Those Electronic Speed Limit Signs Can See How Fast You’re Going Without A Camera: Here’s How






It’s up to every driver to maintain a safe speed while on the road, even if there isn’t a speed limit sign anywhere in sight. Electronic speed limit signs help remove any uncertainty, as you immediately get real-time feedback of just how fast you’re going. This system actually works through the use of radar sensors and not traditional traffic radar cameras, which can give you a ticket in one state, with no cops involved.

The radar technology in electric speed limit signs measures a driver’s speed and shows that information as they approach. The system is built directly into the sign itself and the setup is entirely self-contained. This means that both the detection and feedback functions are integrated into the same unit rather than having to rely on any external equipment. Because of this, the sign can continuously monitor approaching traffic and provide instant feedback, usually without interruption.

These electronic speed signs, also known as dynamic speed displays, may also have a flashing alert or warning message when drivers go above the speed limit. Dynamic speed displays are often seen mounted on portable trailers in work zones or installed as permanent signs in areas like school zones, or sharp curves. So instead of relying on law enforcement, the idea is to give drivers immediate information in an effort to raise awareness, and hopefully slow them down if needed.

How speed displays influence driver behavior

According to a study conducted by the Federal Highway Administration (FHWA), the installation of dynamic speed display signs in the U.S. has led to a clear reduction in vehicle speeds. It found that average speeds dropped by about 7 mph after signs were installed, and in some cases there were even more significant changes after the fact. Perhaps the most important finding is that the reductions in speed weren’t temporary and were actually maintained throughout a full year of observation.

The study also found that drivers tended to adjust their speed more consistently when they received immediate feedback from an electronic sign versus a regular limit sign, which may have a red border in some states. The system proved to be so effective that fewer drivers overall traveled at higher speeds where dynamic speed displays were present. This was especially true in locations where speed limits decreased from higher-speed rural highways into more urbanized areas.

Beyond showing that dynamic speed displays can reduce speeds, research conducted by the Kansas University Transportation Center examined why these systems seem more effective than traditional approaches. Earlier attempts to manage speeds using posted limits yielded only minimal results, but when a dynamic speed display system was introduced, speeds decreased as drivers received immediate feedback. This suggests the effectiveness of such devices is not just due to their visibility, but also to their ability to actively encourage driver awareness at the moment it is most needed.





Source link

Leave a Reply

Subscribe to Our Newsletter

Get our latest articles delivered straight to your inbox. No spam, we promise.

Recent Reviews






It’s easy to assume that vehicles all had internal combustion engines until very recently. Gasoline and petrol engines were the standard for decades, after all, so why would early vehicles be any different? In reality, the early days of the automobile era were more varied than you might expect, and even featured a range of electric cars. Yes, despite electric vehicles not truly taking off until the 21st century, the first electric vehicles are much older than you think; drivers in the 1900s were going around town in electric vehicles — and where there are EVs, there are charging stations.

One such station, visible in the image above, was the creation of General Electric. Formally called the mercury arc rectifier, it took alternating current and sent it through vaporized mercury in a glass tube. This converted it into direct current, which powered up the EV’s battery. The woman in the image, who’s charging a Columbia Mark 68 Victrola, is standing at the control panel, which allowed a user to adjust power levels. 

These chargers could be installed everywhere, including homes, businesses, and public parking garages, supporting the electric vehicle boom of the early 20th century. While 21st-century EV chargers have come a long way from where they were, the basic building blocks are all still there, and it’s fascinating to see.

How EV chargers have evolved since the early 20th century

EV charging has changed a lot in some ways — but not in others. At the core of it all is the aforementioned conversion from AC to DC, which still happens when you charge modern EVs at standard charging stations. The difference is that your vehicle’s on-board charger performs the conversion, not the charger. Old EV chargers took between several hours and a day to charge, and current-day units can similarly take a few hours to well over a day from empty, depending on the charger’s speed. Fast chargers, which provide DC directly, can cut this down to around an hour or less.

Old-school and modern EV chargers also differ in how they provide power to the vehicle. Mercury arc rectifiers connected directly to the negative terminal of the lead-acid battery that needed charging. Nowadays, EVs use dedicated charging ports. Battery swapping was also commonplace in the early 1900s, and companies like General Electric tried to cash in by offering to replace drivers’ old, run-down batteries with new ones for a fee. That’s not yet possible with most mainstream EVs, although companies like Stellantis have tried to introduce EV battery swapping with moderate success.

Even if they were unrefined compared to today’s models, early EVs seemed to be on to something. Why, then, did electric cars fail, and how did gasoline end up becoming the predominant power source for vehicles?

What led to the downfall of the original wave of electric cars

EVs were no mere fad in the 1900s and 1910s. According to the 1900 United States census, 1,575 of the 4,192 vehicles sold that year were electric, with the value of these early EVs — $2,873,464 — accounting for more than half of the total market value of $4,899,443. It wasn’t just EVs, either; other sources of propulsion, like steam, were also vying for a foothold in the automobile market. By the 1920s and 1930s, though, these had all been superseded by the internal combustion engine.

One of the major drawbacks of early EVs was the fact that electricity was not yet widely available. Electrical hookups were a rarity outside of major cities, limiting the use of these vehicles. The lead-acid batteries they used also had their fair share of issues. They needed to be inspected, cleaned, and repaired every few days, making them more of an inconvenience than anything. Worse yet, they had poor mileage, and, with chargers possibly out of reach, many likely didn’t want to risk being stranded while out for a drive.

Eventually, price reductions for gas cars and improvements such as electric starters and better reliability prompted buyers and automakers alike to move away from electric rides. Thus, while the best-selling EVs of 2026 show that it’s a good time for EVs, this electric boom plainly isn’t the first of its kind. Early EVs eventually fizzled out, but they still set the stage for our current fascination with electric vehicles.





Source link