Share the road! It's the battle cry of hordes of bicyclists just trying to get by on streets that belong to them just as much as they do to motorists. Maybe the walkers on the Northern Central Railroad Trail, which runs through Baltimore County from Cockeysville to the Pennsylvania line, should take up the cry, too. We kid . . . some. We love hiking the NCRT, and you can find us there something like 40 out of 52 weekends a year. But the constant barrage of bikers and their trail battle cry--"On your left!"--does get a bit tiresome. Perhaps some arrangement can be made. Bikers get Saturday and hikers Sunday, or maybe certain hours for each mode of transportation: Who's with us?