( ( In ( recent years ) ) ( , ( ( advances ( in ( bridge-building ( and ( tunneling techniques ) ) ) ) ) ( ( have ( ( enabled ( Chinese ( railroad builders ) ) ) ( to ( ( ( reduce ( overall ( track ( length ( and ( increase ( train speeds ) ) ) ) ) ) ) ( on ( rail lines ) ) ) ( through ( rugged terrain ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN In) (NP (JJ recent) (NNS years))) (, ,) (NP (NP (NNS advances)) (PP (IN in) (NP (JJ bridge-building) (CC and) (JJ tunneling) (NNS techniques)))) (VP (VBP have) (VP (VBN enabled) (NP (JJ Chinese) (NN railroad) (NNS builders)) (S (VP (TO to) (VP (VB reduce) (NP (JJ overall) (NN track) (NN length) (CC and) (NN increase) (NN train) (NNS speeds)) (PP (IN on) (NP (NN rail) (NNS lines))) (PP (IN through) (NP (JJ rugged) (NN terrain)))))))) (. .)))
In recent years, advances in bridge-building and tunneling techniques have enabled Chinese railroad builders to reduce overall track length and increase train speeds on rail lines through rugged terrain.
(ROOT (S (NP (NP (DT A) (-LRB- -LRB-) (NN n) (-RRB- -RRB-) (NN increase)) (PP (IN in) (NP (NN length)))) (VP (VBZ happens) (PP (TO to) (NP (NN metal) (NN railroad) (NNS tracks))) (PP (IN during) (NP (NP (DT the) (NN heat)) (PP (IN of) (NP (DT a) (NN summer) (NN day)))))) (. .)))