Runway Crossing Procedure Change
Beginning June 30, 2010, controllers will be required to issue explicit instructions to cross or hold short of each runway that intersects a taxi route. “Taxi to” will no longer be used when issuing taxi instructions to an assigned take-off runway. Instructions to cross a runway will be issued one at a time. Instructions to cross multiple runways will not be issued. An aircraft or vehicle must have crossed the previous runway before another runway crossing is issued. This applies to any runway, including inactive or closed runways.
Changes will also be made to the Aeronautical Information Manual (AIM) and AIP to reflect the new procedures.
Never cross a hold line without explicit ATC instructions. If in doubt ASK!
Reminder: You may not enter a runway unless you have been: instructed to cross that specific runway; cleared to take off from that runway; or instructed to position and hold on that specific runway.
Documents: https://www.faasafety.gov/files/notices/2010/Jun/Runway_Crossing_Procedural_Change_FAAST_Blast.pdf for the Runway Safety notice.