Henry Kerali Lead Transport Specialist The World Bank Introduction to HDM-4 Henry Kerali Lead Transport Specialist The World Bank

Transport and Development Transport sector is vital for economic & social development Roads constitute the largest component of transport Roads require a balance of: Maintenance (or Preservation) Development (or Improvement) Objective of Road Management Consistent and Rational Policy Objectives Sufficient and Reliable Funding Effective Procedures & Management Tools

Economic basis for selecting investment alternatives HDM-4 Objectives . Economic basis for selecting investment alternatives Road standards Pavement standards Alignments

HDM-4 Objectives .. Standard framework for investigating road investments Minimize Road Agency and Road User Costs Non-motorized transport facilities Traffic congestion Vehicle emissions Travel times Transport costs Road accidents

History of the HDM model 2000 ISOHDM RTIM (TRRL) RTIM2 (TRL) RTIM3 The first move towards producing a road project appraisal model was made in 1968 by the World Bank. The first model was produced by MIT following a literature survey and was based mainly on a framework proposed by de Weille. The resulting Highway Cost Model (HCM) highlighted areas where more research was needed to provide a model that was more appropriate to developing country environments with additional specific relationships. Following this, TRRL, in collaboration with the World Bank, undertook a major field study in Kenya to investigate the deterioration of paved and unpaved roads as well as the factors affecting vehicle-operating costs in a developing country. The results of this study were used by TRRL to produce the first prototype version of the Road Transport Investment Model (RTIM) for developing countries. In 1976, the World Bank funded further developments of the HCM at MIT that produced the first version of the Highway Design and Maintenance Standards model (HDMII). Further work was undertaken in a number of countries to extend the geographic scope of the RTIM and HDM models, including; the Caribbean Study by TRRL which investigated the effects of road geometry on vehicle operating costs, the India Study by the Central Road Research Institute which studied particular operational problems of Indian roads in terms of narrow pavements and large proportions of non-motorised transport, and the Brazil Study funded by UNDP, which extended the validity of all of the model relationships.

HDM-4 Concept Predicts road network performance as a function of Traffic volumes and loading Road pavement type and strength Maintenance standards Environment / Climate Quantifies benefits to road users from: Savings in vehicle operating costs (VOC) Reduced road user travel times Decrease in number of accidents Environmental effects The HDM-4 analytical framework is based on the concept of pavement life cycle analysis. This is applied to predict the following over the life cycle of a road pavement, which is typically 15 to 40 years: Road deterioration Road work effects Road user effects Socio - Economic and Environmental effects Once constructed, road pavements deteriorate as a consequence of several factors, most notably: Traffic loading Environmental weathering Effect of inadequate drainage system

Optimum Transport Costs Total Optimum Road User Road Works Design Standards

Road Management Purpose: Typical objectives: To optimise the overall performance of the network over time in accordance with POLICY OBJECTIVES and within budgetary constraints Typical objectives: Minimise transport costs Preserve asset value Provide and maintain accessibility Provide safe and environmentally friendly transport 1. Another way of defining the purpose would be ‘to maintain and improve the existing road network to enable its continued use by traffic in an efficient, safe and environmentally appropriate manner’.

Life Cycle Costs Road Agency Costs Road User Costs Management, Operations Labor, Equipment, Materials Land acquisition Maintenance and Rehabilitation Road User Costs Vehicle operation Travel time Road accidents 1. The cost components are self explanatory. Each item will be costed using “ECONOMIC PRICES” not “MARKET PRICES”. To ensure the analysis is correct all costs in the project will be at a given date and exclude taxes . 2. The proportions of labour and machinery costs will depend upon the choice of technology chosen for the project. Labour intensive projects are often specified by lending agencies and governments these will obviously use less machinery and more labour than a capital intensive project. 3) Land. It maybe that land will need to be acquired for the road construction. Where land cannot be put to any other use (e.g.. For a road crossing a desert) its economic value will be zero but land clearly has a value if it can be used for farming or housing or industrial use.

Comparison of Project Alternatives Discounted RAC (Road works + RUC) Project Life (years) End of Analysis Without Overlay NPV With Overlay

Comparison of Project Alternatives Discounted RAC Without Paving NPV RUC Cost of Paving Project Life (years) End of Analysis

Life Cycle Analysis Predict Road Deterioration Input Data Predict Road Work Effects Repeat for all years VOC, Accident & Time costs Discount Annual Costs & Compare Output NPV, IRR,..

Road Deterioration Predict long term pavement performance Predict effects of maintenance standards Calculate annual costs: Road Agency + Road User Poor Maintenance Standard The figure illustrates the predicted trend in pavement performance represented by the riding quality that is often measured in terms of the international roughness index (IRI). When a maintenance standard is defined, it imposes a limit to the level of deterioration that a pavement is permitted to attain. Consequently, in addition to the capital costs of road construction, the total costs that are incurred by road agencies will include the periodic maintenance, or rehabilitation works applied during the life of a pavement. These in turn depend on the standards of maintenance and improvement specified by HDM-4 users. Road Condition Pavement Performance Curve Rehabilitation Good Time (years) or Traffic Loading

Pavement Performance Pavement Types modelled: Bituminous (AC, ST, etc.) Unsealed (Gravel, Earth, Sand, etc.) Concrete (JPCP, JRCP, CRCP, etc.) Block (Bricks, etc.) Models from pavement performance experiments in: Brazil, Kenya, India, South Africa France, USA, Sweden, Finland, Australia The overall long-term condition of road pavements directly depends on the pavement type and strength, traffic loading, the environment and the maintenance or improvement standards applied to the road. The rate of pavement deterioration is directly affected by the standards of maintenance applied to repair defects on the pavement surface such as cracking, ravelling, potholes, etc., or to preserve the structural integrity of the pavement (for example, surface treatments, overlays, etc.), thereby permitting the road to carry traffic in accordance with its design function. The pavement deterioration models in HDM-4 are based on models derived from results of large scale field studies carried out in Brazil, Kenya, South Africa, Sweden and Australia.

Principles Of Deterioration Models Models are structured empirical Individual distresses modelled separately Relationships are incremental and recursive dY = K a0 f(X1, X2, X3, etc) Modelled sequentially through to roughness Maintenance intervention at end of each year 1. Empirical - based on observed performance of roads. Structured - variables included in the relationships are based on theoretical understanding; i.e. mechanistic behaviour of pavements. 2. Each distress modelled separately; e.g.cracking, rutting etc. 3. Incremental - change in magnitude rather than absolute. Recursive - year on year (possibly seasonal in future). 4. Distresses are inter-related; e.g. cracks let in more water which means that road roughness will increase at a greater rate. Hence there is a logical order in which the computer models the various distresses. 5. At the end of each year, maintenance interventions are applied. These might reset the value of a distress. Next year the model applies the incremental change to this value.

Cracking Initiation Model ICA=Kcia{CDS2*a0exp[a1SNP+a2(YE4/SN2)+CRT} ICA time to cracking initiation, in years CDS construction quality SNP structural number of pavement YE4 traffic loading Kcia calibration factor CRT effect of maintenance

All Cracking Progression CRP = retardation of cracking progression due to preventive treatment Progression of All cracking commences when tA > 0 or ACAa > 0

Pavement Deterioration Concept 1 Water ingress Further cracking Patches Shear Uneven surface Spalling Faster deformation ROUGHNESS Potholes Time Surface Lower strength Area of Cracking Rut depth

Concrete Roads Models From USA Chile Joint Spalling Punch outs Cracking Faulting Slab failures Riding Quality Models From USA Chile

Bituminous Pavements Predicted defects: Cracking Ravelling Edge Break Potholes Riding Quality Skidding

Bituminous Road Deterioration .

Bituminous Road Deterioration ..

Unsealed Roads

Unsealed Road Deterioration ..

Unsealed Road Deterioration …

Road Work Classification Preservation Routine Patching, Edge repair Drainage, Crack sealing Periodic Preventive treatments Rehabilitation Pavement reconstruction Special Emergencies Winter maintenance Development Improvements Widening Realignment Off-carriageway works Construction Upgrading New sections

Road Works

Road Work Effects Condition Reconstruct Overlay Traffic / Time 10

Road User Effects

RUE Components MT Vehicle operating costs (VOC) MT Travel time costs (TTC) NMT Time and operating costs (NMTOC) Accident costs (AC) RUE = RUC + Emissions + Energy + Noise RUC = VOC + TTC + NMTOC + AC

Road User Effects Vehicle operating costs Travel time Road accidents fuel, oil, tyres, parts consumption vehicle utilisation & depreciation Travel time passengers cargo Road accidents Non-Motorized Transport Energy consumption Vehicle emissions & noise The impacts of the road condition, as well the road design standards, on road users are measured in terms of road user costs, and other social and environmental effects. Road user costs comprise: Vehicle operation costs (fuel, tyres, oil, spare parts consumption; vehicle depreciation and utilisation, etc.), Costs of travel time - for both passengers and cargo, and Costs to the economy of road accidents (that is, loss of life, injury to road users, damage to vehicles and other roadside objects). The social and environmental effects comprise vehicle emissions, energy consumption, traffic noise and other welfare benefits to the population served by the roads. Although the social and environmental effects of often difficult to quantify in monetary terms, they can be incorporated within the HDM-4 economic analyses if quantified exogenously. Note that in HDM-4, road user effects can be calculated for both motorised transport (motorcycles, cars, buses, trucks, etc.) and non-motorised transport (bicycles, human powered tricycles, animal pulled carts, etc.).

RUE Features in HDM-4 Effects of traffic congestion on speed, fuel, tyres and maintenance costs Non-motorised transport modelling Effects of road works on users Traffic safety impact Vehicle emissions impact Vehicle noise impact

Motorised Vehicles

Impact of Road Condition on VOC Heavy Truck Bus Road User Costs ($/veh-km) Pickup/utility The figure illustrates the impact of road condition (represented in terms of the IRI) on the operating costs of different types of vehicles. Road User Costs in HDM-4 are calculated by predicting physical quantities of resource consumption and then multiplying these quantities by the corresponding user specified unit costs. It is necessary to ensure that the vehicle resource quantities predicted are in accordance with the range of values observed in the area of application. Car Rickshaw Good Road Condition (IRI) Poor

Non-Motorised Transport

Role of HDM-4 1. Will be discussing the details of the different applications of HDM-4 in later sessions, but this provides an overview. HDM-4 is a decision support system and helps us with the above functions. 2. Note that HDM-4 only has its own database developed specifically for the various analyses which it carries out. It is not a road management system, or pavement management system, in its own right although data can be imported from such systems for use in HDM-4.

Road Management Functions Planning Setting standards and policies Long term estimates of expenditure Programming Medium term work programmes Preparation Detailed project design and work packaging Operations Implementation of works in field 1. These are fairly self explanatory but the trainers should develop typical brief examples from their own countries. Planning - setting standards, broad network, not spatial (e.g. we are concerned with the issue ‘$x spent on the national network over the next y years would result in z% of the network having a roughness less than...’ Programming - works programmes at network level (1,5 year programmes etc) Preparation - detailed designs and work packages Operations - managing the work and scheduling work, monitoring costs etc

HDM-4 Applications Road sector policy studies Strategic planning of road network development, improvement & maintenance Determination of funding requirements Preparation of multi-year road work programmes Economic appraisal of individual road projects Research studies Road pricing Vehicle regulations Pavement design standards

Standards & Policies Road pricing Vehicle regulations road use costs (to define fuel levies) congestion charges weight-distance charges Vehicle regulations axle load limits energy consumption, vehicle emissions & noise Engineering Standards sustainable road network size pavement design and maintenance standards

Strategy Analysis Objectives: Analysis of entire road networks to determine funding needs and predict performance under budget constraints Objectives: Determine budget allocations for road maintenance and improvement Prepare work programs Determine long term network performance Assess impact on road users 2

Strategic Analysis Approach Road Network G F P Matrix H M L Preservation Evaluation Resource Constraints Revenues, Sector budgets Development Candidates Optimal Strategy under Budgetary Constraints Optimization Module

Effect of budget levels Primary Roads Annual Budget $10m $15m $20m Target = 3.5 IRI

Road Network Performance Budget Allocations Feeder Roads $30m/yr Secondary Roads $35m/yr Primary Roads $20m/yr

Budget Scenario Analysis

Optimal budget requirements

Programme Analysis Preparation of single or multi-year expenditure programs under specified budget constraints. Objective: prioritise candidate road projects in each year within annual budget constraint Annual budgets obtained from strategic maintenance plan

Procedure . Use specified standards to screen network & identify candidate projects, e.g. road sections which exceed specified condition roads with inadequate capacity pavements which need strengthening upgrade pavements with high traffic volumes

Procedure .. Determine maintenance or improvement options Specify budget limits & periods Optimise using selected objective Produce optimal list of projects for budget period

Work Programme Output 2003 2004 2005

Project Appraisal Project types Economic indicators New construction, upgrading Reconstruction, resealing Widening, lane addition Non-Motorised Transport lanes Economic indicators Net Present Value (NPV) Economic Rate of Return (ERR) Benefit Cost Ratio (BCR), NPV/C First Year Rate of Return (FYRR)

Project Level Outputs Sensitivity analysis results Scenario analysis Road condition indicators Road user cost details Energy & emissions

HDM Technology Set Knowledge Base Software Models SEE RDWE RUE

HDM Series

Conclusions – Why HDM-4? Transparency of analysis Life cycle analysis capable of: Short, Medium & Long term analyses What-if analysis Internationally accepted analysis framework Availability of technical expertise Local calibration

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