For the historical study I am conducting, I have three layers with roads in 2000, 2008 and 2012 respectively. Only the data for 2000 is complete- i.e. there are additional segments of roads in 2000 that are not present in data for 2008 and 2012. I'm positive that roads did not vanish between 2000 and 2008 :p I would like to add the length of the additional roads from 2000 to that of 2008 and 2012, so that my data is correct and complete. How do I go about it?
Time is not in my favor and I would really appreciate some help. A BIG thanks to all those who would like to help me out :)