Road Soil Research Articles

Experimental validation of a numerical prediction model for free field traffic induced vibrations by in situ experiments

This paper deals with the validation of a numerical model for traffic induced vibrations. Road unevenness subjects the vehicle to vertical oscillations that cause dynamic axle loads, which generate waves propagating in the subsoil. A 2D vehicle model is used for the calculation of the axle loads from the longitudinal road profile. The free field soil response is calculated with the dynamic Betti–Rayleigh reciprocity theorem, using a transfer function between the road and the receiver that accounts for dynamic road–soil interaction. The validation relies on the measured response of the vehicle's axles and the soil during the passage of a truck on an artificial unevenness with speeds varying from 30 to 70 km/h. The agreement between the numerical and the experimental results is good: the influence of the vehicle speed and the distance from the road is well predicted, while the ratio of the predicted and the measured PPV is less than two.

Antimony as a Tracer of the Anthropogenic Influence on Soils and Estuarine Sediments

The aim of this work was to evaluate antimony (Sb) as apotentially valuable tracer of the anthropogenic impact on soilsand estuarine sediments. Antimony was determined in fifteenroadsoils from a medium-size city, La Coruna (NW of Spain);and twelve sediments from two estuaries (La Coruna and Ares-Betanzos). Sb determination was accomplished in a rapid andreliable way by directly measuring the solid samples with anautomatic ultrasonic slurry sampling-ETAAS device. Soil contentsranged from 0.29 to 8.81 μg g-1. A relation between Sbconcentration and motor vehicle intensity was observed.Regarding estuarine sediments, Sb amounted from 0.22 to 1.51 μg g-1, for the La Coruna estuary and 0.24 to 0.71 μg g-1, forthe Ares-Betanzos estuary; higher Sb values were found forcoastal locations whereas lower contents corresponded to `inner'samples. In order to confirm these findings, other pollutantswere studied: As, Cd, Co, Cr, Cu, Ni, Pb, Zn, aliphatichydrocarbons (AH) and polycyclic aromatic hydrocarbons (PAH).These values, along with the Sb ones, were subjected tomultivariate studies intended to elucidate whether Sb correlated(and to what extent) to other well-known anthropogenic pollutants. Thus, Sb became associated to Cd, Cu, Pb and Zn in road soils and to As, Cu, Zn, PAH, Pb and unresolved hydrocarbons, in sediments.

EFFECTS OF ROADSIDE DISTURBANCE ON SUBSTRATE AND VEGETATION PROPERTIES IN ARCTIC TUNDRA

Tundra adjacent to the gravel Dalton Highway in northern Alaska was examined for effects of 15 yr of chronic road and road dust disturbance. Road effects at a nonacidic site (soil pH ≥ 5.0) and an acidic site (soil pH < 5.0) were compared to examine differential susceptibility. Overall, effects on vegetation were more pronounced in acidic tundra. Initial substrate pH appears to control the degree of response to disturbance by road and calcareous road dust. Soil at the acidic site is normally pH 4.0, whereas in the disturbed area next to the road soil pH was as high as 7.3 ± 0.07 (at 2 m from the road edge). Soils next to the road had lower nutrient levels, altered organic horizon depth, higher bulk density, and lower moisture. Effects on snowpack include both increased drifting in the lee of the road and earlier meltout near the road due to dust-induced change in albedo. Permafrost thaw was deeper next to the road at both sites, and potentially could affect road structure detrimentally. Vegetation biomass of most taxa was reduced near the road at both sites. Total aboveground biomass of nonacidic tundra ranged from 330.0 ± 34.72 g/m2 (mean ± 1 se) at 2 m from the road to 690.7 ± 94.52 g/m2 at 100 m away from the road. Total biomass of acidic tundra ranged from 150.5 ± 16.60 g/m2 at 5 m from the road to 743.1 ± 168.98 g/m2 at 100 m from the road. Species richness in acidic tundra next to the road was less than half of that at 100 m away from the road. Community composition was altered most noticeably in acidic tundra. The moss Tomentypnum nitens, dominant in nonacidic arctic tussock tundra, was nearly equally abundant at all distances from the road at the nonacidic tundra site, whereas Sphagnum mosses, dominant in acidic low arctic tussock tundra, were virtually eliminated near the road at the acidic tundra site. Salix lanata was more abundant next to the road at the nonacidic site. Ordinations indicate that variation in vegetation cover is explained by distance from the road. Knowledge of differential effects of road construction and use, including the long-term effects of hydrological alterations and dust mobilization on local corridors, is key information for planning development in areas of arctic tundra. Planned placement of roads in the future should consider the impact of such changes to sensitive (acidic) tundra areas in the Arctic.

Effects of Roadside Disturbance on Substrate and Vegetation Properties in Arctic Tundra

Tundra adjacent to the gravel Dalton Highway in northern Alaska was examined for effects of 15 yr of chronic road and road dust disturbance. Road effects at a nonacidic site (soil pH ≥ 5.0) and an acidic site (soil pH < 5.0) were compared to examine differential susceptibility. Overall, effects on vegetation were more pronounced in acidic tundra. Initial substrate pH appears to control the degree of response to disturbance by road and calcareous road dust. Soil at the acidic site is normally pH 4.0, whereas in the disturbed area next to the road soil pH was as high as 7.3 ± 0.07 (at 2 m from the road edge). Soils next to the road had lower nutrient levels, altered organic horizon depth, higher bulk density, and lower moisture. Effects on snowpack include both increased drifting in the lee of the road and earlier meltout near the road due to dust-induced change in albedo. Permafrost thaw was deeper next to the road at both sites, and potentially could affect road structure detrimentally. Vegetation biomass of most taxa was reduced near the road at both sites. Total aboveground biomass of nonacidic tundra ranged from 330.0 ± 34.72 g/m2 (mean ± 1 se) at 2 m from the road to 690.7 ± 94.52 g/m2 at 100 m away from the road. Total biomass of acidic tundra ranged from 150.5 ± 16.60 g/m2 at 5 m from the road to 743.1 ± 168.98 g/m2 at 100 m from the road. Species richness in acidic tundra next to the road was less than half of that at 100 m away from the road. Community composition was altered most noticeably in acidic tundra. The moss Tomentypnum nitens, dominant in nonacidic arctic tussock tundra, was nearly equally abundant at all distances from the road at the nonacidic tundra site, whereas Sphagnum mosses, dominant in acidic low arctic tussock tundra, were virtually eliminated near the road at the acidic tundra site. Salix lanata was more abundant next to the road at the nonacidic site. Ordinations indicate that variation in vegetation cover is explained by distance from the road. Knowledge of differential effects of road construction and use, including the long-term effects of hydrological alterations and dust mobilization on local corridors, is key information for planning development in areas of arctic tundra. Planned placement of roads in the future should consider the impact of such changes to sensitive (acidic) tundra areas in the Arctic.

Evaluation of Pavement Bearing Characteristics Using Florida Limerock Bearing Ratio Test

A laboratory study performed to evaluate pavement bearing characteristics by the Florida limerock bearing ratio (LBR) test is presented. The LBR is a modification of the California bearing ratio test and has been widely used in Florida for the design of pavement structures. The LBR evaluation is part of a larger research project studying existing pavement conditions in Florida. A field experimental program was recently conducted on 20 selected pavement sites across the state of Florida. The LBR test was performed on pavement soils obtained from the field test sites. The LBR test results were analyzed and compared with the field test results. The AASHO Road Test layer coefficient values (a2) and soil support values (SSVs), which have become classic reference values over more than two decades, were evaluated by using the LBR and field test results. It was concluded that the LBR values could be used to estimate the SSVs for the design of flexible pavements in Florida. The correlation relationships between the LBR values and SSVs were evaluated to better characterize the pavement structures in Florida.

Chemical association of lead in auto shredder residue

Abstract The chemical distribution of lead in two samples of a unique solid waste stream, Auto Shredder Residue (ASR), is investigated employing a variety of chemical and physical analytical procedures. The results of the analysis suggest that the major source of lead contamination in this particular solid waste stream can be attributed to accumulated road dirt which contains particulate lead and amorphous lead oxide associated with the combustion of leaded gasoline. Although some lead oxides are detected as small paint chips associated with electro‐coated paint primers, used to provide corrosion resistance in automobiles, the actual quantities detected are small. The results of a sequential chemical extraction procedure indicate that the environmental mobility of the lead present in ASR is very sensitive to pH conditions. These results have important implications on the classification of the material as a “Hazardous”; or “Non Hazardous”; solid waste.

Heavy metal contents from road soils in Guipúzcoa (Spain)

The heavy metal contents of five sampling points adjacent to roads of varying traffic flow in Guipúzcoa (Spain) were determined. At every point two topsoil samples separated 2–3 m were taken in July 1991. The soil samples were digested with aqua regia and extracted with DTPA. Cd, Cu, Fe, Mn, Ni, Pb and Zn were determined by flame or graphite furnace atomic absorption spectrophotometry. Significant correlations between aqua regia metal levels and DTPA-extractable metal levels were found for Zn, Pb, Cu, Cd and Ni. Most of the metal levels decreased with distance from the source of pollution. The quantity of several metals, mainly Pb and Zn, in the samples increased with the traffic flow. There was a point where the proximity of an industrial area had a major effect on the quantity of several metals.

Laboratory study of CBR of lime-sludge and molasses stabilized soils for secondary roads : Jha, K Proc Indian Geotechnical Conference, 1989, Geotechniques of Problematic Soils and Rocks, Visakhapatnam, 14–16 December 1989V1, P343–346. Publ New Delhi: Sarita Prakashan, 1989

Laboratory study of CBR of lime-sludge and molasses stabilized soils for secondary roads : Jha, K Proc Indian Geotechnical Conference, 1989, Geotechniques of Problematic Soils and Rocks, Visakhapatnam, 14–16 December 1989V1, P343–346. Publ New Delhi: Sarita Prakashan, 1989

The aetiology of scars

THE Oxford English Dictionary defines a scar as “the mark resulting from the healing of a wound or disease process” or “a fault or blemish remaining as a trace of some former condition or resulting from a particular cause”. Thus, as might be expected, a substantial proportion of scars arise either as a consequence of mishap or by reason of planned surgery. Some scars, such as striae gravidarum, arise ‘naturally’ as a consequence of changes in body shape. Apart from pregnancy, breast development in some women and gross obesity in’some individuals can produce similar appearances. The ageing process often causes non-congenital permanent wrinkles to form; the dermal matrix may also change-this, together with alterations in connective tissue fibres, may cause the skin to sag and become deeply furrowed by wrinkles. A few scars are induced deliberately for purpose of body decoration-the ritual markings of certain African tribes (Fig. 1) and the duelling scars popular with officers in the Prussian army during the nineteenth century (Fig. 2) afford examples. Tattooing can, perhaps, be regarded as a form of self-inflicted scar, although disturbance of the skin contours is usually minimal (Fig. 3). Accidental tattooing can arise as a consequence of trauma-impacted road dirt and penetration of the skin by detritus following an explosion are not uncommon (see Groves, these proceedings, Fig. 3). Sometimes trauma, particularly burns, causes a permanent reduction in hair density or permanent changes in skin pigmentation even though otherwise the skin appears to have regained a normal texture and appearance. infection is a common cause of scarring; boils and carbuncles due to staphylococcal infection frequently leave a permanent scar. Severe acne and vaccination afford other examples as do conditions such as leprosy. Possibly the majority of Fig. 1. Keloid scars deliberately produced for purposes of body decoration.

Trace element emissions in aerosols from motor vehicles

Concentrations and size distributions of 27 elements in aerosols collected near a highway and in a highway tunnel were measured on filter and cascade-impactor samples. Concentrations of many elements rise strongly near highways due to entrainment of road dirt. These elements are predominantly associated with large particles that settle out near the highway. Concentrations of elements relative to Pb on motor-vehicle aerosols of appreciable atmospheric residence time are as follows: Br, 0.39 +/- 0.05; Cl, 0.22 +/- 0.04; Ca, 0.11 +/- 0.045; Fe, 0.08 +/- 0.04; Mg, 0.075 +/- 0.030; Al, 0.07 +/- 0.02; Zn, 0.017 +/- 0.004; Ba, 0.015 +/- 0.004; Cu, 0.007 +/- 0.003; Mn, 0.003 +/- 0.001; Cd, 0.0024 +/- 0.0006; Sb, 0.0014 +/- 0.0003; Ni, 0.0008 +/- 0.0006; Co 0.00011 +/ 0.00004; Se 0.000081 +/- 0.000034. The Ba/Pb ratio of aerosols from motor vehicles suggests that they are a major sorce of Ba in many U.S. cities. Except for Pb, Br, Cl, and Ba, motor-vehicle contributions for most elements measured account for <25% of observed atmospheric concentrations in most cities.

Low temperature thermal oxidation of nitric oxide in polluted air

High concentrations of NO x (1500ppb) and high NO → NO 2 conversion rates (100ppbh −1) have been measured in Göteborg during winter-time inversion periods. The conversion takes place without being significantly affected by light and the ozone concentration is always extremely low on these occasions. The dependence of the thermal oxidation 2 NO+ O 2→ 2 NO 2 on temperature, humidity and catalytic activity of different surfaces has been investigated in an extensive kinetic study. The reaction rate has a strong negative temperature dependence with apparent activation energies of −3.5 kj mole −1 for r.h. = 55 % and −7.3 kj mole −1for dry conditions. The reaction is surface catalysed and the experiments indicate that the thermal oxidation takes place in two steps, one rapid equilibrium reaction, forming intermediates such as N 2O 2 or NO 3, and one rate-determining step in which NO 2 is formed. The presence of an aerosol surface increased the reaction rate very slightly, while street surface material had a more significant influence. When the flow reactor walls were coated with salt-snow or road dirt mixtures to simulate the surface of a winter street, the reaction rate increased typically to 3.5 × 10 4M −2s −1 from 2.1 ×10 4M −2s −1 for a clean reactor at −2°C. These values should be compared with the generally accepted value for the reaction rate, which is 1.5 × 10 4M −2s −1 at 25°C. The experimental results allow conversion rates of ~100 NOppbh −1 at rush hours and ~ 40 NO ppb h −1 for normal or low traffic to be rationalized in terms of the thermal NO → NO 2 reaction only, at an NO concentration of ~ 1000 ppb.

Recognition distances and understanding of legends on an experimental motorway signal : Rutley, K.S., and Webb, P.J.Transport and Road Research Laboratory, Crowthorne, Berks, Report No SR-500, 1979, 20 pp

A new type of matrix signal is being considered to improve the effectiveness of the motorway signalling system. In addition to the advice given by the present signal, it would inform drivers of the nature and location of hazards. A prototype three-part signal has been built to display this information, and a number of pictograms have been designed for indicating the nature of the hazard. Measurements were made of the recognition distance of the three parts of the signal. The effect of a normal accumulation of road dirt on matrix signal recognition was assessed at the same time. The pictograms were tested to find out how effective they were in conveying the desired meaning to drivers who had not seen them before. The tests showed that the top advisory panel and the 'distance ahead' panel could be recognised from distances adequate for motorway speeds. Although some of the pictograms on the prototype signal were not recognised from a sufficient distance, modifications have been made to this part of the signal which allow a 60 per cent increase in the linear dimensions of the pictograms within the same overall signal size. The recognition distances of the enlarged pictograms expected to be obtained by the average driver are now adequate. Pictograms which were similar to those currently used on some fixed traffic signs were well understood. New designs were understood by between 40 and 100 per cent of subjects, indicating that some publicity might be needed before they were used. (a) (TRRL)

Statistical applications for road soil surveys : Peronius, A N Highway Engr, V26, N4, April 1979, P15–18

The paper outlines the application of two elementary statistical methods to low cost road soil and materials investigations. A brief account of statistical method, t-distribution and cumulative sums technique is given. The two statistical methods are described for use in different circumstances. It is suggested that these methods would speed up low cost road site investigation work. An example of each method of application is included which shows both their advantages and limitations. /Author/TRRL/

Apparatus for dynamic study of fine grained road soils : Verstraeten, J Cent. Recherches Routieres, F Veverka, V Cent. Recherches Routieres, F Fagnoul, A Univ. Liege, B Conference. Session one. In French Proc. Eighth Int. Conf. on Soil Mech. Found. Engng, Moscow, 1974, V1.2, 1974

Apparatus for dynamic study of fine grained road soils : Verstraeten, J Cent. Recherches Routieres, F Veverka, V Cent. Recherches Routieres, F Fagnoul, A Univ. Liege, B Conference. Session one. In French Proc. Eighth Int. Conf. on Soil Mech. Found. Engng, Moscow, 1974, V1.2, 1974

The influence of sequestrants in The cleaning of internal combustion engines

The cleaning and reconditioning of internal combustion engines is a major operation. This is due to the nature of the soils which have to be removed, these ranging through oil sludges, gums and resins to baked‐on carbonaceous deposits which are sometimes as hard and thick as cement crusts. In addition, there are road soils, lead oxides resulting from the decomposition of leaded fuels, and the ever‐present bogy of rust.

X-ray Evidence for Cement-Clay Interaction

LARGE quantities of Portland cement are used annually for the stabilization of soils for roads, airfields, and other engineering works. While the improvement in engineering properties effected by cement treatment is believed due mainly to the hardening of cement, reactions between hydrating cement and clays leading to the formation of additional cementitious material have been suggested1.

British Food Journal Volume 22 Issue 11 1920

British Food Journal Volume 22 Issue 11 1920