Transport police have claimed a 35% drop in trouble on rail services in the Pontypridd area since six community support officers began operating.
The team of support officers is based at Pontypridd station
The team, based at a police station at Pontypridd railway station, have held almost 1,000 rail-based day and evening patrols in the last six months.
Incidents dealt with range from assaults to drunken behaviour.
Enterprise Minister Andrew Davies will officially open the police station on Pontypridd's platform one later.
Last year, the transport union RMT warned violence on the railways in Wales was reaching "civil unrest" proportions, with incidents including attacks on train staff, bricks being thrown through windows and gang fights spilling onto trains.
In February this year, watchdog group Passenger Focus said rail passengers were more worried about their safety at stations in Wales than in the rest of the UK.
The community support officers (CSO) at Pontypridd are part of a network of 21 recruited to work on rail services across Wales.
The CSOs, and the new police station at Pontypridd railway station, are part of a £600,000 initiative jointly funded by the Welsh Assembly Government, Arriva Trains Wales and British Transport Police.
Six CSOs have been based at Pontypridd since May, covering the Rhondda, Cynon and Merthyr Valleys.
'Fear and apprehension'
British Transport Police Acting Sergeant Dave Morris said the team had conducted 983 uniformed patrols at stations, along railway lines and on train services in the three valleys to provide "high visibility patrols to reassure the public and rail staff".
He said: "One of the biggest problems is congregations of youths late at night with no intention of travelling.
"Some of them are [have been drinking] alcohol. They tend to cause a little bit of fear and apprehension to the travelling public. Some of them to tend to be abusive and throw beer cans around.
"Since we've been operating, we've ejected some 460 people at stations who had no intention to travel."
He said initial figures had shown a 35% reduction in report incidents, ranging from alcohol-related disorder through to assaults, from May to November this year compared to the same six-month period in 2005.
He added: "We're well settled in now. They have learnt the geography and the timetables. It's definitely working."
The new station is located in a former office donated by Arriva Trains Wales.
A spokeswoman said the Pontypridd base placed the British Transport Police patrols at the "heart of the valleys rail network".
She said: "They're known faces on our network. They're people the customers and staff recognise and passengers can approach them if they need to do so."