$3.4B rail plan for South Coast a boondoggle

Massachusetts has seen explosions in cost estimates for two big transportation projects recently. It’s tempting to file both reports in the same pigeonhole. But the projects are quite different.

Some months back, the estimated cost for extending the MBTA’s Green Line trolleys from Lechmere through Somerville to Medford blew up from $2.2 billion to $3.2 billion. Last week, the estimate for extending the T’s commuter rail service from Boston to Fall River and New Bedford ballooned from $2.2 billion to $3.4 billion.

The state is committed to building what’s known as the Green Line Extension, but not yet to what’s called the South Coast project. Both are unneeded, but the South Coast project is by far more objectionable because it would serve far fewer riders.

No transit system anywhere can live off fare box revenues alone. Some subsidy is always necessary. (The T’s is too large, but that’s another topic). How much is reasonable is a political judgment in the broad sense.

The T hauls about 1.1 million riders a day on all routes. It expects a deficit in the fiscal year just begun of $80 million (which may be optimistic), but that doesn’t count the roughly $1 billion the T gets in state aid through its share of the sales tax. Including that, the annual subsidy is about $225 or 62 cents per day for each person living in the 175 cities and towns of the MBTA service area.

That’s an entirely reasonable sum to maintain the option of riding the MBTA whether you ride regularly, occasionally or never.

The new, lower-cost plan for the Green Line Extension sees costs of $2.3 billion (of which the federal government will pick up $1 billion, it is assumed) to serve 37,500 daily riders. Nobody can predict now how much it will boost the system deficit (it will cannibalize some bus revenue), but the investment per rider works out to $61,300.

You can gain a little perspective by calculating just the daily interest cost — before wages, fuel, depreciation and everything else — of that $61,300 (a cost no matter which pocket it comes from): $3.36. That’s not astronomical, but well above the current $2.75 rapid transit fare (that’s without a Charlie Card). Will land use and environmental benefits make the cost worthwhile? Maybe, maybe not.

The South Coast project would serve 4,500 daily riders. The investment per rider would be $756,000. The daily interest cost of that would be $41.40, more than 3 1⁄ times the most 2 expensive ticket, $11.50, on the MBTA commuter rail system, and 12 times the corresponding cost on the Green Line Extension. It’s doubtful land use and environmental benefits, even using expensive electric traction, could make up the gap.

For a system $7 billion behind on maintenance, this cost is ridiculous. Kill this boondoggle while it’s still possible.