SINGAPORE - Unlike many other commuters who are glued to their phones while on public transport, undergraduate Valerie Lee, 19, and her brother Nicholas, 22, keep an eye out for trouble when commuting.

The siblings watch out for suspicious behaviour or objects. They are two of some 48,000 volunteers with the police's Riders-On-Watch (ROW) scheme, a community policing initiative enacted last year to keep crime out of transport nodes.

"Public transport is very essential to everyone so it is important to ensure (everyone's) safety," said Ms Lee, who signed up for the ROW scheme in August last year.

She receives regular updates via SMS about the latest crimes committed on public transport and is informed of the steps to take when she spots something irregular.

Her brother Nicholas, who served his national service as an officer with the Public Transport Security Command (TransCom), shared some of the red flags he looks out for, such as unattended bags that have an oil slick or make ticking noise.

The ROW scheme marked its one year anniversary in July. The police said in a media release on Friday (Sept 4) that they have started a new poster campaign to recruit more volunteers and deter crime.

The posters are being put up in public transport nodes in spaces that were provided for free by SMRT Corporation and SBS Transit, the police added.

The TransCom commander, Deputy Assistant Commissioner of Police Fanny Koh, said it is encouraging that commuters have been supportive of the ROW scheme.

She said: "With the new ROW deterrence visuals on our public transport, we hope that more members of the public like Nicholas Lee and Valerie Lee will join us, to keep the public transport network safe and secure as we commute."