Traffic Light Pole Selection: Vertical, Signal Arm and Double-Arm Poles
Traffic light pole selection starts with the intersection layout, signal head weight, mounting height and arm length. A vertical pole carries one signal head, a signal arm pole reaches out over the lane, and a double-arm pole covers opposing approaches from one foundation.
Pole type comparison
| Pole type | Typical use | Mounting height | Arm length | Signal heads |
|---|---|---|---|---|
| Vertical pole | Pedestrian, side-road, school zone | 3-5 m | 0 m | 1-2 |
| Signal arm pole | Single vehicle lane approach | 5-7 m | 3-6 m | 1-3 |
| Double-arm pole | 4-way intersection or two-way coverage | 6-7.5 m | 2 x 3-6 m | 2-6 |
| High-mount pole | Highway, high-speed approach | 7-9 m | 6-12 m | 2-4 |
1. Why the pole type matters
The pole supports the signal head, resists wind load, and positions the signal over the correct lane. Choosing the wrong pole causes clearance problems, visibility issues, and expensive foundation rework. Procurement teams that skip the pole layout step often end up ordering twice: once for the wrong pole, once for the corrected one.
Start with three questions: Where is the signal head positioned relative to the approaching traffic? How many signal heads does the pole carry, and what is the total load? What is the available foundation depth and soil condition? The answers decide whether a vertical pole, a signal arm pole, or a double-arm pole is correct.
2. Vertical signal poles
A vertical pole stands beside the road or on the shoulder and carries one or two signal heads at the top. It is the simplest and least expensive option, and is the right choice for pedestrian crossings, side-road approaches, school zones, parking entrances and similar sites where the signal does not need to overhang the lane.
Typical specs: mounting height 3-5 m, signal head load 10-30 kg, direct-embedded or flange-base foundation, and one signal head, occasionally two for redundancy. Vertical poles are also used as the support for pedestrian push buttons and small countdown timers. Confirm the pole has pre-drilled mounting plates if you intend to attach accessories.
3. Signal arm poles
A signal arm pole carries a horizontal arm that extends over the approaching lane and suspends one or more signal heads directly above the driver line of sight. This is the most common pole for vehicle approaches on urban and suburban roads.
Typical specs: mounting height 5-7 m to the underside of the arm, arm length 3-6 m, signal head load 30-80 kg across multiple heads, flange-base on a concrete foundation, and anti-vibration hardware for wind resonance. Use a signal arm pole when the signal head must hang over the centre of the lane. The arm length is chosen by the lane width and the required horizontal clearance from the kerb.
4. Double-arm poles
A double-arm pole carries two horizontal arms at the same height, usually oriented in opposite directions. It is used at intersections where the same foundation can support signals for both approaches, instead of installing two separate signal arm poles.
Typical specs: mounting height 6-7.5 m, arm length 2 x 3-6 m, total signal head load up to 150 kg, larger flange-base foundation, and often combined with a luminaire arm for street lighting. Double-arm poles reduce foundation count and simplify cable routing, but the foundation must be sized for the combined load. They are popular in retrofit projects where the authority wants to minimise civil works.
5. Height, arm length and signal head load
Height and arm length together determine clearance. The signal head must hang high enough for the largest vehicle expected on the road (typically 4.5-5.5 m vertical clearance) and far enough over the lane that the approaching driver sees it without parallax.
Use this rule of thumb: vertical clearance to the bottom of the signal head at least 5.0 m on urban roads, 5.5 m on truck routes; horizontal clearance from kerb to the signal head at least 0.6 m, ideally 1.0-2.0 m; arm rise (slope upward from pole to tip) 0-5 degrees for visual comfort.
Total signal head load includes the head itself, the mounting hardware, the visor, and any backplate. Wind load on a 300 mm head with backplate can exceed 60 kg equivalent at design wind speed. Always size the pole for the worst case, not the typical case.
6. Foundation, anchor bolts and wind load
The foundation is what holds the pole in place. Common mistakes include shallow foundations, undersized anchor bolts, and missing reinforcement. A signal arm pole with a 6 m arm in a 35 m/s wind zone may need a 1.5 m deep foundation with M30 anchor bolts on a template.
Soil condition matters: soft clay needs a deeper foundation and larger base; sandy soil uses a bell or auger-cast pile; rock uses an anchored base with chemical anchors; pavement uses a flange-base on a pre-cast foundation. Always commission a foundation design from a structural engineer for high-mount or double-arm poles. The supplier foundation drawing is a starting point, not a final design.
7. Material, finish and corrosion protection
Most traffic light poles are hot-dip galvanised steel to ISO 1461 or ASTM A123. For coastal or high-corrosion environments, additional powder coating or epoxy painting extends service life. Aluminium poles are lighter and naturally corrosion-resistant but more expensive and limited to smaller sizes.
Choose the finish by environment: inland dry uses galvanised only; urban moderate pollution uses galvanised plus powder coat; coastal salt air uses galvanised plus epoxy plus paint, or marine-grade aluminium. Confirm the finish is applied after all cutting, drilling and welding. Field cuts on galvanised poles must be touched up with a zinc-rich repair paint to prevent rust at the cut edge.
8. RFQ checklist for pole selection
Send the supplier the intersection layout with pole location, lane positions and approach directions; the signal head schedule (number, size, weight and mounting height per head); the wind zone (low, medium, high or design wind speed in m/s); the soil report or assumed soil class; the local standard (GB, AASHTO, EN, AS/NZS) and any authority-specific clauses; the finish requirement (galvanised, powder coat, paint system); and the foundation preference (direct-embed, flange-base, pre-cast). This lets the supplier return a quotation that includes pole, arm, base plate, anchor bolts, foundation drawing and finish in one package.
Frequently asked questions
What is the difference between a signal arm pole and a double-arm pole?
A signal arm pole carries one horizontal arm with one set of signal heads over a single approach. A double-arm pole carries two arms, usually oriented in opposite directions, so it can serve two approaches from one foundation. Double-arm poles need a larger foundation and higher total load rating.
How tall should a traffic light pole be?
Urban vehicle approaches typically use 5-7 m mounting height to the underside of the signal arm. Highways and high-speed roads use 7-9 m. Pedestrian-only sites can use 3-5 m vertical poles. Always confirm the vertical clearance under the signal head for the largest expected vehicle.
How deep should the foundation be?
Foundation depth depends on pole height, arm length, wind zone and soil condition. A simple 5 m vertical pole in good soil may use a 1.0-1.2 m direct-embed foundation. A 7 m signal arm pole with 6 m arm in 35 m/s wind usually needs a 1.5-2.0 m reinforced concrete pad with M30 anchor bolts.
Do I need a structural engineer for the foundation?
For high-mount or double-arm poles, yes. The supplier foundation drawing is a starting point, but a structural engineer must verify the design for the local soil, wind zone and seismic category. This protects the authority and the public.
What finish should I specify for coastal sites?
Hot-dip galvanising to ISO 1461 plus an epoxy or polyurethane top coat is the typical specification for coastal or salt-air environments. Some authorities specify marine-grade aluminium instead. Both options significantly extend service life compared with galvanising only.
Can I attach a street light to the same pole?
Often yes. Many double-arm poles are designed with an additional short arm for a luminaire. Confirm the pole structural rating covers the combined load before adding lighting, and check the authority policy on shared signal-and-lighting poles.
Relevant GAOQIAO products
These public GAOQIAO catalogue pages are related to the guide. Open them for the representative description, then confirm the latest drawing and configuration before ordering.
- Vertical signal poles3-5 m vertical poles for pedestrian and side-road applications.
- Signal arm poles5-7 m poles with 3-6 m arms for vehicle lane approaches.
- Double-arm signal polesTwo-arm poles for 4-way intersections and corridor projects.
- LED traffic signal heads100mm, 200mm, 300mm and 400mm heads to mount on the pole.