Hi Troy,
To fix it, you can assign the "Corner" vertex type to vertices where the Fillet Radius feature is being applied, and the "Bezier" type to the next vertices. Please find attached the modified scene (240119_RailcloneIssue_iToo.max), where I have applied these changes within the Edit Spline modifier applied to the "Pavement spline". I hope that helps.
Best regards,