What is the acceptable gap between the tie plate shoulder and the rail base in class 4 track?

In Class 4 track, it is essential for the stability and safety of the rail system that there is no gap between the tie plate shoulder and the rail base. This requirement is in place to ensure that the rail is properly supported, which helps in maintaining correct track alignment and reducing the risk of derailment. An unbroken connection between the tie plate and the rail base facilitates the transfer of loads from the rail to the ties and subsequently to the ballast, creating a cohesive and stable structure. Hence, having no gap is critical for meeting engineering standards and ensuring safe train operations on this classification of track.