Impact of groundwater level on the mechanical response of a flexible pavement structure: a case study at the Torpsbruk test section along county road 126 using Falling Weight Deflectometer

Farhad Salour

Excess moisture presence in pavement unbound layers can result in lower structural stiffness and reduce the service life of road systems. A field study was conducted along the county road 126 near Torpsbruk to investigate the effect of the moisture content on the bearing capacity of a flexible pavement structure and its unbound layers stiffness. The subsurface drainage system of the test road was clogged during a three-month period in summer 2010, raising the groundwater level under pavement structure and therefore increasing the moisture content of the pavement unbound layers. During this period, the groundwater level and the volumetric moisture content of the pavement was continuously monitored using the instrumentations at test site and the structural response of the pavement was evaluated by conducting frequent Falling Weight Deflectometer (FWD) tests with multilevel loads. Using the FWD data, the unbound layers stiffness were back-calculated and their sensitivity to the moisture content and load level were studied. The field measurements showed that the groundwater level can significantly affect the moisture condition of the unbound layers and therefore their stiffness. Both the unbound granular layer and the subgrade showed stress dependent behavior to multilevel FWD loads.



ERPUG 2017

The five year anniversary of  European Road Profile Users' Group (ERPUG) Forum will take place at Ramboll head quarter, Copenhagen, Denmark October 19-20, 2017. 



Vehicle Driver Monitoring: sleepiness and cognitive load

To prevent road crashes it is important to understand driver related contributing factors, which have been suggested to be the critical reason in 94 per cent of crashes. The overall aim of the project Vehicle Driver Monitoring has been to advance the...


Tomas Svensson new director-general

Tomas Svensson was today appointed Director-General of VTI. Tomas has been acting Director-General since January 2017. 


Crash testing bicycles at VTI

For the first time single bicycle crashes have been simulated at the VTI crash safety laboratory.


A case study exploring firefighters’ and municipal officials’ preparedness for electrical vehicles

A VTI-study presents a social perspective on new vehicle technology. It explores the self-reported preparedness of the fire departments (i.e., rescue services) in Sweden’s three largest cities regarding rescue operations involving electrical vehicles (EVs).


Pioneering research on and about bicycles at VTI

Under what circumstances might cyclists lose tyre grip? What actions could then be taken to prevent a crash? VTI is currently developing a theoretical model of the behaviour of bicycle tyres during braking and steering in different situations and on different...


Virtual pedestrians create efficient stations

If more people are to choose sustainable travel, then the public transport stations of the future must be designed so that pedestrians can get where they are going quickly, without congestion or queues. The Swedish Road and Transport Research Institute (VTI)...