A cutting tool assembly for milling a rail top, includes a first section and a second section mounted to the first section. Each section includes a plurality of insert-receiving pockets for receiving a plurality of different types of cutting inserts. The plurality of different types of cutting inserts are arranged in a plurality of helical teeth that may be separated by a helical chip flute. In one embodiment, a first type of cutting insert is formed with a radius, R, a second type of cutting insert is formed with a radius, R1, and a third type of cutting insert is formed with a radius, R2, to perform a milling operation on three different areas of the rail top.