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Welcome to Chris Bennett's and Lis Pedersen's web site. If you are looking for information Chris' current work on affordable housing, please visit www.mygbhousing.info. The video below tells the background to Chris' project.



Maintenance and repairs.

2021 - USA - Total Cost of Vehicle Ownership
 6.94 MB

Detailed analysis of the total cost of ownership (TCO) consisting of all costs related to both purchasing and operating the vehicle. This TCO analysis builds on previous work to provide a comprehensive perspective of all relevant vehicle costs of ownership. In this report, we present what we believe to be the most comprehensive explicit financial analysis of the costs that will be incurred by a vehicle owner. This study considers vehicle cost and depreciation, financing, fuel costs, insurance costs, maintenance and repair costs, taxes and fees, and other operational costs to formulate a holistic total cost of ownership and operation of multiple different vehicles. For each of these cost parameters that together constitute a comprehensive TCO, extensive literature review and data analysis were performed to find representative values in order to build a holistic TCO for vehicles of all size classes. The light- and heavy-duty vehicles selected for analysis in this report are representative of those that are on the road today and expected to be available in the future. Table ES-1 summarizes the main parameters in this study, including the cost components which comprise TCO, the sizes and vocations of vehicles which are analyzed, the powertrains of these vehicles, and the model year for analysis of both current and future vehicles.

A techno-economic model is developed based on road-load simulation results expressed in relation to slip energy (SE) at the tire–pavement interface and the repair and maintenance (R&M) cost obtained from published sources and data from state agencies. Tire SE allows for the consideration of aggressive acceleration and deceleration, high torque conditions (for instance, driving an upslope grade), and roadway curvature. Tire SE data used in this effort were generated using physics-based simulation models of different vehicle types for arrays of road conditions (e.g., grades, curvatures) and driving cycles (i.e., vehicle speed profiles). R&M costs were estimated for various vehicle categories and accumulated vehicle mileage. The approach is based on relating the probability density functions (PDFs) of SE and R&M costs. Asymptotic series expansion for an incomplete gamma function was used to approximate the gamma functions and to determine the gamma ratio function that is used as the coefficient to SE to estimate R&M costs. The average R&M cost per mile results from the model compared with the arithmetic mean R&M cost data from fleet operators and published data. The model can serve as a method for predicting R&M cost as a function of road load to vehicle fleet.

2003 - Improved Maintenance Relationships
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TRL Report R7456 - Excellent report describing a study into maintenance relationships with data from India, Indonesia and Ghana

2003 - Dunkerley - Improved Maintenance Relationships
 3.05 MB

Report describing vehicle maintenance and repair relationships.

A report on the study to obtain better vehicle maintenance cost relationships for HDM-4. Report describes the data collection and preliminary analysis of Indonesia maintenance cost data.

A report on the study to obtain better vehicle maintenance cost relationships for HDM-4. Report describes the data collection and preliminary analysis of Indian maintenance cost data.

A report on the study to obtain better vehicle maintenance cost relationships for HDM-4. Report describes the data collection and preliminary analysis of Ghanain maintenance cost data.

1998 - Revision to HDM-4 Parts Model Parameters
 64.08 KB

Memo describing revisions to parts model parameters

1996 - Parts Consumption Modelling in HDM-4
 24.97 KB

Memo describing issues with parts modelling
Original proposal for HDM-4 maintenance cost modelling

1995 - Cundill - Proposed HDM Maintenance Relationships
 1.22 MB

Report presenting initial proposal for how to model vehicle maintenance and repair costs.


Chris in the NCT Race 

Chris has an adventurous spirit which generally involves cycling, running, or just being out there having a good time. Read his 'Race Reports' below. This is a link to his SPOT GPS tracker. If you are interested in his 'geeky' sport technical blog it is at www.tri-duffer.com. He also has stories of his life as 'An Overtravelled Engineer Working for the World Bank' at World Bank Traveller.


Race Reports


Document Library


  • Chris' published papers and reports are here.
  • His Technical Library  has a range of reports 
  • Golden Bay community projects are here.
  • The history of the ROMDAS company is here.
  • The 'Road to Good Health' HIV/AIDs Toolkit is here.


Technical Library

Chris and Lis

Chris and Lis

We are Lis Pedersen and Chris Bennett. We’ve been married over 30 years and each found our way to New Zealand in the early 1980s from Denmark and Canada respectively. Golden Bay has been our happy place for almost 20 years and we are now based in Pohara just above the beach, with our two cats Coco and Max. 




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