Analysis of pavement condition survey data for effective implementation of a network level pavement management program for Kazakhstan

Pavement roads and transportation systems are crucial assets for promoting political stability, as well as economic and sustainable growth in developing countries. However, pavement maintenance backlogs and the high capital costs of road rehabilitation require the use of pavement evaluation tools to assure the best value of the investment. This research presents a methodology for analyzing the collected pavement data for the implementation of a network level pavement management program in Kazakhstan. This methodology, which could also be suitable in other developing countries’ road networks, focuses on the survey data processing to determine cost-effective maintenance treatments for each road section. The proposed methodology aims to support a decision-making process for the application of a strategic level business planning analysis, by extracting information from the survey data

Improving safety of runway overrun through the correct numerical evaluation of rutting in Cleared and Graded Areas

Aircraft overrun is potentially very dangerous to human life. Statistics show that overrun is mainly due to human errors causing loss of control in wheel alignment, high approach speed, and long touchdown. To prevent such disastrous consequences, advanced material arresting systems are currently being used in the main international airports for construction of Runway Safety Areas (RSAs). Many predictive models have been developed for controlling overrun events: the early reliable numerical models, on the basis of theoretical streamlined assumptions, were gradually replaced. More rigorous models based on Multibody System (MBS) and Finite Element Method (FEM) theories are nowadays much more preferred. These are characterized by high levels of reliability, even though the large number of data required does not always allow an exhaustive description of the domain of analysis. The paper presents an alternative method for predicting rut depths induced by aircraft overrunning. Such method is based on a numerical streamlined model, integrated with measurements from Light Falling Weight Deflectometer (LFWD), to define, section by section, the mechanical properties of soils in Cleared and Graded Areas (CGAs). The method has been validated through in situ tests, showing its high effectiveness and efficiency

Monitoring the Condition of a Bridge using a Traffic Speed Deflectometer Vehicle Travelling at Highway Speed

The Traffic Speed Deflectometer (TSD) is a vehicle incorporating a set of laser Doppler vibrometers on a straight beam to measure the relative velocity between the beam and the pavement surface. This paper describes a numerical study to see if a TSD could be used to detect damage in a bridge. From this measured velocity it is possible to obtain the curvature of the bridge, from whose analysis, it will be demonstrate that information on damage can be extracted. In this paper a Finite Element model is used to simulate the vehicle crossing a single span bridge, for which deflections and curvatures are calculated. From these numerical simulations, it is possible to predict the change in the curvature signal when the bridge is damaged. The method looks promising and it suggests that this drive-by approach is more sensitive to damage than sensors installed on the bridge itself

Evaluation of accelerometers to determine pavement deflections under traffic loads

The purpose of this work was to study the use of accelerometers to measure pavement deflections due to traffic loads. To this end, accelerometers were embedded in two sites: the full scale load simulator Circular Test Track (CTT) and the A1 motorway in Switzerland. Deflections were derived from acceleration measurements using an algorithm that double integrates the measured signal and corrects any errors derived from the procedure. In the motorway, deflections were monitored using a set of three magnetostrictive deflectometers. Additionally, the pavement's material viscoelastic parameters determined in the laboratory were incorporated in Finite Element (FE) models to estimate the theoretical deflections. The calculated deflections were then compared to the measured and to the theoretical deflections. Deflections calculated from acceleration showed a reasonable qualitative correlation to those measured by magnetostrictive deflectometers. In addition, the FE models revealed the inability of the accelerometers to measure very slow or quasi-static motio

Research News, November 2010

Newsletter of the Iowa Department of Transportation's Research and Technology Burea

The influence of support conditions on short- and long-term track behaviour

Railway track support conditions are known to deeply affect the dynamic performance of vehicle-track interaction, influencing the state of the track system both in the short and in the long term. Exactly how much and how is not precisely understood and the notion of track stiffness, although thought to be a key parameter of the track quality, is currently not being monitored systematically. This paper seeks to analyse the influence on the ballast behaviour of track vertical stiffness and especially its spatial non-uniformity, using available experimental data measured at different sites. Mathematical models are developed and the effectiveness of applying under sleeper pads is also investigated. Finally, an iterative procedure based on Guerin’s settlement law is used to take into account the long-term behaviour of the ballast. Such models can help to understand mitigation solutions as well as predicting track quality evolution over time

Analysis of Load-Induced Strains in a Hot Mix Asphalt Perpetual Pavement

This report presents the findings of a research study conducted to investigate the structural performance of a 275 mm hot mix asphalt perpetual pavement constructed as part of the WIM bypass lane at the Kenosha Safety & Weigh Station Facility. Two separate test sections were constructed using variable binder types and in-place air voids. Asphalt strain sensors were fabricated at Marquette University and installed during the construction of the HMA pavement. Sensors were positioned within the outer wheel path and located at the bottom of the 275 mm HMA pavement and at the interface between the lower layers at a depth of approximately 175mm from the surface. Strain sensors were oriented in both the transverse and longitudinal directions. A total of 16 strain sensors were installed during construction. Of these, only three survived to provide strain data under traffic loadings. Deflection data obtained from FWD testing was used as comparative measures to strain measurements obtained during testing and to estimate the combined dynamic HMA layer moduli at the time of testing and to develop monthly trends of dynamic HMA layer moduli as a function of the expected mean monthly mid-depth pavement temperature. A comparative analysis of measured strains to those predicted from FWD measurements provided generally good agreement. A mechanistic appraisal of the constructed test sections was completed using the outputs of the EVERSTRESS pavement analysis program. This analysis computed the expected monthly damage induced by the application of 521,000 monthly ESAL loadings. The results of the mechanistic appraisal indicate the expected service life to 50% bottom-up fatigue cracking is in excess of 90 years for sections with air voids of 4% within the lower layers. If the air void content increases to 5% - 6% in the lower layers, the expected fatigue life may be significantly reduced to between 13 – 32 years

HVS-NORDIC : research report no 2 : tests 09-10, high trafficked pavements on Ring Road II

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