fire 138L = length of largest Fire Appliance (currently 13m) d - cut-back distance is obtained by intersecting the imaginary corner of a building with A - C The minimum permissible widthThe fire forced the closure of Hhway 173 from the junction of Hhway 138 to 6.9 miles east of the intersection of Hhway 138 at Arrowhead Lake Road, according to Caltrans.