This reference page consolidates the engineering facts that spec writers, highway design consultants and ITS integrators need before drafting a tender clause for a variable speed limit sign: pixel pitch options, legibility and viewing distance, power and communications architecture, mounting logic, and the terminology that keeps a cross-border specification unambiguous. It is written for readers specifying either a real-time dynamic speed limit sign or a fixed-message full matrix display for planned incidents and roadworks, so that every clause traces back to a verifiable product fact.
Everything below is taken from the current product page, so it can be copied straight into a technical annex without reinterpretation. No pricing, no promotion — just the parameters a reviewer needs to check a submittal against.
| Sign size | As per requirement (project-specific) |
|---|---|
| Pixel pitch | P16, P20, P25, P31.25, P33.33 |
| Display type | Two-color full matrix LED display |
| LED color options | Single color or full color |
| Communication ports | RS232 / RS485 / RJ45 / GPRS / 3G etc. |
| Power supply | AC110 / 220V; also AC, DC or solar power |
| Working temperature | −40℃ to +80℃ |
| Message formats | English, Arabic, Spanish, special letter forms; symbols, graphics and animation |
| Partition support | Multiple partitions can display tasks simultaneously |
| Programming | Laptop or mobile phone using Donartech software; wireless Bluetooth communication |
| Construction | Weather-resistant construction, powder coat paint |
| Warranty | 2 years |
How to use this table: treat the twelve rows as the mandatory technical annex. Where the authority's equipment specification is silent, the product allows customization in pixel pitch and sign size, so the value can be fixed by the project rather than by a catalogue.
Most tender disputes start with a word, not a component. Fix the vocabulary first, then cite the framework that governs the corridor, then attach numbers to the clause. The table below maps the three names buyers most often mix up.
| Term | Typical usage | What the clause must cite |
|---|---|---|
| Variable speed limit sign | Regulatory display whose limit value is changed over time to match traffic, weather or incident conditions | The controlling authority, the corridors where values may be varied, who may authorise a change, and the audit trail required for each posted value |
| Dynamic speed limit sign | Often used interchangeably with the above; also used for displays driven by live detection such as radar-triggered advisory values | Whether the posted value is regulatory or advisory, and the detection or control source that drives it |
| VMS / CMS (variable or changeable message sign) | The parent family of full matrix displays used for text, symbols and graphics, of which the speed limit display is one application | The message format, character height required, and the partition or page behaviour expected from the display |
National or state road-authority equipment specifications set the mandatory fields: display size, character height, luminance class and required ingress protection. Cite the authority's own document number in the clause rather than a generic product name, and list the fields it defines as a checklist.
Where the display joins a traffic management centre, the clause should name the interface the centre expects, the fallback behaviour if the link drops, and the local programming method allowed for field staff. This is separate from the display's physical specification.
Gantry vs pole mounting, wind loading, access for maintenance and power availability sit with the local road owner. Record these as project-supplied conditions, and require the supplier to confirm the display enclosure and mounting interface against them.
Use this as a starting sentence, then append the authority's referenced document. Highlighted fragments are the terms that most often cause ambiguity if left unspecified.
These three selectors turn the product's own pitch options into a configuration decision. They are planning guidance: the authority's equipment specification and the project drawings always take precedence over any rule of thumb.
| Pixel pitch | Closest comfortable viewing | Planning band for legible approach | Design note |
|---|---|---|---|
| P16 | ≈ 16 m and beyond | ≈ 16 – 48 m | Finest pitch in the range; best where graphics or finer symbol detail matters |
| P20 | ≈ 20 m and beyond | ≈ 20 – 60 m | Common middle option for urban arterials with mixed approach speeds |
| P25 | ≈ 25 m and beyond | ≈ 25 – 75 m | Balances character sharpness against pixel count on larger display faces |
| P31.25 | ≈ 31 m and beyond | ≈ 31 – 94 m | Suits longer approaches where the driver's first read is well upstream |
| P33.33 | ≈ 33 m and beyond | ≈ 33 – 100 m | Coarsest standard option; least LED count per square metre of display |
Decision: plot the driver's first clear line of sight, the last decision point, and the sign position on the corridor drawing. Choose the smallest pitch that keeps the required character height legible between those two points — going finer than needed increases LED count without adding regulatory value.
| Deployment context | What to size for |
|---|---|
| Single-lane or lane-specific control | A display face aimed at one lane's approach, sized so the legend is legible from that lane's first decision point |
| Two to three-lane arterial | A face wide enough to be read from every controlled lane, or one display per lane where values differ |
| Multi-lane highway / gantry | Gantry-mounted display sized for the full signed width, with access provision for module replacement |
| Temporary or roadworks zone | Enclosure and mounting chosen for repeat deployment, with a power plan that does not depend on a permanent feed |
| Condition | What the clause should record |
|---|---|
| Open sky, sunrise or sunset facing | Highest demand case — state the viewing angle and the authority's required luminance class explicitly |
| Urban shading, tunnels and underpasses | Contrast against a dark background; also record any dimming the operator expects overnight |
| Fog, spray and heavy rain corridors | Where the display sits in the driver's sightline, plus the enclosure sealing requirement |
| Night operation | Whether the operator requires fixed output or an adjustable level, and who controls it |
A speed limit display is only as useful as the path that carries the new value to it. This module shows where the display sits in a traffic control topology and which power route fits which site.
Choose where a permanent, reliable mains feed already exists at the mounting point. Simplest to commission and the least site work, but it fixes the sign to locations with an existing supply.
Choose where the site has a DC distribution or battery-backed system and the design team wants the display on the same electrical architecture as the rest of the roadside equipment.
Choose for remote rural segments and temporary deployments where trenching a mains feed is disproportionate. Low power consumption is the enabling product fact here — size the array against the duty cycle the operator expects.
Choose where field staff must change a message without returning to the control room. Messages are programmed from a laptop or mobile phone, with wireless Bluetooth communication available alongside the wired ports.
Decision: list the ports the control centre already supports before selecting hardware. RS232 and RS485 suit wired cabinet connections, RJ45 suits an existing roadside data network, and GPRS or 3G suits sites with no fixed link — but the fallback behaviour when the link drops should be written into the clause, not assumed.
Match the deployment scenario to the product fact that resolves it, then record the buyer decision that must be closed before the tender is issued.
Product fact: integration with traffic control systems over RS232, RS485, RJ45, GPRS or 3G, with weather-resistant construction for permanent roadside mounting.
Decision to close: who authorises each posted value, and which port the arterial's existing cabinet uses.
Product fact: messages can be changed from a laptop or mobile phone with Donartech software, and multiple partitions can display tasks simultaneously.
Decision to close: whether the reduction is issued from the control centre or by the on-site crew, and how each change is recorded.
Product fact: AC, DC and solar power options, with low power consumption and more uptime.
Decision to close: the duty cycle assumed for the solar sizing, and the maintenance access route to the modules.
Product fact: sign size is quoted as per requirement, with customization in pixel pitch and sign size and modular LED panels.
Decision to close: the drawing revision the quotation is based on, and the mounting interface the road owner will accept.
Product fact: the display supports English, Arabic, Spanish and special letter forms, plus symbols, graphics and animation.
Decision to close: the exact character set required and whether graphics are needed in the same partition as the numeric legend.
Product fact: individual display LED modules can be replaced easily, backed by a 2-year warranty.
Decision to close: the spare module quantity to hold per site and the access method for high-level gantry mounting.
Share the display size, mounting arrangement and the corridor conditions you are specifying. Customization is supported as per your demands and drawings, including size, pixel pitch and mounting solutions, and we will confirm the configuration against your project documents.
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View productthe display is offered in p16, p20, p25, p31.25 and p33.33. a finer pitch suits installations where drivers first read the display from closer and where finer symbols or graphics are wanted; a coarser pitch suits longer approaches where a larger pixel still reads clearly. fix the value against the project's approach geometry and the authority's equipment specification before the clause is issued.
communication ports include rs232, rs485, rj45, gprs and 3g, and wireless bluetooth communication is also supported. rs232 or bluetooth is typically used for local programming from a laptop or mobile phone with donartech software, while rs485, rj45 or a mobile data link connect the display to a wider traffic control system.
ac110/220v mains is the standard supply, and the display is also available with ac, dc or solar power. the choice depends on whether a reliable mains feed already reaches the mounting point, whether the site is battery-backed, or whether the location is off-grid. low power consumption supports longer uptime on solar and battery installations.
yes. size is quoted as per requirement, with customization in pixel pitch and sign size, modular led panels and a choice of mounting options. gantry, pole and structure-specific configurations can be built around the project drawings, which is why the drawing revision should be named in the enquiry.
it uses a two-color full matrix led display with ultra-bright, highly legible leds, and can display english, arabic, spanish and special letter forms, as well as symbols, graphics and animation. multiple partitions can display tasks simultaneously. messages are programmed by laptop or mobile phone with donartech software.
the product carries a 2-year warranty, weather-resistant construction and powder coat paint, and individual display led modules can be replaced easily for faster field maintenance. customization is supported as per your demands and drawings — contact us for details on your specific project.
