Last updated: 25 June 2026 | Reading time: ~8 minutes | By GAOQIAO Traffic Engineering Team
Choosing the right LED traffic light size is one of the first decisions a project buyer, traffic engineer or municipal procurement officer must make. Diameter affects visibility, cost, structural loading and regulatory compliance. This guide walks through the four common sizes GAOQIAO manufactures, the viewing distances they support, and the application scenarios where each one is the correct fit.
GAOQIAO manufactures signal heads in the four sizes most commonly specified by international road authorities. Each diameter maps to a viewing distance range and an application category:
These sizes are also the categories that appear throughout our LED traffic light product catalog, so the engineering specifications and certifications referenced in this guide apply to the full range we supply for export.
| Diameter | Typical Viewing Distance | Common Use | Relative Cost per Aspect |
|---|---|---|---|
| 100mm (4") | Up to 50m | Parking gates, dock bays, warehouse lanes | Low |
| 200mm (8") | 50-150m | Residential streets, low-speed intersections | Medium-low |
| 300mm (12") | 150-300m | Urban arterials, standard intersections, highways | Medium |
| 400-500mm (16-20") | 300m+ | Highways, high-speed arterials, fog-prone corridors | High |
Note: viewing distance is highly dependent on the LED lens optical design, the anti-glare hood and ambient conditions. The numbers above are typical industry values for reference only — always confirm with the optical test report shipped with the product.
Use 100mm LED traffic lights where space is constrained and vehicle speed is low. Typical projects include factory entry gates, loading dock bays, parking access lanes, mining haul road crossings and warehouse internal traffic. The smaller diameter reduces wind load on short poles and keeps hardware cost low. For these scenarios, see our 4-inch LED traffic light series.
200mm signal heads are well matched to residential streets, school zones and small intersections where posted speed limits are 50 km/h or less. They are also widely used for pedestrian signals, lane-control signals and reversible lane indicators. Browse the 8-inch LED traffic light range for available aspects and mounting options.
For most urban and suburban road projects, 300mm is the de-facto industry standard. National road authorities in the United States (MUTCD), the European Union (EN 12368), China (GB 14887) and many other jurisdictions accept 300mm as the default diameter for general-purpose vehicle signals. The flagship 12-inch LED traffic light line is the most exported size from GAOQIAO and is available in 1-aspect, 2-aspect, 3-aspect and 4-aspect configurations with optional countdown timers.
Larger diameters are reserved for high-speed arterials (typically above 80 km/h), highways, multi-lane corridors and locations with poor visibility conditions such as fog, sun glare behind the signal or unusual background clutter. The 16-20-inch LED traffic light series is engineered for these demanding conditions and ships with reinforced optical lenses.
Before finalizing the size, confirm the applicable national or regional standard. Common references include:
If your project is exported, also check whether the receiving country's regulator requires type approval or third-party certification. GAOQIAO products carry CE, RoHS, FCC and IP65/IP67 certifications, and full type-approval documentation can be supplied per project.
Diameter influences more than the unit price. Larger signal heads add wind load to the supporting structure, may require heavier poles or upgraded foundations, and increase shipping volume. For a 4-aspect 300mm assembly versus a 4-aspect 200mm assembly, expect roughly 30-50% more weight and a comparable increase in pole foundation cost. Always include the structural cost when comparing diameters — the cheapest signal head is not always the cheapest installed solution.
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For most urban and suburban intersections, 300mm (12-inch) LED traffic lights are the industry standard. They offer a viewing distance of 200-300 meters and are accepted by road authorities in the Americas, Europe, the Middle East, Africa and most of Asia.
100mm (4-inch) signals are used for compact applications like parking access control, dock bays, low-speed industrial yards and warehouse loading zones. 200mm (8-inch) signals suit short to medium viewing distance applications including residential streets and small intersections with speed limits under 50 km/h.
Larger 400-500mm signals are typically required on highways, high-speed arterials (above 80 km/h) and intersections where longer viewing distance or special visibility conditions (fog, sun glare, wide multi-lane roads) demand higher conspicuity. Always confirm with your local road authority's standard before procurement.
Yes. We support OEM/ODM manufacturing for non-standard diameters and aspect counts. Custom optical designs, pole mounting brackets and cabling are quoted per project. Reach out via our cooperation page for a project-specific discussion.
About GAOQIAO — Nanjing Gaoqiao Traffic Technology Co., Ltd. is a Chinese LED traffic light manufacturer with 17+ years of export experience. Our products are deployed in 60+ countries across the Americas, Europe, the Middle East, Africa and Southeast Asia. View our about page or browse the traffic light controller catalog for the matching control system.