This report describes a study into the problems for both the bus operator and the passenger of bus defects which are reported by drivers whilst during or out of service. Analyses have been carried out using historical data on the frequencies of occurrence of defects, times of service depletion and overall repair times for several different bus types from a few urban bus operators in Britain. The frequency, expressed as the number of defects per 1000 km of bus distance operated, which were sufficient to disrupt services varied from about 0.01 to 0.24 and the frequency of other defects could be as high as 3.5 per 1000 bus-km. Many defects were associated with engine auxiliaries and electrical components and their frequencies were found to be affected by the bus age, bus type and time of year. Buses of a particular type aged over 7 years were found to have a frequency more than four times that of buses of the same type aged less than 2 years, and there were similar findings for other bus types. For some operators the older, traditionally-designed buses had lower frequencies of defects, but for other the more modern designs had the lower frequencies. The average amount of repair time spent by skilled staff on buses in one garage was found to be 2.8 hours per defect, or at least 2.2 hours per 1000 km of bus distance operated. The results of these analyses are used to produce guidelines for the length of time required for trials, that should be undertaken by operators, to compare the performance of a small number of (trial) buses with that of the other buses in the same fleet. For a major change in maintenance or operating procedure, likely to affect the frequency of defects or repair times by a large amount, a sample of 100 defects of the trial buses may be sufficient to establish a significant difference in performance and such a trial may only be needed for 3 or 4 weeks. However to test for a relatively minor change, a sample of more than 1000 defects requiring a trial of over 1 year may be needed. Advice of this kind could be used by operators to obtain reliable information on how to minimise the cost of trials designed to test the significance of any proposed change.

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  • Corporate Authors:

    Newcastle upon Tyne University, England

    Claremont Tower, Claremont Road
    Newcastle NE1 7RU, Tyne and Wear,   England 
  • Authors:
    • Jenkins, I A
  • Publication Date: 1979-7

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Filing Info

  • Accession Number: 00312257
  • Record Type: Publication
  • Report/Paper Numbers: Res Rpt. No. 29
  • Files: TRIS
  • Created Date: Jul 22 1980 12:00AM