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Tuesday , 28 May 2024

Weighty Challenges in Weigh in Motion

In a bid to optimise the ever-growing challenges of modern transportation, Weigh in Motion (WIM) technology emerges as a solution to change how vehicles are weighed and monitored on roadways.
Sid Jalan explores the intricacies of this system in India.

Overloaded vehicles pose a significant obstacle for Indian roads, with an estimated 10,000 people killed by overloaded trucks in 2020. Maintaining the weight of these vehicles becomes a pressing requirement for the government, with Weigh-In-Motion systems gaining steam.

In western countries, currently Weigh-in-Motion is actively used for traffic classification and assessing the road’s load bearing capacity for future increase in traffic. In India, we are manufacturing and installing Weigh-in-Motions since 2007, where the technology is actively used for detection of overloaded trucks on National Highways and several State Highways. This system acts as a deterrent in overloading of trucks, as heavy penalties are levied on violators,” states Ashish Bhutani, Managing Director, Ashbee Systems Pvt Ltd.

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The accuracies of Weigh-in-Motion systems completely depends on two major factors a) Quality of installation with proper approach road and pit surround region levels b) Periodic maintenance and servicing of the system. We believe that “A good installation starts with a good civil works” and we ensure that levels around Weigh-in-Motion platforms are at permissible levels and are done under our supervision.

Ashish Bhutani


What is WIM?

Weigh-In-Motion systems consist of an array of sensors that measure various features of moving vehicles. These systems are implemented on flat, smooth, and straight roadways, capturing data such as gross vehicle weight, per-axle weight, axle spacing, and vehicle speed, as vehicles pass over the measurement area. Unlike traditional methods, such as a Static Weigh Bridge and manual inspections, WIM does not require vehicles to stop for measurement – making it highly efficient, especially for trucks.

WIM systems find application on roads and rail tracks, providing valuable data about traffic flow and vehicle statistics. These systems operate under diverse and challenging conditions, necessitating expertise for their implementation, operation, and maintenance. WIM plays a vital role in pavement design (both monitoring and research), bridge design, toll-by-weight systems, facilitating freight movement, and shaping regulations for the transport industry.

Why do we need WIM?

Overloaded vehicles bear a heavy cost, even beyond the loss of life and injuries.

  1. Excess damage to roads – Our roads are designed to handle a specific range of weight for the area covered by any particular vehicle. Without the right reinforcement, overloaded vehicles can cause craters and potholes, which results in increased road maintenance. According to a study, just 10% overloading increases the maintenance cost by Rs 25 lakh per km.
  2. Damage to vehicles – Flouting regulations can lead to multiple risks, including mechanical stress on trucks, transmission failure, impaired braking and steering capabilities, with an increased chance of
    tire blowouts.
  3. This severely raises maintenance costs and downtime.
  4. Environmental impact – A point often overlooked is the higher fuel consumption due to an increased requirement of engine performance. This can spike emissions that are detrimental to the environment and has an indirect impact on the economy, further putting the transportation sector in a bad light.
  5. Damage to vehicles and infrastructure – Weight sensitive infrastructure such as bridges are particularly impacted by overloaded vehicles, especially if there is a tire blowout mid crossing. Overloaded trucks rolling back into other vehicles is another safety concern, with a direct impact on the freight customer if the cargo is not secured correctly.


Implementations in Other Countries

Countries worldwide, including the US, Japan, China, and several European nations, have embraced cutting-edge WIM systems to streamline traffic management, enhance road safety, and gather precise data.

  • Indonesia:

The Indonesian Ministry of Transportation imposed a complete ban on Over Dimension and Overload (ODOL) vehicles from January 1, 2023, to enhance road safety and reduce maintenance expenses. Jasa Marga, an Indonesian highway company, partnered with PT Bia Tekno Solusi to create an automatic vehicle weighing solution. This bridge WIM system incorporates Vidar Smart ANPR cameras (Adaptive Recognition) to detect heavy vehicles and capture license plate images, with a 90% accuracy in the pilot phase. The collected data is then processed to identify the vehicle and determine each wheel’s load. Toll road operators can deny entry to certain vehicles on highways or impose fines for overloading offences, based on the collected data.

  • USA:

In California, the Kistler group provided their WIM system to the infrastructure provider Caltrans, who required an update to their current monitoring system. The aim was to integrate seamlessly with hardware and software systems, with data from the roads reaching their control centre every 30 seconds. This near real-time monitoring allowed for identification of peak times and bottlenecks, providing a blueprint for effective road planning. According to the authorities, there have been no maintenance issues since installation.

What is happening with WIM in India?

India has been ahead of the curve with Weigh-in-Motion technology, something that was introduced years ago. However, the situation seems to have slowed down due to economic factors and a lack
of awareness.

The Indian government has shared that as of February 2022, 467 of 692 toll plazas were equipped with WIM systems. An urgent appeal to install more systems across toll plazas (both old and new) has also been raised in the Rajya Sabha. It was estimated in 2018 that monetary loss due to traffic crashes cost India $58 billion, with overloading being a prime factor. To fulfil the ever-expanding needs, India invited US-based firms for PPPs to develop National Highways in Sept 2022.

Overloaded trucks, carrying materials like cement, tiles, sand, and steel beyond the 9-tonne prescribed limit, are causing cracks, grooves, and other distortions on roads. For instance, the Varanasi Ring Road (Phase 2, pocket 1), a 17-km stretch that opened in October 2021, is already in need of repair due to damage caused by overloaded trucks catering to mining districts in Sonbhadra, Mirzapur, and Bihar.

According to data collected over four months, around 70% of trucks transporting construction material were found to be extremely overloaded, violating the limit. Similar issues of habitual truck overloading are observed on the Chandauli-Prayagraj National Highway, straining roads, bridges, and infrastructure, leading to increased maintenance costs and compromised road safety. State governments, including Kerala and Nagaland, have also reported damages and accidents, prompting the consideration of tighter regulations and stricter punishments for violators under the Motor Vehicles Act.

Bhutani adds, “The Weigh-in-Motions systems comes under regulation of three government bodies namely NHAI, Legal Metrology (Ministry of Consumer Affairs) and BIS. The manufacturers and suppliers need to comply with the technical and functional specifications set by these government bodies. For every new version of product, Model Approvals and Certificates are issued, and new installations and yearly recalibrations also calls for inspection and stamping certificates from legal metrology.”

Additionally, truck drivers in India are often overworked, experience poor health or suffer from impacted vision. However, this is an increasingly complex issue that requires a more permanent solution.

Development and Implementation

According to Bhutani, within Weigh-in-Motion technologies we have graduated from Slow Speed Weigh-in-Motion systems to Medium Speed Weigh-in-Motion systems which can weigh the trucks up to speeds of 50 km/hr. “Going forward with adaptation of Multilane Free Flow and GNSS/GPS based tolling, we are looking forward to manufacture High Speed Weigh-in-Motions which can weigh the trucks up to speeds of 120 km/hr.”

The most widely mentioned technology is Piezo Electric, which is said to be maintenance free, affordable and considered to be environmentally friendly. Along with the implementation of Smart cameras and Virtual WIM, these systems can provide near real-time data for challan issuance and violation enforcement.

“The right approach to implement the Weigh-in-Motion systems is to install the machines when the roads are getting constructed”, adds Bhutani. “It actually takes up negligible civil cost to install, as the road sections need to be casted anyways. The civil and mechanical work can be done hand in hand to install the system. In case when the roads are already constructed, and it is an active highway. We tend to use a less invasive technique where diamond cutters are used to create pit for the installation of the Weigh-in-Motion. Some civil works are required, and the lane can be active in 2-3 weeks depending on site conditions.”

Increasing accuracy and providing reduced downtime for the roads is of essence, with a high-speed capture being key to unlocking the potential of WIM. On-board sensor systems could be potentially installed between the body and chassis, especially for heavy industries, mining, chemicals and infra-aggregate sectors. However, this would require a policy level change from the government.

Bhutani continues, “For the Weigh-in-Motion system to weigh at speeds of 100km/hr and 120 km/hr the accuracies will further compromise. At the high speeds the system has fraction of a second to collect the weight data so the sensor response needs to be super-fast with filters in place to reject noise and process valid weight data to provide accurate readings. We are doing tests and reconfiguring the system to keep the tolerance under +/-10% FSR.”

According to end-use industries, the Highway Toll and Road Safety segment dominates a significant slice of the WIM market. In this context, the request set forth by a Parliamentary Committee to the Ministry of Road Transport and Highways to examine the possibility of charging toll based on weight seems prudent (as opposed to the axle-based toll collection). This initiative, according to discussions by concessioners, would issue automated challans to tackle the deliberate flouting of rules.


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Another development is GNSS tolling – charging road users using the Global Navigation Satellite System (GNSS) sensors that would be fitted inside vehicles.The return on investments of all elements in the project have to ensure, through the effective utilisation of assets. Here comes the importance of an accurate, reliable & redundant weighing system. Many of the existing ones are installed only for the compliance and this will anyway lead to loss.

P V Shreedhar



P V Shreedhar, Vice President, Sales, Essae Digitronics Pvt Ltd says, “GNSS based tolling is the latest development and to a larger extent this will be a viable solution to enable uninterrupted traffic flows. But again, overloading on highways will tend to damage the roads faster and also will certainly invite accidents. How to overcome these challenges by preventing overload – is an issue yet to be resolved.”

What are the challenges with WIM?

Shreedhar adds, “The CAPEX cost of owning these new technologies is high, considering core development in the field of Sensor/Strain gauge/Piezo are mostly happening in Western continent. Adapting similar Technology to India seems like a costly affair but is expected to overcome volumes across the nation since there is a clear vision of MoRTH towards minimal accidents.

“Medium speed WIM’s are to be replaced with High Speed WIM’s in Free flow tolling. Integration of ANPR with HSWIM is a challenge. We have covered more grounds in this domain. From Ministry side, regulations to legally accept HSWIM against Static weighbridge would clear bottlenecks in adapting HSWIM in free flow scenario.

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The installation of WIM and the road condition around the installed WIM are very important for assuring accuracy. Hence, increasing the quality of road around the installed WIM and removing speed breakers will surely enhance the accuracy of weighments. Adopting AI technologies in software will also work in enhancing the accuracy of weighments. .

Varun Kumar Singh


Says, Varun Kumar Singh, Chief Manager- Technical Solutions & Project Engineering, Vaaan Infra Pvt Ltd, “The non-intrusive sensors are prohibitively expensive and are a deterrent to the growth of this industry. The current designs are serving the purpose to a large extent and they should continue to be used till the non-intrusive technologies become affordable and more reliable.


  • Standardisation: Lack of uniformity and standardisation in traffic management solutions and Weigh-In-Motion (WIM) systems hinder global service provision. Different countries and regions use diverse communication network standards and protocols, impacting interoperability. To address this, a common set of protocols for communication and components (sensors and hardware) is needed worldwide to foster the growth of the WIM market.
  • Accuracy: Achieving accuracy in WIM systems has been a persistent challenge. Factors like vehicle braking, acceleration, strong winds, and weather changes can affect reading precision. Weather conditions, such as snow and ice on sensors, also impact consistency. Integrating additional sensors could offer a solution, employing a multi-modal, sensor-fusion approach to enhance accuracy.

One barrier to the WIM market is the high up-front costs of implementation and installation. Gradual decrease in sensor efficacy is another key concern.

“There are a lot of challenges in the electronic hardware designs and installations of these systems. Work is still in progress. Accuracy in a certain band is alright for WIM as this is used more for check weighing for overloaded vehicles (for penalty and road safety). WIM need not be matching the accuracy of a static Weigh Bridge, which are used more for trade.  LIDAR, Quartz Sensors, and AI are currently being tried to generate more accurate and reliable systems for WIM,” adds. Varun Kumar.

But companies are also finding ways to improve accuracy. Says Shreedhar, “We have been developing products for Static and Dynamic applications. Our continuous R&D has led to deeper understanding of hundreds of failure modes, which affects product performance. This enriched product physics has led to continuous improvement in product achieving +/-5% up to speed of 65 kmph which is highest in the Country.”

What is the future, especially with Smart Cities?

Smart cities are driving the demand for efficient, cost-effective, and eco-friendly transportation solutions. Developed and developing nations are heavily investing in smart city initiatives, with WIM systems serving as a valuable component of intelligent traffic management. As smart cities continue to rise, the WIM market is expected to experience accelerated growth.

The future of the WIM market holds various possibilities, as predicted by experts:

  • Advancements in installation methods for increased convenience and cost-effectiveness.
  • Improved integration with other Intelligent Transportation Systems (ITS) for better speed enforcement and environmental measurement capabilities.
  • Enhanced digitalization to enable powerful data collection and processing capabilities.
  • Greater utilisation of Artificial Intelligence (AI), Machine Learning, and Deep Learning technologies instead of relying solely on new sensor developments.
  • Potential modifications to the law, allowing for higher error margins compared to static scales’ requirements.
  • Augmenting WIM systems with additional sensing technologies to gather more detailed vehicular information.
  • Development of automated ticketing systems for streamlined enforcement.
  • Progress in non-intrusive detection methods over the next five years.

Shreedhar sums up , “India being the lead developing country on the Technology-front, has been concerned on Road damages and maintenance for more than a decade now that indirectly increases burden on national fossil fuel requirements with high US dollar dependency. In the recent vision of the Ministry, it is evident that the focus has shifted towards addressing road safety through intelligence built in High-Speed camera, AI, and Deep learning software. In next three years, majority of expressways in India would have achieved controlled accident rates towards achieving Zero-accident Tolerance.

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