My Cart: 0 item(s)
_2.png "Shadows ReadyTheme")
radarspeedsignblog
Radar Speed Signs: How They Work, How Much They Slow Traffic, and What They Cost
Key Takeaways
- A radar speed sign (also called a driver feedback sign or dynamic speed display) measures the speed of an approaching vehicle with Doppler radar and shows it on an LED display next to the posted limit.
- They work by feedback, not enforcement. Standard radar speed signs do not take pictures or issue tickets, though some models log speed data or add a camera option.
- Texas Transportation Institute measured an 18 percent drop in school-zone speeds (50 mph to 41 mph), and Montana State University found reductions of 5 to 10 percent on rural roads. Manufacturers commonly report reductions of up to 9 mph.
- Prices run from about $2,400 for an 11- or 12-inch solar sign to $8,000 or more for 18-inch displays with data logging, plus $1,200 to $8,500 for a trailer or dolly if you need portability.
- Solar power is standard. A 20- to 50-watt panel keeps the sign running with no wiring, which is why most units install in an afternoon.
What is a radar speed sign?
A radar speed sign is an electronic sign that detects the speed of an oncoming vehicle and displays it in large LED digits, usually beneath a "YOUR SPEED" legend and next to a static or LED speed limit. When a driver exceeds the limit the digits flash, change color, or trigger a "SLOW DOWN" message. You will also hear them called driver feedback signs, dynamic speed display signs (DSDS), speed feedback signs, or "your speed" signs.
The idea is simple: most speeding is inattentive rather than deliberate, and a driver who is shown their own number slows down. Because the sign gives feedback every time, it keeps working at 2 a.m. when no officer is present.
Browse the radar speed signs LED Lighting Solutions carries, including pole-mount and dolly-mount models.
How radar speed signs work
- Detection. A K-band Doppler radar module measures the speed of the nearest approaching vehicle, typically from 300 to 1,000 feet away depending on the model.
- Display. The speed appears in 11- to 18-inch LED digits. Larger digits are legible from farther away and are used on higher-speed roads.
- Response. Above a threshold you set, the sign flashes the digits, switches from green or amber to red, adds a strobe, or shows a message. Many signs cap the display (for example at 20 mph over) so nobody races the sign.
- Power. A solar panel charges a battery pack. Hardwired 120 V and battery-only versions exist for special cases.
- Data. Mid-range and premium models log every vehicle's speed and time, so you can prove a problem exists and measure improvement. Some models upload to the cloud.
How much do radar speed signs slow traffic?
The effect has been measured many times, and the pattern is consistent: the biggest reductions come from the fastest drivers and in the locations where speeding is worst.
| Study | Setting | Result |
|---|---|---|
| Texas Transportation Institute | School zones | Average speed fell 18%, from 50 mph to 41 mph |
| Texas Transportation Institute | Other sites | Reductions averaged about 10% or less depending on the site |
| Western Transportation Institute, Montana State University | Rural highways | Speeds reduced roughly 5 to 10% |
| Manufacturer field data (Carmanah) | Mixed | Reductions of as much as 9 mph |
Sources: Texas Transportation Institute dynamic speed display sign research; Western Transportation Institute; Carmanah Technologies product data. NHTSA's Countermeasures That Work rates speed feedback signs as a proven, low-cost countermeasure.
One honest caveat: on long rural stretches with no other cues, the effect can fade as drivers get used to the sign. Rotating a portable sign between sites every few weeks, or pairing the sign with occasional enforcement, keeps the effect fresh. School zones, where the audience changes daily, do not show the same fade.
Do radar speed signs give tickets or take pictures?
A standard radar speed sign does neither. It has no camera, stores no license plates, and is not connected to any enforcement system. Its job is feedback.
Some models can be ordered with a camera or with data logging that records speeds and times (not identities). Agencies use that data to decide where enforcement or engineering changes are needed. Automated speed enforcement cameras are a separate category of device governed by state law, and LED Lighting Solutions does not sell them.
Choosing the right radar speed sign
| Digit size | Readable from | Best for | Example |
|---|---|---|---|
| 11 to 12 in. | About 400 ft | Neighborhoods, HOAs, campuses, parking areas, 25 to 35 mph | Solar LED radar speed sign EV11, 11-inch Your Speed solar sign |
| 15 in. | About 600 ft | Collector streets and school zones, 35 to 45 mph | Solar LED radar speed sign EV15 |
| 18 in. | 800 ft or more | Arterials, rural highways, work zones, 45 mph and up | Solar LED radar speed sign EV18, SP100 solar radar speed sign |
Then decide on mounting: a permanent pole, a dolly you can roll between sites, or a trailer for work zones and rotating deployments. Portable units are popular with police departments that move a sign in response to complaints.
What radar speed signs cost
| Configuration | Typical price |
|---|---|
| 11- to 12-inch solar pole-mount sign | $2,400 to $3,400 |
| 15-inch solar sign with data logging | $3,000 to $4,000 |
| 18-inch solar sign, full matrix or strobe | $4,000 to $8,000 |
| Add a dolly for portability | $1,200 to $1,400 |
| Add a solar trailer | $5,000 to $8,500 |
LED Lighting Solutions catalog pricing and competing listings, September 2026. Installation extra. Grant programs such as Highway Safety Improvement Program funds and state safe-routes-to-school programs often cover radar speed signs.
Solar power: sizing the panel and getting through winter
Nearly every radar sign sold today is solar, and nearly every complaint about one traces to December. A radar sign draws far more than a flashing stop sign because the display is large and the radar runs continuously, so the panel has to match the region and the duty cycle.
| Display | Sun Belt | Middle latitudes | Northern states |
|---|---|---|---|
| 11 to 12 in. | 20 W panel | 30 to 50 W | 50 W or dual panels |
| 15 in. | 30 W | 50 W | 60 to 90 W |
| 18 in. | 50 W | 60 to 90 W | 90 W plus larger battery |
Guidance for 24-hour operation with adaptive dimming, based on LED Lighting Solutions product configurations. School-hours-only schedules need less.
Four settings keep a sign alive in winter: adaptive dimming at night, detection-triggered display (the sign goes dark between vehicles), scheduled operation for school zones, and a lithium battery, which holds capacity in the cold where lead-acid loses half. Mount the panel facing south, tilted about 45 degrees, with no shade between 9 a.m. and 3 p.m.; a panel extension cable lets it sit above the sign if needed. Prefer a static flashing limit sign instead? See solar flashing speed limit signs.
Frequently Asked Questions
Can radar speed signs give tickets?
No. A standard radar speed sign only displays your speed. It has no camera and is not connected to enforcement. Automated speed cameras are a separate device regulated by state law.
Do radar speed signs take pictures?
Standard models do not. Some can be ordered with an optional camera or with data logging that records speeds and times without identifying vehicles.
How much does a radar speed sign cost?
Solar pole-mount radar speed signs run about $2,400 to $8,000 depending on digit size and features. A dolly adds $1,200 to $1,400 and a trailer $5,000 to $8,500.
How effective are radar speed signs?
Studies show average speed reductions of 5 to 18 percent. Texas Transportation Institute measured an 18 percent drop in school zones, and Montana State University found 5 to 10 percent on rural roads. Effects are largest among the fastest drivers.
Can you buy a radar speed sign for your neighborhood?
Yes. HOAs and private communities buy radar speed signs regularly. On a public street you will need approval from the city or county, which often welcomes a community-funded sign.
How far away does a radar speed sign detect cars?
Typically 300 to 1,000 feet depending on the radar module and vehicle size. Larger 18-inch displays pair with longer-range radar for high-speed roads.
Do radar speed signs work at night?
Yes. LED digits are bright enough to read at night and the sign dims automatically to avoid glare. Solar models store daytime energy to run all night.
What size solar panel does a radar speed sign need?
A 20-watt panel suits a 12-inch sign in sunny southern states. Middle latitudes need 30 to 50 watts, and northern states or 18-inch displays need 50 to 90 watts for 24-hour operation. Adaptive dimming and detection-triggered display cut the requirement substantially.
Can I put a speed limit sign on my property?
On private property, yes. On a public road only the road authority can post a speed limit. A radar speed sign that displays the existing posted limit is usually approved quickly.
Need help choosing? LED Lighting Solutions stocks MUTCD-compliant solar signs, lighting, and work zone equipment and ships from our U.S. warehouse. Contact our team or call for volume pricing.