Generally, given a fixed population, I think that improved transportation doesn't increase property values, but rather redistributes the value of property from areas near jobs to areas further away along the improved transportation. For example, starting in the 50's highways were built which allowed people to live outside of the city and commute in. Property values in the suburbs went from very low value farmland to hundreds of thousands of dollars per acre today. As these commuting routes became saturated property value in cities has recovered, since it is less and less possible to commute in a reasonable amount of time.