Bus passengers in Sydney's inner west may be able to summon smaller vehicles to pick them up on demand, according to Andrew Constance's vision for a franchised bus operation in the area.

But the bus union has rubbished the idea, saying on-demand buses are a fanciful notion for the inner city.

The M52 currently runs from Parramatta to the city. Credit:Peter Rae

In the two years since Mr Constance assumed the Transport Minister's job from Gladys Berejiklian, he has been an enthusiast for using technological change to overhaul transport services.

The minister legalised the use of ride-sharing services such as UberX in 2015. And now that he has embarked on his first major industrial relations battle in the job – a face-off with inner west bus drivers that has already triggered a day's strike – he is keen to open up public transport to new ways of doing things.