent on the Silver Line, and 72 percent on ferries. All of the percentages were based on T estimates of what traffic would normally be at that time.

It also appears that most riders who tried public transit during the tunnel shutdown did not continue riding after the tunnel reopened. Ridership dropped on the Blue Line and ferries, while ridership gains held on the Orange Line and commuter rail.