Former Labor minister Kate Lundy says figures on the capital's worst crash intersections back the Canberra Liberals' argument for a Barton Highway flyover.
Latest figures showed more than 500 crashes occurred at the Barton Highway-Gundaroo Drive-William Slim Drive roundabout in the past five years, making it by far the most common site for an accident in the ACT.
Now an NRMA director, Ms Lundy said the flyover was the obvious ideal solution.
"If the resources are available and able to justified then that would be the best outcome," she said.
"Roundabouts are often the second best solution, but are adequate in terms of the safety and functionality – the issue here is the persistent statistics of crashes leads the argument strongly in favour of a more substantial investment in the form of a flyover."
In 2014 there were 117 crashes at the site. One of these crashes involved serious injuries and four crashes led to minor injuries. Roundabouts on Parkes Way were the next two worse sites, with 83 crashes at the intersection with Coranderrk Street and 71 at the southern end of Anzac Parade.
The ACT government has committed $10 million to install nine sets of traffic lights and add an extra lane to each of the four approaches to the key Barton Highway roundabout. Construction was set to begin next month.
The Canberra Liberals had instead promised to build a $35 million three-span flyover.
Liberals road spokesman Alistair Coe said a reputable planner had provided structural drawings and backed the costings, but Planning Minister Mick Gentleman said a similar interchange was recently costed by the government at about $50 million.
Ms Lundy, who ended her 19-year Senate career in March, said with roundabouts making up four of the five worst intersections, the ACT government and the National Capital Authority should have a conversation about their value.
"In many cases they are exactly the right solution, but when you get statistics like this that is worthy of constant review," she said.
"While every government has to manage their resources, you have to look at the whole cost to society of such a large number of accidents."
The Territory and Municipal Services statistics on crashes away from intersections also played into the major parties' road policy debate, with Ms Lundy backing calls for a full duplication of Gundaroo Drive in Gungahlin.
The road has had 189 crashes in the past five years between Gungahlin Drive and Ginn Street, with a stretch of Commonwealth Avenue in the Parliamentary Triangle the second worst "midblock" site for crashes with 146.
The Liberals will have further flyers out in the next month spruiking their promise to duplicate a stretch of Gundaroo Drive more than three times the length of that promised by Labor.
"If the data shows that problems can be resolved by making that road investment, we'd certainly be encouraging both major parties to make that stronger commitment," Ms Lundy said.
In the past five years there has been only one fatal crash at the worst 10 ACT intersections for casualty accidents, which was at the Belconnen Way-Gungahlin Drive union.
Most accidents at ACT intersections, 2010-2014
1.Barton Highway/William Slim Drive/Gundaroo Drive 515
2.Coranderrk Street/Parkes Way 427
3.Anzac Parade/Parkes Way 289
4.Hume Circle 251
5.Athllon Drive/Drakeford Drive/Isabella Drive 220
6.Hindmarsh Drive/Tuggeranong Parkway 209
7.Athllon Drive/Drakeford Drive 205
8.Hindmarsh Drive/Yamba Drive 201
9.Baldwin Drive/Ginninderra Drive/Haydon Drive 187
10.Melrose Drive/Yamba Drive/Yarra Glen Roundabout 182
Most accidents on ACT roads (excluding intersections), 2010-2014
1.Gundaroo Drive (between Gungahlin Drive – Ginn Street/Nari Street) 189
2.Commonwealth Avenue (Flynn Drive (West) Commonwealth Avenue (North) Ramp – Albert Street) 146
3.Tuggeranong Parkway (Cotter Road (West) Tuggeranong Parkway (South) Ramp/Tuggeranong Parkway (North) Cotter Road (West) Ramp – Tuggeranong Parkway (South) Hindmarsh Drive (East) Ramp) 145
4.Tuggeranong Parkway (Hindmarsh Drive (West) Tuggeranong Parkway (South) Ramp –Drakeford Drive/Sulwood Drive) 134
5.Tuggeranong Parkway (Greenhill (West) Tuggeranong Parkway (South) Ramp – Tuggeranong Parkway (South) Cotter Road (East) Ramp) 133
6.Parkes Way (Glenloch Interchange – Parkes Way (West) Lady Denman Drive (South) Ramp) 127
7.Parkes Way (Clunies Ross Street (South) Parkes Way (East) Ramp – Parkes Way (East) Edinburgh Avenue (North) Ramp/Lawson Crescent (North) Parkes Way (West) Ramp) 110
8.Northbourne Avenue (Condamine Street/Ipima Street – Macarthur Avenue/Wakefield Avenue) 95
9.Hindmarsh Drive (Launceston Street – Hindmarsh Drive (West) Tuggeranong Parkway (South) Ramp/Tuggeranong Parkway (South) Hindmarsh Drive (East) Ramp) 80
10.Tuggeranong Parkway (Cotter Road (East) Tuggeranong Parkway (North) Ramp – Tuggeranong Parkway (North) Cotter Road (West) Ramp) 80
Source: TAMS Directorate