Pavement Slope Research Articles

Modelling Runoff from Permeable Pavements: A Link to the Curve Number Method

Permeable Pavement (PP) models are valuable tools for studying the implementation of PPs in urban environments. However, the runoff simulated by traditional models such as the Curve Number (CN) is different from that created with PP models, as infiltration is computed differently. However, many investigations compare the runoff created by both models to extract broader conclusions without considering how the two models are related. Hence, this research explores the relation between runoff simulated by one general model, selecting the widespread CN model as a baseline, and the PP model provided in the Storm Water Management Model (SWMM). Correlation was set using the hydrograph created with the CN in a single event as a baseline and obtaining the best pavement permeability value from the PP model by calibration. The influence of storm depth, pavement slope, catchment shape, and PP type was also analysed. Calibration was conducted based on the Nash–Sutcliffe coefficient, but peak and volume performances were also studied. The results show that it is possible to link runoff hydrographs computed with the PP model to those created with the CN method, although that relation is not useful for the entire CN range. That relation is practical for CNs higher than 88 and shall be helpful for urban planners and researchers to compare several pervious/impervious scenarios in urban drainage models more robustly. One direct application is to compare the runoff computed by both models without changing the method that simulates runoff. It shall be enough to change a unique parameter that can be linked to a certain imperviousness by the CN.

The Key Technologies of Road Elevation Detection Based on Sensor Fusion

The detection of long-distance pavement elevation undulation is the main data basis for pavement slope detection and flatness detection, and is also the data source for 3D modeling and quality evaluation of pavement surfaces. The traditional detection method is to use a level and manual coordination to measure; however, the detection accuracy is low and the detection speed is slow. In this paper, the high-speed non-contact vehicle-mounted road undulationelevation detection method is adopted, combined with the advantages of each sensor measurement; three methods are proposed to detect the road undulation elevation: rotary encoders, accelerometers, attitude sensor data fusion detection; GPS RTK detection; and Kalman filtering detection. Through modeling and experimental comparison, Kalman filter detection is not disturbed by the environment, and the detection accuracy is higher than the current international standard.

An improved computation method for asphalt pavement texture depth based on multiocular vision 3D reconstruction technology

The depth of an asphalt pavement structure is an important index used to reflect the anti-skid performance of the pavement, which directly affects the driving safety of vehicles. In the current specifications (e.g., China, European and American standards), the mean texture depth (MTD) of an asphalt pavement is generally measured by the sand-patch method (SPM). However, SPM is easily affected by the operator’s subjective experience and experimental environment, resulting in low accuracy and high scatter in the data. In view of such shortcomings, a fast and accurate method to obtain the texture depth of asphalt pavement was proposed by designing a new test tool and a computer-aided calculation method. The multiocular vision theory was adopted to reconstruct a three-dimensional (3D) point cloud model of pavement texture. To reflect the concavity and convexity of pavement texture and eliminate the influence of pavement slope, the iterative closest point (ICP) algorithm was employed to obtain the datum reference plane (DRP). On this basis, the pentahedral volume calculation method suitable for evaluating the texture depth of an asphalt pavement was proposed. Laboratory experiment results using SPM were inverted by equal volume calculation to obtain the texture reference plane (TRP) and MTD'. Meanwhile, a 3D average maximum elevation (Avg.EL) algorithm was obtained by the evolution of two-dimensional mean profile depth (MPD). Furthermore, three parameters, namely MTD, MTD', and Avg.EL, were used to measure the texture depth of two field pavement sections in service. The experimental results showed that the correlation between MTD' and MTD was better than that between Avg.EL and MTD, and the degree of scatter was smaller. MTD' could be used directly as a reference value for MTD. In the present work, the 3D volume calculation method of asphalt pavement texture depth was proposed, which integrates the technical flow of image acquisition, model reconstruction, and algorithm analysis. The developed method provides a technical reference for the application of computer vision technology in the analysis of pavement texture depth.

Fuel Consumption of Wheeled Vehicle and Transportation Costs during Highway Construction/Reconstruction

A method is proposed for determining the fuel consumption of a wheeled vehicle depending on its speed, road surface flatness and road slope in the longitudinal direction. The purpose of the research is to derive mathematical relationships for calculating the fuel consumption of vehicles, which is one of the transport cost factors during the construction/reconstruction or overhaul of a highway. The proposed polynomial dependencies for calculating fuel in addition to vehicle speed, road surface flatness and its longitudinal slope take into account the mass-dimensional parameters of vehicles involved in road traffic. New mathematical relationships between the speed of wheeled vehicles, road surface flatness and longitudinal road slope allow to simulate the change in the value of fuel consumption of a wheeled vehicle when the speed of traffic flow or the slope of the road surface changes in the forward or reverse direction of the vehicle. In a graphic way, the influence of the pavement slope on the value of fuel consumption, both loaded and unloaded wheeled vehicle is presented. When determining transport costs associated with the highway construction, reconstruction or overhaul it is proposed to use empirical mathematical relationships, which make it possible to obtain fuel consumption with an accuracy of 5 % and save up to 15 % of budget (private) investments. The analysis of scientific publications of the existing approach determine the transport costs associated with highway construction, reconstruction or overhaul. The presented method for determining the fuel consumption of wheeled vehicles with small and large loading capacity increases the accuracy of determining transportation costs and reduces the level of financial costs for highway construction, reconstruction or overhaul.

Stabilization of Red Soil using Potassium Hydroxide Treated Polypropylene Fiber

Red soil is not commonly used alike other kind of soils in engineering field. So, a trial is created to stabilize the red soil by adding potassium hydroxide treated polypropylene fibers. This project work aims to search out the effect of addition of 0%, 0.25%, 0.5%, 0.75%, 1%, 1.25% treated polypropylene fibers to stabilize the red soil. Its consistency properties, compaction properties, and strength parameter are tested. In this project the results of addition of treated polypropylene fiber is investigated and is compared therewith of the untreated red soil. The testing program was conducted in two phases. Within the first phase, the physical, and chemical engineering properties of the red soil samples were studied by conducting Specific gravity, Grain size distribution, Liquid limit, Plastic limit, UCS and CBR Tests. Within the second phase of the test program, red soil was mixed with 0%, 0.25%, 0.5%, 0.75%, and 1% of treated polypropylene fiber as percentage of dry weight of red soil. After mixing different percentage of polypropylene fiber and conducting various tests we ought to observed that the value of UCS was increased by 93.12% at 0.75% PP fiber, which makes clear that higher load can be beared after adding it. The value of MDD was also increased by 3.3 %. The soaked CBR value has been increased from 4.24% to 6.37% with 0.75% of polypropylene fiber by which it’s cleared that it can be used for pavement in areas where water table is high. Unsoaked CBR value has been increased from 8.32% to 11.06% with 0.75% of polypropylene fiber.Which make clear that we can increases the slope of pavement for stability of slope and also reduce the thickness of pavement in highway and railway which reduces the cost of construction.So, we observed that 0.75 % of treated polypropylene fiber can be used to stabilize the red soil.

The interception capabilities of slotted drains as pavement surface drainage systems

The following two slotted drain installation scenarios were reviewed in this paper: a slotted drain operating individually without a median barrier and a slotted drain operating with an adjacent barrier installed along the longitudinal length of the drain. The interception capability of the two installation scenarios was experimentally reviewed and compared while imitating various conditions typically expected on South African pavements. The applied sheet flow, slotted inlet sizes and pavement slopes (longitudinal and cross slopes) were varied throughout the experiment. Interception efficiencies of the slotted inlets were experimentally calculated as a ratio of total intercepted sheet flow to the total sheet flow applied to the pavement layouts. The sheet flow applied during the experiment was analysed to estimate the rainfall intensities and flow depths that can typically occur on the different pavements for which the interception capability of the slotted inlets was reviewed. It was estimated that rainfall intensities of more than 1 000 mm/hr and flow depths higherthan 10 mm were imitated during the experiment. More than 98% of the maximum applied sheet flow of approximately 3.0 £/s/m was intercepted by the 30 mm slotted inlets regardless of the pavement slope values and type of slotted drain layout. The conclusion reached was that both these slotted drain installation scenarios operating in practice for the conditions tested would have the capability to sufficiently remove the surface water to promote road safety during wet pavement conditions.

Influence of the built environment of Nanjing\u2019s Urban Community on the leisure physical activity of the elderly: an empirical study

BackgroundUrbanization and aging are global phenomena that offer unique challenges in different countries. A supportive environment plays an important role in addressing the issues of health behavioral change and health promotion (e.g., prevent chronic illnesses, promote mental health) among older adults. With the development of the socio-ecological theoretical model, studies on the impact of supportive environments on physical activity have become popular in the public health field in the EU and US. Meanwhile, very few Chinese studies have examined the relationship between built environment features and older adults’ physical activity at the ecological level. The purpose of the study is to investigate how the factors part of the built environment of Nanjing’s communities also influence leisure time physical activity among the elderly.MethodsUsing a socio-ecological model as a theoretical framework, we conducted a cross-sectional study of 399 elderly people from 19 communities in Nanjing, China, using a one-on-one questionnaire to collect data, including participants’ perceived built environment and self-reported physical activity. A multivariate linear regression method was used to analyze the factors influencing their recreational physical activity.ResultsThis study found that compared to older people with low average monthly income, the recreational physical activity of the elderly with average monthly incomes between 1001 and 2000 ¥ (β = 23.31, p < 0.001) and 2001 ¥ or more (β = 21.15, p < 0.001) are significantly higher. After controlling for individual covariates, street connectivity (β = 7.34, p = 0.030) and street pavement slope (β = − 7.72, p = 0.020), we found that two out of ten built environment factors indicators influence their physical activity. The importance of each influencing factor ranked from highest to lowest are monthly average income, street pavement slope, and street connectivity. Other factors were not significantly related to recreational physical activity by the elderly.ConclusionsOlder adults with a high income were more likely to participate in recreational physical activity than those with a low income. In order to positively impact physical activity in older adults and ultimately improve health, policymakers and urban planners need to ensure that street connectivity and street pavement slope are factored into the design and development of the urban environment.

Surface drainage evaluation of asphalt pavement using a new analytical water film depth model

Water film formed on the pavement surface would cause potential hydroplaning, so evaluation of pavement drainage is critical in the pavement safety analysis. However, the widely used water film depth (WFD) models are empirical models. The empirical data contributing to model development and the storm design of the empirical models limit their application scope and reduce their accuracy. This study develops an analytical WFD model by simulating the dynamic of the sheet flow on the pavement surface. Pavement permeability, texture, and geometry combined with rainfall coefficient are considered as the intervening factors on WFD. The proposed new analytical WFD model assists in capturing the highest intensity and covers the impacts of accumulated rainwater on WFDs. In order to acquire the rainfall data and the field WFDs data for the model application and validation, Pavement Drainage Measuring Instrument is developed in this study. Indeed, pavement texture, pavement slope, and pavement permeability are measured by LS-40 surface texture analyser, SurPro3500 walking profiler, and seepage instrument, respectively. Subsequently, a case study of WFD prediction on 10 test sites is provided based on the new analytical WFD model and the two widely used WFD models (PAVDRN and Gallaway model). Finally, a validation test is conducted by comparing the predicted WFDs with the field measured WFD (reference). The results from Kendall correlation method illustrate that the proposed new analytical WFD model (correlation coefficient of 0.7433) is more accurate in WFDs prediction for asphalt pavement than the PAVDRN model (correlation coefficient of 0.3343) and the Gallaway model (correlation coefficient of 0.4201). The new analytical WFD model can be applied by transportation agencies for pavement drainage evaluation.

Automatic geometry measurement for curved ramps using inertial measurement unit and 3D LiDAR system

Abstract Although road geometry data can be automatically collected using instruments mounted on survey vehicle, measurement of curved ramp geometry is still of low effectiveness and accuracy due to manual or semi-automatic detection of PC (Point of Curvature)/PT (Point of Tangent) as well as influences of vehicle vibration and wandering. In this study a new method is presented for automatic measurement of ramp geometry in network level using IMU (Inertial Measurement Unit) and 3D LiDAR (Light Detection And Ranging) system. Firstly, horizontal alignment measurements are implemented: 1) an improved K-Mean clustering method and linear fitting method are integrated for automatic PC/PT station detection; 2) an algorithm is developed for automatic lane marking identification and localization for vehicle's trajectory calibration; 3) curve radius and length are measured based on roadway centerline. Subsequently, pavement slope is calibrated using IMU and transverse profiling data. Finally, nine segments are chosen from highway ramps as test bed, and validation tests are conducted using the field measurement. The test results show the average errors for curve detection and curve radius measurement are 5.89% and 1.99% respectively, and the P-value for longitudinal and cross slope measurement are 0.621 and 0.989 respectively, which indicate the proposed method is robust in ramp geometry measurement. The significant of the proposed method is three folds. First, it integrates and synchronizes the IMU and 3D LiDAR system in geometry measurement. Second, it solves the common problems of mobile survey on vehicle wandering and vibration. Third, it is of high accuracy and effectiveness, and can be used for roadway survey in network level.

Clogging potential evaluation of porous mixture surfaces used in permeable pavement systems

Service life of permeable pavements is strongly influenced by the infiltration capacity reduction produced due to the progressive clogging of the interconnected pores. This study focused on the effect of rainfall intensity and duration as well as the pavement slope, on the clogging and de-clogging processes of permeable pavements. For this purpose, a rainfall simulator was used in order to test porous asphalt and pervious concrete samples with void contents of 15, 20 and 25%. In order to simulate the permeability reduction in permeable pavements during their service life, test samples were clogged using three different sediment concentrations: 0.5, 1.0 and 2.0 kg/m2. Three different rainfall intensities (50, 100 and 150 mm/h) and two different rainfall durations (15 and 30 min) were tested over the test samples. The infiltration capacity of the test samples was assessed in newly built conditions, and for each clogging scenario before and after rainfall simulations. Results showed that rainfall patterns as well as pavement slope significantly affect the infiltration capacity of clogged permeable materials, being higher after longer and intense rainfall events and for lower pavement slopes. Overall, PC mixture showed a best performance in terms of infiltration capacity and self-cleaning capabilities.

Field test validation of water film depth (WFD) prediction models for pavement surface drainage

During storm events, unsafe water film would be formed if the rainwater cannot rapidly drain off pavement surface, leading to potential hydroplaning. Therefore, estimation of water film depth (WFD) is a critical process in analysing pavement hydroplaning safety. A number of models have been developed to predict WFD with empirical or analytical methodologies based on surface texture properties, pavement slope, rainfall intensity, and pavement types. However, their effectiveness in WFD predictions has not been verified with field test data. This study attempts to design a field test to validate the effectiveness of four widely used WFD prediction models. To achieve this goal, pavement texture and geometry data are acquired by the LS-40 surface texture analyzer and SurPro3500 walking profiler, respectively. In order to measure the rainfall intensity and WFD, Pavement Drainage Measuring Instrument (PDMI) is developed in this study. Six test sites covering different pavement material, geometry and texture features, are selected in this study for WFD models validation. Finally the Dunnett’s test is utilized to verify the predicted WFDs for flexible and rigid pavement based on the field data. Results indicate that: (1) the WFDs obtained from empirical PAVDRN and Gallaway models are more accurate than other two models; (2) these two models are more suitable for WFDs estimation of flexible pavement than that of rigid pavement; (3) rainfall intensity calculated by 5 min rainfall duration covers the effect of rainfall on WFD better.

Hydroplaning on Sloping Pavements Based on Inertial Measurement Unit (IMU) and 1mm 3D Laser Imaging Data

The hydroplaning risk would increase on sloping pavements due to the fact that the presence of longitudinal and cross slopes would decrease the wheel load of vehicles perpendicular to the pavement surface. In previous studies, the effects of pavement slope on vertical wheel load and relevant hydroplaning speed prediction are ignored. To address this potential problem, the paper presents two improved models based on the existing Gallaway and University of South Florida (USF) models. Firstly, 1mm 3D laser imaging data is continuously collected at highway speed with the 1mm 3D PaveVision3D Ultra system, and simultaneously cross slope is acquired with an Inertial Measurement Unit (IMU) system and calibrated with1mm 3D data. A 4.35 km pavement section with five horizontal curves is selected to investigate hydroplaning speed predicted from Gallawayand USF models, and the two improved models. 1mm 3D pavement surface data is used to estimate texture information for the models in lieu of traditional spot-laser based texture measurement devices. Findings show that hydroplaning speeds at pavement segments with large slopes are lower than that at pavement segments with no grades. Moreover, pavement segments with potential hydroplaning risk are identified by comparing predicted hydroplaning speeds with posted speed limit. The significance of this paper is integrating the real-time 1mm 3D texture data and IMU data into the improved models for potential hydroplaning prediction of sloping pavement in network level survey.

Validation of a Hydraulic Model to Prevent Emulsion Flowing in Chip Sealing

Chip sealing is a pavement surface treatment that consists in the application of an asphalt binder (bitumen or bituminous emulsion) on an existing pavement followed by the spreading of aggregate chips and by the rolling of the surface, in order to embed the aggregate into the binder. This treatment is typically used as preventive maintenance technique of asphalt pavements, in order to seal fine cracks and improve skid-resistance of road surfaces. Moreover, chip sealing is often employed on rural roads, that carry low traffic volumes and are often characterized by critical conditions such as small radius of curvature and/or high longitudinal slopes. In the latter case, the application of the bituminous emulsion becomes a crucial concern as an excessive flowing of the bitumen could take place due to the high pavement slope and its spreading could become not uniform. In order to investigate these aspects, in this study a hydraulic model of the theoretical flow of bituminous emulsions on high longitudinal slope road surfaces was proposed and validated through a laboratory experimental investigation. To this aim, an original laboratory equipment (Chip Seal Laboratory Simulator), that allows the simulation of the most critical conditions during field activities, was properly designed and realized. The theoretical analysis and the experimental validation suggested practical recommendations in terms of longitudinal working speeds in critical contexts, very usual in practice.

Influence of stratigraphy and slope on the drainage capacity of permeable pavements: laboratory results

A small size laboratory test-bed was realized at the University of Genoa in order to evaluate the drainage capacity of permeable pavements by monitoring inflow, runoff and sub-surface outflow. The laboratory test programme was designed to investigate the influence of rainfall intensity and pavement slope on the hydrologic response of permeable pavements. Four permeable pavement systems combining two paving types (concrete cell and pervious brick) with two filter layers made of recycled glass aggregate and a mix of gravel and coarse sand are tested. The hydrologic response of permeable pavements is analysed by using a dimensionless volume index (discharge coefficient) and a timing index. Laboratory results reveal that the hydrologic performance is fairly consistent for all the investigated permeable pavements. The recycled glass aggregate turns out to be a valid solution. No surface runoff occurs even at 98 mm/h rainfall intensity.

Mitigating seal coat damage due to superheavy load moves in Texas low volume roads

Over the past few years, the number of Super Heavy Load (SHL) moves on the Texas highways has drastically increased, resulting in severe damage, particularly on low volume roads. One of the major failure modes on these low volume roads is peeling the fresh seal coats that have been employed as a primary maintenance option by the Texas Department of Transportation (TxDOT). In this paper, a mechanistic-empirical (M-E) guideline that incorporates a Microsoft Excel spreadsheet program was developed to aid in the evaluation and characterization of the damage (peel-off) potential of seal coats when subjected to SHL vehicle loading. Field validations were conducted to validate and calibrate the guideline. It was observed that the pavement surface temperature is the most critical factor along with pavement slope in travel direction, combination of aggregate and binder types, and curing period. Additionally, the texture depth that was measured using the sand patch test method was found to play a significant role in characterizing and controlling seal coat damage. Overall, the developed M-E guideline exhibits great promising potential to serve as an aid for evaluating and mitigating seal coat damage due to SHL vehicle loading on low volume roads in Texas.

Estimations of Soil Conservation Service Curve Numbers for Concrete and Asphalt

The purpose of this study was to collect data to estimate curve number (CN) values for concrete and asphalt surfaces and to determine how these values are affected by rainfall intensity and duration, and pavement slope. Two concrete and two asphalt pavements of size 15.24 m×3.05 m at respective slopes of 2.2 and 4.6% and 2.4 and 5% were constructed to conduct field experiments. A water distribution system was specially designed and constructed to simulate rainfall at variable intensities. A total of 64 experiments were conducted. Rainfall intensities ranged from 0.635 to 36.29 cm∕h (0.25 to 14.28 in.∕h) , and rainfall durations ranged from 0.25 to 4 h . The CN for concrete was 100 for all conditions. The CN values for asphalt ranged from 97 to 100 with an average of 99. Statistical tests indicated that the average CN values for concrete and asphalt were not equal. As expected, there was a direct relationship between curve number and rainfall intensity and an inverse relationship between curve number; and ...

Drainage hydraulics of permeable friction courses

This paper describes solutions to the hydraulic equations that govern flow in permeable friction courses (PFC). PFC is a layer of porous asphalt approximately 50 mm thick that is placed as an overlay on top of an existing conventional concrete or asphalt road surface to help control splash and hydroplaning, reduce noise, and enhance quality of storm water runoff. The primary objective of this manuscript is to present an analytical system of equations that can be used in design and analysis of PFC systems. The primary assumptions used in this analysis are that the flow can be modeled as one‐dimensional, steady state Darcy‐type flow and that slopes are sufficiently small so that the Dupuit‐Forchheimer assumptions apply. Solutions are derived for cases where storm water drainage is confined to the PFC bed and for conditions where the PFC drainage capacity is exceeded and ponded sheet flow occurs across the pavement surface. The mathematical solutions provide the drainage characteristics (depth and residence time) as a function of rainfall intensity, PFC hydraulic conductivity, pavement slope, and maximum drainage path length.