Final report. Volume 5, Research on the Interrelationships Between Costs of Highway Construction, Maintenance and Utilization

Abstract

This Volume records the activities of the PICR User Cost Surveys Group which conducted a large vehicle operating cost survey in Central, Western and Southern Brazil during the period 1975 to 1981. The Group was responsible for the collection and analysis of vehicle maintenance parts and labor costs, tire costs, depreciation and interest charges, and drivers' salaries. In addition, fuel consumption and speed data were collected, the latter when easily available, to serve as consistency checks on the equations derived from experimental data. The Group was also responsible for collecting data on surface roughness, as well as vertical and horizontal geometry characteristics of the routes of those operators registered in the survey. The primary data collection phase ran from 1975 to 1979. and 26 staff members were employed , comprising 14 field workers , 8 clerical assistants and 4 supervisors. More than two years was spent in developing and testing appropriate methodologies, documentation and data p.rocessing systems for the collection, checking, .storage and analysis of both operating cost and highway characteristic data. Contact was made with over 300 companies and more than 2500 vehicles were regis tered for survey membership. Operating cost data were then collected on_ a regular basis from company records. Many difficulties had to be overcome during this period. A number of companies only had records of a few cost components and, where possible, assistance was givento provide the necessary documentation and training to collect missing items. Some companies dropped out of the survey and data collection in others was discontinued because the route characteristics of their vehicles were found to be redundant to the needs of the PICR. Finally, data on over 1600 vehicles derived from 132 companies were available in for preliminary analysis. 1979 Highway characteristics were collected using two specially instrumented vehicles. Roughness was measured with a Maysmeter and calibration maintained through a GM Profilometer and Quarter-Car~Simulator which generated a se~ies of profile~ for a calibration course of highway sections established near Brasflia. Vertical geometry w~s measured using a linear accelerometer connected to a panel scale capable of recording grade changes + of - 1% + to - 12%. Horizontal measurements were taken from a standard aircraft directional gyro compass, mounted in the survey vehicles. Over 85,000 km of roughness and geometry data were collected after measuring more than 36,000 km of operators' routes. After .editing, these data had then to be combined with the vehicle operating cost data so that a single file comprising both dependent and independent variables could be made available for analy~is. The second PICR Phase covered the period 1980 to 1981. The staff was reduced to 5, who were principally engaged in conducting more detailed analyses. The statistical methods employed were rationalized into distinct groups of techniques and advanced econometric procedures employed. An important technique which provided a number of the equations reported herein was the generalized least squares estimation of the error ~omponent model. The latter considers. the company specific error term and the vehicle specific error term which jointly form the components of the unknown random error term consider~d by ordinary least squares techniques. This is one of the first reported application of error components analysis in the field of transportation stu - dies. All the different techniques are detailed in the analysis pro - cedures section of this Volume. The analyst was able to run a selec - tion of these techniques simultaneously on any data set. This made comp~rison of the results and the choice of recommended equations an easier task. Vehicle operating cost information presented for analysis cover the full range of vehicles operating on Brazilian highways. These are grouped into cars_. utility vehicles, buses, medium trucks and heavy articulated vehicles for analysis purposes. The results of the anal - yses of fuel consumption, oil and grease consumption, maintenance parts and labor, tire consumption, depreciation and interest charges and vehicle speed are presented. All five vehicles classes are used in the analyses except for speed which is restricted to cars and buses, and tire costs which are analysed by tire size. The equations recommended in this Volume concentrate on estimating roughness, vehicle age, vehicle characteristics (where appropriate) and geometry effects only when these appear unambiguous. A substantial amount of time was spent estimating the effect of geometry on the various operating cost items and details on the progress made are given in both main text and selected appendices. It is clear that more time is needed to resolve th~ issue. Further small analyses, .together with the findings of the operating cost study in India, presently being analysed, may result in the emergence of a more coherent pattern of the geometry effect on user costs. The PICR User Survey data are the most comprehensive collec~ ed to date and are important both to Brazil, where out-of-date cost tables are widely used and the international research community~ where they .complement the Kenya. Caribbean and India studies. The PICR survey data covers a spectrum of vehicle types and appears to be the only study with a full range of truck classes. The data have now passed through several phases of analysis and the results presented in this Volume. together with the relevant technical memoranda, can be regarded as an interim final form. They are now ready for extensive evaluation in a variety of economic exercises. When they have passed these tests they can be viewed as being in final form for the period ending December 31, 1981. Comparistins are made between total operating costs predict - ed from the various equations recommended in this Volume and prevail - ing transport service rates and tariffs. The results are encouraring and give confidence to the view that the recommended equations will provide better predictions of vehicle operating costs than anything currently used in Brazil. It is recommended that a user cost manual be prepared to allow the results of the PICR survey to be widely disseminated.