How long does it take a pedestrian to cross the road in Sydney?

The answer changes on a Sunday but, during the week, it will be up to twice as long as it does in London.

The waiting time to cross the road in Sydney's CBD was cut from about two minutes to 90 seconds for cars, bikes and pedestrians in January. But in London, at about 200 intersections, the maximum waiting time for pedestrians is now set at 40 seconds.

That circular device placed at traffic lights in the Sydney CBD makes no difference to the time it takes to get permission to cross the road for most of the week.

Since 1994, at all intersections across the Sydney CBD, the "green men" get set to "automated pedestrian phases" that disable the button signals from 7am to 7pm on Monday to Thursday, and from 7am to 9pm on Friday.

On Saturday, there's no point tapping the disc at busy intersections from 8.30am to 9pm. But on Sunday, button bashing is useful, and will affect how long it takes to legally cross the road.

Automatic phases also run in areas where there is a "high level of pedestrian activity, at specific times of the day", a Transport for NSW spokeswoman said.

"These phases are constantly reviewed against demand profiles of road users and other changes that may affect the network," the spokeswoman said.

"Shorter wait times have kept pedestrians moving and could potentially reduce the risk of jaywalking and pedestrian crashes."

Studies in America, Canada, New Zealand and Europe found delaying pedestrians at lights for more than a minute results in more illegal crossings and 30 seconds seems to be the threshold that both children and adults are willing to wait.

Pedestrian council chairman Harold Scruby said the way Sydney prioritises car movements over people was at odds with international best practice.

"When Jan Gehl [a professor of urban design from Denmark] visited Sydney a few years ago he noticed the wait time in the CBD was up to two minutes, and he said it was one of the worst [wait times] he’d seen in the world," Mr Scruby said.

"If we want to be a great city we need to put pedestrians first."

Professor David Levinson from the School of Civil Engineering at the University of Sydney said traffic signals in the city should be shifted to be more pedestrian friendly to encourage more walking.

"Traffic signals give priority to motor vehicles over pedestrians. This inequality undermines many of the stated goals of transport, health and environment policy," Professor Levinson said.

"Sydney uses adaptive signals so that they're designed to maximise the throughput for cars and so they'll extend the green light for cars but that results in there being more 'don't walk' time for pedestrians."