The waiting time for a taxi is still the biggest bugbear for commuters, though it has improved since 2013, according to an annual study of taxi service quality.

The survey by the Land Transport Authority (LTA) found that while 96.4 per cent of the 1,200 respondents felt waiting time to be important, just 86.2 per cent said they were satisfied with the time they actually had to wait.

The gap between their expectation and satisfaction of about 10.2 percentage points was the widest of all attributes surveyed, said the LTA. "From the survey, commuters feel that taxi services could be further improved in the area of taxi waiting times," it said.

Besides waiting time, respondents in the Taxi Customer Satisfaction Survey, now in its third year, were also asked to rate safety, driver knowledge of routes, customer service, comfort, ease of booking, taxi-stand accessibility, and information on taxi services.

These attributes registered smaller gaps between expectation and satisfaction of 1.5 percentage points to 7.3 percentage points.

The survey, conducted in August and September last year, polled regular taxi commuters aged 15 and above at cab stands.

Marketing manager Victoria Barker, 30, said: "At my workplace in Circular Road, it can be tricky to get a cab during (the) evening peak hours... The waiting time can be as long as half an hour."

But while the gap for waiting times still needs improvement, it has "shown an encouraging trend of continued improvement", said the LTA. In 2014, the difference was 11.8 percentage points, and in 2013, 15.5 percentage points.

The LTA put the improvement down in part to measures it took to increase taxi availability. Last year, 90.8 per cent of the 28,000 taxis here plied the roads during peak hours, up from 82.4 per cent in 2012.

Under a taxi availability framework it implemented in 2013, cab operators must ensure the bulk of their fleets are on the roads during peak hours, or face financial penalties.

The LTA said private-hire car services such as Uber and GrabCar have also provided commuters with an alternative option, resulting in improved waiting times for cabs.

Overall, however, commuters are generally satisfied with the quality of taxi services. Around 97.3 per cent of respondents felt so, which is only a slight dip of 0.8 percentage point from 2014.

Nonetheless, the persistent service gap could be why a growing proportion of respondents feel more cabs should be on the roads. Around 42.9 per cent of those surveyed last year said taxi availability standards should be raised, compared with 29.2 per cent in 2014.

National Taxi Association executive adviser Ang Hin Kee said this may not cut waiting times but could lead to drivers cruising empty on the roads. Instead, demand and supply can be better met through the wider use of third-party cab-booking apps, he said. "Cabbies don't have to depend on visually spotting passengers, or going to taxi stands."

Commuter Nurul Syuhaida, a 28-year-old translator, said. "I live in Bukit Batok and it can take up to 20 minutes to flag down a cab during the weekends. If I use an app to book, it takes just five minutes."

The LTA said that for next year's report, it will include questions on customer satisfaction with third- party taxi-booking apps and private-hire car services.