They are quick on the draw, doodling away while other commuters busy themselves with their mobile phones.
The artists are part of a small group of individuals, known as the Commute Sketchers, who document their surroundings while travelling on trains, buses and other forms of transport. They share their drawings on Facebook.
Now, some of their creations will go on display at train stations and bus interchanges.
Sketches by eight artists will be framed and put on display at North East Line and Downtown Line stations as well as at bus interchanges across the island.
SBS Transit chief executive Gan Juay Kiat said: "We decided to put up some of these beautiful sketches at our bus interchanges and train stations on the North East and Downtown Lines so that more people can enjoy them.
"These works of art capture the different expressions and actions of commuters on paper. It is living art, and we hope it adds more colour to the walls of our interchanges and stations."
The first set of sketches has already been put up at the Bedok, Bishan, Boon Lay and Clementi bus interchanges.
There are also plans to showcase them at four train stations, including Beauty World on the Downtown Line and HarbourFront on the North East Line.
It was Mr Erwin Lian, an adjunct art lecturer at a polytechnic, who approached SBS Transit to display some of the artwork by the group.
The 37-year-old, a member of Commute Sketchers, said: "Our inspiration comes from the commuters and thanks to SBS Transit, we have the opportunity to share our work on a wider platform."