Short answer: use one row of poles when the road is no wider than the mounting height, a staggered layout up to about 1.5 times the height, and poles on both sides opposite each other above that. Keep spacing at about 3 to 3.5 times the mounting height for modern cut-off LED luminaires. Typical results: 6–8 m poles for 6–7 m roads, 10–12 m poles for four-lane roads.
Pole height, spacing and layout decide uniformity, glare and the number of poles per kilometre, which is often the largest cost line in a lighting tender. These are planning rules; the final layout should be confirmed with a photometric calculation using the luminaire’s IES file.
Key numbers
- China’s urban road lighting standard CJJ 45-2015 limits spacing to 3 H for cut-off luminaires, 3.5 H for semi-cut-off and 4 H for non-cut-off (H = mounting height).
- For a single row of cut-off luminaires, mounting height should be at least the effective road width; staggered layouts need at least 0.7 times and opposite layouts 0.5 times.
- Arm overhang should not exceed one quarter of the mounting height, and luminaire tilt should stay at or below 15°.
1. The four layouts
| Layout | Where it fits | Notes |
|---|---|---|
| Single-sided | Roads up to about the mounting height in width | Lowest cost; the far side is darker, so check uniformity |
| Staggered (zig-zag) | Roads about 1 to 1.5 times the mounting height | Good uniformity across the road; longitudinal uniformity needs care |
| Opposite (both sides) | Roads wider than about 1.5 times the mounting height | Most even result on wide roads; most poles per kilometre |
| Central double-arm | Dual carriageways with a median | One pole lights both carriageways; often combined with opposite layouts on very wide roads |
2. Height and spacing ratios
CJJ 45-2015 Table 6.1.2 gives the limits by layout and luminaire type. Weff is the effective road width: the carriageway width minus the arm overhang on each side that has poles.
| Layout | Cut-off | Semi-cut-off | Non-cut-off |
|---|---|---|---|
| Single-sided | H ≥ Weff, S ≤ 3H | H ≥ 1.2 Weff, S ≤ 3.5H | H ≥ 1.4 Weff, S ≤ 4H |
| Staggered | H ≥ 0.7 Weff, S ≤ 3H | H ≥ 0.8 Weff, S ≤ 3.5H | H ≥ 0.9 Weff, S ≤ 4H |
| Opposite | H ≥ 0.5 Weff, S ≤ 3H | H ≥ 0.6 Weff, S ≤ 3.5H | H ≥ 0.7 Weff, S ≤ 4H |
These categories were written for conventional lanterns. Most LED street lights have wide asymmetric optics and are fully cut-off, so the 3H spacing limit is the safe starting point; good optics often reach 3.5H in a calculation.
3. A starting table by road width
| Road (carriageway width) | Layout | Mounting height | Spacing | Poles per km |
|---|---|---|---|---|
| Village road, 4–5 m | Single-sided | 6 m | 18–21 m | 48–56 |
| Residential street, 6–7 m | Single-sided | 8 m | 24–28 m | 36–42 |
| Collector road, 9–10 m | Staggered | 9–10 m | 27–35 m (each side twice that) | 29–37 |
| Four-lane road, 14–15 m | Opposite | 10–12 m | 30–40 m | 50–67 |
| Dual carriageway, 2 × 7.5 m with median | Central double-arm | 10–12 m | 30–40 m | 25–34 |
Our own worked table, assuming a 1 m arm overhang and cut-off LED luminaires at 3–3.5H spacing. The light output per pole then follows from the lighting class; see our road lighting classes guide.
4. Arm, tilt and setback
- Overhang: no more than H/4. A long arm moves light over the road but adds wind load and cost; with asymmetric LED optics, 1–1.5 m is usually enough.
- Tilt: 15° or less. Tilting a luminaire to reach the far side increases glare; use wider optics or a staggered layout instead.
- Setback: keep poles back from the kerb as the local road authority requires, and protect them on high-speed roads.
- Junctions: place a pole before each conflict point so drivers see pedestrians and vehicles in silhouette, and raise the class one step.
5. Spacing and cost for solar lighting
With grid lights, the cheapest design is usually the fewest poles. With solar lights the trade-off changes: wider spacing needs more light per pole, and every extra lumen needs more panel and battery. Moving from 30 m to 25 m spacing adds 20 % more poles but cuts the energy each light needs by about 17 %, which can bring a road within the range of all-in-one lights. Our all-in-one vs split guide and sizing guide show the energy side.
FAQ
What is the standard spacing between street light poles?
About 3 to 3.5 times the mounting height for LED luminaires: 24–28 m for 8 m poles, 30–35 m for 10 m poles. The lighting calculation decides the final figure.
How high should a street light pole be for a 7 m road?
For a single row of poles, about 7–8 m mounting height. A staggered layout can use 6 m poles.
Single-sided or both sides?
Single-sided when the road width is up to the mounting height; staggered up to about 1.5 times; opposite above that.
Does pole height include the foundation?
No. Mounting height is from the road surface to the luminaire. Pole length adds the part below ground or the base flange arrangement, which depends on the foundation design.
How we help
Our steel poles are formed in lengths up to 15 m, with arms and flanges to your drawing. Send us the road width, layout and lighting class, and we will propose the pole height, spacing and luminaire with a calculation.
Sources: CJJ 45-2015 Standard for lighting design of urban road, Table 6.1.2 and clauses on overhang and tilt; EN 13201-2 and CIE 115 lighting classes. The table by road width and the solar spacing example are our own engineering guidance. Related: high-mast lighting, LED street lights.