What has emerged as the likely route would take trams into Parkes, down King George Terrace, through Barton and later onto Adelaide Avenue before it would arrive in Woden.

The ACT government appears to be betting that a more lengthy plunge into the parliamentary zone will populate its trams better with commuters than a less circuitous route from Civic to Woden, perhaps especially when it is connected to other city centres.

Aside from questions about trip times, the artist's impressions of the Parkes route should bring pause for Canberrans to consider the way light rail would change the face of its parliamentary zone.

It's a question that's already reared its head when the National Capital Authority administering the precinct warned Canberra's iconic Parliament House vista could become a giant bottleneck if two lanes of traffic on Commonwealth Avenue Bridge were permanently closed for light rail under one proposed route.

As the centre of federal government in Australia, there is something fitting about opening the parliamentary triangle to more people through another form of public transport.

It's a grid of streets that can infuriate motorists with scant parking and absurd waits at intersections, and for pedestrians, the zone could use an easier path between the lake, Parliament House and national institutions. Canberra should use this debate to rethink the flow of traffic - motor, foot and otherwise - through this space.

The light rail project also raises questions about how Canberrans should live alongside, and use, a precinct that also belongs to non-Canberrans. Light rail in Parkes might open it up and connect it better to the city, but the route must also respect the area's buildings and both their national and historical stature.

In one artist's impression, light rail passing in front of Old Parliament House presents possibly the largest change to the appearance of the parliamentary zone since the decision to locate Parliament House on Capital Hill.

Passing so close to Old Parliament House, the tram would arguably diminish the building, or at least steal its thunder. Seen from a different angle, the route appears to open up the space by closing it to motorists.

Rail is something cities worldwide have often been at pains to hide underground, or thread along back streets. The option to run light rail through Parkes makes a visual feature of the network, one that visitors to the Australian War Memorial would see looking down Anzac Parade towards Parliament House. The tram would move across the opposite view for anyone looking from Old Parliament House. This would be a major change to the symbolic corridor.

Canberrans and the ACT government might well be comfortable with this. The National Capital Authority, and both houses of federal parliament, have different voices to heed, and their approval is needed.

The parliamentary triangle now sits apart from the rest of Canberra, a planning and administrative feature that protects it. Light rail may bring it closer to other parts of the capital, an idea Canberrans could be better placed to judge once the stage one route is operating.