Frequently Asked Questions

1. Why should I install a radar speed sign ?

The principal reason is to educate drivers about the speed at which they drive, especially in locations where speed would appear to be consistently excessive. Radar speed signs are proven to be effective traffic calming devices.


The installation of a radar speed sign can help you…

  • Respond to the concerns of local residents who have identified zones where speeding is prevalent
  • Take proactive action to secure specific high risk zones such as schools, bus stops, sharp bends etc…
  • Positively modify driver behaviour by means of education and information and not by repression or threat.
  • Collect the traffic statistics (average speed, maximum speed, traffic density etc.) that will allow you to  identify the zones that require your attention in terms of implementation of additional road improvements or safety measures.
  • Solve a noise problem
  • Take positive action to curb excess speeding without having to resort to costly solutions such as the construction of speed bumps, roundabouts or chicanes.


A radar speed sign helps you meet 3 objectives :

  • Enforce speed limits and positively influence driver behaviour
  • Re-inforce driver awareness. For example, a text such as “WARNING SCHOOL” has the effect of sending a message that renders the driver aware of nearby risk and almost inevitably results in a reduction in speed.
  • Re-focus driver attention by means of instant visual feedback (the radar display is eye-catching and is visible from long distance, vehicule speed as well as warning messages can be programmed to ‘flash/blink’)
2. How effective is a radar speed sign ?

Our customer feedback indicates that there is, in the overwhelming majority of cases, a concrete and tangible reduction in the average speed recorded in the vicinity of an Evolis device. A significant proportion of customers have quantified this reduction as high as 25%.

These positive results are heavily dependent upon the quality of the radar speed sign : In particular the detection range (the distance at which the unit reacts to driver speed)  but also the intensity/clarity of the signs display.


There are 2 principal reasons as to why the presence of a radar speed sign will modify driver behaviour.

  • The first is a deterrent effect.

The mere presence of a radar speed sign instantly triggers driver awareness and the tendency is to slow down immediately ; this applies in particular where the instance of excess speed could be described as ‘moderate’ (0-10mph) ; Such motorists are very often unaware that they are speeding and are not necessarily looking at their speedometer.

According to a study conducted in 2014 by the French government agency CEREMA, the instances of excess speeding are reduced by close to 50% around the presence of a radar speed sign.

For motorists who ARE aware they are speeding, the mere fact that their speed is displayed for all to see can not only trigger a feeling of embarrassment or indeed shame, but can also enhance the realisation that their excess speed is not a trivial matter.

  • The second reason is a fear of enforcement.

Motorists who see a radar speed sign understand that the authorities have installed there it for a reason and are very likely to ask themselves if other more repressive measures are in place nearby (police control or speed camera). In addition, a certain proportion may well consider the possibility that the radar speed sign is in some way directly linked to the police services. Either way, the end result is that motorists will tend to slow down.

3. Is a radar speed sign effective in the long term ?

In a word, yes. Whether it be 2, 3 or 10 years after installation, a radar speed sign has as significant an impact as it had on the first day of use.


As mentioned in the question above ‘How effective is a radar speed sign?’ the visual stimulation that the radar emits has a direct psychological impact on the motorist, albeit for different reasons dependent on the driver. For motorists unaware of their excess speed there is the deterrent effect; for those who are aware there is the ‘fear of the police’ effect.

It is worth noting that a 2 year study conducted by the CEREMA concluded that the removal of a radar speed sign resulted in a return to the speeds recorded before the installation of the sign.

The positive feedback of our customers underlines the long-term impact of our signs, notably those who re-invest in supplementary signs several years after their first investment (over a third of our clients have re-ordered with us after the acquisition of a first Evolis radar speed sign)


To evaluate the effectiveness of a radar speed sign in the long term, it helps to distinguish two driver profiles:

  • Regular users (local residents …) are reminded everyday as to their driving speed. As opposed to what you could term a fixed/classic road sign, the radar speed sign  has not only an instant effect (instant visual feedback) but also a subliminal influence on motorist behaviour (awareness of potentially dangerous driving). Over time, drivers become used to a less aggressive manner of driving and are most likely to maintain this behaviour on a long-term basis.
  • Occasional users (those in transit) will experience the ‘surprise’ effect and will tend to slow down, regardless of when the radar speed sign was installed.
4. How does a radar speed sign combat different kinds of speeding ?

An Evolis radar speed sign automatically adapts its message and presentation according to the speed detected ; this renders it particularly efficient as a means combatting different degrees of speeding.

  • If the recorded speed is between 1 and 10mph over the limit , the speed is displayed in red with the text ‘SLOW DOWN’.
  • Speeds of in excess of 10mph over the limit generates a flashing red display with a stronger message ‘TOO FAST’

Motorists who are driving  in excess of the limit, but only marginally so, are not necessarily aware and the radar speed sign acts as a gentle reminder for them to slow down.

Those who are driving at more than 10mph over the limit present a different scenario and are most likely to be fully aware of what they are doing ; In this case the message received from the radar speed sign will still have the effect of speed reduction. The reasons are likely to be less altruistic and more likely to be linked to ‘fear of the police’ but the end result is the same.

5. Who installs radar speed signs, and where?

Most of our customers are Local Authorities. Anywhere where there are moving vehicles and anywhere where there are risk situations : Towns, Villages, Cities, Schools, Roadworks, Accident black-spots…

That said, we have noted that majority of our radar speed signs are installed in towns of 5000 inhabitants or less ; more often than not this kind of community has a main or trunk road running through it.  A radar speed sign is an extremely cost effective traffic calming device in such an environment.

We also note that more and more local authorities are enforcing a speed limit of 20mph in secluded residential areas. Many such bodies are turning to us to acquire a radar speed sign in order to reinforce this message.

6. How mobile is a radar speed sign ?

The Evolis radar speed sign is an extremely versatile device that can be configured (and moved) to match your requirements.

Permanent use : You can decide to install your sign on a permanent basis at a chosen location. For example, close to a school approach road or a recognised accident blackspot.

Semi permanent use : You can also decide to move your radar speed sign from time to time. (Certain communities share the cost of a radar device with a nearby town or village and move the sign between the two on a regular basis). It is a relatively simple operation to disconnect and reconnect a unit from one existing lamp post to another. In the case of a solar powered unit, you simply move the radar sign with its pole and concrete block OR move the sign and solar panel to a pre-prepared pole and block elsewhere.

Ultra-mobile use : A battery powered radar speed sign can be installed on a tripod ; this affords you a huge deal of flexibility in that it allows you move the device on a day to day basis. For example, a device can be placed close to roadworks during the day and then moved to secure a night-time event such as a concert or market.

7. Where are radar speed signs most commonly installed?

Radar speed signs are extremely versatile and can, by and large, be installed as and where you wish (that said, there are 4 important installation guidelines for you to take note of, see below). They are most commonly installed…

  • At approach roads to towns and villages : The sign acts to remind the motorist that the speed limit has, or is about to, change.
  • In the vicinity of schools and crèches: The Evolis Radar Speed Sign can be programmed so that it displays a specific message but only at certain times of day. (i.e. ‘Caution-School’)
  • Around roadworks
  • Ahead of crossroads, roundabouts or recognised accident blackspots


4 important guidelines for the positioning of a Radar Speed Sign :

  • It must be installed so that it is directed PARALLEL to the direction of the road, and placed so that it on the passenger side of oncoming vehicles.
  • It should be installed, as far as possible, at a right angle to the slope of the road (our devices can be easily angled)
  • The sign must be visible to motorists but not interfere or block existing road signs
  • The bottom of the sign should be positioned at no lower than 8ft from ground level (quite simply, to avoid collisions with pedestrians: especially those who are carrying children on their shoulders!)
8. How does a radar screen sign work ?

The Evolis radar speed sign is equipped with what is known as a ‘Doppler’ radar antenna.

The Doppler antenna emits a magnetic wave which bounces off the first moving vehicle within its range. The wave will echo back to the antenna, which in turn calculates the vehicle speed (the margin of error is 1%) based on the frequency of the returning wave.

The recorded speed is then sent to the radar screen. Speeds are calculated and re-calculated in a fraction of a second but for better visibility the screen display is refreshed on the basis of one update per second.

9. How accurate is the speed displayed by a Radar Speed Sign ?

The accuracy of the speed reading depends on 2 factors.

  • First and foremost, the quality of the Doppler antenna housed within the radar casing
  • Secondly, the display refresh capacity (the ability of the screen to display the recorded speed in real-time).


The Evolis Radar Speed Sign has a detection accuracy of +/-1% & the speed display is refreshed once per second (a quicker refresh rate is possible but counterproductive in that it can easily distract the motorist).

Both the above elements combine to render the EVOLIS an extremely reliable Radar Speed Sign and a simple glance at the speedometer will reassure motorists that they are in communication with a device that is trustworthy and dependable.

10. Is a radar speed sign well accepted by motorists and residents ?

Undoubtedly yes. Radar speed signs are a relatively recent concept but their effectiveness contributes to their overwhelmingly positive image, notably for local residents.

What is perhaps surprising is the observation that Radar speed signs have a high reputation amongst motorists too:  A huge proportion of the occurrences of excess speed are committed by otherwise responsible drivers who simply aren’t aware that they have slipped over the speed limit. A radar speed sign allows for a style of ‘soft’ enforcement;  a gentle reminder  that allows motorists to modify their own speed.

For over 90% of people questioned (study : CEREMA), a radar speed sign is informative, preventive, educational and as such, justified.

11. How to choose your radar speed sign ?

A radar speed sign can only be deemed as effective if there is a proven reduction in vehicle speeds.  The greater the time period that the motorist is in ‘two-way communication’ with the sign; the greater the effect upon his or her behaviour and the greater the chance that speed will be reduced.


So, in order to be effective a radar sign must possess

  • a long detection range
  • a sufficient quality of display that renders it clearly visible from a long distance (number of LEDs, intensity & contrast)

It has to see and it has to be seen. Bear this in mind if you are contemplating the purchase of a radar speed sign.


Models on the market do show huge differences in terms of detection range : some detect at up to 150m, 200m and some (such as the Evolis) at up to 300m…

Certain models available on the market will display speed with 1 or 2 lines of LEDs whereas others (such as the Evolis) will use up to 3 lines ; this represents a colossal difference in terms of quality and visibility of display.


With its long-range detection and vivid, dynamic screen display, the Evolis radar speed sign is a device that will maximize your chances of positively impacting upon driver behaviour.

12. What are the power options for an Evolis radar speed sign?

An Evolis Radar Speed Sign can be powered in one of 4 ways:


The MAINS PACK offers 2 options :

1) Mains electricity : quite simply by plugging or hard wiring the device into the mains electricity network.

2) Street lighting network : A simple connection allows you to use your existing street lights to charge the internal batteries of the radar during lighting hours. When the street lights are turned off, the batteries then supply the power to your radar sign.



3) Solar panel : The sign’s internal batteries are charged by its own solar panel (the solar panel is installed on the same post as the radar sign and connected by means of two furnished cables).



4) External battery charger : the built-in batteries are charged by an external charger (in much the same way as you would use an external  car battery charger).


Regardless of your choice of power source, every Evolis radar speed sign interacts with road users in exactly the same way. The only difference to be aware of is that it is a more complex operation to move a sign connected to the mains electricity supply than for a battery or solar powered unit.

13. What is, and how do you prevent the ‘Race Effect’ ?

During the first few years of their existence, the presence of a radar speed sign proved to have one particular kind of negative side-effect which we termed the ‘Race Effect’ : A tiny proportion of motorists would actually increase their speed around radar signs in order to generate the maximum possible speed reading.


Nowadays, this ‘Race Effect’ can be very easily counteracted and eradicated by the setting of a maximum speed threshold. Your Evolis radar speed sign will quite simply display a blank screen if an on-coming vehicle is approaching at a speed of more than 11mph over the speed limit. Although the speed reading will not be shown, the motorist will still be confronted with the message ‘TOO FAST’.

You can re-configure this factory setting to match your own preferred settings if you wish. For example, you can programme the device so that the blank screen is replaced by a flashing Warning Triangle. Equally, you can modify the ‘blank screen’ threshold from its current level at 11mph etc…

14. Can the Evolis radar speed sign record and store road traffic information ?

Yes, an Evolis radar speed sign gathers road traffic information which it stores in its internal memory.

This data can then be downloaded to your PC for analysis via a USB cable (furnished), via Bluetooth or a GPRS connection. Note : the GPRS option allows long distance, remote internet connection from PC’s/tablets: it does NOT come as standard on our Evolis packs but can be included on demand.


Average speed, maximum speed, vehicle counts and V85 analysis are all recorded by the Evolis radar speed sign and the itegrated software allows you to transform this data into charts and graphs for easy analysis. Please note that this data is collected for traffic travelling in BOTH DIRECTIONS ; this allows you to compare the behaviour of those who see the sign AND those who don’t.

The integrated software also allows you not only to create charts and graphs, but also to export them into PDF format.

15. How do I install an Evolis radar speed sign ?

What generally determines the type of installation is your choice of power supply.


1) In case of solar power, the radar speed sign is usually mounted onto its own dedicated pole which is in turn fixed into to a concrete block. This will support the weight of both the radar and the solar panel but will also allow you to easily move the radar and change its location. You can also prepare a number of ‘pre-holed’ blocks at various locations and this will allow you to move the radar from place to place without having to move the concrete block.


2) For units connected to mains electricity or an existing street light, the sign is invariably installed onto an existing pole. You then, quite simply, plug the device into the circuit. This is a very straightforward operation and fully explained in the User Guide furnished with the Evolis. The waterproof plug connectors you’ll require are also contained in the purchase pack.


3) If the chosen power source is that of external battery charger, the Evolis radar is most often installed onto an easily moved tripod in order to guarantee maximum mobility of the device. (Note, if you opt for this type of power source, the external charger is supplied along with the radar device)

16. How much does it cost to install a radar speed sign ?

Over and above the purchase price of the device, the cost of installing a radar speed sign depends on the choice of power source.

Solar power : The provision of the concrete block and full installation will generally cost between £500 and £1000 depending on the number of devices installed.

Mains supply or Existing street lighting network : Generally speaking this is a less expensive operation, typically costing between £200 and £600 (including the installation of a 30Ma circuit breaker)

Some radar speed sign models (such as the Evolis) are designed so as to be easily installed by your own technical services. This significantly reduces the installation cost.

17. How easy is it to install an Evolis radar speed sign ?

The installation process is surprisingly easy and most certainly within the scope of your average handyman. Unlike certain other models of Radar Speed Sign the Evolis is designed to be installed by 1 person, regardless of the choice of power source.


Solar powered devices are incredibly simple to install. As regards the mains or street light powered models, the electrical connections are similar to those of your towns Christmas decorations.


In addition, there is no need to worry unduly as regards the angle setting of the Evolis Radar Speed Sign; it requires to be set so as to point parallel to the direction of the road and, as far as is possible, at a right angle to the gradient.

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