Perhaps you should try some spelling variations:
"improving railway performance metrics." » "improving utility performance metrics.", "improving railway performance contracts.", "improving railway performance measures.", "improving railway performance contract.", "improving rail performance metrics.", "improving early performance metrics."
"improving rural performance evidence." » "improving pupil performance evidence.", "improving thermal performance evidence.", "improving overall performance evidence.", "improving urban performance evidence.", "improving social performance evidence."

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving rural performance evidence.") OR ("improving railway performance metrics."))~.
• Removing quotes may allow a broader search: (( improving rural performance evidence. ) or ( improving railway performance metrics. ))~.
• Adding a wildcard symbol may retrieve word variants: (("improving rural performance evidence.") or ("improving railway performance metrics."))*.