A smart city project started by Google's sister firm Sidewalk Labs to track mobility patterns in the US city of Portland, Oregon has been shelved.

Last year, Sidewalk also ditched an ambitious project to build a digital city in Toronto, following controversy about the scale of its plans.

Portland confirmed the project would no longer go ahead.

Sidewalk said the scheme had most recently been in the hands of a spin-off company, Replica.

Replica told the BBC it was unwilling to share data to the level of detail requested by the city.

"At Replica, we believe better insights should not come at the cost of personal privacy. We were not willing to compromise on our privacy principles, which frustrated our Portland Metro client and ultimately led to an early end to the project."

In a statement, Metro, the city agency in charge of the project, told the BBC: "After review of the draft data, Metro ended its relationship with Replica. Metro did not pay Replica for any services. We wish Sidewalk Labs the best with its future work."

Sidewalk Labs began piloting location data software in Portland in May 2019, and the product Replica became a spin-off company in September of that year.

The software used non-identifiable mobile location data to show how people move through a city.

The plan was to use the data to make policy decisions about where to build bike lanes, how and when to repair roads and to make sure bus services were efficient and reaching all communities.

But Fast Company reported there were concerns about a lack of transparency around how the technology worked.

And RedTailMedia, which broke the news that the project had been ditched, referred to "data disputes and damaged trust".

'Lab rats'

Data collection and a perceived lack of transparency were also among concerns when Sidewalk Labs signed a major deal to reinvigorate a huge area of disused waterfront land in Toronto.

The vision had been to create a city full of technology, from timber skyscrapers to autonomous cars and heated sidewalks. Much of the plan rested on mass data collection from sensors around the area, which a lobby group of concerned citizens questioned the need for. They likened themselves to "lab rats" in a city experiment.

And an independent panel set up to scrutinise the plans said some of its ideas seemed to be "tech for tech's sake".

There were questions about how the deal was brokered in the first place.

Sidewalk Labs unexpectedly announced that its ambitious plans would be scrapped in May last year, citing "unprecedented economic uncertainty" following the coronavirus pandemic.

But many saw that as an excuse for ending a project that it had been forced to scale back significantly.

Much of the controversy came down to the question of whether cities should be making deals with huge corporations such as Alphabet - the parent firm of both Google and Sidewalk Labs.

At the time, the Canadian Civil Liberties Association said it was "inappropriate" for a firm like Google to design privacy policies to govern city neighbourhoods.

After the failure of the project, Sidewalk Labs set up a range of spin-off firms and divisions, all looking at different aspects of smart cities. These include:

Delve - a firm that uses AI software to design urban landscapes
a division looking at factory-made timber buildings
Pebble, a low-cost vehicle sensor to enable "better parking"
a division looking at ways to reduce the cost of electricity