Acrylic Sound Barrier STC Ratings: What Grade Do You Need for Highway, Railway or Industrial Noise Walls?
STC (Sound Transmission Class) is the rating that tells you how much noise a transparent noise barrier panel actually blocks. But not every STC number works for every project. This guide explains how to match STC rating to your application, why acrylic is preferred over polycarbonate for noise walls, and what thickness and STC combination RP River People recommends for highways, railways and industrial plants.
STC Rating Quick Reference
| STC Rating | Noise Reduction | Typical Application |
|---|---|---|
| STC 20-25 | Light speech audible | Not recommended for traffic noise |
| STC 25-30 | Loud speech muffled | Industrial boundary walls (low noise) |
| STC 30-35 | Traffic noise reduced 50-60% | Residential highway noise barriers |
| STC 35-40 | Traffic noise reduced 60-70% | Urban highway / railway barriers |
| STC 40+ | High-speed rail / heavy industrial | Railway lines near hospitals / schools |
Why Acrylic Instead of Polycarbonate for Noise Walls?
Both are transparent and both block noise, but for outdoor noise barriers the industry standard is cast acrylic, not polycarbonate:
- Weathering: Acrylic retains optical clarity for 15+ years outdoors. Standard PC yellows in 3-5 years; UV-coated PC costs more and still discolors faster.
- Surface hardness: Acrylic resists graffiti and sand abrasion. PC scratches easily and needs hard coating, which adds cost.
- Density and STC: At equal thickness, acrylic (1.19 g/cm3) and PC (1.20 g/cm3) perform similarly on STC – so weathering wins the choice.
- Cost: Cast acrylic noise wall panels are 15-25% cheaper than coated PC at the same STC rating.
Thickness to STC Match for RP Acrylic Barrier Panels
- 12 mm cast acrylic ≈ STC 28-30
- 15 mm cast acrylic ≈ STC 32-34
- 20 mm cast acrylic ≈ STC 35-38
- 25 mm laminated acrylic ≈ STC 40+
For most highway residential barrier projects, 15-20 mm acrylic is the sweet spot. For railway lines near hospitals or schools, specify 20-25 mm.
Fabrication and Shipping Notes
- RP cuts acrylic barrier panels to your panel drawing, with pre-drilled holes for aluminum posts.
- Panels ship on custom wooden crates; a standard 2 m barrier panel weighs about 60 kg.
- Edge finish: diamond-polished edges reduce glare and improve weather resistance.
- UV-resistant co-extruded acrylic is recommended for projects expected to last 10+ years.
Get a Noise Barrier Quote
Send us your project type (highway, railway, industrial), required STC, panel dimensions and quantity. RIVER PEOPLE PLEXIGLASS (RP) has supplied transparent acrylic noise barrier panels to infrastructure projects in over 80 countries since 1995. Request a noise barrier quote.
Related: Acrylic Noise Barrier Product Page | Noise Barrier Projects
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