1887

oa Civil Engineer in South Africa - Metropolitan transportation : problems, projections and solutions

 

Abstract

Until a few years ago transportation studies were rather simple mechanical processes, usually yielding questionable proposals, with the result that expenditure in implementing transportation schemes ran the risk of being wasteful. Two elements of this problem are the difficulty of sampling and collating base land-use and transportation data and choosing or developing models which will realistically project the data to the target dates chosen.


In the Cape Town Study one of the difficulties encountered was that of effectively transferring data, aggregated in zones of homogeneous land-use, to traffic generation zones. Another difficulty was how best to deal with the socio-economic and travel characteristics of the non-white population. Because major unforeseeable incidents and developments such as fuel price increases, booms, depressions and changes in employment policies must have a tremendous influence on travel parameters, the outputs of projection models are often grossly inaccurate and of little real value.
A partial answer to this dilemma is to broaden the scope of forecasting to cover a spectrum of possible future situations rather than a unique one. A method now favoured is the use of .
A further general problem is how best to optimize modal split between bus, train and private cars. A compromise between several conflicting factors must be sought In order to optimize the use of all the presently available and future proposed facilities.

Tot 'n aantal jare gelede was vervoerstudies taamlik eenvoudige meganiese prosesse wat gewoonlik twyfelagtige voorstelle tot gevolg gehad het, met die gevolg dat uitgawes aan die implementering van vervoerskemas verkwistend bestee mag word. Twee elemente van hierdie probleem is dle moeilikheid wat ondervind word in die monstering en vergelyking van basiese grondgebruik- en vervoerdata en die keuse of ontwikkeling van modelle wat die data realisties tot die gekose voorgenome datum sal projekteer.


In die Kaapstadse Vervoerstudie was een van die probleme wat ondervind is die van die doeltreffende oorplasing van data, byeengebring in sones van homogene grondgebruik, na verkeerverwekkingsones. Nog 'n probleem was hoe om die sosio-ekonomiese en reiskenmerke van die nie-blanke bevolking te hanteer. Omdat belangrike onvoorsienbare gebeure en ontwikkelinge soos brandstofprysverhogings, oplewing en daling van die ekonomie en veranderinge in indiensnemingsbeleid 'n geweldige invloed op reisneigings en gewoontes moet hê, is die resultate van projeksiemodelle dikwels uiters onakkuraat en van min werklike waarde.
'n Gedeeltelike antwoord op hierdie probleem is om die omvang van die voorspelling te verbreed om 'n spektrum van toekomstige situasies, eerder as 'n enkele een, te dek. 'n Metode wat nou guns gewen het is die gebruik van .
'n Ander algemene probleem is hoe om die modaleverdeling tussen bus, trein en private motors te optimaliseer. 'n Skikking tussen verskillende teenstrydige faktore moet gevind word ten einde die gunstige gebruik van al die huidig beskikbare en toekomstig voorgestelde geriewe te verkry.

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/content/civeng1/23/6/EJC24851
1981-06-01
2016-12-04
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