Strategies to Facilitate Photovoltaic Applications in Road Structures for Energy Harvesting

Photovoltaic (PV) facilities are sustainable and promising approaches for energy harvesting, but their applications usually require adequate spaces. Road structures account for a considerable proportion of urban and suburban areas and may be feasible for incorporation with photovoltaic facilities, and thereby have attracted research interests. One solution for such applications is to take advantage of the spare ground in road facilities without traffic load, where the solar panels are mounted as their conventional applications. Such practices have been applied in medians and slopes of roads and open spaces in interchanges. Applications in accessory buildings and facilities including noise/wind barriers, parking lots, and lightings have also been reported. More efforts in existing researches have been paid to PV applications in load-bearing pavement structures, possibly because the pavement structures cover the major area of road structures. Current strategies are encapsulating PV cells by transparent coverings to different substrates to prefabricate modular PV panels in factories for onsite installation. Test road sections with such modular solar panels have been reported, where inferior cost-effectiveness and difficulties in maintenance have been evidenced, suggesting more challenges exist than expected. In order to enhance the power output of the integrated PV facilities, experiences from building-integrated PVs may be helpful, including a selection of proper PV technologies, an optimized inclination of PV panels, and mitigating the operational temperature of PV cells. Novel integrations of amorphous silicon PV cells and glass fiber reinforced polymer profiles are proposed in this research for multi-scenario applications, and their mechanical robustness was evaluated by bending experiments.

Influence of Small Vehicle on Transiting Test Method for Measuring Building Wind Pressure Coefficients

The transiting test method is a new approach for structural wind resistance research. However, traffic on the test road inevitably influences test results. In this study, the symmetrical CAARC standard tall building model was used to investigate the influence of a small vehicle near the test vehicle. A small vehicle was set up as an interference vehicle to drive around the test vehicle under different cases during the test. Results indicate that the mean wind pressure coefficient during the overtaking period is higher than that during the no overtaking period. The enlarged relative velocity and the small test vehicle velocity increase the overtaking interference and the data calculation time required to eliminate the overtaking influence. The overtaking influence only occurs if the test vehicle is overtaken by the small vehicle in the adjacent lane. The influence of the overtaking behavior of a small vehicle can be eliminated after the data calculation time exceeds 26 s. Moreover, the wake of small interference vehicle no longer influences the transiting test results after the spacing reaches 24 m.

Performance Evaluation of Different Insulating Materials using Field Temperature and Moisture Data

Including insulation layers in pavement structures has become a common strategy to minimize frost penetration in cold regions. This study investigated the performance of two different insulation materials, extruded polystyrene board and bottom ash, in a test road in Edmonton, Alberta, Canada, eight years after construction. The two insulation materials were used in a fully instrumented test road, including three insulated sections 20 m in length. The insulated sections are as follows: the first section has 1 m of bottom ash (B. Ash), the second section has a 10 cm polystyrene layer (Poly-10), and the third section has a 5 cm polystyrene layer (Poly-5). Both B. Ash and polystyrene layers were placed on top of the subgrade layer, at a depth of 70 cm from the surface. A conventional section next to these three sections was used as the control section. Volumetric water content data and temperature variation were used to analyze the influence of the insulation materials on the subgrade. It was concluded that both B. Ash and Poly-10 layers protected the subgrade from freezing. The Poly-10 section showed the lowest rate of change in subgrade temperature during the monitoring period. B. Ash and Poly-10 reduced the frost depth by 23% and 70% compared with the control section, respectively. It was concluded that Poly-10 protected the subgrade soil from freezing and excessive moisture more effectively than B. Ash; however, the temperature in the layer above the insulation layers (pavement base layer) was significantly lower during winter for the Poly-10 section.

Permanent Deformation and Temperature Monitoring of Subgrades Using Fiber Bragg Grating Sensing Technology

The hidden nature of subgrades makes the effective monitoring of their deformation very difficult. This paper addresses this issue by proposing the use of fiber Bragg grating (FBG) sensing technology. Here, an FBG is encapsulated within a monitoring tube formed from a polyvinyl chloride tube, and one end of the monitoring tube is fixed perpendicular to a concrete column, forming a cantilever beam monitoring system. The deformation is assessed according to the theoretical relationship between the horizontal strain on the FBG embedded in the monitoring tube and the vertical displacement of the cantilever beam. Then, the relationship between the variation in the wavelength of light reflected by the encapsulated FBG and the temperature and horizontal strain is obtained on this basis by calibration experiments. The monitoring tubes are buried at a proscribed depth below the top surface of the subgrade, which facilitates the monitoring of the deformation and temperature of the subgrade at different stages of construction through the collection of FBG wavelength data during different periods, such as after embedding the monitoring tubes, the completion of the test road surface, and during the period of operation. The proposed technology is verified by employing the system to monitor the instantaneous maximum deformation and permanent deformation of a subgrade under dynamic loads. The monitoring results demonstrate that the instantaneous maximum deformation values of the subgrade at 0.25 m and 0.5 m below the surface are 695.40 μm and 574.02 μm, respectively, and the corresponding permanent deformation values are 53.00 μm and 41.54 μm, respectively. The FBG sensor system is thereby verified to provide a reliable method for conducting long-term continuous, accurate, and efficient subgrade deformation and temperature monitoring.

Insights and Findings Following 11 Years of Test Road Exploitation

Road pavement is one of the most important components of road structure. Long-term monitoring changes in the state of road pavement under real conditions of load and climate allows to determine surface degradation mechanisms, select sustainable road building materials and their mixes, rationally employ asphalt paving technologies, and improve quality control. For a number of years, road pavement structures have been studied that should best meet the Lithuanian climate conditions and withstand the increasing impact of vehicle load. Thus, for that purpose, specially designed, constructed and tested roads or road sections for different pavement structures are most appropriate. One of those was constructed in 2007. The experimental road (hereinafter, the Test Road) consisted of 27 different pavement structures (PSs) produced of various materials. The study aims to evaluate the effect of different materials on variations in the bearing capacity of the pavement structure (PS), the sustainability of the structure, and the formation of ruts in 2007–2018. In this way, difference in bearing capacity, rutting depth between sections, and loaded and unloaded lanes was estimated. Further, the statistical analysis of these factors was conducted. Investigations have shown that the minimum bearing capacity of 754 MPa established after 11 years did not affect the formation of rut depth that was less than 1.0 cm. The PSs covered with the used asphalt granules, a larger asphalt base course on gravel, the sand mix base course, and granite aggregate mixed with sand base course were accepted as one of the PSs with the highest bearing capacity with PSs exceeding 929 MPa. The bearing capacity of the PS containing a 20 cm aggregate base course is on average higher by 30 MPa than PS holding a 15 cm aggregate base course.

A Novel Strategy For Transformation Of Conventional Road Lighting To Smart Road Lighting

In recent years, smart road lighting (SRL) design and application researches has been increasing rapidly. However, SRL applications remain pilotproject and cannot become widespread sufficiently. Main reason for this is that, although the cost of production of LED luminaires is reduced, when existing road lighting systems are transformed to LED road lighting, existing electrical installations and lighting poles cannot be used. Increased investment costs due to electrical installation and poles renovation, decrease interest in SRL transformation. In this study, an innovative solution is developed to decrease the costs of the SRL. First, a new LED luminaire is designed, which can work without changing the installations and poles of the existing projects. Then a test road is created using DIALux software, and the newly designed lighting installation is compared with completely redesigned one and conventional road lighting. Thus, contributions are provided for spreading of the SRL transformation, using low cost SRL approach.

EFFECT OF DIELECTRIC CONSTANT ON ASPHALT LAYERS THICKNESS BASED ON GROUND PENETRATING RADAR DATA ANALYSIS

The ground penetrating radar (GPR) in roads is use to investigate the pavement structure layers thickness on network and project level, misaligned dowels and tie bar in concrete pavement, moisture and ground water level, air voids of asphalt layers, and to assure the quality control. Since, pavement layer thickness and materials properties are the key parameters for pavement bearing capacity and residual life determination the effective and reliable GPR analysis procedure is substantial for pavement management system. However, in order to determine asphalt layers thickness the dielectric constant or GPR velocity have to be known. The most common practice to determine the dielectric constant of specific pavement layer is to drill the cores at least every 1 km, as combination of destructive and non-destructive methods. The objective of this study is to investigate the effect of the dielectric constant to asphalt layers thickness determination accuracy. The dielectric constant of asphalt layers and GPR measurements were performed in the 27th pavement sections of the Test Road. The dielectric constant of asphalt layers calculated based on drilled cores data. Analysing the wearing, binder, and base layers separately and in combination. Finally, the errors of determined thicknesses of pavement layers were compared with actual thickness. To determine the dielectric constant influence to the asphalt layer thickness of road sections were investigated by drilling cores and determined the actual thickness. The dielectric constant based on core data and GPR measurements were compared.

Evaluation of the Coordination of Structural Layers in the Design of Asphalt Pavement

The purpose of asphalt pavement structural design is to get a materially-coordinated and structurally-durable product, and a pavement structure with good road performance by combining the structural layer materials reasonably. However, due to lack of a rational evaluation index on the parameter combinations of structural layer materials, the structural layer materials are poor in terms of coordination, have low efficiency, and the actual use period is much lower than the designed working life. Therefore, it is very important to conduct research evaluating the coordination of the structural layer materials. In this study, the sensitivity of mechanical parameters and equivalent envelope area are proposed as new indexes to evaluate the coordination of material design of asphalt pavement structure layers. Software is developed to calculate the equivalent envelope area that can quantitatively evaluate the coordination among different layers and visualize the mechanical transfer behavior of each structural layer. Based on the equivalent envelope area index, this study incorporates two new steps in the design of pavements, namely the structural form comparison and optimization, and proposes a new structural design process. Finally, the rationality and reliability of the equivalent envelope area index are verified by presenting fatigue life calculation and field verification in a test road. The results propose a clear evaluation index of the coordination of material design of each structural layer, which makes the structural design of the asphalt pavement more scientific and reasonable.