Maryland Transportation Authority issued the following announcement on July 19.

The Southbound Tunnel is scheduled to be closed at 9 p.m. on the evenings of July 22 and 24-26, 2018, for maintenance operations. Re-opening is scheduled to take place at 5 a.m. on the following morning.

The Northbound Tunnel is scheduled to be closed at 9 p.m. on the evening of July 23, 2018 for maintenance operations. Re-opening is scheduled to take place at 5 a.m. on the following morning.

This is a tentative schedule that is subject to change at any time due to weather, traffic conditions, emergency incidents, or priority closures.

Original source can be found here.