The Republic's first three-door, single-deck bus began service yesterday, plying a 22km route between Choa Chu Kang bus interchange and New Bridge Road bus terminal.
Service 190, operated by SMRT, travels daily through areas such as Orchard Road and Chinatown.
Another three-door bus in service is a double-decker operated by Tower Transit on service 143.
The two buses, designed by ST Kinetics using chassis from Germany's MAN Truck and Bus, are part of a six-month trial by the Land Transport Authority (LTA) to study "the impact of such designs in improving commuter flow".
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The two rear doors are used by passengers to get off the bus.
SMRT Buses and Road Services managing director Tan Kian Heong said the firm had a "wealth of information and commuter feedback" that could help LTA assess the suitability of three-door buses.
A survey of 22,000 commuters last year found 90 per cent supported having a third door.
Both the single-deck and double-deck three-door buses include features such as a digital passenger information display system, USB ports as well as wheelchair space and seats that can be folded up to accommodate more standing passengers when necessary.
SMRT said that it had trained five bus captains to familiarise them with the operations of the new bus, and will train more in the future.
Commuters told The Straits Times they found the rear door useful. Madam Noreena Mohd Ibrahim, who takes service 190 from Choa Chu Kang to the National Dental Centre for check-ups, said it can be difficult to alight when the bus is crowded. "Having the rear door makes it easier for passengers to get off the bus," said the 47-year-old housewife.
Madam Margaret See, a wheelchair user, said that the extra door could save everybody time, as it is a long wait for other passengers to get off before the bus captain can lower the ramp.
"Now with the third door, I need not have to wait any more," said the 60-year-old housewife.
Walk through the new three-door single deck bus. http://str.sg/4E4i