A valid Form B (and related rules) authorizes a foreman to occupy or foul a main track. A train has to get permission to enter and pass through Form B limits by the foreman/employee in charge, but a train must still have some type of main track authority as listed in 6.3.

Not listed as a type of Form B, but clearly by track bulletin, a foreman could potentially be the authority for a train to occupy the main track under Rule 15.4. It is listed in 6.3 as a proper type of main track authority.

15.4 Protection When Tracks Removed from Service

Before a track is removed from service it must be protected.

A track bulletin may protect tracks removed from service by designating the track and naming the points at each end of the track. Trains must not use this track, unless the track bulletin states the name or title of an employee who may authorize use, and this person directs all movement. Movements must be made at restricted speed.

Proper authority must also be received to pass an absolute signal displaying a Stop indication to enter the out of service track. Except at interlockings, after stopping, movements may pass Stop indications within the out of service limits. Movements within the out of service limits may pass Stop and Proceed indications without stopping.

When required, the train dispatcher must advise crews of alternate routes and switch positions.