In urban systems, accident files are established for intersections and midblock sections.A determination is made as to whether N-S streets ar E-W streets are to take precedence.This is required lo avoid two files, one for the intersection of First Ave. and Main Sr.,and another for Main St.and First Ave. A main file is established for each facility in the primary direction. Subfiles are then established for each intersection street and each midblock section. Midblock sections may be identified by the street addresses they encompass or by the intersections they lie between.Thus the file for a facility might be established as follows: