Projects / Programmes
Influence of road surface unneveness on accuracy of bridge weigh-in-motion results
| Code |
Science |
Field |
Subfield |
| 2.01.03 |
Engineering sciences and technologies |
Civil engineering |
Constructions in civil engineering |
| Code |
Science |
Field |
| T220 |
Technological sciences |
Civil engineering, hydraulic engineering, offshore technology, soil mechanics |
| Code |
Science |
Field |
| 2.01 |
Engineering and Technology |
Civil engineering |
weigh-in-motion, vehicle-bridge interaction, road surface unneveness, dynamic loading of bridges
Researchers (1)
| no. |
Code |
Name and surname |
Research area |
Role |
Period |
No. of publicationsNo. of publications |
| 1. |
27532 |
PhD Maja Kreslin |
Civil engineering |
Head |
2016 - 2017 |
162 |
Organisations (1)
Abstract
Prediction of traffic loads on bridges is a challenging task, because they vary with time and location. Development of weigh-in-motion (WIM) technology has mitigated this issue as WIM systems acquire reliable and unbiased data of all heavy duty vehicles in free-flow traffic (axle loads and spacings, gross weights, velocities…). These data are vital for many applications related to effective traffic and road infrastructure management (traffic studies, preselection of the overloaded vehicles, pavement design, assessment of realistic structural safety of bridges …). In general, two different types of WIM installations can be found, pavement WIM systems and bridge WIM systems. Both measure the dynamic response of the supporting structures (pavements or bridges) and attempt to calculate the best approximation of the static axle loads and gross weights of the crossing vehicles.
ZAG has been, in cooperation with industry, developing bridge WIM systems for over 25 years. These products are not only used in Slovenia but also in around 20 other countries around the world. A mayor advantage of bridge WIM systems compared to their pavement versions is that they are portable (can be moved from one location to the other) and are installed and maintained without traffic interruption and without damaging the pavement. However, these systems require a bridge, which, if available, is often sensitive to environmental influences. The key factor is unevenness of road surface that causes unpredictable dynamic vehicle-bridge interaction. This is a major issue when trying to calculate the best possible approximation to the static weights of the vehicles. While with the pavement systems this can be avoided by installing the systems only into smooth road sections, bridges typically come with imperfections of road surface before and after the bridge that cannot be avoided.
The influence of road surface unevenness on vehicle-bridge interaction is a complex problem. In literature, this problem is known but no solution exists that would efficiently improve accuracy of bridge WIM results on sites with bad pavement. Therefore, the main objective of this proposal is to develop a simple, yet sufficiently accurate procedure that will efficiently mitigate the effect of road surface profile in bridge WIM results. Achieving this goal will require using existing information, experience in mathematical modelling and parametric studies and, vitally, detailed knowledge about installation, operation and use of bridge WIM systems. These are preconditions that the project results will be implemented in practice. All research results will be verified by measurements on test sites, initially with selected test vehicles and, in final stages, with random vehicles from the traffic flow which axle loads will be confirmed with static scales.
It is expected that results will considerably improve accuracy, reliability and usability of bridge WIM systems as they will be less sensitive to the smoothness of the road surface. This is today the main reason that customers, despite the many other advantages (portability, accuracy of smooth running surfaces, no need to stop traffic ...), prefer pavement WIM over bridge WIM systems. WIM market is in recent years expanding, also due to the single European transport policy. If the Slovenian bridge WIM industry could satisfy 10-20% of the world needs for WIM this would have extraordinary economic benefits. Solving the problem will also contribute to better understanding of the behaviour of bridge structures, particularly the dynamic effects of traffic on the bridges, which is today generally overestimated. This will allow solving problems associated with old and damaged bridges in a far more optimal way, in terms of financing, infrastructure users and the environment. All this will reduce costs of infrastructure maintenance and the related indirect costs of industry and users which is estimated in Millions of Euros in Slovenia alone.
Significance for science
Weighing of vehicles in motion (Weigh-in-motion or WIM) is today a key technology in many fields related to effective management of traffic and road infrastructure. Some typical examples of deployment of WIM data are: development of site-specific traffic load models used to calculate realistic safety of bridges, prescription of remedial measures for pavements, analysis of freight traffic flows, preselection of overloaded vehicles that jeopardise traffic safety and result in unfair competition with respect to those who respect the rules. WIM topic was included into numerous international projects, with notable contribution of Slovenian researchers. Its relevance can be demonstrated through a number of papers in scientific journals and at conferences. Every four years ISWIM, the International Society for Weigh-in-Motion, organises an international conference on WIM, which spread the knowledge about WIM technologies and applications of WIM data. The fact is that only WIM technologies can provide realistic and reliable data on traffic loads. All pavement and bridge WIM systems measure the dynamic response of structures (roadways or bridges) in order to calculate the best estimates of the static axle loads and gross weight of the vehicles. As with other measurements, accuracy of results depends on various factors. Unevenness of the road surface, which is directly related to the dynamic interaction between the vehicle and the bridge, is just one of them and has been discussed in detail within the framework of this research project. The problem in complex, but has been successfully resolved . Based on the results and new knowledge accumualted within the project, we are and will be able to significantly contribute to a) modeling of such problems, b) understanding the influence of road surface unevenness on the dynamic loading of bridges, and c) further development and competitiveness of bridge WIM systems.
Significance for the country
The Slovenian bridge WIM (weigh-in-motion system) system (SiWIM®) is the only commercially available bridge WIM (B-WIM) in the world that already gained significant reputation among the users. However, despite being used in over 20 countries worldwide it still has not achieved appreciation that it deserves due to its flexibility and high accuracy of results under »ideal« conditions. One of the main obstacles is the road wearing course which surface is almost never smooth. Through research in the framework of the project, the manufacturer got new knowledge about the influence of road surface unevenness on accuracy of bridge weigh-in-motion results, which he will be able to use for marketing of the SiWIM® which will promote Slovene achievements. The existing bridge WIM system is the result of collaborations with various research institutions in the context of national and EU projects (COST323, WAVE, SAMARIS, ARCHES, BRIDGEMON, and TRIMM) and within the International Society for WIM. Long-term cooperation has been established with the University College Dublin and Trinity College Dublin, where the authors of the most advanced theoretical bridge WIM studies in recent years come from. Other important partners in this field are the French national infrastructure institute IFSTTAR and University of Santa Catharina from Brazil. ZAG’s research and implementation activities related to bridge WIM are presented regularly at international conferences and as lectures at universities and ministries (Brasil, Sweden, Oman, India, Belgium, OECD..). Results and knowledge obtained within this research project will allow to strengthen active coopertion with Slovenian and foreign institutions.
Most important scientific results
Interim report,
final report
Most important socioeconomically and culturally relevant results
Interim report,
final report
