The "third rail" along the Metro Blue Line extension from Stadium Armory to New Carrollton will be charged today with 750 volts of electricity, enough to instantly kill anyone who steps on it.

The 7 1/2 miles of Metro tracks run parallel to the Penn-Central tracks for most of the extention. The electricity which powers the trains, is necessary to finish construction of the line, scheduled to open in mid-November.

Metro spokesman Cody Pfanstiehl urged everyone to keep away from the Metro tracks to avoid injury. He said Metro built an eight-foot fence topped with barbed wire to keep people out and covered the third rail, which is the "electrified" rail, with coverboard, a gray plastic protective material that helps insulate against electrical burns. Warning signs were posted on the fences this weekend, he said.

Those precautions are standard procedures when Metro builds track above ground, Pfanstiehl said. But since the are had a great deal of pedestrian traffic, Metro officials have also been meeting with school children and community groups for five months to alert them to the danger of walking over the tracks, he explained.

The extension of the line will include Minnesota Avenue and Deanwood stations in the District of Columbia and Landover, Cheverly and New Carrollton stations in Prince George's County.