The Red Songtao has been running since around October of 2012 so has become reliable. Based out of Pae Mai on the Klong Rd, the Red Songtao Route follows the klong south, then by the railway station and through Ban Gai to Soi 94 and then north back up Phetchkasem Rd by Market Village and the Colonnade Mall. It then goes along Naepkhaehat Rd. to Soi 41 and back to the Klong Rd via Soi 58 and back down to Pae Mai.
The fare is 10 Baht from one end of the route to the other.