Comparison of Capacity Models for Two-Lane Roundabouts

2003 ◽  
Vol 1852 (1) ◽  
pp. 114-123 ◽  
Author(s):  
Ola Hagring ◽  
Nagui M. Rouphail ◽  
Henning A. Sørensen
Keyword(s):  
Test Site ◽  
Primary Objective ◽  
Level Of Service ◽  
Gap Acceptance ◽  
Flow Rates ◽  
Traffic Stream ◽  
Considerable Impact ◽  
The Right ◽  
Complex Capacity

Multilane roundabout capacity models are presented and contrasted in the context of a case study. A two-lane roundabout in Copenhagen, Denmark, was investigated, and data were collected that enable the estimation of critical gaps, follow-on times, entry capacity, and delay. The primary objective of this research was to evaluate the need for more complex capacity models than currently exist in order to properly represent driver gap-acceptance behavior at multilane roundabouts. The complexity arises when drivers are assumed to simultaneously accept pairs of critical gaps in the outer and inner circulating lanes before they enter the roundabout. This approach requires that circulating-lane headways and critical gaps be evaluated independently and not be superposed in a single traffic stream as most current capacity guides assume. The approach also implies that circulating-lane volume allocation can have a considerable impact on entry capacity. The field results indicated that indeed there were differences in the gap-acceptance behavior for drivers entering in the right approach lane, with critical gaps estimated at 3.68 s and 4.49 s for the inner and outer circulating lane, respectively, at the test site. In contrast, drivers entering in the left approach lane exhibited no difference in critical gaps among lanes (4.64 s for the inner lane and 4.68 s for the outer lane). Finally, the lane allocation of circulating flow did have a significant impact on capacity, particularly at large circulating-flow rates. This finding implies that the origin and destination of the flow constituting the circulating traffic must be accounted for in estimating capacity. Even small errors in capacity estimation were found to have a significant impact on delay and level of service.

Case Study

2011 ◽  
pp. 191-200
Author(s):  
Brenton Worley ◽  
Greg Adamson
Keyword(s):  
Open Source ◽  
Level Of Service ◽  
Recent Experience ◽  
It Flexibility ◽  
Commercial World ◽  
Agile Approach ◽  
The Right

In the commercial world, SOA implementation practitioners are finding a gulf between tools, whether vendor-based or open source, and the practical first needs of customers. Future-facing tool developers are addressing problems of orchestration to achieve the SOA promise. Most corporations, however, have not yet established either the services to be abstracted, or the governance requirements around exposing those services, such as the right level of service granularity. This case study is based on recent experience in the utility and retail sectors. The drivers for each are compelling: a business-driven need for IT flexibility. Examples are provided to show that customers in both sectors need to develop their architecture and governance before attempting to choose the right tools. Confusion also exists between tools and off-the-shelf solutions in the SOA environment. The challenge of agile approach for SOA development is also examined.

Qualifications and International Mobility: A Case Study of the European Chemicals Industry

2001 ◽  
Vol 175 ◽  
pp. 85-94 ◽  
Author(s):  
Heather Rolfe
Keyword(s):  
Vocational Training ◽  
International Mobility ◽  
Member States ◽  
European Centre ◽  
Considerable Impact ◽  
National Boundaries ◽  
The Right

The right of European citizens to work in other member states has been in place for many years, yet levels of movement have been lower than expected. Employers play a central role in facilitating mobility, by recruiting across national boundaries and transferring staff. Their practices are therefore likely to have a considerable impact on the extent of movement, and on the type of employees involved. This article explores the practices of employers in the chemicals industry, a key sector of the European economy. The focus of the research, which was commissioned by the European Centre for the Development of Vocational Training (CEDEFOP), was on the recruitment and transfer practices of employers, and their treatment of ‘foreign’ qualifications. The article identifies the range of approaches found in the industry and presents some of the main issues to employers in relation to recruitment and transfer across member states.

scholarly journals Multi Vehicle-Type Right Turning Gap-Acceptance and Capacity Analysis at Uncontrolled Urban Intersections

2018 ◽  
Vol 48 (2) ◽  
pp. 99-108 ◽  
Author(s):  
Doddapaneni Abhigna ◽  
Dipak P. Brahmankar ◽  
Kodavanti Venkata Raghavendra Ravishankar
Keyword(s):  
Capacity Analysis ◽  
Vehicular Traffic ◽  
Gap Acceptance ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
Vehicle Type ◽  
Traffic Stream ◽  
Critical Zones ◽  
The Right

Intersections are the critical zones where conflicting, merging and diverging movements influence the intersection capacity. Uncontrolled intersections in particular pose dangerous situations to vehicular traffic. During peak vehicular flow, the unpredictable crossing behavior of minor stream vehicles induces delay and reduces the capacity of the intersection. Capacity at uncontrolled intersections is typically measured either by gap acceptance method, empirical regression approaches and conflict technique. Gap acceptance is an important characteristic for analyzing uncontrolled intersections. The behavior of different vehicle types and gap of subject vehicle type from minor street taking right turn to merge with major traffic stream is analyzed using gap acceptance method. The objective of the current study is to analyze the effect of major stream vehicle type combinations on the minor stream vehicle gap-acceptance behavior and to determine the capacity of the minor stream taking into account the influence of the right turning vehicles. The capacity of minor stream calculated using Highway Capacity Manual (HCM) 2010, Luttenin’s model, and Tanner’s model are compared. It is observed that two wheelers are more aggressive than three wheelers for most of the major stream vehicular combinations observed in this study.

The Calculation of Turbulent Diffusion Coefficients in Aquatic Ecosystems

2019 ◽  
Vol 70 (11) ◽  
pp. 3903-3907
Author(s):  
Galina Marusic ◽  
Valeriu Panaitescu
Keyword(s):  
Transport Equation ◽  
Turbulent Diffusion ◽  
Diffusion Coefficients ◽  
Aquatic Ecosystems ◽  
Specific Area ◽  
Left Bank ◽  
The Right ◽  
Prut River

The paper deals with the issues related to the pollution of aquatic ecosystems. The influence of turbulence on the transport and dispersion of pollutants in the mentioned systems, as well as the calculation of the turbulent diffusion coefficients are studied. A case study on the determination of turbulent diffusion coefficients for some sectors of the Prut River is presented. A new method is proposed for the determination of the turbulent diffusion coefficients in the pollutant transport equation for specific sectors of a river, according to the associated number of P�clet, calculated for each specific area: the left bank, the right bank and the middle of the river.

Design of water allocation model: efficiency and risk aspects

2005 ◽  
Vol 5 (3-4) ◽  
pp. 9-16
Author(s):  
C. Kim ◽  
D. Han
Keyword(s):  
Water Allocation ◽  
Primary Objective ◽  
Allocation Model ◽  
Proportional Allocation ◽  
Model Efficiency ◽  
Service Sectors ◽  
Expected Benefits ◽  
Water Allocation Model ◽  
Allocation Methods

The primary objective of this study is to improve the methodology for water allocation focused on efficiency and risk aspects. To attain the primary objective, this study sets up an objective function to maximize social expected benefits, and considers three types of allocation methods. Three types of allocation methods are optimal, proportional, and fixed allocation between regions and service sectors. The results of case study area shows that the fixed allocation method is preferred to the proportional allocation in most cases except that the variance of flow is small with respect to efficiency. Also, efficient and less-risky allocation is simultaneously obtained in some cases, while efficiency and risk show the relation of trade-off in other cases.

Traditionalism and politics: A case study of Northern Nigeria

1967 ◽  
Vol 2 (4) ◽  
pp. 509-524 ◽  
Author(s):  
B. J. O. Dudley
Keyword(s):  
Social Change ◽  
Local Government ◽  
Status Quo ◽  
Political Elite ◽  
High Time ◽  
The Political ◽  
Northern Nigeria ◽  
The North ◽  
The Right

In the debate on the Native Authority (Amendment) Law of 1955, the late Premier of the North, Sir Ahmadu Bello, Sardauna of Sokoto, replying to the demand that ‘it is high time in the development of local government systems in this Region that obsolete and undemocratic ways of appointing Emirs’ Councils should close’, commented that ‘the right traditions that we have gone away from are the cutting off of the hands of thieves, and that has caused a lot of thieving in this country. Why should we not be cutting (off) the hands of thieves in order to reduce thieving? That is logical and it is lawful in our tradition and custom here.’ This could be read as a defence against social change, a recrudescence of ‘barbarism’ after the inroads of pax Britannica, and a plea for the retention of the status quo and the entrenched privilege of the political elite.

scholarly journals Ionic Runoff as a Way to Determine the Degree of Karst Denudation (Case Study Jasov Plateau, Slovak Karst, Slovakia)

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1449
Author(s):  
Alena Gessert ◽  
Imrich Sládek ◽  
Veronika Straková ◽  
Mihály Braun ◽  
Enikő Heim ◽  
...  
Keyword(s):  
Heavy Rain ◽  
Similar Amount ◽  
Karst Water ◽  
Karst Spring ◽  
Snow Melting ◽  
Flow Rates ◽  
Karst Springs ◽  
Degree Of Protection ◽  
Episodic Events

Estimation of the catchment area of a karst spring is not possible in all areas for various reasons. The Slovak Karst is protected by the highest degree of protection and karst springs are used as a source of drinking water for the second largest city in Slovakia, Košice. From this reason, no results on ionic runoff or chemical denudation have been published from this area and the most appropriate way to obtain information about the denudation rate is to determine the ionic runoff. This paper provides an overview of ionic runoff results based on sampling and analysis of karst water from six springs in the period November 2013–October 2016 (three hydrological years) and periodic measurements. Springs have significantly fluctuated flow rates from 0 L/s in summer and autumn up to 192 L/s, and episodic events during the snow melting and heavy rain in the spring of 2013 are also known (more than 380 L/s). The total value of ionic runoff for the area of 40,847 m3/y.km2 is comparable with the Vracanska Plateau in Bulgaria, which lies at a similar altitude and with a similar amount of precipitation.

scholarly journals Monitoring Lakes Surface Water Velocity with SAR: A Feasibility Study on Lake Garda, Italy

2021 ◽  
Vol 13 (12) ◽  
pp. 2293
Author(s):  
Marina Amadori ◽  
Virginia Zamparelli ◽  
Giacomo De Carolis ◽  
Gianfranco Fornaro ◽  
Marco Toffolon ◽  
...  
Keyword(s):  
Surface Water ◽  
Wind Waves ◽  
Test Site ◽  
Water Velocity ◽  
Surface Velocity ◽  
Medium Size ◽  
Small Scale ◽  
Lake Garda ◽  
Marine Applications

The SAR Doppler frequencies are directly related to the motion of the scatterers in the illuminated area and have already been used in marine applications to monitor moving water surfaces. Here we investigate the possibility of retrieving surface water velocity from SAR Doppler analysis in medium-size lakes. ENVISAT images of the test site (Lake Garda) are processed and the Doppler Centroid Anomaly technique is adopted. The resulting surface velocity maps are compared with the outputs of a hydrodynamic model specifically validated for the case study. Thermal images from MODIS Terra are used in support of the modeling results. The surface velocity retrieved from SAR is found to overestimate the numerical results and the existence of a bias is investigated. In marine applications, such bias is traditionally removed through Geophysical Model Functions (GMFs) by ascribing it to a fully developed wind waves spectrum. We found that such an assumption is not supported in our case study, due to the small-scale variations of topography and wind. The role of wind intensity and duration on the results from SAR is evaluated, and the inclusion of lake bathymetry and the SAR backscatter gradient is recommended for the future development of GMFs suitable for lake environments.

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