A 91-year-old man died and a 70-year-old woman was left with life threatening injuries in a two-car crash on the road on Wednesday afternoon.

Police have not indicated that road conditions were a contributing factor in the incident as they are still investigating.

However, the ACT's opposition transport spokesman Alistair Coe hoped the government would urgently assess what road safety improvements could be done.

Road safety minister Shane Rattenbury expressed his condolences for the families affected by Wednesday's tragedy.

"It is extremely sad the ACT road toll now stands at four this year – that is already four deaths too many," Mr Rattenbury said.

"As a community we must all play our part in working towards Vision Zero [a zero road toll] and I remind all road users to take extra care on our roads."

Transport minister Meegan Fitzharris would not comment on the road condition, citing the police investigation.

Three memorials are scattered along a two-kilometre stretch of the road. It has been the scene of at least five deaths since 1998. In 2011, a 41-year-old Kambah man died after he lost control of his vehicle on the intersection with Mugga lane. In 2005, a 29-year-old Farrer man died in a head-on crash on the road, and an 81-year-old Isabella Plains man died in a two-car crash at the Mugga Lane intersection in 1998.

There have also bee several reports over the years of serious injuries there. These include six people hospitalised after a truck overturned in 2007, three people severely injured after a three-car crash at the intersection with Erindale Drive in 2004 and two people hospitalised after a driver attempted a U-Turn in 2000.

Six years ago, the ACT government injected $245,250 of funding to improve the Long Gully Road and Mugga Lane intersection, which was described as "once of the ACT's worst blackspots" and saw 23 crashes in the previous five years.

In a submission to an 2015 NRMA survey of the worst roads in NSW and the ACT, a Canberran listed their concerns about Long Gully Road.

"Deep ditches on either side of road, heavy trucks that speed down hill, no safe breakdown area," the submission read.

"If forced you would probably roll the car due to no road edging."

Ecologist Don Fletcher has previously listed the road one of Canberra's kangaroo collision hotspots.

Some social media users expressed the need for various upgrades on the road.

"They should put a speed zone along that stretch of road. How many more people have to die before they do?" one person wrote.

"Too many deaths on that road over the years," another person's comment read.

ACT Health did not provide an update on the condition of the 70-year-old woman injured in Wednesday's crash on Thursday night.