One of powerful tools to build and edit GPS routes has available now, that's called 3D Route Builder. This tool developed by Hybrid Geo Tools and using for fine grain control over paths directly in Google Earth. These can then be either built from scratch or based on existing KML/KMZ, GPX or Garmin Training Center TCX (Edge and Forerunner 305). They can then be retraced at scalable real time speed.

Please read detail specifications below this :

• Fine grain, live control over 3D paths in Google Earth - compliments the built-in Path Editor
• Google Earth embedded in 3D Route Builder
• Edit and build paths - modify or create from scratch accurate GPS and Garmin data sets with altitude and time-stamps
• Import, edit or create time-stamps including selective re-scaling and nudging
• Synchronize with video (e.g. helmet cam recordings)
• Playback routes in real time with helicopter tracking
• Get altitude and location data from Google Earth
• Adjust altitude and location of one or more points in centimeter increments
• Correct barometric drift
• Smoothing of altitude profiles
• Import KML/KMZ, GPX or Garmin Training Center TCX (Edge and Forerunner 305)
• Export data as GPS Exchange Format (GPX), Google Earth (KML, KMZ), Garmin (CRS or TCX), Salite (Mountain Pass profile format), (Customizable) Comma Separated Values, and Pro-Cycling Manager XML format