Comparative Analysis of Effects of Heavy Vehicles on Roads in Southern and Northern Nigeria

The prevalence of flexible pavement deterioration in the country has been adduced largely by highway researchers to trucks or heavy vehicles carrying much in excess of permitted legal limits. This study investigated levels of deterioration of Abuja-Kaduna-Kano road (Northern region) and Port Harcourt-Enugu road (Southern region) caused by heavy vehicles through a 14 day traffic counts conducted at 5 strategic points each in the Northern and Southern regions. Traffic data generated were analyzed with AASHTO Design Guidelines (1993) to evaluate Equivalent Single Axle Loads (ESALs) and Vehicle Damage effects on the road. The Traffic Volume, Average Daily Traffic (ADT), and Heavy Vehicle per day (HV/day) were estimated to be 2,063,977; 147,427; and 12,246 respectively in the Northern region, while in the Southern region they were estimated to be 750,381; 53,670; and 20,951 respectively. Motorcycles, Passenger cars, Mini-buses/Pick-ups, and Heavy vehicles constitute 18.7%, 49.7%, 23.3% and 8.31% of the total traffic volume respectively in the Northern region while in the South they constitute 4.6%, 30.1%, 26.2% and 39.1% respectively. ESALs were estimated according to AASHTO Design Guidelines in the Northern and Southern regions as 547,730 and 836,208 respectively. An average Load Equivalency Factors (LEFs) of 3.43 and 3.02 were estimated for each heavy vehicle plying the Northern and Southern roads respectively and this could explain some failures (alligator cracks, potholes, depressions, linear or longitudinal cracks along the centre line amongst others) inherent on the road.

Developing Mixed Traffic Equivalency Factors to Estimate Saturation Flow at Urban Signalized Intersections

This study proposes a time occupancy approach to estimate passenger car units (PCUs) at urban signalized intersections with different interaction levels between vehicles under saturated green time conditions. The study shows a variation in PCUs with varied traffic and geometric conditions. Traffic data have been collected through videography techniques at signalized intersections in three metropolitan cities in India. Traffic flow discharge and clearance time of different vehicular categories have been extracted from the video during the saturated green time. The observed ranges of dynamic PCU values for two-wheelers, three-wheelers, big cars, light commercial vehicles, and heavy vehicles are 0.12 to 0.32, 0.45 to 0.80, 1.40 to 1.80, 1.60 to 2.20, and 3.50 to 6.50, respectively. Regression-based PCU models have been developed for each vehicle category to address the variation of individual vehicle PCUs with traffic compositions and flow rates. The model analysis shows that traffic compositions and flow rates are significantly affecting the PCU values. The PCU is a complex parameter requiring several field attributes. Therefore, to overcome the complexity of estimating PCUs, a concept of flow equivalency factor (FEF) has been proposed based on the estimated PCUs. The FEF can directly convert the mixed motorized vehicular flow into an equivalent standard passenger car flow without actually making use of different vehicles’ PCU factors. All the developed models have been validated for field conditions and results are found promising with field data. The developed approach can be used effectively for developing countries with a mixed traffic stream.

Development of a laboratory analytical method beneficial to the policies of the Canada-wide standards for dioxins and furans

An enzyme-linked immunosorbent assay (ELISA) was tested for its ability to screen for PCDD/F in soils and sediments at 50, 1000 and 10,000 picograms toxic equivalents per gram of soil pgTEQ g-₁ (n=48, r²=0.994, slope=0.94). These results relied on two concepts developed in this thesis. The first, a congener correction factor, corrects ELISA results for differences in how ELISA and GC-HRMS calculate the dioxin content of a sample. The congener correction factor increased the correlation between ELISA and GC-HRMS TEQ values calculated using World Health Organization (WHO) toxic equivalency factors (TEF) from 83% to 94%. The correlation between ELISA and GC-HRMS TEQ values calculated using North Atlantic Treaty Organization (NATO) TEF remained strong when the correction factor was applied, falling from 102% to 94%. The second concept, a sample algorithm allows ELIAS to efficiently measure unknown PCDD/F concentrations between 30 and 10,5000 pgTEQ g-¹. The algorithm successfully placed 24 of 28 samples into their correct concentration ranges in a maximum of two ELISA each. A cost analysis of using the algorithm predicted that ELISA can screen samples three times faster than GC-HRMS while at a 60% reduction in operating cost. The success of ELISA in conjunction with its time and cost savings indicate that it can replace GC-HRMS in situations where the high precision of GC-HRMS is not required.

Development of a laboratory analytical method beneficial to the policies of the Canada-wide standards for dioxins and furans

An enzyme-linked immunosorbent assay (ELISA) was tested for its ability to screen for PCDD/F in soils and sediments at 50, 1000 and 10,000 picograms toxic equivalents per gram of soil pgTEQ g-₁ (n=48, r²=0.994, slope=0.94). These results relied on two concepts developed in this thesis. The first, a congener correction factor, corrects ELISA results for differences in how ELISA and GC-HRMS calculate the dioxin content of a sample. The congener correction factor increased the correlation between ELISA and GC-HRMS TEQ values calculated using World Health Organization (WHO) toxic equivalency factors (TEF) from 83% to 94%. The correlation between ELISA and GC-HRMS TEQ values calculated using North Atlantic Treaty Organization (NATO) TEF remained strong when the correction factor was applied, falling from 102% to 94%. The second concept, a sample algorithm allows ELIAS to efficiently measure unknown PCDD/F concentrations between 30 and 10,5000 pgTEQ g-¹. The algorithm successfully placed 24 of 28 samples into their correct concentration ranges in a maximum of two ELISA each. A cost analysis of using the algorithm predicted that ELISA can screen samples three times faster than GC-HRMS while at a 60% reduction in operating cost. The success of ELISA in conjunction with its time and cost savings indicate that it can replace GC-HRMS in situations where the high precision of GC-HRMS is not required.

Extension of Equivalent System Mass for Human Exploration Missions on Mars

NASA mission systems proposals are often compared using an equivalent system mass (ESM) framework wherein all elements of technology to deliver an effect- its components, operations and logistics of delivery- are converted to effective masses since this has a known cost scale in space operations. To date, ESM methods and the tools for system comparison have not considered complexities wherein systems that serve a mission span multiple transit and operations stages, such as would be required to support a crewed mission to Mars, and thus do not account for the different mass equivalency factors operational during each period and the inter-dependencies of the costs across the mission. Further, ESM does not account well for the differential reliabilities of the underlying technologies. Less reliability should incur an equivalent mass cost for technologies that might otherwise provide a mass advantage. We introduce an extensions to ESM to address these limitations and show that it provides a direct method for analyzing, optimizing and comparing different mission systems. We demonstrate our extended ESM (xESM) calculation with crop production technologies -- an aspect of the developing offworld biomanufacturing suite -- since it represents a case with strong coupling among stages of the mission and a relatively high-risk profile.

Novel Framework for the Quantification of Pavement Damages in the Overload Corridors

Recent traffic trends and permit issuance show significant mobility demands in the energy sectors across the nation. The increase in the axle loads and frequency of operations of over-weight (OW) trucks resulted in severe damage to transportation infrastructures. Traditionally, the damage imparted by OW vehicles has been quantified by means of the equivalent axle load factors (EALFs) concept. However, because of the nature of assumptions in the development of damage equivalency factors, the field distresses substantially deviate from the prediction models. Therefore, this study aimed to bridge this gap by developing a mechanistic framework to determine damage equivalency factors tailored toward the specific characteristics of OW vehicles operating in the OW corridors, while considering the environmental conditions and the unique features of transportation facilities in the network. To achieve this objective, initially, the authors devised a plan to collect traffic information using portable weigh-in-motion devices at two intervals for 10 representative sites in the energy corridors of Eagle Ford Shale region. Subsequently, a series of nondestructive tests were conducted in the field to determine the material properties of the pavement layers for further numerical simulations. This information was further incorporated into a 3D finite element system to calculate critical input parameters in the modified damage factor models. The proposed mechanistic approach confirmed that the modified damage factors were substantially higher compared with traditional industry-standard values. Further investigation of environmental factors and pavement profiles in this study underscored the significance of these components for accurate assessment of the damage equivalency factors.