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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.



Reports on different aspects of HDM.

2018 - Roads Economic Decision Model Software
 4.33 MB

The Roads Economic Decision Model (RED) was developed under the Road Management Initiative (RMI), a key component of the Africa Transport Policy Program (SSATP) aiming at improving the decision-making process for the development and maintenance of low-volume roads. The model performs an economic evaluation of road investments options using the consumer surplus approach and is customized to the characteristics of low-volume roads such as a) the high uncertainty of the assessment of the model inputs, particularly the traffic and condition of unpaved roads; b) the importance of vehicle speeds for model validation; c) the need for a comprehensive analysis of generated and induced traffic; and d) the need to clearly define all accrued benefits. RED computes benefit for normal, generated, induced, and diverted traffic, and takes into account changes in road length, condition on the dry and wet seasons, geometry, surface type, and accident rates. Users can add to the economic analysis other benefits or costs such as social benefits and environmental impacts, if computed separately. RED is setup on a series of Excel workbooks, which collect all user inputs and present the results on an efficient manner, performing sensitivity, switching values and risk analyses. The current version of RED (Version 4.0), released in April 2018, which is available only in English, adds optionally CO2 emissions benefits or costs to the cost benefit analysis. RED version 3.2 is available in English, French and Spanish. With the same input data, both Version 3.2 and 4.0 produce the same results.

2015 - Road User Charges Model Software
 441.02 KB

The Road User Charges Model (RUC) estimates road user charges required to ensure that, for a particular country, the costs of operating and maintaining all roads are fully-funded, and that each vehicle class covers its variable costs. The model is an Excel workbook that: (i) estimates annualized maintenance costs needed to maintain a stable road network; (ii) defines countrywide annual recurrent expenditures, annual investments needs, and source of financing; (iii) estimates road user revenues from annual license fees, fuel levies, load damage fees, and tolls; (iv) analyzes the allocation of road user revenues and optimizes road user charges; and (v) computes externalities and summary macro indicators. Some of the functionality of the RUC model can be found on the RONET model.

The paper presents an optimal control theory-based procedure for finding the optimal timing and intensity of pavement maintenance treatments, which was adjusted based on the models for pavement deterioration and road user costs from the HDM-4 and RUCKS models. The model for improvement in pavement condition after a maintenance treatment was calibrated according to Paterson’s bilinear model. The closed-form solution is then compared to the solution obtained by using genetic algorithms (GAs). In both methodologies special attention was given to the quality of the “optimal” solution in terms of evaluating: (i) the time between the maintenance treatments; (ii) minimal/maximal thicknesses of overlays calculated in the optimal maintenance plan; and (iii) parameters defining pavement condition before and after the maintenance treatment. The comparison between the two methodologies allowed analyzing limitations in each one of them and led to improvements in the “optimal” solution.

2009 - HDM4 - Volume 1: Model Overview
 2.52 MB

Volume 1 of HDM-4 documents giving model overview.

2009 - HDM-4 - Overview of the Model
 2.52 MB

An oveview of the HDM-4 model. Updated for Version 2.

2009 - HDM-4 - Application Guide
 4.65 MB

A guide on how to apply HDM-4 for different types of analyses.

2008 - World Bank - HDM-4 Training Course Presentations
 12.9 MB

Presentations from the World Bank's HDM-4 training course.

2008 - World Bank - HDM-4 Training Course Case Studies
 4.05 MB

Case studies used for World Bank HDM-4 training.

This paper proposes the use of gradient search methods with what-if models to find the true optimums. It shows, with case studies, the feasibility of using the steepest descent method and the conjugate gradient method along with HDM-4 to find the true optimum maintenance options.

2004 - Japan - Pitfalls of HDM-4 Strategy Analysis
 92.38 KB

This paper suggests guidelines on the selection of good maintenance and improvement policies for all links while doing strategy analysis with dynamic sectioning approach. In addition to the trade-off in terms of accuracy and convenience with the use of the road network matrix approach versus dynamic sectioning approach,practitioners are confronted with several practical issues involved in doing strategy analysis such as the relationship between the “planning period” of the strategic plan and the “analysis period” of the HDM runs for analyzing it, obtaining a uniform outlay of investments over the planning period, etc.

2003 - HDM-4 - Overview of HDM-4
 613.96 KB

HDM-4 Volume 1 - An overview of the model

1998 - Australia - Structured Testing of the HDM-4 RUE Model
 576.25 KB

Report describing the testing of HDM-4 Beta for Australia and issues that were encountered

This report describes reasonableness testing of PDWE Models (Pavement Deterioration and Works Effects) for Australia.

ARRB proposal on how HDM-4 should be tested and implemented for Australia
Paper on how to undertake environmental assessments.

1995 - Sweden - IT Strategy and Software Development
 473.9 KB

Paper on IT strategy and software development for HDM-4 from Sweden

1995 - ISOHDM Technical Relationships Study Interim Report
 97.41 KB

Interim report from the HDM-4 Technical Relationships Study in Malaysia.

1995 - International - Review of Experience With HDM-III
 1.12 MB

A review of how HDM-III was used in studies in different countries.
Proceedings from a workshop held to discuss the framework for strategic and programming analyses in HDM-4

1995 - HDM-4 - Concept Outline of Strategic Analysis
 681.03 KB

Conceptual design for strategy analysis by Bill Paterson

Inception report from the HDM-4 Technical Relationships Study in Malaysia.

1994 - HDM-4 Workshop - Vol 2
 13.14 MB

Workshop on HDM-4 held in Malaysia. Contains a wide range of papers on application of HDM-III and other issues.

1994 - HDM-4 Workshop - Vol 1
 12.78 MB

Workshop on HDM-4 held in Malaysia. Contains a wide range of papers on application of HDM-III and other issues.
Responses from various people on the proposals and issues raised at the HDM-4 Inception Workshop

1994 - Archondo-Callao - HDM Manager Training Materials
 406.99 KB

Training materials from the World Bank for HDM Manager.

1994 - Archondo-Callao - HDM Manager Manual
 2.47 MB

User manual for the HDM Manager - a front end to HDM-95.

1993 - HDM4 - Inception Workshop Report
 3.64 MB

Report on workshop held in UK in 1993 to lay the foundations for the ISOHDM Project which developed HDM-4

1993 - HDM-4 - Report on HDM-4 Inception Workshop
 3.64 MB

Report summarizing the papers and issues presented at the Inception Workshop for HDM-4.

1992 - Archondo-Callao - HDM-III Training Materials
 321.98 KB

Training materials from the World Bank on HDM-III.

1992 - Archondo-Callao - HDM-95 Manual
 354.22 KB

User manual for HDM-95.

1989 - Paterson - Synthesis of HDM Relationships
 796.15 KB

Paper summarising HDM-III's pavement deterioration and vehicle operating cost relationships.

1989 - NZ - New Zealand Vehicle Operating Costs Model
 58.76 MB

Road Research Unit Bulletin 82. This is the first NZVOC Model which was used to generate the vehicle operating costs for the Project Evaluation Manual.

1987 - World Bank - HDM-III: Vehicle Operating Cost Models
 19.51 MB

HDM-III reference manual Volume 3

1987 - World Bank - HDM-III: User's Guide
 13.01 MB

HDM-III reference manual Volume 2
HDM-III reference manual Volume 5

1987 - World Bank - HDM-III: Model Description
 12.94 MB

HDM-III reference manual Volume 1

1986 - NZ - Representation of Traffic Data
 6.74 MB

Conference paper showing how traffic flow data over a year has a bi-modal distribution and how this can be modelled. Provided key foundational work applied later in HDM-4.


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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