Major differences between variable and standard speed signs

Your speed sign while you drive along any road is the typical rectangular signs on the edge of the road that inform about the safe speed on a particular route. The speeds are perfect when the conditions are normal but fail to provide a safe threshold of speed when weather, road work, or traffic conditions deviate from the normal. The speed feedback sign or the variable speed sign comes in handy in such situations. These signs are implemented on a highway or near school zones or other high-volume corridors. They can be programmed and adjusted by authorities as per the current conditions from a remote location.

The working of variable speed signs

These speed feedback signs consider operating speed, sight distance, road condition, weather information, traffic volume, and more to post a reasonable speed limit on that particular road. In contrast, your speed sign does post the speed but without taking into account any such parameters. These variable speed signs also have an LED display that can provide more information to the driver than speed. They can inform the user that there is a traffic jam ahead and suggest an alternate route, and they can advise of slippery or wet surfaces due to weather conditions, and more.

Proven benefits of variable speed signs

While your speed sign on the side of the road is easy to manufacture as a simple metal piece with paint on it, they usually need replacement and maintenance. The variable speed feedback signs have a robust cabinet architecture that is fully welded to ensure perfect screen performance, even in the harshest of environments. They also detect the ambient light through probes in the display to adjust the brightness automatically. They are easy to install with a simple plugging that offers network and platform access. They are energy efficient and can also be controlled remotely. They also do not need any maintenance during their years of operation and are usually quite rugged structures.

The adoption of variable speed signs

While the normal signs are seen on every road, your speed signsthat display these latest speed feedback signsare yet to find better adoption across the globe. Using them is to lower the driver’s speed when they reach a problem area to flow the traffic smoothly. This also provides drivers more time to react to the road’s changing conditions and makes the road safer. This helps reduce the occurrence of an accident and also decreases the severity of an accident. They help immensely, but their initial costs are seen as a hindrance to their usage.

The control algorithm

The brain behind these speed feedback signs is their control algorithms. This algorithm decides what your speed sign shows on a particular day as per a variety of conditions. The algorithm fulfills the purpose of a variable speed limit system by increasing safety and efficiency and decreasing environmental impacts. While most of the algorithms are based on a fixed threshold as per the law of the land or allow only advisory speed as per the flow of traffic. Research papers show that they can be manufactured for a great level of complexity. Some of them can even provide algorithms to manage traffic in an area microscopically.

The purpose of using these variable speed feedback signs and their design differ widely. The results of these characteristics and design will have a direct result on the traffic performance as per your speed sign and the data they capture. Performance indicators like traffic efficiency, traffic safety, and environmental impact are some of the most favored to create these traffic management algorithms. One should specify the system’s purpose to ensure the proper algorithm for a variable speed sign. This input should be easy to measure, affect current traffic conditions, and be able to reflect the speed limit changes while being easy to interpret.

Types of speed limit systems

Other than your speed sign that does not interact, these variable speed feedback signs have two main types of approaches to handle the traffic. The first one is a simple method to increase safety by reducing the speed in an area. This reduces the accident incidence to go down and decreases the probability of any further secondary incidents. The second type of signs is the homogenization systems that prevent a traffic breakdown by only slightly reducing the speeds. This allows the traffic to flow at close to capacity while avoiding unstable traffic conditions.

Types of algorithms

Depending upon the type of your speed sign, four types of control algorithms are commonly used. These algorithms decide what your variable speed feedback sign will control. The algorithms are rule-based, fuzzy-logic, analytical, and control theory. The simplest is the rule-based ones that have preset thresholds to identify situations. The fuzzy-logic decides as per a set of rules and measured inputs to decide a road’s reasonable speed. In comparison, analysts calculate the traffic based on a measured reality. The control-theory algorithm is the optimal strategy that works through local feedback loops to use model predictive controls.

What works?

When tested with any of your speed signs under laboratory conditions and simulations, all of these algorithms work well. But the costs involved and a general reluctance of bureaucracy to change their way of working are the major hurdle in using and installing any variable speed feedback signs. Their usage globally has proven to reduce incidents and homogenization of the traffic that solves bottlenecks, congestions and provides higher mean speeds. The usage of these signs provides peace of mind to the driver who is more likely to comply with legal speed limits, and a uniform flow of traffic brings down the pollution in an area.

About RJ Frometa

Head Honcho, Editor in Chief and writer here on VENTS. I don't like walking on the beach, but I love playing the guitar and geeking out about music. I am also a movie maniac and 6 hours sleeper.

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