See this Google post for more details
"In Louisville, Google Fiber installation crews had been using a process called “shallow trenching” that involved laying fiber cable two inches beneath the sides of roads in the city and covering them up with sealant. The company seemed optimistic about this plan until some of the cable started becoming exposed over time, requiring a second cover-up with hot asphalt. It seems Access realized it had to go a bit deeper with the cabling; in San Antonio, a similar method is used — but the fiber is laid at least six inches deep into the ground. Google Fiber has at times faced legal challenges from rivals (like AT&T) that don’t want to share utility poles, so shallow trenching is also a way around that hurdle.Google Fiber is leaving Louisville in humiliating setback | The Verge
Unfortunately, things have somehow gone so awry in Louisville that Google Fiber claims it would need to rebuild the entire network to get everything to a satisfactory point, and it seems Alphabet just isn’t interested in blowing the cash that would be necessary to do that. So instead, Google Fiber will today alert Lousville customers that their service will end on April 15th."