Academic literature on the topic 'Damaged Roads'

After natural/man-made disasters, a major challenge faced by governments is to ensure a speedy recovery of roads and transportation networks. In order to achieve this, a new road recovery priority (RRP) model has been developed to identify key issues and their inter-relationships giving a better understanding of factors that govern prioritisation across the affected regions. Interviews are conducted with experts in road reconstruction and maintenance organisations to investigate respondents’ evaluation and understanding of the RRP model in terms of its ease of use, usefulness, comprehensiveness, applicability, feasibility and structure. A questionnaire survey is conducted to investigate the impact of the important proposed affecting factors that can be critical for successful implementation and application of the RRP model in the road rehabilitation sector. A field survey is carried out to collect data which are essential to determine parameters in the model’s application. Four case studies are carried out to investigate the RRP model’s application in a variety of road conditions. The application of this model may solve the problem of decision making in road recovery priority determination in a hierarchical manner so that the recovery process can be accomplished from an urgent repair need to a lower recovery priority.

Scientific research has identified road roughness as a significant factor that contributes to increased vehicle dynamic wheel loads and therefore damage to pavements and bridges. The other factors include vehicle speed and vehicle suspension type. More specifically and regarding road roughness, research has shown that damaging effects are caused by certain wavelengths and features in road profiles and not the overall road roughness. Various methods of classifying road roughness based on the ride quality are available. These methods, though important, are limited in identifying the location of features along road profiles that cause exceptionally high dynamic wheel loads hence damage. It is the development of a methodology for identifying the location of these abnormally high dynamic wheel forces that this thesis addresses. A vehicle-road interaction model was developed for this research. This computer model uses a quarter vehicle model and recorded road profile elevation data to simulate the response of half a vehicle axle (quarter vehicle) driving along a road. 47 road profiles over 17 bridges were measured to run the model. Signal processing techniques developed by electrical and mechanical engineers have been used as an additional tool to road profile analysis. These techniques are very powerful and their application to road profile investigations is significant. Using computer simulation and by combining ride and damage criteria analysis, a methodology of identifying segments of road that induce high dynamic wheel forces and the location of abnormally high dynamic wheel forces has been established.

Moisture damage of the asphalt mixture is defined as the loss of strength, stiffness and durability due to the presence of moisture (in a liquid or vapour state) leading to adhesive failure at the aggregate-bitumen interface and/or the cohesive failure within the bitumen or bitumen-filler mastic. The presence of moisture can accelerate the distress of asphalt pavement in several different modes, such as rutting, fatigue cracking, thermal cracking and the formation of potholes. In the field, the moisture damage normally happens first at the interface of two pavement layers or at the bottom of pavement layers and develops gradually upward. Once moisture has come into contact and interacted with the asphalt mixture, moisture damage could be developed by the following mechanisms: detachment, displacement, spontaneous emulsification, pore pressure, and hydraulic scour. It should be mentioned that moisture damage is not limited to only one mechanism but is the result of a combination of several mechanisms. As mentioned previously, the common modes of moisture damage of asphalt mixtures are a loss of adhesion between the aggregate and bitumen and/or a loss of cohesion in the mixture. Among these two failures, the adhesive failure is recognised as the main mode of moisture damage. Hence, the physico-chemical interactions between aggregates and bitumen in the presence of moisture are believed to partially govern the moisture sensitivity of asphalt mixtures, which can also affect the serviceability, performance and durability of the asphalt pavement. This thesis describes the work that was carried out with regard to the moisture damage evaluation of aggregate-bitumen bonds through different procedures. The fundamental properties of the individual material such as the chemical composition and rheological properties of bitumen, moisture absorption, surface morphology and mineralogical composition of aggregates were first characterised. Two types of equipment, namely the dynamic contact angle (DCA) analyser and dynamic vapour sorption (DVS) system were used for determining the surface energy of the bitumen and aggregates, respectively. The obtained surface energy results were then combined thermodynamically to determine the work of adhesion between aggregate and bitumen, and the reduction in the adhesive properties if water is introduced into the system. Three established mechanical tests consisting of the standard peel test, Pneumatic Adhesion Tensile Testing Instrument (PATTI) test and a pull off test were developed and redesigned to make sure that these tests are practical, reliable and feasible to measure the bonding strength of aggregate-bitumen combined specimens. The composite substrate peel test (CSPT) was developed to prepare composite substrates using crushed coarse aggregates as a more practical replacement for the aggregate substrates prepared from aggregate boulders. Finally, the moisture damage results from mechanical tests and thermodynamic results were compared and correlated with the basic physico-chemical properties of the original materials. The results showed that in the dry condition, all techniques used in this research, including the mechanical tests and the surface energy tests led to similar results, with bitumen rather than aggregates dominating the bonding properties of aggregate-bitumen systems. After moisture conditioning, the four mechanical tests, including standard peel test, CSPT, PATTI test and pull-off test showed similar moisture sensitivity ranking and failure surface results demonstrating the good correlation between these four tests. In addition, based on the comparison conducted, the four mechanical tests are all considered to be reliable to evaluate the moisture sensitivity of different aggregate-bitumen systems. However, based on the aggregates considered in this research, the moisture sensitivity parameters obtained from the surface energy tests are suggested unreliable to evaluate the moisture sensitivity of aggregate-bitumen systems.

Various configurations of unidirectional carbon/epoxy composite rods were impacted radially, inspected using micro-CT scanning equipment, and tested in axial compression to measure the residual strength after impact. This data was used to correlate the relationship between impact energy, residual strength, and the peak crack area and total crack volume along the length of the specimens. These specimens represent local members of open three-dimensional composite lattice structures (e.g., based on isogrid or IsoTruss® geometries) that are continuously fabricated using advanced three-dimensional braiding techniques. The specimens were radially impacted with 2.5 J (1.9 ft-lbs), 5.0 J (3.7 ft-lbs), 7.5 J (5.6 ft-lbs), 10 J (7.4 ft-lb), 15 J (11 ft-lbs), and 20 J (15 ft-lbs) of energy, and compared to undamaged control specimens. The unidirectional core specimens were 8 mm (5/16") in diameter and were consolidated with various sleeve configurations and materials. Sleeves differed in types (bi-directional braided sleeves or unidirectional spiral wraps), nominal sleeve coverage of the core fibers (full or half), and sleeve material (Nomex Thread or Dunstone Hi-Shrink Tape). The unsupported length of the specimens used in this research was 50.8 mm (2") to ensure a strength-controlled compression failure rather than a failure due to buckling. After impact, the specimens were scanned using a micro-CT scanner at resolutions of 50 and 35 microns and subsequently tested in axial compression. The micro-CT scan images were analyzed to measure the crack areas along the specimen. From this analysis, the peak crack area and total crack volume along the length of the specimen was calculated. Similar to past research, as the impact energy increases, the residual compression-strength-after-impact decreases. As the impact energy increases, specimens with shrink tape sleeves had the largest increase in peak crack area and overall crack volume while specimens with full spiral sleeves had the lowest increase in peak crack area and overall crack volume. A bimodal increase is evident in the peak crack area and total crack volume over the length of the specimen where specimens impacted at 15 J (11 ft-lbs) showed the highest peak crack area across all sleeve types. There is a slight correlation between the increase in peak crack area and overall crack volume and the decrease in residual compression strength after impact. Shrink Tape, while yielding a higher quality specimen with greater compression strength prior to impact, did not protect the specimens against damage due to impact as well as other sleeve types. This was shown by the large decrease in residual compression strength after impact and increase in peak crack area and overall crack volume as the impact energy increased.

Näringslivet efterfrågar ett införande av 74 tons lastbilar på det statliga vägnätet. Det finns ett flertal fördelar med att höja maximala bruttovikten från nuvarande 64 till 74 ton. Däremot är höga bruttovikter direkt kopplade till bärighetsrelaterade skador. Syftet med denna studie är att ligga till grund för vidare arbete av Trafikverket. Detta för att uppnå bättre kontroll på hela det statliga vägnätet och den tunga trafikens inverkan. Studien har utgått från observationer i PMSv3, ett webbaserat system med grafiska tvärprofiler baserade på vägytemätning samt information om det statliga belagda vägnätet. Observationerna innefattar mönsteridentifiering av återkommande tvärprofilstyper tillskrivna skador av den tunga trafiken. Resultatet av tvärprofilstyperna har sedan analyserats och beskrivits som representativa spårtyper för det statliga vägnätet. Slutsatsen är att det finns indikation på mönster av spårtyper. Utifrån observationerna i PMSv3 har spårtyperna formulerats som hypoteser för vidare forskning.<br>The wood industry asks for an imposition of 74-ton trucks on the national road system. There are several advantages of increasing the maximum gross weight from 64 to 74 tons. On the other hand, high gross weights are directly connected to structural road damage. The purpose of this study is to serve as foundation for further research by the Swedish transport administration. The ulterior goal is to reach better control on the national road system. The basis of the study is a web-based system - PMSv3, which contain road information and transverse road profiles. The observations in PMSv3 have led to rut-types ascribed due to heavy gross weights. The conclusion is that rut-patterns indications exist. Based on the observations in PMSv3, the rut-types have been formulated as hypothesis for further research.