5.3 Speed Caps, Overtaking, Lane Changes and Reversing
Key Takeaways
A bus above 5 t GVM or another vehicle above 12 t GVM has a maximum of 100 km/h where the posted limit is higher.
The handbook identifies speed-limiter requirements for buses above 14.5 t and goods vehicles above 15 t built after 1 January 1988, subject to applicable exemptions.
Signal and give way when changing lanes; stop a reversing movement whenever the path or guide is uncertain.
Use the lowest applicable ceiling
Tasmania’s posted speed applies to both light and heavy vehicles, with vehicle and licence exceptions. If the posted limit exceeds 100 km/h, a bus above 5 t GVM or another vehicle above 12 t GVM is limited to 100 km/h. A heavy vehicle learner is limited to 90 km/h even in a higher zone. Any lower posted limit, access condition or safe speed must also be respected.
A speed limiter is equipment restricting maximum powered road speed. The handbook identifies buses above 14.5 t GVM and heavy goods vehicles, including prime movers, above 15 t GVM built after 1 January 1988 as requiring limitation to 100 km/h. Specific legal exemptions can apply, including certain older primary-production vehicles. Check the actual vehicle category and applicable standards rather than teaching that every truck above 15 t, regardless of age, has identical requirements.
A limiter does not prevent every downhill overspeed: gravity can accelerate a vehicle beyond a powered-speed setting. Monitor speed and use the proper descent plan. Do not tamper with the limiter, and report a malfunction. The road speed cap and the equipment requirement are different obligations.
Decide whether overtaking is worthwhile
A long vehicle needs more distance to pass and return safely. Assess the speed difference, length of both vehicles, available visibility, oncoming traffic, gradients and any lanes or lines prohibiting the manoeuvre. A small speed advantage can require a surprisingly long pass. You cannot exceed the speed limit to complete it faster.
For illustration, a truck travelling at 100 km/h gains on a vehicle at 90 km/h at only 10 km/h, or 2.78 m/s. If an assumed total relative gain of 100 m is needed to move from the initial safe gap to a safe position ahead, that takes about 36 seconds. The truck travels about 1,000 m during that time. The assumed gain is a teaching input, not a prescribed overtaking distance; real safe margins and oncoming traffic can require more.
| Before passing | During passing | Returning to lane |
|---|---|---|
| Check legality, visibility and sufficient clear distance | Maintain lawful speed and a stable path | Ensure full clearance, not just cab clearance |
| Check mirrors and blind spots | Watch for changed traffic or road conditions | Signal and give way as required |
| Allow for load and gradient | Avoid crowding the vehicle being passed | Restore a safe following gap |
Do not begin before a crest or blind bend where the visible road is too short. Do not overtake a vehicle stopped at a pedestrian crossing. A turning vehicle and its sign can impose additional restrictions. If a pass becomes unsafe, choose a controlled lawful response rather than force an oncoming vehicle onto the shoulder.
Being overtaken
Do not increase speed while another vehicle is overtaking. Maintain a predictable path and provide reasonable space. An impatient driver behind does not make an unsafe shoulder usable. Where a suitable lawful opportunity exists, allowing traffic to pass can reduce pressure, but never move into a soft verge or obstructed shoulder simply to be courteous.
Long-vehicle separation outside built-up areas helps overtaking traffic return between vehicles. Preserve it where the rule applies. If another vehicle returns ahead, ease back to restore the necessary gap rather than close the space deliberately.
Lane changes and merging
When moving from one marked lane to another, signal and give way to vehicles in the destination lane. Check mirrors and blind spots just before moving; an earlier check can become stale. A truck’s indicator does not confer priority. Allow the trailer to complete the lane movement smoothly without cutting across an adjacent vehicle.
Distinguish a marked lane ending from two unmarked lines of traffic merging. When your marked lane ends, you give way to traffic in the continuing lane. Where lines of traffic merge without a marked lane change, the vehicle behind gives way to the vehicle ahead. Apply the road layout, not a blanket 'zipper always' slogan.
Reversing
Avoid reversing where a forward route is practical. Before reversing, inspect the path, ground, overhead space and rear clearance. A pedestrian can enter after the inspection, so continue monitoring. Use a trained guide where needed, agree signals and keep the guide in a safe visible location. If the guide disappears or a signal is unclear, stop immediately.
Reverse slowly enough to stop within the visible clear path. Use mirrors and camera aids without assuming they show every area. Keep people out of the path and articulation crush zones. Stop and get out to recheck if uncertainty develops. A reversing alarm warns others but does not transfer the driver’s responsibility to them.
Key decisions
Keep the speed cap, limiter requirement and safe-speed decision separate. Only overtake, change lanes or reverse when the full movement can be completed safely.
Official sources
Road Rules 2019, speed, overtaking, lane changes and reversing; handbook speed limiters and manoeuvres; Tasmanian ADR 65 applicability. Sources checked 10 October 2026.
While reversing with an agreed guide, the driver loses sight of the guide. What should they do?
Stop immediately and re-establish safe communication and visibility
Continue slowly because the alarm is sounding
Assume silence means the path is clear
Accelerate to finish the manoeuvre sooner
Sections you finish are checked off in the contents.