The gradient of a through route is the slope parallel to the direction of travel. Movement becomes more difficult as gradient increases. The table below shows the three parameters that should be assessed when considering the gradient required.[1][2] Parameters can be calculated using the procedure outlined at the end of this section.
Through routes in existing developments may have gradients higher than the maximums in the table below. Where the mean gradient exceeds the maximum value, the through route should ideally be redesigned as a ramp, which includes rest areas. This allows maximum through-route gradients of up to eight per cent while still remaining accessible to wheelchair users.[3] Where this is not possible and the through route is next to a road, the mean and maximum gradients should be no more than that of the adjacent roadway and include signage noting the gradient so pedestrians can assess whether the path is suitable for them.
Generally, through route gradients in all new developments should be less than the permitted maxima. If they exceed them, the developer should show why this was unavoidable.
The driveways guidance advises on situations where footpaths cross driveways.
Through-route gradients table
| Parameter | Definition | Maximum value | Requirement |
|---|---|---|---|
| Mean gradient | The change in vertical elevation measured between two points. | Up to 3% | No additional considerations for longitudinal gradient |
| >3% but less than 5% | Level rest areas at least 1200mm in length provided at least every 18m. Note that shared paths should be treated differently as frequent landings can destabilise people on bikes or scooters. | ||
| Maximum gradient | The change in vertical elevation measured at 0.6m intervals along a route. | 8%, over a distance no greater than 9m. Gradients greater than 8% are increasingly difficult for many people to negotiate independently. |
Treat as a ramp if exceeding the maximum. Provide wayfinding signage directing users to alternative (less steep) routes |
| Rate of change of gradient | The total variation in slope measured at 0.6m intervals along a route. | 13% |
The following equation are used to calculate mean and maximum gradient.
|
Gradient =
Rate of change of gradient =
An example equation of calculating the mean, maximum and rate of change of gradient along the lenth of the through route. |
Example of gradient calculation:
| Parameter | Calculation |
|---|---|
| Mean gradient (between A and D) |
|
| Maximum gradient (between A and D) |
= 8% This is the steepest gradient of the three sections between points A and D (ie between A and B (2%), B and C (8%) and C and D (4%)) |
|
Rate of change of gradient |
= (gradient to right of B) – (gradient to left of B) = 8% – (-2%) = 10% |
The Te Ara Ki Tai shared path case study provides an insight into the impact of gradient on various users of a shared path and how this can be managed.
[1] Axelson, P.W. et al. (1999). Designing sidewalks and trails for access. US Department of Transportation(external link)
[2] Standards New Zealand. (2001). NZS 4121:2001 Design for Access & Mobility.
[3] MBIE Building Code Compliance(external link)
