Arlington is about to start blasting for the project to add new elevators to the Rosslyn Metro entrance. (Photo: TBD Staff)

It's time to start blasting big holes in the ground for the Rosslyn Metro station's new high-speed elevator project, meaning that there will be planned nightly blasting between 1 a.m. and 5 a.m. for the next couple of months. North Moore Street, as well as the existing elevators and two of the escalators leading into the station, will have to be closed during the blasts, according to an alert from Arlington County.

Notification of the nighttime blasts will come in the form of amber blinking lights as a five minute warning and red blinking lights as a one minute warning. The "all-clear" will be marked by a green flashing light.

The Rosslyn station improvement project include a new entrance to the Rosslyn Metro station via three high speed elevators located on the block between North Moore and North Lynn Street across from the existing entrance, as well as a new underground mezzanine level with fare gates, ticket machines, and a station operator's booth.

After the first couple of months, crews will be able to blast during the day and the street and surrounding metro accesses will not need to be closed, according to the county.

In addition to the usual precautions, Arlington County is requiring its contractor to take additional measures to alleviate disruption from the blasting, according to the alert. These include:

• A cover constructed of steel and wood on the top of the blast shaft along with blast mats - both designed to mitigate vibration and prevent fly rock;

• Water scrubbers incorporated in the ventilation system to reduce fumes; and

• Hydraulic drill to reduce noise.

Questions can be directed to Arlington's Department of Environmental Services at 703-228-3173 or RosslynStationProject@arlingtonva.us.