Traders and shoppers objected to plans for about 250 parking spaces outside the ACT Magistrates Court to be lost over four years as a construction compound for the city-to-Gungahlin line was built, close to the planned Northbourne Avenue terminus.

On Wednesday Capital Metro Minister Simon Corbell said the government was considering two new options as a result of community objections, and the total number of car parks across two sites on London Circuit would grow from about 460 to more than 500.

Both plans would see half of the car park opposite the Melbourne Building closed for the temporary compound.

Retailers and the ACT Property Council gave the plan a mixed response, with one shop owner warning it was inevitable Sydney and Melbourne Building businesses would close.

Option one would have reconfiguration of Magistrates Court and Canberra Theatre car parks, as well as a new temporary overflow car park built off Theatre Lane to increase capacity. As many as 160 spaces would remain near the court and 40 new spaces would be created.

The plan would take about six months to complete, with limited impact on existing parking.

Option two would have a new temporary parking structure built to create multi-levels in about half of the Magistrates Court car park, adding about 40 new spaces.

Construction would take about six months and half of the Magistrates Court car park would be closed.

A final decision is due within months. Neither plan will mean any loss of disability parking spaces.

City businesses and Sydney and Melbourne Building traders will be consulted about the two options, and the consortium chosen to build the line will advise the government when the changes would be required, with construction set to start next year.

"The advice I have had to date is the options have been generally well received but we'll need to do further work to get the decision right. Any change to the car park does involve some disruption."

Shop owner Gary Rumble, of Kingsize Big and Tall, said he estimated more than 60 per cent of his customers used the car park.

"To close it for one day would be a day too long," he said.

"Like a lot of business owners, I believe it is the wrong place. The other areas they should consider are the other end of London Circuit, on the other side of the police station, where there would be no impact on restaurants and retail."

Mr Rumble said patients visiting nearby medical offices couldn't be expected to walk longer distances because of reduced parking.

Business owners and the Canberra CBD group criticised the plans, which come months after the government moved to increase parking fees and extend paid parking until 10.30pm in the city.

The ACT government has decided to limit the amount of car parking spaces taken up by a Capital Metro construction compound – a move welcomed by the Property Council of Australia.

Property Council executive director Catherine Carter said about 500 retail and service businesses with 3500 staff were within a 10-minute walk of the area.

"The Capital Metro compound area should be just that – a compound, not a construction workers' car park.

"Workers must find their own car park at every other development site in the city, and Capital Metro should be no different. If the area is to be used solely as a compound, it may be possible to reduce its size," Ms Carter adds.

She called on the government to build a two-storey car park outside the court and keep it after tram services begin.

Mr Corbell said bid information had been received for the main line and a possible 3.2-kilometre extension to Russell.

Opposition transport spokesman Alistair Coe said Canberrans would be inconvenienced.

"At a time when city traders are already doing it tough, this decision will make it even harder to visit businesses located on or around London Circuit," Mr Coe said.