The average length of a rural route is 55 miles.
( ( ( The ( average length ) ) ( of ( a ( rural route ) ) ) ) ( ( is ( 55 miles ) ) . ) )
(ROOT (S (NP (NP (DT The) (JJ average) (NN length)) (PP (IN of) (NP (DT a) (JJ rural) (NN route)))) (VP (VBZ is) (NP (CD 55) (NNS miles))) (. .)))
The rural route is on average 55 miles.
( ( The ( rural route ) ) ( ( is ( on ( average ( 55 miles ) ) ) ) . ) )
(ROOT (S (NP (DT The) (JJ rural) (NN route)) (VP (VBZ is) (PP (IN on) (NP (JJ average) (CD 55) (NNS miles)))) (. .)))