Movable Speedhump

Movable Speedhump
Intelligent Traffic Calming

A movable speed hump solves the disadvantages of the current rigid speed humps. The intelligent speed hump.

Disadvantages rigid humps
The application of rigid humps on tracks with buses results in problems with the labour conditions of the busdrivers. But also the passengers experience a large discomfort and time schedules become more difficult to realize.

Emergency vehicles, such as firefighters cope with serious delays due to the rigid humps. Some people even argue that the time delay has more negative effects than the positive effects of the lower speeds.

On top of these disadvantages the neigbourhood will be disturbed due to the sound and vibration issues related to rigid humps.


Intelligent Flexible Hump
To solve these disadvantages a flexible speed hump has been developped. This intelligent hump responds to 95% of the lightweight traffic as a normal hump, which results in effective traffic calming.

For heavyweight vehicles, such as buses and fire fighters, the intelligent speed hump automatically lowers its riding plate. The riding plate bends down, due to the weight of the vehicle.

The good news is that this is possible with a simple, reliable and robust construction. There is no complicated equipment such as sensors or hydraulics.

Low Maintenance
The intelligent speed hump is maintenance free for a period of 7 years. At this moment (march 2010) about 80 intelligent humps have been installed since 2005, mainly in the Netherlands. There is also a refence project in Kopenhagen and there is serious interest from Europe and the rest of the world.

Construction
The intelligent speed hump mainly consists out of a concrete base, some rubber elements and a steel riding plate with a grit layer. The grit layer is a proven system, which has been installed on thousands of bridges in various countries. The simple and patented concept has proven itself as a reliable quality product. From our experience we can expect a maintenance free lifetime of 7 years. After this period, some rubber elements need to be replaced.

Effect on speed
The achieved effect on measured speeds is obviously a crucial factor. The graph represents an independent speed measurement in Rotterdam. The after measurements were performed 2 months after placement so that the measurements were performed on the stable situation.

The graph shows an important reduction in speeds. The V85 limit has dropped from 42 to 32 km/h. The measurements are based on a mix of lightweight and heavyweight vehicles.

Speed reduction is based on a number of principles. The visual effect is obvious and causes drivers to slow down. Secondly, speeding results in unwanted discomfort for the driver of the lightweigt vehicle, so that he will adapt his speed the next time. For larger and heavy weight vehicles the speed reduction is based on a narrowing effect and due to the fact that other lightweight vehicles will slow down.


Buses will experience a slight discomfort, which will also force them to slow down. The end result is that 85% of the drivers have adjusted their speeds as designed.

In Zeddam (NL) we even placed a version with a design speed of 25 km/h, without disturbing buses and emergency vehicles.

Various design speeds are available: 25, 30, 40, 50 en 60 km/h

Livable Neighbourhood

Conventional rigid humps often result in complaints from citizens. These complaints are caused by heavy traffic that bounces over the humps, resulting in sound and vibrations. Especially when the distance between the hump and the houses are short. With the intelligent speed hump the heavy weight vehicles drive over a flat surface, thus avoiding peak noises and vibrations. A smart, double acting rubber damping system ensures a smooth passage.

The intelligent speed hump easily fullfills the sound requirements as specified by various laws. Due to optimizations, we can avoid peak noises inside and outside houses for all frequency bands.

The lower speeds result in a feeling of safety without the irritation of peak sounds and vibrations.


Specifications
1- The discomfort values for the bus driver are in accordance with ISO 2631-1. See also the graph with the comparison of a rigid hump.

2- Soundmeasurements easily comply with requirements as set by laws, such as equivalent sound values. But also peak noises, as measured inside and outside houses do not give rise to sound related complaints.

3- Vibration measurements comply with the Dutch regulations SBR-A and SBR-B. These regulations set limits to vibration levels to avoid damage to houses (SBR-A) and to avoid inconvenience (SBR-B) due to vibrations. For other countries similar regulations sometimes exist. It implies that the intelligent speed hump performs much better than rigid speed humps and can be widely applied. In case of doubt, consult our expert.



Technical background
The intelligent speed hump mainly consists of a concrete base, some rubber elements and a steel riding plate with a grit layer. The riding plate can be described as a large steel leafspring which works similar to the leafsprings of trucks.

Lightweight traffic will have to take the full height of the hump, as the riding plate will hardly bend down, for this lightweight vehicles. Heavyweight traffic starting from about 10 tons will cause the riding plate to bend down. With 5 tons per axle, the riding plate is fully flat, so no height at all. For buses, with a front axle load of about 3.5 tons, there is still a small height of about 2 cm to overcome. As soon as the heavyweight vehicle enters the intelligent hump, the riding plate moves down immediately.

The height of the riding plate will maintain constant after many passages of heavy traffic. The stresses in the steel plate, maintain well below the elastic limit, so that the steel will come back in place all the time.



Self cleaning
As the riding plate is being pushed down on a regular basis, the air underneath will be blown away on a regular basis. The moving air cleans the unit automatically. There is no need for cleaning at all.

Installation

The simple installation process takes place in a number of steps. Create a rectangular hole in the road surface. Create a nice flat layer of stabilized sand. Placement of the element is done by TTS, directly from the truck to the sandbed. Fill the joints with flexible material as commonly used in road building.

The only maintenance required is the replacement of some rubber elements after 7 years. After about 14 years the grit layer needs to be replaced.

The intelligent speed hump is available for various design speeds (V85) 25, 30, 40, 50 en 60 km/h. Available widths are 2.75, 3.00, 3.25 en 3.5 meter. for every lane in principle one element is required. The unit can also be placed in the centre of the road with vehicles passing in two directions.

The intelligent speed hump is an effective traffic calmer without the disadvantages for buses, emergency vehicles and without the complaints of citizens.