A document obtained under freedom of information shows a bill of $44,501 for airfares and $8701 for accommodation.

Mr Gentleman was accompanied by his then chief of staff Adina Cirson, public servants Gary Rake and Ben Ponton, and several industry representatives.

When the trip was announced in February 2016, it was said non-government delegates would pay most of their own costs, with the government offering a $2000 grant to those representing peak bodies.

The FOI document records grant payments of $6000.

The delegation visited Tucson, Arizona; Seattle, Washington; and Vancouver, British Columbia. The purpose was to look at best-practice urban design, transport planning and sustainable development.

Mr Gentleman reported to parliament on his travels in May 2016.

"Each of these cities has made a major investment in improving their transport system," he told the assembly.

"In every case, some form of light rail was included, and in every case the success of their light rail system to date is triggering discussion about the future expansion to a larger network."

In Tucson, the minister saw "a wonderful example of the transformative effect of light rail", which runs just under 10km and connects the downtown area to a shopping precinct and the University of Arizona.

City officials said the streetcar had stimulated an additional layer of culture and lifestyle in Tucson.

"The delegation was told, and could clearly see, that the areas adjacent to the light rail were denser and had a high level of activity throughout the day and night," Mr Gentleman reported.

"We visited the precinct late on a Sunday afternoon and found a thriving hub. Restaurants and bars were full. There were people walking along the streets and relaxing in parks. Retail shops were still open and busy after 5pm."

It was claimed that more than 200 new businesses had opened along the route.

"In Seattle, we saw a great project where affordable social housing had been developed, essentially, in the airspace above an existing art centre," he said.

"With a full redevelopment and separate stratum leasing, the art centre gained a new set of facilities on the same tenure that they previously had, while new residents benefited from social housing built in a much sought-after arts precinct.

"The pride and dignity this project brought to all parties was simply outstanding."

In Vancouver, Mr Gentleman said delegates saw "the immense potential" of combining university and city renewal ambitions in one coordinated program of development.

Some delegates also visited Portland, Oregon.

A spokesman for the minister said lessons from the trip were proving useful in helping guide the next stage of the light rail network to improve transport while helping to stimulate investment and economic activity.

"The delegation also informed changes proposed for the Territory Plan to implement active living principles into all new developments in the ACT to improve connectivity, add more public space and encourage physical activity. Consultation on this finished last Friday," he said.

"There were many lessons from the delegation about the best design and locations for community housing which is something the government continues to work on.

"For example the 25 new energy efficient housing units in Coombs, which are located next to the local centre and close to bus routes and primary school."

Public transport advocate David Johnston, who obtained the travel expenses, said $70,000 was "a very large amount of money" to spend given the decision to proceed with stage one of the light rail project had already been made.

"There wasn't any likelihood of changes being made to stage one based on the findings of this study tour," he said.

"I am also sure that one competent ACT government transport policy officer could have found out more useful information about the success, or otherwise, of light rail projects in North America in less than one week without leaving town.

"Hasn't Mr Gentleman heard of the internet, video conferencing and telephone conferencing? These options would have been far more cost effective and efficient uses of ratepayer dollars."

Opposition leader Alistair Coe said the minister should explain what value taxpayers obtained from the trip.

Mr Gentleman's office provided a detailed report on key learnings from the trip when requested by The Canberra Times.