The estimated replacement cost for the Cape Cod bridges has risen by half a billion dollars, to $4.5 billion.
The new estimate for the Bourne and Sagamore bridges comes from a planning workshop held in May. The Federal Highway Administration led the four-day workshop in Boston, with participation from state officials, engineers, and others.
They conducted what’s known as a Cost and Schedule Risk Assessment, which looks at all the things that could go wrong with the bridge project, how likely they are, and how those problems would affect the schedule and cost.
The assessment found there is a reasonable probability that building the bridges will take longer than planned, said David Anderson, manager of the bridge project for engineering firm HNTB.
A longer timeline drives the cost up.
If building the new bridges does take longer, Anderson said, “the result of it taking longer is it's going to cost more. It's going to cost more due to inflation. It's going to cost more just trying to anticipate what the market conditions may be at the time of bid.”
Estimates of the construction time have ranged from six to eight years.
Anderson spoke Tuesday at a meeting of the Cape Cod Bridges Program Advisory Group, which includes many Cape leaders. They met at Massachusetts Maritime Academy in Bourne.
He said the cost analysis was performed earlier than usual, which means the project still has time to reduce the risk of delays.
Officials at Tuesday’s meeting also discussed the condition of the Bourne Bridge, which could require major maintenance if federal funding to replace it doesn’t arrive within five years, according to the U.S. Army Corps of Engineers.
The state has decided to replace the bridges in phases, with the Sagamore Bridge first in line.
Officials say that means careful decisions will have to be made about how much maintenance to do on the Bourne Bridge, to keep it safe for travel without putting federal funding at risk.
“What we're trying to do is just keep things moving along at a sufficient condition, by doing smaller maintenance work,” said Bryan Cordeiro, who manages the bridge project for the Massachusetts Department of Transportation. “I know it's not ideal, but if we move forward with a major rehab, there's no way that we get funding for a replacement, because we're good for the next 35 to 40 years.”
