The Metropolitan Highway System, a network of major bridges and tunnels in and around Boston, will likely need $1.6 billion in maintenance and upgrades over the next decade, according to a review presented to transportation officials Monday.

“We have a big job ahead of us,” Transportation Secretary Stephanie Pollack said.

Jack Moran, director of asset management for the state Department of Transportation, told the department’s board that a review of the MHS projected a total cost of $1.6 billion for design, maintenance and construction on key infrastructure pieces within the system. Suggestions include rehabilitation of the Sumner Tunnel, installation of new ventilation in the Prudential Tunnel and ceiling replacement in the Callahan Tunnel.

Moran said the report, required to be performed every three years because of the bonds used to fund the system, should not be taken as an imminent construction list, but rather as an indicator of what will need to be addressed in the future.

“There weren’t that many surprises in here,” Moran said. “This report is a technical engineering report based on conditions and costs. Now comes the challenge of turning that into a construction program where we can deliver projects.”

Based on the report, MassDOT leaders will prioritize the MHS’s needs and determine the appropriate order in which they should be addressed. The department will form a working group by March 1 to help with planning, and the projects will likely be funded in the 2020-2024 capital investment plan.

Pollack said the various projects must be chosen in an order that minimizes traffic impacts.

“Now that we have really good data, we need to figure out what order to do these projects in,” she said.

In December, Moody’s Investors Service upgraded to A2 from A3 the rating on the Metropolitan Highway System senior lien revenue bonds, with a rating outlook of stable. The MHS has around $933 million of senior lien revenue bonds outstanding and around $851 million of subordinated lien revenue bonds.

MHS assets comprise the turnpike east of Route 128, the Sumner, Callahan and Ted Williams tunnels, the Tobin Bridge, the Central Artery North Area and the Central Artery, according to Moody’s. The overall MHS network consists of almost 250 lane miles of roadway, of which about two-thirds are tolled. The network also includes 227 bridges and viaducts and seven major tunnel structures, including the three that run under Boston Harbor.

In its December assessment, Moody’s wrote, “Management’s greatest challenge remains the need to control operating costs and make adequate investments in the MHS assets to maintain the state-of-good repair amid limitations to issue new debt and limited support for future toll rate increase.” Analysts wrote that they “currently do not expect any future toll rate increases but MassDOT’s board has the ability to increase toll rates without requiring additional approvals. Current toll rates are low compared to other metropolitan areas providing economic flexibility to raise tolls, if necessary.”