Massachusetts Avenue is closed from Duvall Street to the traffic circle where Montgomery County and the District meet.
The fire chief said road closure may last overnight and into Tuesday.
Police said some lanes remain closed as crews work to repair the water main break.
The governor-elect could move ahead on busway construction or revive a plan to widen the highway.
Lowering tolls might get voters' attention, but it's unlikely to happen.
A short segment of eastbound Aspen Hill Road is closed.
Traffic is snarled while crews repair water pipe break and gas leak.
Two lanes are closed near Exit 198.
Non-perishable food will be collected at toll facilities to benefit Maryland Food Bank.
Road work still to come as part of Walter Reed expansion will snarl Wisconsin Avenue