Antiquated slam-door train carriages will finally be phased out under a blueprint for change on the railways.
Some 1,700 new coaches will be delivered by 2004 on routes including those run by South Central.
The company has just two modern sliding door trains on its Brighton to London lines, according to a commuter watchdog.
The Brighton Line Commuters pressure group says most of South Central's carriages are 'potentially dangerous' 30-year-old slam-door models.
It is part of a £30 million government package to be spent improving the railways over the next ten years.
The long-awaited blueprint for change was published today by the Strategic Rail Authority (SRA).
It sets out ambitious plans for new rolling stock, extra services at peak times and a revamping of more than 1,000 stations across Britain.
The SRA's plan will have major implications for commuters travelling into London from the surrounding counties, including Sussex.
Both South Central, which took over from Connex in August last year, and Thameslink should benefit from the proposals.
Thameslink, in the process of developing the Thameslink 2000 project to provide more frequent central London services, will see its franchise enlarged south of the Thames.
Ultimately, Thameslink 2000 will benefit Sussex commuters, taking pressure off the groaning London Underground system.
The SRA's plan should also deliver safety improvements to passengers across the country.
The Train Protection Warning System, designed to stop trains going through danger signals and prevent crashes, should be completed by the end of 2003.
Shelley Atlas, who chairs the Brighton Line Commuters group, said investment in new trains, although long overdue, would be welcomed by passengers.
She said: "We want to see slam-door trains got rid of as soon as possible. We consider them to be potentially very dangerous."
Miss Atlas said timetabling by Thameslink and South Central needed better co-ordination.
"We want to see the time-tabling issue looked at very closely so there is better inter-linking of services by the two companies."
However, reaction to the report from South Central and Thameslink was slow to come, with both companies digesting its implications before issuing detailed statements.
Richard Bowker, chairman of the SRA, admitted the rail network had struggled to deliver good performance.
He said it was essential to invest in people so passengers felt good about using the railways.
He added: "I want to see fewer accountants, fewer lawyers and fewer consultants. Instead, I want to see more engineers, more operators, more project managers and especially more young graduates, apprentices and school leavers joining an industry with a future."
A spokeswoman for South Central said: "We welcome the report and will be studying it over the next day or so before issuing a detailed response."
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