A driveway long section is a side-on slice along the centreline of the driveway, from the street to the garage. It shows height against distance — nothing about width, and nothing about the crossfall.
Read in the right order it answers the only question that matters: can a vehicle travel this without touching.
What is on the drawing
| Item | What it tells you |
|---|---|
| Reduced levels (RL) | Height at each named point, against a datum |
| Chainage or distance | How far along the driveway each point sits |
| Zone lengths | How long each constant-grade run is |
| Gradients, as ratios | How steep each run is |
| Transition locations and lengths | Where the grade changes, and over what distance |
| Platform or slab level | The finished level the driveway has to arrive at |
An RL is a height relative to a datum, not a height above the ground. RL 10.000 at the boundary and RL 11.450 at the platform means a rise of 1.450 m between them — the absolute numbers do not matter, the difference does.
Read it in this order
- Both ends first. Boundary RL and garage slab RL. Their difference is the total rise or fall.
- Total length. Boundary to garage. Rise divided by length gives the average grade.
- The steepest zone. Not the average — the average can comply while a zone in the middle does not.
- The length of that steep zone. Under QDC NMP 1.1 the run steeper than 1 in 5 has to stay within 6 m to use the 1 in 4 concession.
- Both transitions. At each end of the steep section, at least 1 m at no steeper than 1 in 8.
- The arrival. Whether the last zone actually meets the slab level, and at what grade.
Steps 3 to 5 are where drawings fail. A profile that passes on average and fails in the middle is the normal case, not the exception.
Ratios, and which way they point
A gradient written 1:6 means one unit of rise for six of horizontal distance. A bigger second number is flatter — 1:20 is close to level, 1:4 is the steepest a Queensland residential driveway is allowed to reach.
The ratio alone does not say up or down. That comes from the profile line or an arrow, and getting it backwards is the single most expensive misreading available: a driveway drawn falling when the site rises does not just fail, it cannot be built.
Conversions between ratios, percentages and degrees are set out in how steep can a driveway be.
A published example
Section B of IPWEA standard drawing RS-050 — the sheet used by several South East Queensland councils — is a long section, and a good one to read. It gives the vehicle crossing as a sequence of defined segments with a table of heights above the invert of channel at set distances, rather than a single grade.
That is what a complete long section looks like: every zone dimensioned, every grade stated, and levels tabulated so nothing has to be scaled. Detail in the Gold Coast article.
What gets a drawing sent back
- Grades shown but no zone lengths, so the 6 m steep-run limit cannot be checked
- A transition marked but not dimensioned
- Levels at the ends only, with the middle left to be scaled off the page
- No statement of which document the design is to — see which one applies
- A crossover profile that stops at the boundary, when the council's drawing governs the part in front of it
Disclaimer
General information, not advice. References to QDC NMP 1.1 summarise it as published rather than reproducing it, and it is a non-mandatory part of the Queensland Development Code. Councils and individual approvals may require something different. Confirm what applies with the relevant council or a qualified certifier.
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