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PSP Weigh-in-Motion Systems for Bridges

PSP Lead Image

PSP develops the bridge weigh-in-motion (iBWIM) system, which measures the load on bridges when traffic passes over them.

The cost-efficient iBWIM uses the bridge as a weighing platform with three main purposes, namely recording the statistical data of heavy goods vehicles (HGV), bridge re-assessment and pre-selection for traffic control.

The system bypasses the issues of alternate sensors, such as traffic counters and web-cams, which provide delayed results.

iBWIM identifies overloaded axles and vehicles, as well as assists with the evaluation of bridges to set required measures. It also provides more precise classification of trucks and opportunities to expand vehicle toll categories.

Easy-to-install weight monitoring system for bridges

iBWIM is easily installed underneath bridges, with an additional web-cam deployed beside the road.

Trucks are weighed, analysed and filtered according to legal requirements. An overloaded vehicle is defined if it exceeds a pre-set axle weight or gross vehicle weight (GVW), whereby the gear and axle weight is distinguished.

The results can be sent to a smartphone or any other device, which provides basic information and the expected time span until data can be processed. Results are accurate and vary between +/- 5%.

Weight-in-motion traffic measurements

As soon as a truck crosses a bridge, the iBWIM measures strains and vibrations on lanes in each direction using up to 64 sensors installed underneath the bridge. The sensors are connected in groups of eight with a computer-based ‘spider’ data collector, and synchronised within a bandwidth of 1ms.

The spiders are interconnected via a local network that supplies them with energy. A computer installed in the router pre-analyses the data and then sends it via a global system for mobile (GSM) connection to a local database.

The entire process takes between 1s and 3s, depending on traffic volumes and connection quality. Measurements can be performed at various locations along the road as well as railway network before the data is forwarded to a database and processed further. The final data is sent on request to mobile devices or desktop computers.

Assessment of vehicle measurement data

After the data has been collected, it is analysed by the iBWIM algorithm using raw signal parameters, such as speed, axle spacing and weight. The analysis is combined with data from other sensors and high-speed cameras to obtain a complete picture of the HGV crossing the bridge.

Accurate commercial WIM system for bridges

iBWIM is the first commercial WIM system for bridges to have been successfully established in Austria.

The system records high-quality measurements compared to static weighing processes, and can be used under the toughest environmental conditions.

Enabling the measurement of real traffic loads, iBWIM is a tool that may be used as an additional traffic monitoring system. It records reliable information regarding axle loads, load patterns, road surfaces and bridges.

Overload data for computer simulations

iBWIM data can be used in computer simulation programmes to simulate a structure’s entire lifecycle. It enables calculation of ageing processes or provision of statements on a structure’s load bearing capacities.

Real-time traffic monitoring

The monitoring system may also be used in real-time operation for traffic monitoring purposes. iBWIM measurements are sent to mobile computers immediately after recording and post-processing.

iBWIM provides ASFINAG with a tool for optimising its maintenance efforts and reducing operational costs.

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Press Release

PSP Introduces the iBWIM Spider 5

PSP has launched the iBWIM Spider 5.

Product and Services
White Papers

Use of BWIM Data for Bridge Assessment

The object of this paper will be to describe the way from Bridge-Weigh-In-Motion (BWIM) data to the assessment of bridge structures under the consideration of the real traffic loading.


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Press Release

7 March 2019

PSP has launched the iBWIM Spider 5.

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5 March 2018

In 2017 and 2018, we developed the SpiderCentral, a new tool that can collect environmental data at iBWIM measurements.

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7 December 2016

During the development of the new iBWIM Spider, PSP also developed a independent measuring system which essentially uses the technology of our Spider but in a flattened way.

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1 September 2016

During the last few months we improved the hardware of our heartpiece, the iBWIM Spider.

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Regional Offices

PSP – Petschacher Software + Project GmbH

Am Hügel 4, A-9560 Feldkirchen


+434276 / 3378

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