De-icing Materials Research Articles

Closed-loop snowplow applicator control using road condition measurements

Closed-loop control of a snowplow applicator, based on direct measurement of the road surface condition, is a valuable technology for the optimisation of winter road maintenance costs and for the protection of the environment from the negative impacts of excessive usage of de-icing chemicals. To this end, a novel friction measurement wheel is designed to provide a continuous measurement of road friction coefficient, which is, in turn, utilised to control the applicator automatically on a snowplow. It is desired that the automated snowplow applicator deploy de-icing materials right from the beginning of any slippery surface detected by the friction wheel, meaning that no portion of the slippery road surface should be left untreated behind, as the snowplow travels over it at a reasonably high speed. This paper describes the developed wheel-based measurement system, the friction estimation algorithm and the expected performance of the closed-loop applicator system. Conventional and zero velocity applicators are introduced and their hardware time delays are measured in addition to the time delay of the friction estimation algorithm. The overall performance of the closed-loop applicator control system is shown to be reliable at typical snowplowing speeds if the zero velocity applicator is used.

Toxic impact of the de-icing material to street greenery in Riga, Latvia

There is little information on the ecological composition of snow on roads as well as the toxic effect of de-icing salt on the ecological status of the street trees ( Tilia x vulgaris H.) in Latvia. Tilia x vulgaris is one of the most widespread tree species of street greenery in the boreo-nemoral zone – in Central, Northern and Eastern Europe. This investigation was done to find out the accumulation of de-icing salt (main elements – sodium and chlorine) in the snow–soil–plant system of street greenery in the central part of Riga (2004–2005), in order to reveal the toxic effect on the ecological status of the street trees ( Tilia x vulgaris). Snow, soil and leaf samples were collected from 27 study sites (eight objects) in the central part of Riga with intense traffic and from three control sites (one object) located in a park area. In a majority of cases, the status of street trees could be characterized as damaged. There was a high heterogeneity in the Na and Cl concentrations even along one street. Significantly, increased levels of Na and Cl in urban snow, soil and leaf samples were found in comparison with the background values. There was close correlation between the Na, Cl concentration in the leaves and the extent of leaf necrosis. Principal new information on the critical level for observation visual Tilia x vulgaris leaf necrosis was stated based on our results: 0.14% Na and 0.66% Cl concentrations in the leaves.

Estimation and validation of PM 2.5/PM 10 exhaust and non-exhaust emission factors for practical street pollution modelling

In order to carry out efficient traffic and air quality management, validated models and PM emission estimates are needed. This paper compares current available emission factor estimates for PM 10 and PM 2.5 from emission databases and different emission models, and validates these against eight high quality street pollution measurements in Denmark, Sweden, Germany, Finland and Austria. The data sets show large variation of the PM concentration and emission factors with season and with location. Consistently at all roads the PM 10 and PM 2.5 emission factors are lower in the summer month than the rest of the year. For example, PM 10 emission factors are in average 5–45% lower during the month 6–10 compared to the annual average. The range of observed total emission factors (including non-exhaust emissions) for the different sites during summer conditions are 80–130 mg km −1 for PM 10, 30–60 mg km −1 for PM 2.5 and 20–50 mg km −1 for the exhaust emissions. We present two different strategies regarding modelling of PM emissions: (1) For Nordic conditions with strong seasonal variations due to studded tyres and the use of sand/salt as anti-skid treatment a time varying emission model is needed. An empirical model accounting for these Nordic conditions was previously developed in Sweden. (2) For other roads with a less pronounced seasonal variation (e.g. in Denmark, Germany, Austria) methods using a constant emission factor maybe appropriate. Two models are presented here. Further, we apply the different emission models to data sets outside the original countries. For example, we apply the “Swedish” model for two streets without studded tyre usage and the “German” model for Nordic data sets. The “Swedish” empirical model performs best for streets with studded tyre use, but was not able to improve the correlation versus measurements in comparison to using constant emission factors for the Danish side. The “German” method performed well for the streets without clear seasonal variation and reproduces the summer conditions for streets with pronounced seasonal variation. However, the seasonal variation of PM emission factors can be important even for countries not using studded tyres, e.g. in areas with cold weather and snow events using sand and de-icing materials. Here a constant emission factor probably will under-estimate the 90-percentiles and therefore a time varying emission model need to be used or developed for such areas. All emission factor models consistently indicate that a large part (about 50–85% depending on the location) of the total PM 10 emissions originates from non-exhaust emissions. This implies that reduction measures for the exhaust part of the vehicle emissions will only have a limited effect on ambient PM 10 levels.

A Comparison of Snow Quality in Two Swedish Municipalities – Luleå and Sundsvall

In municipal planning of locations of snow deposits and investigations of the environmental effects of snow dumping, the partitioning of contaminants between particulate and dissolved matter is of great importance. This paper compares snow quality in two Swedish municipalities – Lulea and Sundsvall over time. The two municipalities have differences in used de-icing material and winter conditions. Because Lulea has a longer winter season and a lower average temperature, higher accumulations of chemicals were found in Lulea than in Sundsvall. A multiple regression analysis indicated relationships between the dissolved fraction of heavy metals and the concentration of suspended solids and chloride.

Sodium accumulation in soils and plants along Massachusetts roadsides

The most common de-icing material applied by the Massachusetts state highway department is sodium chloride (NaCl). In Massachusetts, the rate of application of de-icing agents is about 240 lb (110 kg) of sand and 12 lb (5.5 kg) of NaCl per lane mile (1.6 km). The objective of this research was to examine injury to plants along roadsides and to assess relationships of damage to the amount of Na detected in plants and soils. The damage on most plant species was manifested as burning or browning of the leaves or needles. Coniferous species, especially pines (Pinus spp.), were sensitive to NaCl injury. In coniferous species, the damage appeared as browning on the ends of the needles, but new growth was not affected. Most of the damage occurred on the needles on the tree side that faced the road and where salt spray from cars or plows could have been a factor in the degree of damage. Widespread damage was also seen on spruce (Picea spp.), sumac (Rhus typhina), and mountain laurel (Kalmia latifolia) along roadsides. With sumac, injured plants had only 10% of the foliage as uninjured plants. Some salt-tolerant species, apparently undamaged by NaCl, in the same vicinity as the damaged plants, were various oaks (Quercus spp.), maples (Acer spp.), grasses (mixed species), ferns (mixed species), and yarrow (Achillea millefolium). The Na concentrations in the leaves of pines, sumacs, grasses, and oaks decreased as the distance from the road increased. The Na concentrations in pine needles were 3356 mg kg− 1 at 10 feet, 1978 at 15 feet, and 1513 mg kg− 1 at 20 feet. The Na concentrations in maple leaves decreased with the Na concentrations being 249 mg kg− 1 at 10 feet and falling to 150 mg kg− 1 at 30 feet. The concentrations of Na in roadside soil ranged from 101 mg kg− 1 at 5 feet to 16 mg kg− 1 at 30 feet from the roadside, with a marked decrease in the Na concentration in the soil after 15 feet. The pH decreased as the distance from the road increased ranging from 7.60 at 5 feet to 5.78 at 30 feet. The electrical conductivity values decreased as the distance from the road increased and ranged from 0.16 dS m− 1 at 5 feet to 0.12 dS m− 1 at 30 feet. This study suggests a relationship between Na accumulation, in leaves and in soil, and injury to roadside plants.

A combined molecular dynamics and Raman spectroscopy approach for designing ice-metal interfaces

Understanding the structure and interatomic interactions of an ice-metal interface plays a fundamental role in the design of deicing coatings. This is demonstrated by a novel approach, combining vibrational results from laser Raman spectroscopy with molecular dynamics simulations to obtain insights into icing on solids which, in turn, lead to design criteria for minimizing adhesion. An atomistic model of ice-copper interaction is constructed based on electronic structure calculations and used to show that reasonable molecular geometry and binding energy at the interface can be obtained. Through molecular dynamics simulations we find that the ice layer adjacent to the copper surface is structurally more disordered than the layers further away, a result which is verified by the Raman spectra of vibrational frequencies. The primary adhesive bond is made by the adsorption of oxygen atoms at the lattice sites of the metal substrate. The information obtained by Raman spectroscopy and molecular dynamics is then exploited to arrive at specific recommendations for designing polymeric deicing coatings and materials.

STRENGTHENING AND REFURBISHMENT OF SEVERN CROSSING. PART 4: TRRL RESEARCH ON SEVERN CROSSING.

Keywords TRANSPORT AND ROAD RESEARCH LABORATORY, TRRL STRENGTHENING, REFURBISHMENT, CROSSINGS, RESEARCH, BEHAVIOUR, BRIDGES, CRACKS, CRACKING, FATIGUE, TESTING, TESTS, STRESS, MEASUREMENT, CABLES, CORROSION, STEELWORK, TEMPERATURE, WIND, DECKS, ORTHOTROPIC, STEEL, DECKS, SURFACING, TROUGHS, PLATES, WEBS, JOINTS, HANGERS, FLOTATION, DIAPHRAGM, SUSPENSION, STAYS, CABLE STAYED, WELDING, SEVERN BRIDGE, RIVERS, BEAMS SEVERN, ENGLAND, WALES UK... Show All