With some more cars coming in from the CRRC assembly plant in Springfield, the T can now run a longer test train of the new cars - so maybe they're still on track to get at least one of the trains in service by the end of this year. Ari Ofsevit watched it bound through Assembly last night.
Lori Magno also spotted the train - and was able to see it filled with sandbags.
But don't worry - it's not the T's answer to trains leaking in the rain. The heavy bags are meant to simulate the weight of riders.