It would be very tempting  to leap to support the Green Line extension through Somerville to Medford.  After all, anything that modernizes our nation’s oldest mass transit system is a good thing, and this particular plan was promised years ago to environmental advocates as part of the deal that brought us the Big Dig. Somerville is a hot spot right now, a booming city with significant development going on, perhaps some of it in anticipation of that Green Line extension. This long-proposed project is as appealing to me as the North-South rail connection linking North and South Stations, so logical that former Democratic Governor Mike Dukakis and former Republican Governor Bill Weld have joined forces to push for it. These are exactly the kind of infrastructure upgrade we should be advancing rather than build a velodrome for you-know-what.

But modifications will need to be made if the Green Line is indeed to be extended. The reason?  The price tag has grown to nearly $3 billion from the $953 million estimated when the economy was in recession. Cost escalation is not unusual.  The Big Dig itself, which has been a boon for drivers and for quality of life in the city, started out at a couple of billion and over time escalated to seven times that amount.  It diverted monies needed for transportation elsewhere in the state, but the up side has been worth it.

When it comes to the proposed Green Line extension, identifying a precise cost has been like trying to nail Jello to the wall. And the rapid escalation is made even more problematic by Tuesday’s report of underestimates in the cost of repairing and improving the transit lines already in operation. We now have a repair backlog of well over $7 billion. This nasty problem of expansion without adequately maintaining what we have is not new.  Twenty years ago, public policy analyst Charlie Chieppo documented it.  Former state Inspector General Greg Sullivan, now head of Pioneer, keeps beating the drum today.

Metrowest Daily News editorial page editor Rick Holmes has provided a thoughtful analysis of why the state should rethink the Green Line extension.  He reminds us we need to be sure what the transportation and environmental benefits really will be,  assess just how crucial the extension really would be to Somerville’s already booming economy, and question whether the money could be better spent meeting other transportation needs. The feds have approved $1 billion for this project, but that alone is not reason enough to plunge ahead.

Charlie Baker faced a similar dilemma with the Big Dig as Governor Bill Weld’s Administration and Finance Secretary.  He had to make the mega-project work and figure out a way to cover the wildly increased costs. It’s reassuring to think that he and his Transportation Secretary, Stephanie Pollack, are committed to transportation, environment as well as fiscal solvency. Last winter’s T melt-down makes this a defining issue for the Baker administration.  We need to dream big and stretch to achieve a 21st century vision while understanding the limits of our still 20th century funding capacity.

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