The proposed development of 750 homes, shops and a park at the Newmarket site is expected to cause traffic flow to increase by about 17 per cent in 2021 during the morning peak on the already congested Barker Street.

But the figure, listed in traffic modelling supporting the development application, ignores the increase in cars that will use the road under plans to close parts of nearby High Street for the construction of a terminus for the CBD and South East Rail Line.

Residents are concerned ambulances will struggle to reach the emergency department at the Prince of Wales Hospital as traffic worsens along Barker Street, although the service itself says it will not make a submission or comment on the development proposal.

The street is also one of the main entry points for the University of New South Wales, and the proposed development would border Randwick Girls' High School, Randwick Boys' High School and Rainbow Street Public School.

Super fund Cbus Property bought the 5-hectare site, used by the Inglis family as a thoroughbred sales complex since 1917, for an estimated $260 million. It wants to build 19 buildings, ranging in height from two to 8 storeys, with 750 homes, shops, an urban plaza and public park on the site.

Cbus' analysis says that the development would generate 385 vehicle trips and 346 vehicle trips during the morning and afternoon peak and concludes that with the addition of some clearways the surrounding network has the capacity to cope.

But local politicians, residents and parents say this traffic figure is grossly underestimated, as it does not include the proposed closure of parts of High Street.

The Cbus traffic modelling is based on surveys of the area taken in 2010 and 2015, before the environmental impact statement for the light rail terminus was placed on exhibition. This statement says local traffic movement would change, with traffic flows to increase on adjacent routes and in particular Barker Street.

Local Liberal MP Bruce Notley-Smith, whose own government paved the way for the development when it rezoned the stable yards in 2015, has thrown his support behind commissioning an independent traffic study.

"I think there are huge question marks about the traffic congestion in the area and whether going to that density is appropriate," Mr Notley-Smith said.

Parents from the schools that will border the development are also concerned that the construction of eight storey buildings will allow people to overlook children in school grounds.

"The eight storey buildings in the current development application are along the border overlooking all three school grounds. That's unacceptable to us from a welfare or well being perspective," Randwick Girls High School P&C vice president Lynda Monteiro-Wallace said.

"As a resident, a parent and a community member it's just a irresponsible high density development that should not be accepted in its current form."

The development is valued at $160 million and will be determined by the Joint Regional Planning Panel, rather than Randwick Council. Cbus Property did not want to comment.

The plan is on public exhibition until April 5. The Inglis horse empire is set to take up a new home at Warwick Farm in western Sydney, with the move anticipated to occur in 2018.