In 2014-15, the network spent $11.8 million driving empty vehicles 12,420 kilometres a day. The network also raised $24.7 million in revenue from fares, advertising and charter hires.

Opposition transport spokesman Alistair Coe said dead runs were an inevitable part of running a bus network although improvements were necessary.

"From a policy point of view, this demonstrates the difficulty of Canberra's geography when it comes to running public transport," he said.

Dead runs – or trips from a depot to service routes – cost $32,416 a day and represented 18 per cent of the 25 million kilometres travelled by drivers during 2014-15.

Minister for Territory and Municipal Services Shane Rattenbury said dead runs were reduced to 17.9 percent of overall journeys, slightly higher than the benchmark of 17.4 per cent.

"It's [due to] work on timetables and improving the flow of buses and where they go," he said.

"It's also been the creation of extra services and amenities so drivers don't have to go back to the depot to have a break."

In 2013-14, the network spent close to $17 million on dead running.

Canberra buses travelled up to 19,000 kilometres without passengers in 2012, which was further than a return trip to Beijing.

Today, the daily dead run distance is equivalent to a one-way trip to Los Angeles International Airport.

Mr Rattenbury said the opening of a decommissioned bus depot in Woden would further improve efficiency.

The proposal was first mooted by former TAMS minister Katy Gallagher in 2012, when Canberra buses travelled 19,000 kilometres a day without passengers.

"We need the Woden depot for two reasons; one is to cut dead running and the other is to have enough space for buses," Mr Rattenbury said.

"Both the Tuggeranong and Belconnen depots are nearing capacity with a slight expansion of the fleet."

Mr Coe said he would also consider additional bus terminals and questioned why the government had not already opened one.

"It's certainly something we would look at as it has been identified as being a potential solution for dead running in Canberra and for more efficient public transport network," he said.

"There has been talk about a facility in Fyshwick and perhaps one in Mitchell as well and none of these seem to have progressed a great deal."

Mr Rattenbury said the ACTION staff had worked hard to improve efficiency and would continue to do so in coming years.

"It's always a tricky balance and the key focus is frequency and reliability of services - they are the two things that matter most to the customers," he said.

"Getting dead running right behind this is more of a back end thing that the customers don't really care about, but it is very important to the overall performance of the business."

Mr Coe also criticised the government's move to ban advertisements for junk food, fossil fuels, gambling, alcohol and weapons on Canberra buses.

The government already prohibits political, religious, antisocial and tobacco advertising from appearing on the fleet.

"I think it is absurd to be honest," Mr Coe said. "You now have a situation where you could have a McDonald's advertisement on a bus shelter but you can't have one on the bus pulling up to the shelter."

But Mr Rattenbury has said the changes reflected the values of the Canberra community and the government's policy objectives.

"We are seeking to promote healthier diets, and obviously on buses, particularly where you've got a lot of school children travelling, we want to have messages on our own buses consistent with the sort of things we're talking about to kids through schools," he said.