Heavy vehicles on the South Eastern Freeway

The South Eastern Freeway forms part of the Adelaide to Melbourne road corridor and is an important strategic freight route for South Australia.

The South Eastern Freeway down-track is from Crafers to the intersection of Portrush, Cross and Glen Osmond roads.

The down-track is a sustained continuous gradient which ends with traffic lights at one of Adelaide’s busiest intersections. This presents heavy vehicle drivers with unique and significant challenges rarely encountered on other descents across Australia.

When descending the South Eastern Freeway, truck and bus drivers must:

  • engage low gear at Crafers and remain in this gear to the bottom of the South Eastern Freeway
  • reduce speed to a maximum 60 km/h, unless otherwise signed at a lower speed or your load requires a slower speed, from Crafers to the bottom of the South Eastern Freeway
  • stay in the left lane between Crafers and the Measdays Bridge.

Map showing the very long steep descent from Crafers West to Glen Osmond

Use of the primary brake - the intent of the low gear offence is not to completely prohibit the use of the primary brake if necessary in the circumstances. By law, the driver must use a gear that is low enough for the vehicle to be driven safely without relying on the primary brake to slow down.

Lower speed limits - speeds may need to be further reduced to comply with any variable or temporary speed limit signs that are in place. For example due to bad weather, roadworks or as a result of a crash.

For more information about how to descend the South Eastern Freeway safely, - visit the Department for Infrastructure and Transport’s website

Offences and penalties

When descending the South Eastern Freeway, truck and bus drivers failing to use low gear or exceeding the speed limit by 10 km/h or more risk significant fines, demerit points and loss of licence.

You could also face imprisonment if convicted by a court for aggravated careless driving or for a second South Eastern Freeway speed or low gear offence.

These penalties apply to the portion of the South Eastern Freeway down-track between the Crafers Interchange and the major intersection of Portrush, Cross and Glen Osmond Roads.

Section 45C of the Road Traffic Act 1961

The South Eastern Freeway speed (Section 45C(1)) and low gear offence (Section 45C(2)) of the Road Traffic Act 1961 and associated higher penalties were introduced in 2019 following a recommendation from a Coronial Inquest after two serious crashes in 2010 and 2014 involving out of control heavy vehicles that tragically resulted in the loss of lives and serious injuries.

They better reflect community expectations, particularly around first offences, while maintaining strong penalties for repeat offenders who have chosen to disregard the law, putting themselves and other road users at greater risk.

For more information about the expiation fees and other penalties that apply to drivers and business vehicles, visit the Department for Infrastructure and Transport’s website

Vehicles affected by the laws

Examples of vehicles that may be subject to the laws based on GVM or seating capacity include:

  • emergency service vehicles*
  • animal transport vehicles
  • school and tour buses
  • cranes
  • drilling rigs
  • sweepers
  • tip trucks
  • tow trucks
  • large utilities
  • vans and motor homes
  • chauffeur vehicles
  • taxi bus.

The laws do not apply where the gross combination mass (GCM) of a vehicle towing another vehicle such as a trailer, horse float or caravan exceeds 4.5 tonnes in total. While such vehicle combinations are not captured by the laws, it is important to remember that drivers should always drive according to road conditions to ensure a safe descent.

Exemptions: in the event of an emergency, exemptions apply to emergency vehicles in relation to the offences of using low gear and exceeding the relevant speed limit on the South Eastern Freeway descent.  Emergency vehicles are expected to use flashing red or blue lights or sirens and take reasonable care when driving in an emergency.

Is your vehicle a heavy vehicle, truck or bus?

'Truck' and 'bus' have the same definition as in the Australian Road Rules (ARR).

  • A BUS is defined as a motor vehicle that seats over 12 adults including the driver. The definition of a bus is based on the number of seats, regardless of the gross vehicle mass (GVM) or whether the seats are occupied or vacant. Small buses with 1-12 seats are not subject to the speed and low gear restriction on the South Eastern Freeway.
  • A TRUCK is defined as a motor vehicle with a gross vehicle mass (GVM) over 4.5 tonnes regardless of the body type of the vehicle (excluding tractors, trams and buses).

The GVM is not the tare mass. It is the GVM that is recorded and relied on for registration purposes.

If you are unsure if your vehicle is a truck or a bus, or you need to check your GVM:

  • refer to your registration details certificate
  • check using the mySAGOV account
  • call Service SA on 13 10 84.

Signage and speed cameras

Advisory signs have been installed on the approach to the down-track to remind drivers to descend safely and avoid heavy penalties.

These advisory signs, as well as speed limit and low gear signs that refer to trucks and buses, apply to drivers of all heavy vehicles and buses as defined above.

Speed cameras operate along the section of the South Eastern Freeway where the legislation applies. These cameras are operational and drivers can be penalised for road safety offences at these sites.

Why are these laws needed

In 2021, the South Eastern Freeway, between Crafers and Glen Osmond, carried an average of 48,000 vehicles per day with approximately 5,200 classed as heavy vehicles.

Heavy vehicles pose a greater risk to other road users due to their mass and rigidity, thereby creating greater impact forces if they are involved in a crash. The speed of a vehicle has also been shown to impact on both the risk of the vehicle being involved in a crash and the resulting severity of any crashes that may occur.  Due to their momentum, heavy vehicles will take much longer to stop than lighter vehicles.

In 2010 and 2014, two serious crashes involving out-of-control heavy vehicles on the South Eastern Freeway down-track tragically resulted in loss of lives and serious injuries, and prompted a South Australian Coronial Inquest.

Since late 2014, a maximum speed limit of 60 km/h has applied to all trucks and buses between the Crafers Interchange and the bottom of the freeway.

In response to the Inquiry, two offences were created which resemble existing Australian Road Rules but are associated with significantly higher penalties when committed by truck and bus drivers on this stretch of road.

The laws aim to improve road safety on the South Eastern Freeway and reduce heavy vehicle crashes involving brake failure and excessive speed.

Need help?

Contact Service SA


Only send general enquiries online. Service SA will respond within 3 working days.

If the matter is urgent or is specifically about your current licence or registration, phone or visit a Service SA centre instead.

Enquire now


Call Service SA between 9:00 am and 5:00 pm Monday to Friday, excluding public holidays:

In person

Service SA centre locations and opening hours.

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Page last updated 12 July 2023

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