Papers by Richter Opoku -Boahen
Abstract: The question of the number of toll lanes to open on the Accra – Tema motorway and indee... more Abstract: The question of the number of toll lanes to open on the Accra – Tema motorway and indeed on various tolling facilities in Ghana to effectively handle arriving traffic and the long queues they generate has been of interest for a while now. Until now this question has, at best been addressed only on ad-hoc basis without any prior scientific analysis. Model prediction of the behaviour of toll lanes under traffic loading is only possible if the performance characteristics of the lane types are known. Traffic flow through the toll lane types of both plazas on the Accra –Tema motorway in Ghana was videotaped at peak hours and analyzed to ascertain their performance characteristics. The manual lanes performed with a capacity of 5.9 veh/min while the E – zone lane’s capacity was established as 8.6 veh/min. The mean inter-vehicle time per vehicle for the manual lanes was 10 seconds when considering peak 15 min capacity periods with a mean service time and headway of 5 seconds per v...
International Journal for Traffic and Transport Engineering, 2015
Saturation flows which are important for the design of signalized intersections and capacity anal... more Saturation flows which are important for the design of signalized intersections and capacity analysis depend on the vehicle mix in the traffic stream. Traffic mix in the Savannah Accelerated Development Authority (SADA) zone in Ghana may be classified as mixed due to the high proportion of motorcycles; this makes it very different from the rest of Ghana. In this study, passenger car unit values and saturation flow rates were determined at three signalized intersections in the Tamale metropolis. Traffic volume at the three signal intersection approaches were videotaped during the peak to ensure saturation flow and queuing conditions. The three hour films were played on a laptop computer and the traffic flow manually classified into four groups: motorcycles, tricycles, car/taxis and buses/trucks. The data were analyzed using regression techniques to determine saturation flow. Average saturation flow values of between 3252 pcu/hr and 3810 pcu/hr were observed with the high values being...
Article published in International Refereed Journal of Engineering and Science (IRJES), 2013.
In many west and east African cities, road traffic mix is characterised by high volumes of two wh... more In many west and east African cities, road traffic mix is characterised by high volumes of two wheeler motorcycles which traverse the roadway without lane discipline. For many years, the Transport Research Laboratory UK (TRL) provided guidelines and parameters for the design of transport facilities based on their research in some countries. In signalised intersection design and traffic operations on roadway facilities, passenger car unit values (PCU) and saturation flows are very important and can vary across cities owing to differences in traffic mix and vehicle characteristics as well as differences in driver behaviour, regulation and enforcement. Local values no matter how crude may be preferred. The traffic mix and performance characteristics on roads in the Tamale metropolis and other northern cities in northern Ghana differ from the other regions due to the high number of motorised two wheeler vehicles in the traffic stream as well as bicycles. Even though this is known, there...
Journal of Civil Engineering Research, 2015
Geosynthethic reinforcement application in roadworks is finding increased application. In many tr... more Geosynthethic reinforcement application in roadworks is finding increased application. In many tropical countries. gravel borrow material of adequate quality which meets the technical specifications for pavement layer construction is problematic. In this study, the effect of geotextile strengthon California bearing ratio values when placed at predetermined location in anexperimental pavement layer was studied. Natural gravel soil was selected and tested without reinforcement. Then by placing a layer of a certain geogrid above the third layer within the sample height, the effect of geogrid reinforcement on California bearing ratio values were investigated. This was undertaken for two strengths of geogridin both soaked and unsoaked conditions. The results show that California bearing ratio values increases with increasing goegrid strength for soaked and unsoaked conditions. The California bearing ratio increased by 12% and 31% in the soaked condition for Tx160 and Tx170 geogrids respectively. The CBR also increased for unsoaked conditions. The use of geogrid reinforcement in road pavements layers can result in increased strength and environmental benefits.
Geogrid reinforcement is gaining acceptance as an effective way of improving on the properties of... more Geogrid reinforcement is gaining acceptance as an effective way of improving on the properties of naturally occurring soils for road pavement construction. In many tropical countries, weak lateritic subgrades are common and often rejected after proof rolling during construction due to poor strength. The specific objectives of this research were to 1) Determine the effect of strength of geogrid reinforcement material on the California Bearing Ratio of a sample of relatively poor lateritic subgrade material under soaked and unsoaked conditions and 2) Establish the effect of geogrid reinforced subgrade on the design thickness of low volume paved roads. A natural lateritic subgrade soil was selected and tested without reinforcement. Then by placing a layer of a tri-axial geogrid above the third layer within the sample height, the effects of geogrid reinforcement on California Bearing Ratio values are investigated. This was undertaken for two strengths of geogrid in both soaked and unsoaked conditions. The California Bearing Ratios of the soil-geogrid subgrade was used to determine the pavement layer thicknesses for a low volume paved road using the Transport Research Laboratory Road Note 31 method of pavement design. The results indicate that base course layer thickness reduction as a result of geogrid reinforcement for a subgrade decreases with increasing traffic class. A minimum of 15% base course layer thickness reduction was observed for a surface dressed road with natural gravel base course.
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Papers by Richter Opoku -Boahen