Extract from AS 2890.1 - driveway grades

 

AS/NZS 2890.1:2004 26

(b)

(c)

(d)

(e)

(f)

(g)

(h)

(iii) A stepped ramp comprising a series of lengths each exceeding | in 6 (16.7%)
PP P g
grade shall have each two lengths separated by a grade not more than of | in 8
(12'%4%)‘and at least 10 m long.

Straight ramps: private or residential car parks (other than domestic driveways, see
Clause 2.6)—as follows:

(i) Longer than 20 m—1 in 5 (20%) maximum.

(ii) Up to 20m long—1 in 4 (25%) maximum. The allowable 20 m maximum
length shall include any parts of grade change transitions at each end that
exceed | in 5 (20%).

(iii) A stepped ramp comprising a series of lengths each exceeding | in 5 (20%)
grade shall have each two lengths separated by a grade of not more than | in 8
(12'%%) and at least 10 m long.

Grade change transitions will be required in both cases where grades are at or near the
maximum, see Item (e).

Curved ramps—as for straight ramps, except that the grade shall be measured along
the inside edge, i.e. the line marked with radius R; in Figure 2.9.

Changes of grade—To prevent vehicles scraping or bottoming, changes in grade in
excess of—

(i) 12.5 percent algebraically (1 in 8) for summit grade changes; or
(ii) 15 percent algebraically (1 in 6.7) for sag grade changes;

require introduction of a grade transition between the main grade lines as illustrated
in Figure 2.10.

Grade transitions—Transitions of 2.0 m in length will usually be sufficient to correct

’ bottoming or scraping at grade changes up to 18 percent. They may be in the form of

a simple chord with grade calculated as half the algebraic sum of the two adjacent
grades, as illustrated, but for vehicle occupant comfort may be constructed as short
vertical curves. Grade changes shall be checked using the method at Appendix C in
any of the following circumstances:

(i) | Grade changes of 18 percent or more.
(ii) Where there are successive grade changes less than 3 m apart.

(iii) Where vehicles with unusually low ground clearances are to be catered for. A
modified ground clearance template to suit the particular vehicle characteristics
will be required.

(iv) Any other case where there may be doubt as to whether adequate ground
clearance has been provided (e.g. along the kerb lines of a curved ramp).

Longer transitions or other adjustments to the grade line may be required in these
cases.

Sloping floors—In some parking structures the floor is sloped to provide the
connection between parking levels. Maximum gradients for such floors shall be as
specified in Clause 2.4.6.1.

At and near access driveways—Limiting grades across footpaths and property
boundaries, and at vehicular control points and queuing areas near entry and exit
points are specified in Clause 3.3.

Domestic driveways—see Clause 2.6.

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