A leading international transport consultant says Perth's obsession with building new freeways is "weird" and the opposite of what is happening in the rest of the developed world.

Enrique Penalosa, a Colombian presidential candidate last year and current member of the New York mayor's transportation reinvention commission, said most developed nations viewed new freeways "like poisonous rivers" - to be avoided at all costs.

"You can't live next to them," Mr Penalosa said yesterday. "You can't walk alongside them, you can't cross them - and they don't solve the congestion problems they are meant to fix.

"It is so weird that you in Perth continue to build new roads and new freeways when the rest of the developed world has stopped.

"London and Paris has bad congestion, but if someone suggested a new freeway to solve their problems, they would be sent to a psychiatrist. People would think they were mad.

"It's just not being done.

"The fact that you are still building new roads, and I saw some of them being built when I arrived at Perth Airport, is old-fashioned - the thinking of 50 years ago."

New freeways are like poisonous rivers, says Envrique Penalosa.

Mr Penalosa, on his second visit to Perth, was also mayor of Bogota for three years and became recognised for using innovative urban planning to improve mobility and quality of life for citizens.

He is also a scholar at the Institute of Urban Research of the University of Pennsylvania and is on the London School of Economics' cities program advisory board.

Mr Penalosa said Perth's sprawl had to stop and the city should embrace higher density living. "It doesn't matter how tall a building is - it is more important what happens when that building reaches the ground," he said.

"Is it interesting and engaging. Are there lots of restaurants and bars, interesting places?

"It doesn't matter what is built - a new freeway or a high-rise building. The question should always be: will it improve the way we live?

"If the answer is no, it shouldn't be built."

Mr Penalosa said rapid transit buses should not be overlooked as a solution for Perth's congestion woes.

He said buses operating in dedicated lanes could be just as effective as heavy or light rail.

"Buses can be more flexible and, with their own lane, can move thousands of people efficiently and quickly," he said.

"In Bogota, we transport 50,000 people a day with our rapid bus transit - that's bigger than most subway systems in the world.

"Authorities in Perth need to think differently.

"You are not going to solve the problems of today with the same approach you have had for 50 years, an approach that actually caused the problems you are trying to solve."

Mr Penalosa was in Perth to speak at this week's PublicSymposium, a two-day forum organised by FORM.