How the US Army plans to keep its massive 70-ton Abrams tanks from tearing up DC roads

A US M1A1 Abrams tank. Spc. Christian Carrillo/US Army Nearly 30 M1A1 Abrams tanks will roll down Constitution Ave. in DC for the Army's 250th birthday. The service is finalizing plans to prevent the heavy 70-ton tanks from damaging the road. Engineers will use steel plates and track pads to…