The MBTA red line is maxed out. As are most of the system’s polychromatic transit lines. Anyone who travels the T during rush hour knows that.

And anyone who reads the Urban Land Institute’s dire assessment of the T’s situation has to question the wisdom of the state’s smart growth policy or the breakneck speed with which Cambridge and other cities are welcoming development and caving to developers’ cries for relief from zoning restrictions.

At a time public transportation is virtually overwhelmed by financial constraints, as well as too many riders, I would like to suggest that the cities who rely on the red line as a lifeline for commerce and community activity join together to buy the Massachusetts Bay Transit Authority some new red line cars.

Rather than wait for a cash-strapped legislature with statewide concerns and political pressures to respond to the T’s serious cash shortfall, the red line cities most affected, and with the most to gain, should step up to the plate. The cost of one complete set of cars, or two — who knows how many trains we’re talking about? — could be shared proportionately between Cambridge, Boston, Quincy, Braintree and so on, depending on the number of stations in each community. Or by some other formula that might make better sense.

We could spend years arguing about where the money should come from and who’s responsible for the T’s budget shortfalls, or we could act now and take the initiative. It’s time for those cities that most benefit from the red line to put their money where their future lies.

Paul Steven Stone is a novelist and essayist living in Cambridge. He can be reached at [email protected]. Share your own essays by e-mailing [email protected].