British Transport Police (BTP) has joined forces with ScotRail, local police and community wardens to combat a crime wave on board trains and at local stations.
BTP bosses say they have used plain clothes officers to tackle problems like this in the past and could do so again.
The pledge comes after a series of worrying incidents — including a number of assaults — on the Wemyss Bay line.
They have left some passengers so frightened that they have deserted the service, amid claims that ticket examiners had also been advised to lock themselves in the back cab for their own safety.
Inspector Gary Brown, of BTP, said: “There was a spike in November and that is when we launched a dedicated operation on the Wemyss Bay line, working with ScotRail, police and Inverclyde Council wardens.
“There has been a wide variety of issues including trespass, stone throwing at trains and public order offences such as anti-social behaviour.
“There has been quite a dramatic reduction, a 44 per cent reduction in assaults from nine to five.
“Plain clothed patrols were used in the past and is one of the tactics that could be used in the future.
“We have been using high visibility patrols on late night trains to reassure passengers.
“Officers are tackling low level anti-social behaviour carried out by large numbers of youths and we are working to reduce this as much as possible.
“We are working with authorities to deal with this robustly and report incidents to the procurator fiscal and children’s reporter and conducting follow-up visits to their home addresses.”
Trespass, stone throwing and public order offences such as anti-social behaviour are all up while ‘serious line of route incidents’ — such as damage to trains or obstruction on the track — have more than doubled.
One of the problems facing passengers is that yobs have been able to board trains without paying, before going on to cause trouble.
Earlier this year the Tele revealed a catalogue of problems on the route.
In January a ticket examiner was hit by a can of beer which had been thrown across a carriage, while in another incident a rock was hurled, smashing a glass panel.
Other incidents included a fire extinguisher being left trackside close to Drumfrochar Station, near the scene of a fatal derailment back in 1994, plus further reports that trains were being vandalised on a daily basis.
Constable Ally Burns, inset, neighbourhood officer for Branchton and surrounding areas, says youngsters as young as 13 are using trains to travel to meeting points points further down the line.
He said: “They are not paying their fare and causing anti-social behaviour due to the big crowd of them.
“We are giving extra attention to the railways at particular times when kids are using the train from Drumfrochar and Whinhill to Inverkip and Wemyss Bay.
“The age group is between 13 and 17, it could be even younger than 13.”
He stressed that youngsters were travelling from all over Inverclyde including Port Glasgow.
Constable Burns added: “We had complaints from passengers about large groups. It seems to be their mode of transport of getting around.
“There can be 30 or 40 youths at the one time, using different trains to meet at a particular station.
“They use social media to keep in touch. It is a continuation of last summer when there were issues at the beach in Inverkip.”
Community wardens are now monitoring disorder at railway stations and CCTV cameras are being used to capture images of unruly crowds, while local officers are liaising with BTP and ScotRail.
Members of the public are also being urged to play their part.
Anyone who wants to report an incident on the line should call 0800 40 50 40 or text 61016.