Shortly after stepping out on the bridge, Jon felt the entire walkway narrow.
( ( Shortly ( after ( ( stepping out ) ( on ( the bridge ) ) ) ) ) ( , ( Jon ( ( felt ( ( the ( entire walkway ) ) narrow ) ) . ) ) ) )
(ROOT (S (PP (RB Shortly) (IN after) (S (VP (VBG stepping) (PRT (RP out)) (PP (IN on) (NP (DT the) (NN bridge)))))) (, ,) (NP (NNP Jon)) (VP (VBD felt) (S (NP (DT the) (JJ entire) (NN walkway)) (ADJP (JJ narrow)))) (. .)))
The walkway narrowed as Jon stepped out on the bridge.
( ( The walkway ) ( ( narrowed ( as ( Jon ( ( stepped out ) ( on ( the bridge ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN walkway)) (VP (VBD narrowed) (SBAR (IN as) (S (NP (NNP Jon)) (VP (VBD stepped) (PRT (RP out)) (PP (IN on) (NP (DT the) (NN bridge))))))) (. .)))