ANALYSIS ON THE INFLUENCE OF ACCUMULATION EFFECT OF LANDSCAPE COLOR ON TRAFFIC SAFETY IN THE FOGGY SECTIONS OF EXPRESSWAYS

The landscape color of expressways has a significant impact on a driver's visual response, thus affecting the incidence of expressways traffic accidents. Although this problem has been analyzed and discussed from different angles, there is rare quantitative analysis on the influence of accumulation effect of landscape color on the traffic safety in foggy sections of expressways. In this paper, the color combination and stroboflash of fog lamps on both sides of the road were designed from the perspective of the color research of road landscapes, and the cumulative effect of colors and stroboflash of fog lamps on the drivers’ mind was also studied. Then the interactive cumulative model based on landscape color and driving time in heavy-fog environment was established. Finally, multi-group of fog-lamp colors and spacing experiment program allowing a visibility of 200–500m in fog environments was designed by using Tobii eye-movement instrument and the UC-win/Road simulation software. According to the program, simulations were performed on several drivers to test the influence of road-landscape colors in foggy environments on the drivers' visual psychology. The results of the simulation experiment showed that the colors and stroboflash of fog lamps on both sides of the road have a positive effect on the drivers’ safety when the visibility range is 200–500m, and the driving speed is less than 70 km/h, in addition, the red and yellow were found to have the largest influence among all the studied colors. These results show that it is necessary to design landscape colors in the foggy sections of expressways

Service Radius Model and Service Scope Optimization of City Public Parking Garage

The service radius of public parking garage is related to the supply of parking spots and parking behavior characteristics of drivers. However, the empirical and statistical methods in the optimization of public parking garage have limitations. Based on the theory of value engineering and satisfaction, an optimization model for public parking garage service radius is established, which satisfies the requirements of both drivers and owners. Then, an amended model is proposed by using accessibility theory and the principle of moment balance. This model, in consideration of city resistance and walking impedance, is modified from the circular service scope to an irregular polygon, which is more suitable for the actual situation. Finally, the method is verified by a practical example. The results suggest that the optimization model of the service radius and the optimization method of service scope can not only balance the needs of drivers and public parking garages’ owners, but also improve the operation efficiency of parking garages, so that they are more fit for the actual situation of parking service areas. This paper provides new ideas and methods to determine public parking garage service radius and service scope

Research on dynamic stress and excess pore water pressure of asphalt pavement under hydraulic-mechanical coupling

The impact of the initial static stress field on dynamic calculation results was considered, a three-dimensional refined coupling system model was constructed using finite element software, and the time domain and space domain distribution laws of dynamic stress and excess pore water pressure of saturated asphalt pavement under moving load were investigated.The findings show that the influence of the initial static stress field on the pavement dynamic calculation results will increase as the pavement depth increases. On the bottom surface of the upper layer, when the initial static stress field is not considered, the errors in vertical dynamic stress and excess pore water pressure are 29.6% and 30.8% respectively. As compared to dry pavement, the tensile stress on saturated asphalt pavement increases, and the stress attenuation rate slows when the load passes, putting the pavement structure in an undesirable situation. The negative peak value of the hydrodynamic pressure in the higher layer drops linearly as the permeability coefficient of the upper layer increases. In contrast, the negative peaking of the vertical dynamic stress grows linearly. Under the situation of potholes, the dynamic stress components in six directions of the saturated asphalt pavement all rise dramatically. Among the three shear stress components, τyz increases the most under the condition of pavement pothole, which is 345% higher than that without pothole. Among the three normal stress components, the vertical dynamic stress has the largest increase, which is 156% higher than that without potholes, and the increase in shear failure of the pavement is greater than that of tensile failure. The research findings will be helpful in determining the degradation process of saturated asphalt pavement and in designing asphalt pavement structures in rainy areas

ANALYSIS ON THE INFLUENCE OF ACCUMULATION EFFECT OF LANDSCAPE COLOR ON TRAFFIC SAFETY IN THE FOGGY SECTIONS OF EXPRESSWAYS

The landscape color of expressways has a significant impact on a driver's visual response, thus affecting the incidence of expressways traffic accidents. Although this problem has been analyzed and discussed from different angles, there is rare quantitative analysis on the influence of accumulation effect of landscape color on the traffic safety in foggy sections of expressways. In this paper, the color combination and stroboflash of fog lamps on both sides of the road were designed from the perspective of the color research of road landscapes, and the cumulative effect of colors and stroboflash of fog lamps on the drivers’ mind was also studied. Then the interactive cumulative model based on landscape color and driving time in heavy-fog environment was established. Finally, multi-group of fog-lamp colors and spacing experiment program allowing a visibility of 200–500m in fog environments was designed by using Tobii eye-movement instrument and the UC-win/Road simulation software. According to the program, simulations were performed on several drivers to test the influence of road-landscape colors in foggy environments on the drivers' visual psychology. The results of the simulation experiment showed that the colors and stroboflash of fog lamps on both sides of the road have a positive effect on the drivers’ safety when the visibility range is 200–500m, and the driving speed is less than 70 km/h, in addition, the red and yellow were found to have the largest influence among all the studied colors. These results show that it is necessary to design landscape colors in the foggy sections of expressways

Exploring the Impacts of Driving Environment on Crashes in Tunnel–Bridge–Tunnel Groups: An Eight-Zone Analytic Approach

Tunnel–bridge–tunnel groups (TBTGs) are emerging roads that often involve simple road alignments, but complex driving environments. Investigating crashes occurred in TBTGs is essential for revealing the driving environment–adaptability relationships for such roads. This study seeks to analyze the crash characteristics of component sections in TBTGs with different driving environments and compare the impact of differences in the key factor on the crashes. After TBTGs were defined through a proposed safety-critical distance metric determined via visual theory and actual crash analyses, an eight-zone analytical method considering road types and lighting was developed to probe into crashes in TBTGs. The results show that the proper safety-critical distances for bridge–tunnel and tunnel–tunnel groups are 150 and 500 m, respectively. In TBTGs, the crash rate in ordinary sections is higher than that in bridges and tunnels, particularly in the access zone. The first passed tunnel witnesses a higher proportion of crashes at the access zone and transition zone than the second tunnel. The influence of bridge and tunnel ratios on crashes is related to the ratio and type of bridges and tunnels. The findings presented herein can provide evidence-based guidance for the safety design and management of TBTGs

Enhancing the Raveling Resistance of Polyurethane Mixture: From the Perspective of Polyurethane Adhesive

Polyurethane mixture, made of waste rubber particle, aggregate, and polyurethane adhesive, has low raveling resistance which affects the durability of the mixture. The objective of this study is to enhance the raveling resistance of polyurethane mixture. The content of polyol in the hydroxyl component was determined by Fourier transform infrared spectroscopy. The suitable curing conditions for polyurethane adhesive to enhance the raveling resistance were selected by the orthogonal experiment and mechanical tests. The relationship of the raveling resistance with crosslink density and elastic modulus was tested and calculated through the wear test. The results showed that when the ratios of the isocyanate component to the hydroxyl component were 1:3.2, 1:6.3, and 1:9.5, respectively, the isocyanate component was excessive. The ranking of the significance of the influence factors, from high to low, was first the curing temperature, then curing time, and finally the blending ratio; within the ranges of blending ratio, curing temperature, and curing time selected in this study, the appropriate blending ratio was 10:2, and the curing time was 6 h. For the polyurethane mixture involved in this study to obtain high raveling resistance, if a crosslinking agent or a new polyurethane adhesive is added, the tensile strength and tensile elastic modulus should be in the range of 3.02 to 3.27 MPa and 5.50 to 6.02 MPa, respectively; when using the FS2 polyurethane adhesive directly, the suitable curing conditions for the mixture are 90 °C and 6 h or 80 °C and 6 h. The results from this study could be beneficial for obtaining a high raveling resistance for the polyurethane mixture

Laboratory Investigation of the Water Damage Resistance of Tuff Asphalt Mixture Modified with Additives

To improve the water damage resistance performance of a tuff asphalt mixture, a tuff mixture with cement and a liquid anti-stripping agent was used as the research object, and limestone and tuff mixtures without additives were selected as contrast samples. Through an improved boiling test and a water stability test before and after aging, the modification effect of the tuff mixture with additives of different types and contents on water damage resistance was evaluated to obtain the appropriate type and content of additives. On this basis, the other road performance measures of the selected mixture were further evaluated by immersion rutting and beam bending tests to verify the modification effect of the additive on the tuff mixture. Results showed that adding the appropriate cement content to the tuff mixture provided excellent resistance to the water damage effect. An optimal content of 2% cement additive in the mixture was obtained, and its high-temperature anti-rutting and low-temperature bending performance were also verified. Adhesion between tuff aggregates and asphalt polymer under water conditions was significantly improved and close to that of limestone aggregates. The modification effect of water stability after mixture aging was better than that of the anti-stripping agent. The residual stability and freeze–thaw splitting strength ratio of 2% cement content mixture were increased by about 21.5% and 16.7%, respectively, compared with those of the tuff mixture control

Crash analysis of mountainous freeways with high bridge and tunnel ratios using road scenario-based discretization.

Mountainous freeways with high bridge and tunnel ratios are a new type of road that rarely contain many special road sections formed by various structures. The crash characteristics of the road are still unclear, but it also provides conditions for studying how various road environments affect traffic. In view of the various structures and differences in the driving environments, a scenario-based discretization method for such a road was established. The traffic-influence areas of elementary and composite structures were proposed and defined. Actual data were analyzed to investigate the crash patterns in an entire freeway and in each special section through statistical and comparative research. The results demonstrate the applicability and validity of this method. The crash rates were found to be the highest in interchange and service areas, lower in ordinary sections, and the lowest in tunnels, being mostly attributed to collisions with fixtures. The crash severity on bridges and bridge groups was significantly higher than that on the other types of road sections, being mostly attributed to single-vehicle crashes. The annual average daily traffic and driving adaptability were found to be related to crashes. The findings shed some light on the road design and traffic management implications for strengthening the traffic safety of mountainous freeways

Investigation on Possibility of Waste Vegetable Oil Rejuvenating Aged Asphalt

In order to guarantee the service performance of recycling asphalt mixture with reclaimed asphalt pavement (RAP), asphalt rejuvenator shall be added. In the last five years, vegetable oil-based rejuvenators have received more and more attention due to their green and regenerative advantages. The object of this paper is to investigate the feasibility of rejuvenating aged asphalt by a kind of waste vegetable oil (W-oil). The effect of W-oil on the performance of aged asphalt is characterized by a safety property test, aging property test, and pavement performance tests; the pavement performance tests included traditional tests and a rheological test. The results show that both the safety property and aging property of rejuvenated asphalt with W-oil meet the specification requirements. According to the results of traditional performance indexes (i.e., penetration, soften point, and ductility), the pavement performance of rejuvenated asphalt can be recovered to the level of virgin asphalt. According to the results of performance indices obtained from the rheological test, the optimum dosage of W-oil is determined to be 13.4 wt %. Compared with virgin asphalt, the rutting property of rejuvenated asphalt is equivalent to that of virgin asphalt, and the workability is slightly poorer; however, the fatigue property and low temperature property have been significantly enhanced. W-oil cannot only improve the pavement performance of aged asphalt, it can also guarantee good safety property and aging property. Therefore, W-oil is of great potential to serve as an asphalt rejuvenator for rejuvenating aged asphalt

Laboratory Investigation of the Water Damage Resistance of Tuff Asphalt Mixture Modified with Additives

To improve the water damage resistance performance of a tuff asphalt mixture, a tuff mixture with cement and a liquid anti-stripping agent was used as the research object, and limestone and tuff mixtures without additives were selected as contrast samples. Through an improved boiling test and a water stability test before and after aging, the modification effect of the tuff mixture with additives of different types and contents on water damage resistance was evaluated to obtain the appropriate type and content of additives. On this basis, the other road performance measures of the selected mixture were further evaluated by immersion rutting and beam bending tests to verify the modification effect of the additive on the tuff mixture. Results showed that adding the appropriate cement content to the tuff mixture provided excellent resistance to the water damage effect. An optimal content of 2% cement additive in the mixture was obtained, and its high-temperature anti-rutting and low-temperature bending performance were also verified. Adhesion between tuff aggregates and asphalt polymer under water conditions was significantly improved and close to that of limestone aggregates. The modification effect of water stability after mixture aging was better than that of the anti-stripping agent. The residual stability and freeze–thaw splitting strength ratio of 2% cement content mixture were increased by about 21.5% and 16.7%, respectively, compared with those of the tuff mixture control