Work out road width requirement instantly with clear inputs, formula shown and shareable results.
Access road width is driven by peak hour demand. Daily trips are the plot count times trip generation per plot, and the peak hour is typically ten to fifteen percent of the daily total. Dividing by lane capacity gives the number of lanes, at 3.5 metres each, with a two lane minimum for two-way access regardless of demand.
Peak demand
Peak hour trips = plots x trips per plot per day x peak hour share
Width
Lanes = max(2, ceil(peak trips / lane capacity)); width = lanes x 3.5 m
Preliminary estimate only. Road widths in a layout are set by development control regulations including fire access and utility corridor requirements.
Peak hour trips = plots x trips per plot per day x peak hour share. Access road width is driven by peak hour demand.
No. Minimum widths for fire tender access, on-street parking, footpaths and utility corridors usually govern on residential layouts long before traffic capacity does.
This calculator takes 4 inputs: Plots served, Vehicle trips per plot per day, Peak hour share of daily trips, Lane capacity. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.