Evaluation of the effectiveness of traffic calming measures on vehicle speeds and pedestrian injury severity in Ghana

Objectives: Each year, pedestrian injuries constitute over 40% of all road casualty deaths and up to 60% of all urban road casualty deaths in Ghana. This is as a result of the overwhelming dependence on walking as a mode of transport in an environment where there are high vehicular speeds and inadequate pedestrian facilities. The objectives of this research were to establish the (1) impact of traffic calming measures on vehicle speeds and (2) association between traffic calming measures and pedestrian injury severity in built-up areas in Ghana.

Method: Vehicle speeds were unobtrusively measured in 38 selected settlements, including 19 with traffic calming schemes and 19 without. The study design used in this research was a matched case–control. A regression analysis compared case and control casualties using a conditional logistic regression.

Results: Generally, the mean vehicle speeds and the proportion of vehicles exceeding the 50?km/h speed limit were significantly lower in settlements that have traffic calming measures compared to towns without any traffic calming measures. Additionally, the proportion of motorists who exceeded the speed limit was 30% or less in settlements that have traffic calming devices and the proportion who exceeded the speed limit was 60% or more in towns without any traffic calming measures. The odds of pedestrian fatality was significantly higher in settlements that have no traffic calming devices compared to those that have (odds ratio [OR]?=?1.98; 95% confidence interval, 1.09–4.43). The protective effects of a traffic calming scheme that has a speed table was notably higher than those where there were no speed tables.

Conclusion: It was clearly evident that traffic calming devices reduce vehicular speeds and, thus, the incidence and severity of pedestrian injuries in built-up areas in Ghana. However, the fact that they are deployed on arterial roads is increasingly becoming a road safety concern. Given the emerging safety challenges associated with speed calming measures, we recommend that their use be restricted to residential streets but not on arterial roads. Long-term solutions for improving pedestrian safety proposed herein include bypassing settlements along the highways to reduce pedestrians’ exposure to traffic collisions and adopting a modern way of enforcement such as evidence-based laser monitoring in conjunction with a punishment regime that utilizes the demerit points system.     

WATER QUALITY AND MACROINVERTEBRATE POPULATIONS BEFORE AND AFTER A HAZARDOUS WASTE CLEANUP1

ABSTRACT: Water samples and macroinvertebrates were collected from Finley Creek, Indiana, both before and two years after the cleanup of a nearby hazardous waste site. Water quality constituents were compared between years. Below the disposal site higher concentrations of constituents were found before and after the cleanup. However, two years after the cleanup, an improvement of water quality was observed. Total dissolved solids decreased by 52% and macroinvertebrate taxa increased by 44%.     

Toxicity testing of highly volatile chemicals with green algae

A gas-tight system for toxicity testing of highly volatile chemicals with the green algaChlamydomonas reinhardtii was developed. The procedure permits maintenance of constant and defined concentrations of the tested compounds in the vessels. To ensure sufficient CO₂-supply, new bipartite test vessels were used. These vessels allowed spatial separation of a HCO₃-/CO ₃ ^2? buffer used for CO₂ supply and the alga culture to avoid growth inhibition due to ionic strength. Several volatile chlorinated hydrocarbons have been tested. Their EC10 values were several orders of magnitude lower than those obtained with open test systems.     

Assessment of management-dependent nutrient losses in tropical industrial tree plantations

Industrial tree plantations in the tropics usually follow short rotations and intensive site management including slash and burn, and the use of heavy machinery. We attempt to quantify the implied nutrient losses (harvest export, erosion, slash and burn, leaching) in order to give plantation managers a chance to understand the significance of their planning and decisions. We used the scarce globally available information and a case study plantation in East Kalimantan, Indonesia (Acacia mangium and Eucalyptus deglupta). Adaptation involves problems and is discussed in some detail. Results are approximate only. Assuming a harvest volume of 200 m3 ha(-1), we assessed a loss of 427-680 kg ha(-1) N, 12-13 kg ha(-1) P, 178-252 kg ha(-1) Ca, 276-370 kg ha(-1) K, and 45-57 kg ha(-1) Mg per rotation. Of this overall loss, stand harvest accounted for 18-29% (N), 21-30% (P), 56-26% (K), 48-64% (Ca) and 22-37% (Mg). This means that the cumulative loss by erosion, slash and burn, and leaching exceeds that of the harvest. These losses can be influenced by management.     

Growth and development of smooth bromegrass and tall fescue in TNT-contaminated soil

Plants can be used for effective and economical remediation of soil provided they are tolerant or resistant to contaminants. This study was conducted to determine effects of 2,4,6-trinitrotoluene (TNT) on growth and development of smooth bromegrass and tall fescue. Seeds of both species were grown in contaminated and non-contaminated soil mixed at ratios to obtain a range of concentrations and also in non-contaminated soil underlain by contaminated and non-contaminated soil mix. Germination, shoot and root dry weight, root length and area were measured. Germination and height of both species decreased with increasing TNT concentration. Shoot dry weight from tall fescue was 50% greater than smooth bromegrass at a given TNT concentration. Root length, area and dry weight of both species decreased with increasing TNT concentration. Root area and dry weight were greater for smooth bromegrass compared to tall fescue. This research indicates tall fescue and smooth bromegrass can germinate and grow in soils with concentrations less than 31 and 24 mg TNT l(-1), respectively.     

Cytological observations on spruce needles after prolonged treatment with ozone and acid mist

Light and electron microscopic studies of four clones of 5-year-old Picea abies trees subjected to ozone and acid mist treatment showed, that: (1) Clones respond differently to the treatment, with clone 14 the most sensitive clone. (2) Main effects were observed in the mesophyll; the vascular strand showed minor cellular changes. (3) Needle shape and ratio of intercellular area to cross section was clone- age-dependent, with a clear increase in intercellular space associated with the treatment (clone 14 and 11 only). (4) Accumulation of tannins in vacuoles was clone-specific. (5) Strong starch formation was found in all samples; in clones 14 and 133 this formation was enhanced by the treatment in older needles, if number of starch grains per cell was calculated. (6) The accumulation of plastoglobules in plastids depended on clone and age, with the older needles containing more globules. In clones 11 and 133, the treatment led to an increase in the number of plastoglobules. (7) Grana stacking in all clones and both needle ages subjected to ozone and acid mist was significantly reduced. The observed changes in the ultrastructure of needle tissue are comparable to those found in field investigations with similar conditions, or phytotron studies evaluating pollution effects on spruce trees.     

Smoldering Combustion (STAR) for the Treatment of Contaminated Soils: Examining Limitations and Defining Success

Smoldering combustion, commercially available as the Self‐sustaining Treatment for Active Remediation (STAR) technology, is an innovative technique that has shown promise for the remediation of contaminant source zones. Smoldering combustion is an exothermic reaction (net energy producing) converting carbon compounds and an oxidant (e.g., oxygen in air) to carbon dioxide, water, and energy. Thus, following ignition, the smoldering combustion reaction can continue in a self‐sustaining manner (i.e., no external energy or added fuel input following ignition) as the heat generated by the reacting contaminants is used to preheat and initiate combustion of contaminants in adjacent areas, propagating a combustion front through the contaminated zone provided a sufficient flux of air is supplied. The STAR technology has applicability across a wide‐range of hydrocarbons in a variety of hydrogeologic settings; however, there are limitations to its use. Impacted soils must be permeable enough to allow a sufficient flux of air to the combustion front and there exists a minimum required concentration of contaminants such that the soils contain sufficient fuel for the reaction to proceed in a self‐sustaining manner. Further limitations, as well as lessons learned and methods to mitigate these limitations, are presented through a series of case studies. In summary, the successful implementation of STAR will result in >99 percent reduction in contaminant concentrations in treated areas, limited residual contaminant mass, reduced groundwater contaminant mass flux which can be addressed through monitored natural attenuation; and an enhanced site exit strategy, reduced lifecycle costs, and reduced risk. ©2016 Wiley Periodicals, Inc.