Infrastructure is "on the cusp of going mainstream" as an asset class for real estate investors, said IPD co-founder Ian Cullen at a Movers and Shakers property panel on alternatives this week.

"If we were running this discussion in five years' time, we would probably see that infrastructure had leapfrogged into the mainstream," he said.

IPD is running a pilot infrastructure index in Australia, one of the world's most mature infrastructure markets, which it hopes to extend to other countries in due course.

Panellists said there needed to be ways for real estate investors to gain infrastructure exposure without having to take on operating responsibilities, which demanded bringing additional expertise on board.

"The question is, how do you commoditise infrastructure so that it can give a suitable return to a real estate investor? We are looking for some kind of wrapper that will enable people to invest in infrastructure, and to go to sleep at night without having to worry about the management of a very complex asset," said Steve Smith, chief investment officer at British Land.

Cullen also expressed his ­disappointment that residential property was still considered an alternative asset class in the UK.

"In most markets there wouldn't be the least question that residential is a mainstream asset class, and in many countries it makes up more than 20% of conventional ­portfolio allocations," he said.

Responding to a question on whether a growing investor appetite for risk could fuel growth in alternative real estate investment in the near future, Mark Creedy, managing director of fund management at Unite Group, said: "It is too early to say whether there really is a greater appetite for risk, but most investors are interested in a balanced portfolio and want some risk around the margins, which alternative investments can provide."