Pavement Engineering Services

GN Northern provides pavement engineering services and has several years of demonstrated experience with many satisfied clients. GN Northern specializes in solving complex pavement engineering problems and offers high standards of quality pavement engineering and field testing services. We have an outstanding record for on-time and high-quality work.

As part of the haul roads pavement evaluation study, a construction traffic analysis is performed to determine the frequency of the different truck loads based on the estimated operational truck traffic. This includes estimated frequency and weight of each type of truck on each section of the haul routes. This information is then used to analyze the structural integrity of the haul routes based on the maximum truck frequency and weights.

Based on the results of field testing, laboratory testing and traffic analyses, analysis is conducted to determine the Remaining Service Life (RSL) of current pavement structures. Recommendations are presented for the improvements of the haul routes (overlay) to support the loads using the 1993 AASHTO Pavement Design Guide. SpectraPave 2 model is used to determine the thickness of aggregate layer to support the forecasted construction traffic loads.

The scope of pavement engineering and testing services include:

  • Pavement Evaluation
  • Rigid (Concrete) Pavement Design
  • Flexible (Asphalt) Pavement Design
  • Falling Weight Deflectometer Test
  • Pavement Coring
  • Ground Penetrating Radar (GPR)
  • Subgrade Improvement Techniques
  • Asphalt Pavement QC Testing
  • Aggregate Surfaced Road Design
  • Traffic Analysis
  • Laboratory CBR Testing
  • Video Recording
  • Soil Stabilization & Geosynthetics
  • Dynamic Cone Penetrometer Test
  • Life Cycle Cost Analysis
  • Pavement Condition Index Survey

Falling Weight Deflectometer Test

Falling Weight Deflectometer (FWD) test is a standard test widely used in pavement engineering to assess structural condition and analyze truck load carrying capacity of flexible and rigid pavements. The test is used to readily obtain in-situ characterization of multiple pavement layer stiffness. It is a non-destructive test using a non-intrusive device that applies dynamic loads to the pavement surfaces similar in magnitude and duration to that of a single heavy moving wheel load. The process calculates the elastic modulus of individual layers in a multilayer system (e.g. asphalt concrete on top of a base course on top of the subgrade) based on surface deflection reacting to testing loads. FWD testing is performed at 1/10th mile intervals in one traveling direction on each selected roads using the standard 7 sensor Strategic Highway Research Program (SHRP) spacing using 6,000 and 9,000 pounds forces. FWD testing locations are recorded using GPS coordinates.

Ground Penetrating Radar (GPR)

Ground Penetrating Radar GPR unit is used to obtain pavement thickness data. The GPR unit collects the pavement thicknesses data in a non-destructive manner operating at highway speeds and at any length or time interval. Geo-reference data is processed continuously and simultaneously and is automated and integrated with the GPR data collection process with a +/-1 meter accuracy. The GPR method identifies the exact location of any changes in the asphalt and subbase thicknesses and provides a uniform band of thickness data. The data is acquired and stored by the GPR Software. This method reduces the amount of saw/drill cutting cores into the existing pavement. 

Pavement Coring to determine Thickness

Cutting and obtaining core per roadway section depending on the overall length of the section

Video Recording

Video recordings are conducted to document a visual record of conditions of the pavement surfaces of existing roads for pre- and post-construction. Continuous video recording are performed in one traveling direction for the entire length on each road. The speed of travel is maintained as such to observe and ascertain the general conditions of the road while viewing the video with date stamp for pre- and post-construction monitoring.

GN Northern has completed haul roads studies for the following projects:

  1. Desert Claim Wind Farm haul roads study, Kittitas County, Washington; for enXco Development Corporation.
  2. Miller Ranch Wind Energy Project haul roads study, Klickitat County, Washington; for enXco Development Corporation.
  3. Juniper Canyon Wind Energy Project haul roads study, Klickitat County, Washington; for Ibedrolla Renewables.
  4. School Section 16 Wind Energy Farm haul roads study, Klickitat County, Washington; for enXco Development Corporation.
  5. Big Horn II Wind Energy Project Klickitat County, Washington; for Ibedrolla Renewables.
  6. Biglow Canyon Phase II and Phase III Wind Energy Projects, Sherman County, Oregon; Blattner Energy.
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