Traffic sign base plate aluminum plate selection

Why the traffic sign base plate should be “according to the material policy”?

In the average daily traffic of more than 100,000 vehicles on provincial highways, a sign due to improper choice of material base plate may be structural deformation within 3 years; and in the coastal typhoon prone areas, ordinary pure aluminum signage often survive less than 5 years will appear corrosion perforation. As the key infrastructure of traffic safety system, the material selection of traffic sign base plate is directly related to the safety of public property and maintenance cost. This article is based on GB/T 3190-2008 “Aluminum Alloy Plate and Strip” standard, combined with 120+ engineering project cases, to reveal the underlying logic of scientific selection for you.

A. Sign base plate aluminum alloy selection technology matrix

1. Comparison of basic material properties

Alloy grade Tensile strength (MPa) Elongation (%) Density (g/cm³) Applicable scene Reference price (yuan/ton)

1060 55-165 1-35 2.7 Small city sign 12,000-15,000

6061-T6 100-150 8-12 2.7 Highway signposts 18,000-22,000

6063-T5 80-120 5-10 2.7 Tollbooth ETC Signs 16,000-19,000

7075-T6 250-320 4-5 2.8 Cross-sea bridge warning signs 35,000-42,000

Technical Note: The crystal structure of pure aluminum plate (1060) is poorly dense and susceptible to inter-crystalline corrosion when exposed to ultraviolet light for a long period of time.

6061-T6 achieves strength enhancement through T6 heat treatment (solid solution + aging), and elongation remains standard for industrial grade applications.

7075 alloy contains zinc and magnesium elements, suitable for extreme corrosive environments but poor welding performance.

B. Size specifications and thickness design specifications

1. Highway sign board size matching principle

Triangle ban signs: 450 × 450mm → Selected 4 × 8ft aluminum plate cutting

Rectangular directional signs: 600 × 800mm → standard 4 × 8ft sheet optimal utilization rate

Octagonal warning sign: 800 × 800mm → need to customize shaped cutting (loss rate ≤ 15%)

2. Thickness grading standard

Application Grade Minimum Thickness (mm) Recommended Thickness (mm) Design Basis

Rural road 1.2 1.5 JTG D81-2017 Design specification for highway safety facilities

First-class highway 1.5 2.0 GB 5768-2017 road traffic signs and markings

Highway 2.0 2.5 JTJ 074-2019 Design rules for highway traffic safety facilities

Cross-sea bridges 2.5 3.0 ISO 17634-1:2015 Anti-corrosion of offshore structures

C. Anti-corrosion treatment process and life cycle cost

1. Comparison of surface treatment technology

Treatment process Salt spray resistance time (h) UV resistance grade Cost index (1-5★) Applicable environment

Anodizing 96-192 8-10 grade ★★★★☆☆ City road

Fluorocarbon spraying 300-480 12-15 levels ★★★★☆ Highway

Hot-dip zinc coating 1,000-1,500 6-8 levels ★★★☆☆☆ Rural roads

Epoxy resin composite 500-720 9-11 levels ★★★★☆ Industrial parks

2. Full Life Cycle Cost Modeling

Take a single 2.5m² highway signage as an example (with a service life of 8 years):

Item Pure aluminum sheet solution 6061-T6 solution

Material cost ¥2,100 ¥3,400

Maintenance frequency Replacement every 3 years Replacement every 8 years

Coating repair cost ¥800/time -

Total holding cost ¥9,500 ¥7,200

D. Empirical Analysis of Typical Engineering Cases

Case 1: Beijing-Shanghai Expressway Reconstruction and Expansion Project (2020-2022)

Challenge: Average daily traffic volume of 150,000 vehicles, 38% of heavy-duty trucks

Solution:

Adopt 6061-T6 alloy, thickness 2.8mm

Surface fluorocarbon spraying (film thickness 45μm)

Reserved holes for M8 bolts to support modular replacement

Results:

Zero maintenance record for 5 years

Surface discoloration rate <5% (GB/T 1771 standard)

Case 2: Anti-corrosion upgrade of Hainan Island Ring East Highway (2021)

Challenge: 6-8 typhoons per year, salt spray concentration 5,000ppm

Innovative design:

7075-T6 substrate + double-layer composite coating (primer epoxy resin + top coat fluorocarbon)

Three-dimensional reinforcement structure (wind pressure ≥12kN/m²)

Effectiveness:

Weather resistance increased by 300

Service life extended to 12 years