how to do linear reference in ARC GIS
This may be of help:
http://help.arcgis.com/en/arcgisdesktop/10.0/pdf/linear-referencing-tutorial.pdf
Chris Donohue, GISP
help topics What is linear referencing?—Help | ArcGIS for Desktop
tutorial An overview of the linear referencing tutorial—Help | ArcGIS for Desktop
toolbox An overview of the Linear Referencing toolbox—Help | ArcGIS for Desktop
datasets Linear referencing datasets in ArcGIS—Help | ArcGIS for Desktop
probably enough for now
