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 risk." » "improving pupil performance risk.", "improving thermal performance risk.", "improving overall performance risk.", "improving rural performance size.", "improving rural performance based.", "improving rural performance _.", "improving urban performance risk.", "improving social performance risk."

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 risk.") OR ("improving railway performance metrics."))~.
• Removing quotes may allow a broader search: (( improving rural performance risk. ) or ( improving railway performance metrics. ))~.
• Adding a wildcard symbol may retrieve word variants: (("improving rural performance risk.") or ("improving railway performance metrics."))*.