Fast Falling Weight Deflectometer and Accelerated Pavement Testing
Accelerated Pavement Testing (APT) has been a valuable tool for innovation and understanding of pavements since the early 1900s. It enables accelerated testing to predict and validate pavement performance. The Fast Falling Weight Deflectometer (FastFWD) offers a solution for in-situ Accelerated Pavement Testing (APT), bridging the gap between the Heavy Vehicle Simulator (HVS) and small-scale laboratory tests.
The FastFWD is specifically designed to apply load pulses to the pavement surface, simulating the load produced by a moving vehicle wheel. It delivers a 5 times faster drop rate compared to the original Falling Weight Deflectometer (FWD).
The Fast Falling Weight Deflectometer (FastFWD) is a 5 times faster per drop version of the original Falling Weight Deflectometer (FWD). The FWD is designed to simulate the load produced by a moving vehicle, while the FastFWD applies load pulses to the pavement surface. The load pulse is measured by a load cell with a resolution of 0.1 kPa, and the pavement response is recorded by up to 15 deflection sensors with a resolution of 0.1μm.
The accompanying post-processing software, Dynatest ELMOD (Evaluation of Layer Moduli and Overlay Design), allows for back-calculating pavement layer moduli based on the impact load and surface deflection basin. These results effectively contribute to evaluating pavement structural conditions and overlay design, using empirical or mechanistic-empirical pavement design guides.
Key features and benefits:
- The Fast Falling Weight Deflectometer (FastFWD) is 5 times faster per drop than the Falling Weight Deflectometer.
- No hydraulic components, reducing maintenance requirements.
- Utilises the same sensor setup and user interface as the Falling Weight Deflectometer.
- Compliant with AASHTO R 32 and the UK Correlation trial.
- Enables 75% more test points per hour or 45% less traffic exposure.
- Lower maintenance costs compared to alternatives.
- Easy operator and service personnel training.
- Consistent data with the Dynatest Model 8002 FWD.
- Upgrade capability from Model 8002 FWD to FastFWD.
Standard Equipment
- Four segmented loading plate with
swivel accommodates uneven or rutted
pavement surfaces - Air/Pavement Temperature Sensors
- Distance Measuring Instrument
(DMI) - On board generator for standalone
operation
Advances
- A single direct drive, 3-phase torque motor and ball screw assembly drives the new system replacing the hydraulic system in FWD
- Very fast—up to 160 test points per hour
- 8002 FWD’s can be upgraded to the new FastFWD Model 8012 system
- Less maintenance costs—no hydraulic system
- Less impact due to reduced survey time
Available Upgrade Options
- Folding trailer for ease of shipment
- Global Positioning System (GPS)
- Camera system for plate location or photo-logging
- Trailer mounted light(s) or strobe(s)
- Rear or Rear & Transverse Sensor Extension Bars
- Ground Penetrating Radar
- Spare parts kit
The use of Falling Weight testing
Data collected from the Dynatest FastFWD can be used for determination of structural capacity of in-service pavements to analyse the physical properties of the pavement. When analysing the data from the Dynatest FastFWD with the ELMOD software, it is possible to obtain information about the condition of the road, such as: surface layers, subgrade layer, layer moduli, layer types, thickness, range of moduli, Poisson’s ratio and bearing capacity.
This information can be used to estimate overlay requirements, remaining life of the pavement, and effective creation of a Pavement Management Plan.