A rail company has refuted claims changes to its timetable will disrupt passengers.
South Central will cancel all direct services travelling along the coast through Brighton from May 18.
People travelling between Worthing or Lancing to Falmer or Lewes will have to change trains at Brighton.
Some have complained about having to rush to a different platform to continue their journey.
Matthew Ball, spokesman for South Central, said: "When the cross-Brighton service goes across the tracks, it locks up the rest of the station for three minutes four times an hour.
"If there are delays to this service, it can cause problems everywhere else. Some people will have to change trains but it should be an easy change to make."
The new services should also improve connections at other stations such as Lewes.
Mike Hewitson, of the Rail Passengers' Committee, agreed with the changes but wants South Central to explore ways of making a direct train journey across the Sussex coast possible.
He said: "The problem is the cross-Brighton service comes at the expense of people trying to get to London."
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