Mianyang Fujiang Bridge LED Lighting | Inclined Arch Bridge Illumination Engineering
Mianyang, Sichuan, China | Urban Infrastructure Bridge Illumination | DMX512 RGBW, on/off 4000K | Completed May 2025 | Client: China Railway 18th Bureau
Project Overview
The Fujiang Bridge in Mianyang Science and Technology City is a twin inclined-arch cable-stayed bridge spanning the Fujiang River — one of central Sichuan’s most prominent urban infrastructure landmarks. Completed in May 2025 for China Railway 18th Bureau, the lighting project required a three-product system covering 2,637 custom bridge barrier lights across the full bridge run, RGBW colour rendering on the twin inclined arches and barrier rails, and RGBW floodlighting at the bridge pier bases, all integrated into the city road management authority’s centralised lighting control platform.
The bridge barrier lighting system — LWW-GRB series three custom specifications, 2,637 units in total — is the engineering centrepiece of this project. These fixtures were not selected from catalogue: they were conceived, prototyped, evaluated through two formal review meetings and one release confirmation, and manufactured to meet the specific optical, structural, and installation requirements of this bridge. The arch and pier systems add RGBW spectacle; the bridge barrier lights deliver the functional illumination that replaces high-mast road lighting entirely.
Key Challenges & TPK Solutions
Six Engineering Problems on One Bridge — How Each Was Solved
Three Pipe Diameters, Three Installation Geometries
The bridge uses two barrier pipe diameters — D108mm on main carriageways and D75mm on inner barriers — each requiring a different fixture body width and clamp geometry. Straight sections, curved approaches, and variable-grade ramps each present a different mounting angle, making a single universal fixture specification impossible.
Three Custom Specifications, One Purpose-Designed Family
TPK developed three distinct LWW-GRB specifications matched to each pipe and location type: LWW-GRB-W70 series (1.2m / 12W, 1,250 units) for main D108mm carriageway straight runs; LWW-GRB-W55 series (1.0m / 12W with bespoke mounting saddle and D75mm steel tube, 912 units) for curved and graded sections; and LWW-GRB-W55-L6 (0.6m / 4W, 475 units) for inner D75mm barriers. All three were developed within the same project cycle from a single need assessment.
Driver Glare at 1.4m Eye Level — the Disqualifying Criterion
Standard LED barrier fixtures at carriageway height (approx. 1.4m from road surface) project light directly into the eyes of drivers in adjacent lanes. Competing products evaluated during the pre-tender phase produced visible glare at this height — a condition the client flagged as an immediate disqualifier. The specification required a demonstrably lower glare output than any alternative.
New-Tooled Lens + Stamped Metal Anti-Glare Shroud + Full Blackout Treatment
TPK invested in a new optical lens mould — not an off-the-shelf lens, but a purpose-tooled design — that reduces yellow-spot glare by 30% while maintaining luminous efficacy. A stamped-metal anti-glare shroud was manufactured to a new die, positioned precisely over the LED array. Both the PCB board and the shroud interior were sprayed black to eliminate secondary reflections. The combined result: overall glare reduction of 30% at 1.4m driver eye level versus the competing specification. Photometric confirmation: all three LWW-GRB variants achieve a 12–13° vertical half-beam angle with 12×106 asymmetric distribution and 0.0% upward light emission.
Mounting Angle Consistency on a Curved, Graded Bridge
The specification required all barrier fixtures to maintain approximately 40° to the road surface — the angle at which the asymmetric optic achieves its designed illumination pattern. On a structure with longitudinal grade changes and horizontal curves, every mounting position presents a slightly different geometry, and no two barrier pipes are in exactly the same orientation.
Purpose-Drilled Pipe Saddles with On-Site Angle Adjustment
The barrier mounting pipes were drilled to a custom template that sets the nominal 40° angle for the prevailing road gradient at each section. The snap-fit clamp system — inserted and locked with a single screwdriver rotation, requiring no pre-drilled alignment holes — allows fine angular adjustment during installation. Each unit was individually set and verified on site. This is the most labour-intensive element of the installation: no two sections were identical, and the adjustment required skilled on-site calibration across the full 2,637-unit run.
Long-Term Weatherproofing Without Glue-Fill Degradation
Conventional bridge barrier lights use potting compound (glue-fill) to seal the LED chamber. In outdoor environments with UV exposure, thermal cycling, and moisture, potting compound degrades — allowing water ingress between the light-emitting surface and the cover lens. Dust and condensation trapped inside the optical chamber progressively reduce luminous output over the fixture’s service life.
Structural Waterproofing — No Potting Compound
The LWW-GRB series uses a structural waterproofing approach: the entire fixture body is sealed at the housing level, eliminating the optical chamber that fills and degrades in conventional designs. The arc-profile housing sheds water and resists dust accumulation. The cover lens uses Bayer 2807 grade transparent PC with >90% transmittance, UV stabilised to <5% yellowing over 5 years. IK10 impact rating ensures the fixture survives accidental impact — a realistic risk on a publicly accessible bridge barrier. Annual lumen depreciation is rated at <5%.
No Drilling on Load-Bearing Steel Arch and Pier Concrete
Both the twin inclined arch ribs and the bridge piers are primary structural elements. The client’s structural engineer prohibited drilling, anchor-bolt penetration, or any direct mechanical fixation to these surfaces across all 1,292 arch wall washer units and pier floodlight units.
Welded Angle-Iron Secondary Structure + Dual Safety Retention
TPK fabricated welded angle-iron secondary mounting frames clamped to arch rib flanges and welded to pre-reserved steel connection plates embedded in the pier concrete. All 1,292 LWW-PZT-W38 arch units and SP-F310A pier units mount to these secondary structures — zero penetration of primary structural elements. Every elevated and below-deck fixture carries a stainless-steel safety lanyard providing redundant retention against vibration-induced loosening.
1km DMX512 Signal Run from Remote Management Platform
The DMX512 control system is housed in the road management authority’s central platform, approximately 1 kilometre from the furthest fixtures on the bridge. Standard DMX512 signal degrades significantly beyond 300m, producing scene errors, colour desynchronisation, and fixture dropout across this run length.
Multi-Stage DMX Signal Extension and Repeater Architecture
TPK deployed a DMX signal extension and amplified repeater architecture distributing the signal across multiple segments, maintaining full integrity across the 1km run. All 1,292 arch wall washers and pier floodlights execute scene transitions and colour programming simultaneously with zero dropout from the single remote control point.
Core Focus
Bridge Lighting That Passes Both the Safety Test and the Aesthetic Test
The LWW-GRB bridge barrier light series was not an available product when this project was specified. It was developed for this project — from need assessment through prototype iterations, ten-plus stakeholder sessions, two formal engineering review meetings, and a product release confirmation — on a timeline from first brief (October 2024) to production-ready (December 2024). The optical, structural, and installation engineering documented here represents that complete development cycle compressed into a single bridge project.
The result replaces high-mast road lighting on the bridge entirely. The LWW-GRB bridge barrier fixtures illuminate two full carriageway lanes from barrier height — photometric data confirms far-lane-edge illuminance of 33.2 lx at the maximum coverage distance — while generating zero upward light emission (confirmed 0.0% upper hemisphere output across all three specifications).
- Three custom specifications, 2,637 bridge barrier lights — LWW-GRB-W70-L12 ×1,250 units, LWW-GRB-W55-L10 ×912 units (with bespoke saddle mount), LWW-GRB-W55-L6 ×475 units — matched to D108mm and D75mm barrier pipe diameters.
- 30% glare reduction — achieved through new-tooled lens, stamped-metal anti-glare shroud, and full blackout treatment of PCB and shroud interior.
- 12–13° vertical / 12×106 asymmetric distribution — 0.0% upward emission across all three variants.
- Structural waterproofing — no potting compound; IK10 impact rating; Bayer 2807 PC lens with <5% yellowing over 5 years; <5% annual lumen depreciation.
- 1,292 RGBW arch wall washers + RGBW pier floodlights — all via zero-penetration welded secondary structures with dual safety retention.
- 1km DMX512 signal integrity — full scene coherence across the complete fixture population from a single remote control point.
What the System Delivers
2,637
Bridge Barrier Lights
−30%
Driver Glare
1km
DMX Signal Run
The Fujiang Bridge project is a complete bridge lighting engineering case: a purpose-developed product family, six distinct installation engineering challenges, three fixture categories, and a control system integrated into municipal infrastructure. For TPK Lighting, this project demonstrates that bridge lighting at this scale is not a product supply exercise — it is an engineering development engagement. The LWW-GRB bridge barrier light family developed for this project — with its custom optical tooling, structural waterproofing architecture, and snap-fit angle-adjustable mounting system — is now available as a catalogue product for comparable bridge and road barrier illumination projects.
LWW-GRB-W70 L12
1.2m · 12W · 4000K · D108 barrier · 1,250 units
LWW-GRB-W55 L10
1.0m · 12W · 4000K · Custom saddle · 912 units
LWW-GRB-W55 L6
0.6m · 4W · 4000K · D75 barrier · 475 units
LWW-PZT-W38
38W · IP67 · RGBW · Arch & barrier rail · 1,292 units
SP-F310A
200W · IP66 · RGBW · 8° lens · Pier base · 82 units
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