Highway Soil Research Articles

Evaluation the Effect of SFO on Plant Growth and Soil Properties in Deicing Agent Contaminated Soil

In order to reduce the damage of deicing salt to green belt soil in highway, the research used organic multi-fertilizer SFO featured with water conservation and anti-deicing salt to test the effect on plant growth and soil moisture and ion composition in Jingcheng high way, Beijing, It set 12 t/hm27.5 t/hm24.5 t/hm2 dosage processing in test Experimental index include plant growth, soil moisture, ion composition and the improvement effect of saline-alkali soil. In treatment of 4.5 t/hm2 and 7.5 t/hm2 SFO dosage, the fresh treetop growth of Juniper were increased 25.9% and 85.7% higher than that of CK, but less than that in treatment of 12 t/hm2 dosage. The soil moisture in all treatments was improved 0.8% -2.1% high than that in CK. The analysis showed that SFO can regulate the ion balance of soil, Ca2+Mg2+K+ content of soil in all treatments were raised as the increasing of SFO dosage, but the Na+Cl-ion contens decreased 38% and 48% on average than that of CK,and the Sodium Adsorption Ratio (SAR) significantly was reduced markedly. In which the 7.5 t/hm2 dosage treatment of SFO is the best effect. The results certificated that SFO has the comprehensive effect on reducing soil salinization and can improve soil structure and the soil moisture, and can be applied in controlling soil salinization of green belt caused by using deicing salt in high way widely.

Evaluation of Four Kinds of Water and Soil Conservation Measures on Highway Side Slope

Four kinds of protective measures and three contrast measures were chosen on Harbin-Suifenhe highway to analyze the effects of different types of soil and water conservation measure on highway side slope soil. The results showed that Soil and water conservation measures of highway side slope increased water holding capacity and soil conservation capacity significantly. The saturated water holding capacity, capillary water holding capacity and field water holding capacity of E, PP grid measure were 1.79 times,1.60 times and 1.62 times respectively of that in contrast 1 measure. E, PP grid measure, resin network measure and spread planting measures reduced runoff 58.5%, 59.3% and 50.8% compared with contrast measures. Consider of landscape and cost factors, spread planting measures was recommended to use on the smaller slope degree of highway side, E, PP grid measure, resin network measure were recommended to be used on the steep slope of highway side, hex hollow brick measure was not recommended.

高速道路盛土のり面における植生別の土壌炭素ストック変化量

高速道路盛土のり面における植生別の土壌炭素ストック変化量

Experiment Study on Reinforcement Effect of Composite Foundation in Saline Soils

Using DPT and plate loading test, the paper analyzed different reinforcement effects from four different reinforcement technologies－gravel piles method, dynamic compaction method, dynamic compaction replacement (DCR) method and impact compacted method for Cha-Ge highway saline soils ground located in salt lake area, and got the following conclusions: (1) DCR method has the best reinforcement effect, and impact compacted method has the worst. There is a difference of 166.9 % between them. (2)Tamping energy is important on reinforcement effect to the last three methods and related directly to the values of the strengthened bearing capacity and deformation modulus. The DCR method and gravel piles method mentioned above are useful on reducing the settlement of natural saline soils foundation. In recent years, a lot of ground treatment methods are widely used to consolidate soft soil foundation for its short period and simple construction and so on. Numerous scientists and engineers have obtained useful results and experience from DCR and gravel piles foundation treatment of soft soil [1,2,3,4]. (e.g., A. G. Phear, S. J. Harris, 2008; Dong,Yan and , 2009; Huang, Zhou and He, 2006; Liu, 2006;); But the reinforcement in regions of saline soils, such as DCR hasn't been well researched; theoretical study is far behind engineering practice; so it is hard to build up the design theory and method..

Heavy Metal Concentrations in Industrial, Agricultural, and Highway Soils in Northern Iran

In this article, heavy metal concentrations of lead (Pb), cadmium (Cd), and zinc (Zn) in industrial, agricultural, and highway soils in the north of Iran (Amol-Babol) have been investigated. The soil samples were collected randomly from the identified areas and after transfer to the laboratory, they were dried in an oven and then ground by mill and passed through a 2 mm polyethylene sieve. A mixture of HNO3 and HCL was used to extract the metals existing in samples. The measurement of Zn, Cd, and Pb was done by Perkin-Elmer Atomic Absorption Spectrometer (AAS), model 603, after filtration by number 42 Whatman paper. Mean concentrations of the metals were calculated in mg/kg in industrial, agricultural, and highway soils, respectively as follows: Pb 213±132, 19.70±9.5, 84±38; Cd 4.90±3.80, 1.9±1.2, 0.95±0.40; and Zn 214±111.50, 112±47, and 107±39.50. The highest concentration of these metals was observed in industrial area soils. According to the obtained results, the mean concentration of Pb and Cd in the industrial areas of Amol and Babol was more than the permissible limit of Iran's environment conservation organization and Zn concentration in all of the studied regions was less than the permissible limit (400 mg/kg). A significant statistical difference has also been observed between the mean concentration of Pb, Cd, and Zn in the industrial, agricultural, and highway soils and their background concentration.

Improving fine-grained gypsiferous soil by increased compaction

Presented in this paper is a study of the effect of compactive effort (CE) and long-term soaking on the strength characteristics of a clayey gypsiferous subgrade soil. The tested soil is A-6 (6) soil according to American Association of State Highway and Transportation Officials (AASHTO) soil classification system. To study the effect of CE and long term soaking on the properties of the tested soil, various California bearing ratio soil samples were prepared and compacted at optimum moisture content of the modified AASHTO compaction, but using four different chosen CEs of 12, 25, 56 and 70 blows/layer and then soaked for 0, 4, 7, 15, 30 and 120 days. The California bearing ratio (CBR) tests indicate that the CBR increases significantly in a nonlinear manner with increasing CE for all soaking periods, indicating improvement in soil strength with increased compaction. The rate of increase dies out with increasing CE. The CBR tests reveal also that there is a serious drop in the CBR due to soaking for all CEs.

高速道路のり面土壌の二酸化炭素固定量調査

本稿は，京都議定書の枠組みに位置づけられている植生回復に関する報告対象のうち，土壌に焦点を当て二酸化炭素固定量の把握に向けた土壌調査を行なった。まず，調査の背景を述べた上で，人的撹乱の少ない高速道路のり面を対象に土壌有機炭素固定量を把握するための研究の枠組みを示し，高速道路のり面の土壌が二酸化炭素の吸収源であることを確認するとともに，整備後概ね 20 年間の炭素含有量は，0-10cm と 10-30cm の上下差分量の方が 0-30 cm の平均値よりも経過年数と高い相関を示した。

Rhizosphere Influence and Seasonal Impact on Phytostabilisation of Metals—A Field Study

Field experiments were conducted to assess the influence of plant growth and amendment addition on phytostabilisation of copper (Cu), lead (Pb), manganese (Mn) and zinc (Zn) along highway soil in southwest British Columbia, Canada. The plant species tested were Lolium perenne L (perennial rye grass), Festuca rubra L. (creeping red fescue) and Poa pratensis L. (Kentucky blue grass) and the amendments, lime and phosphate. The treatment efficiencies were assessed during different seasons as a completely randomized factorial experiment in split plot design. The research tasks involved: (1) quantifying the seasonal extent of metal accumulation in soil and assessing the seasonal impact on metal speciation for different soil amendments and plant species; (2) determining seasonal accumulation differences between sampling periods in plant parts; and (3) assessing the influence of root–soil interactions on metal dynamics. The amendments decreased the exchangeable fraction and plant uptake of all four metals. The lowest mobile fractions (exchangeable and carbonate bound) were found in soils growing Festuca for Cu, Lolium for Mn and a Lolium/Poa/Festuca combination for Pb and Zn. Metal accumulation and metal dynamics in the rhizosphere soil are compared with those of the bulk soil. The final outcome was the development of a remediation strategy for all four metals involving suitable plants and amendments and incorporating seasonal and rhizosphere influences.

Alaska Melilotus Invasions: Distribution, Origin, and Susceptibility of Plant Communities

ABSTRACT Melilotus alba and M. officinalis were introduced to Alaska in 1913 as potential forage crops. These species have become naturalized and are now invading large, exotic plant–free regions of Alaska. We determined distributions of M. alba and M. officinalis in Alaska from surveys conducted each summer from 2002 to 2005. Melilotus alba and M. officinalis occurred at 721 and 205 sites, respectively (39,756 total sites surveyed). The northward limit for M. alba and M. officinalis was 67.15°N and 64.87°N, respectively. Both species were strictly associated with soil disturbance. Melilotus alba extended no farther than 15 m from road edges except where M. alba on roadsides met river floodplains and dispersed downriver (Matanuska and Nenana Rivers). Melilotus has now reached the Tanana River, a tributary of the Yukon River. Populations on floodplains were most extensive on braided sections. On the Nenana River, soil characteristics did not differ between where M. alba was growing versus similar areas where it had not yet reached. The pH of river soils (7.9–8.3) was higher than highway soils (7.3). Upland taiga plant communities grow on acid soils which may protect them from invasion by Melilotus, which prefer alkaline soils; however, early succession communities on river floodplains are susceptible because soils are alkaline.

Improving a gypsum sand roadbed soil by increased compaction

A silty sand of the SM group according to the Unified Soil Classification System and of the A-1-b group according to the American Association of State Highway and Transportation Officials (AASHTO) soil classification system, with about 28% gypsum content, was tested in the laboratory for California Bearing Ratio (CBR) under four different compaction efforts. Twenty-four pairs of CBR soil samples were completed at the optimum moisture content derived from a modified AASHTO compaction test. To achieve different compaction efforts, four groups, each of six pairs of samples, were compacted using 10, 30, 50 and 70 blows per layer respectively. The individual pairs in each group were then soaked for different periods of time—4, 7, 15, 30, 60 and 120 days—while subject to a surcharge load of 40 lbf (178 N). The CBR test results show the significant effect of compaction effort on CBR value. An increase in soaking period causes a significant decrease in the CBR for each degree of compaction effort. Samples made under low compaction efforts are affected more by soaking than those made under high compaction efforts.

Retention Capacity and Environmental Mobility of Pb in Soils along Highway Corridor

Although lead (Pb) emissions have dropped drastically with the phase-out of tetra-ethyl lead (TEL) as a fuel additive, Pb deposited along highway corridors continues to be of concern because of its toxicity. This paper provides comprehensive data on the extent and distribution of Pb in roadside soils, Pb interaction with soils as a function of soil composition, the retention capacity of soil based on batch adsorption tests, the retention mechanism of Pb using selective sequential extraction, the potential for mobility using batch desorption tests with simulated rain and winter road salt, and column leach tests. Highway soils on high-traffic sections near Burnaby, Canada were found to have Pb accumulations up to 1628mg/kg soil. Contamination was mainly in the top 0.3m, with concentrations rapidly decreasing to the background level at a depth of 0.6m. The top layer contained more organic material and had a high adsorption capacity. Highway soils were found to have 3–10 times higher Pb adsorption capacities than the amount currently deposited. Selective sequential extraction indicated low exchangeable Pb in highway soils. Batch desorption tests with leaching solutions of H2O (pH 5.5), HNO3 solution (pH 4.0) and aqueous NaCl solution (0.17M) indicate low likelihood of significant leaching. Selective sequential extraction, leachate extraction and desorption tests show that Pb has limited mobility in highway soil.

Two-Dimensional Moisture Flow-Soil Deformation Model for Application to Pavement Design

Seasonal cycles of wetting and drying in highway subgrade soils induce corresponding cycles of soil swelling and shrinkage that contribute to roughness and loss of serviceability of pavements. The design of defensive measures to mitigate the effects of this process requires a realistic model of moisture diffusion and associated swelling and shrinkage of soil. A Windows-based two-dimensional finite element program, FLODEF, is presented; it performs a sequentially coupled flow-displacement analysis for the prediction of vertical movement in highway subgrade soils. The theoretical formulations of moisture flow and stress-deformation components of the model are introduced first. Parametric studies illustrate capabilities of the model to evaluate the effectiveness of vertical moisture barriers, horizontal barriers, soil replacement or improvement, and paved medians in reducing swell-shrink deformations beneath highway pavements.

Herbicide Runoff along Highways. 2. Sorption Control

Controversy remains about the importance of nonlinear sorption isotherms, desorption rate limitations, and aging effects, collectively referred to as nonideal sorption processes, in controlling the fate and transport of organic contaminants. Herbicide runoff from highway soils represents a good test case for assessing the relative importance of nonideal sorption because runoff flow rates are often high, soil-water contacttimes are short, and significant time is available for contaminant aging after application. This study examines the sorption and desorption of five herbicides with a wide range of properties (isoxaben, oryzalin, diuron, clopyralid, and glyphosate) on soil samples from two roadsides in northern California and uses the results to examine field runoff data from multiple rainy seasons. Nonideal sorption processes do not appear to be significant in determining herbicide runoff at the field sites because (i) sorption isotherms were linear or slightly nonlinear for all compounds but glyphosate, (ii) field runoff concentration ratios between isoxaben and oryzalin were consistent with linear partitioning predictions, (iii) runoff leaving the site appeared to be in equilibrium with local soil concentrations, and (iv) desorption distribution coefficients for aged herbicides on soil samples collected from the field site did not differ substantially from those obtained in short-term laboratory adsorption experiments. Collectively, these findings indicate that linear equilibrium models are adequate for predicting the concentration of herbicides in runoff in these field settings and that more complicated nonideal models do not need to be invoked. Vegetated slopes effectively reduced the herbicide loads, with average removals of 35-80% occurring as runoff traversed a 3-m segment 1 m from the edge of the spray zone.

Explaining the Hveem Stabilometer Test: RelatingR-value,S-value, and the Elastic Modulus

AbstractThe Hveem stabilometer is used by several states to obtain materials characteristics for designing pavements. This paper presents equations that relate the Hveem stabilometer R-value and S-value with the elastic modulus. It is shown that the elastic modulus is dependent on the following: the R- or S-value, the exudation pressure, the overconsolidation ratio, the Poisson's ratio, and the angle of internal friction of the material. It is also shown how the compaction pressure might affect the calculation if the material is time-dependent or viscoelastic. An example problem is provided to show how to calculate the elastic modulus using these pertinent factors. Typical laboratory test data are also presented to demonstrate the relationship between the R-value and the elastic modulus for three different highway soil materials. It is shown that the exudation pressure is indicative of the moisture content of the test samples. The R-value and elastic modulus are shown to be quite sensitive to the moisture content.

Heavy metal contamination in highway soils. Comparison of Corpus Christi, Texas and Cincinnati, Ohio shows organic matter is key to mobility

Heavy metal content of roadside soil samples from along the interstate highway systems in Corpus Christi, Texas and Cincinnati, Ohio was measured to as- sess the degree of contamination such soils contain and the likelihood that this contamination can be remobilized. High values of Ba, Cu, Pb, and Zn can be attributed to anthropogenic effects related to motor vehicles, whereas Cr and Ni variations are best ascribed to natural processes. The anthropogenic substances are strongly correlated to the amount of organic matter in the soil. Sequential ex- traction experiments, however, show that this organic matter is not extractable by agents that normally solubilize soil organic matter, so these metals are bound to an in- soluble form of organic matter that is itself probably an- thropogenic. The insolubility of the heavy metals and Ba indicates that these constituents are not likely to move in solution to water supplies, but they would still be subject to physical remobilization by roadway maintenance or even by grass mowing. Inhalation of small dust particles poses a potential health hazard to highway maintenance workers that needs to be assessed.

Geospatial Distribution of Metal Elements in Transportation Land Use Surficial Soils

Highway traffic generates heavy metals and particulate matter through various vehicular and tire-pavement abrasion mechanisms. These abraded materials are deposited, they accumulate, and they are transported by storm water. Soils subject to years of such loading can serve as a sink and a potential source for heavy metals. The results of geotechnical analyses, heavy metal distributions, drainage influences, and correlations to geotechnical indices for surficial (0 to 15 cm) glacial till samples recovered from two transects along a heavily traveled urban interstate highway were compared with a control site subjected to only urban atmospheric deposition. This investigation indicated, for this site, that heavy metal accretion in the surficial soils is a function of depth, surface drainage patterns, distance from the pavement edge, and soil indices. Particulate-bound heavy metal deposition and accretion or export were a function of surface flow conditions such as velocity, flow depth, and surface cover. Results indicated that heavy metal accretion rapidly decreases as a function of distance from the traveled roadway. Along the longitudinal transect, correlations between heavy metals and soil organic content were statistically significant, particularly for copper. Along the transverse transect, correlations between soil plasticity, organic content, and heavy metals were statistically significant. Although there is little control of traffic levels and past accretion, indices such as soil organic content and plasticity index, as well as pavement runoff surface drainage patterns, can provide information about whether highway soils might act as a sink or source of heavy metals and, consequently, if best management practices may be justified.

Effects of Prior Precipitation and Source Area Characteristics on Threshold Wind Velocities for Blowing Dust Episodes, Sonoran Desert 1948–78

Abstract A better understanding of the effects of precipitation and source area on blowing dust in the Sonoran Desert has been sought through the study of 1190 dust episodes occurring during the 1948–78 time period at Blythe, California, and Yuma, Arizona. Threshold mean hourly wind speeds (MHWSs) increase directly with prior precipitation in proportion to the inhibiting effect of the vegetation canopy, which blooms following periods of increased precipitation. Because of the time required for the vegetation canopy to fully develop and the persistence of the vegetation canopy once developed, correlation between the threshold MHWS and precipitation is highest for 4–6-month windows of total precipitation prior to each dust event at both stations. Many dust events associated with unusually low MHWSs are clustered in time, and these events can be correlated with interstate highway construction and soil preparation for new irrigation projects. Since threshold MHWSs for blowing dust lie well below the recorded ...

Analysis of Methods Used in Time Domain Reflectometry Response

Time domain reflectometry (TDR) is a new technique that can be used to measure indirectly the in situ volumetric moisture content of soil. A growing body of research has been conducted in providing a variety of prediction equations to estimate the volumetric moisture content using the dielectric constant calculated from the apparent length obtained from the TDR reader. However, limited research has been conducted to determine which of several available procedures should be used to obtain the apparent length of the TDR response to be used in calculating the dielectric constant. As a result, evaluating which procedure yields the most accurate assessment of the volumetric moisture content of soils is the object of this paper. There are five known methods of analyzing the apparent length of TDR responses. They are the method of tangents, method of peaks, method of diverging lines, alternate method of tangents, and the Campbell scientific method. Twenty-eight soil samples, from the FHWA seasonal monitoring program, were obtained throughout the United States and Canada and used in a laboratory study. Three levels of moisture and five levels of compaction were initially planned for use with each soil sample. A total of 361 data points were eventually obtained and used to analyze each method. The method of tangents proved the most accurate method of estimating the volumetric moisture content. Current studies are ongoing to provide improved multiple regression models to estimate the volumetric moisture content on highway soils.

Analysis of Methods Used in Time Domain Reflectometry Response

Time domain reflectometry (TDR) is a new technique that can be used to measure indirectly the in situ volumetric moisture content of soil. A growing body of research has been conducted in providing a variety of prediction equations to estimate the volumetric moisture content using the dielectric constant calculated from the apparent length obtained from the TDR reader. However, limited research has been conducted to determine which of several available procedures should be used to obtain the apparent length of the TDR response to be used in calculating the dielectric constant. As a result, evaluating which procedure yields the most accurate assessment of the volumetric moisture content of soils is the object of this paper. There are five known methods of analyzing the apparent length of TDR responses. They are the method of tangents, method of peaks, method of diverging lines, alternate method of tangents, and the Campbell scientific method. Twenty-eight soil samples, from the FHWA seasonal monitoring program, were obtained throughout the United States and Canada and used in a laboratory study. Three levels of moisture and five levels of compaction were initially planned for use with each soil sample. A total of 361 data points were eventually obtained and used to analyze each method. The method of tangents proved the most accurate method of estimating the volumetric moisture content. Current studies are ongoing to provide improved multiple regression models to estimate the volumetric moisture content on highway soils.

Clay mineralogy, major elements geochemistry and strength characteristics of three highway subgrade soils in southwestern Nigeria

Clay mineralogy, major elements geochemistry and strength characteristics of three highway subgrade soils in southwestern Nigeria