The chance of snow overnight means the chance for a nasty commute Friday morning, so local officials said they are taking steps to keep roads clear.

District officials said they have already treated bridges and elevated structures with brine. Virginia road crews said they are pre-treating trouble spots such as bridges and ramps on interstates 66, 95, 395, and 495 with liquid magnesium chloride.

They also have more than 500 trucks poised to be deployed across Northern Virginia and 170 trucks ready in the District.

They aren’t expecting much – about half an inch. But low temperatures can make it stick and freeze in spots, making for slick roads and sidewalks. They offer the following tips:

•  Drive only if it is absolutely necessary and consider taking Metro.
•  Drive slowly and maintain safe distances from other vehicles.
•  Give emergency and snow vehicles a wide berth so they can do their jobs. Avoid passing snowplows or trucks spraying chemicals.
• Clear sidewalks of snow and ice within 24 hours of the end of the storm and help neighbors do the same.
• When driving on ice, do not slam on brakes. Turn gently and slowly.