Additional modules include:
Historically, HDM-4 prioritized economic efficiency (Net Present Value). Today, agencies are demanding carbon footprint analysis. New hdm-4 software
| Software | Focus | Integration with HDM-4 | |----------|-------|------------------------| | | Network-level optimization | Can import HDM-4 deterioration models | | RoadAssist (World Bank) | Simplified project appraisal | Lighter version of HDM-4 principles | | Pavement LCCA (FHWA) | Lifecycle cost only | Less comprehensive than HDM-4 | | VOC Tools (PIARC) | Vehicle operating costs only | Used as a sub-module within HDM-4 | Engineers use it to compare different design options—such
This is the most detailed level, used to evaluate a specific road investment. Engineers use it to compare different design options—such as choosing between asphalt and concrete—based on the Net Present Value (NPV) and Internal Rate of Return (IRR). Key Components of the HDM-4 Model traffic direction | PMS database
| Data Layer | Key Inputs | Typical Source | | :--- | :--- | :--- | | | Road ID, length, width, surface type, traffic direction | PMS database, GIS | | Pavement Condition | Initial IRI, cracking %, rut depth (mm) | Laser profilometer, manual surveys | | Traffic | AADT, vehicle class distribution (car, bus, 2-axle truck, articulated truck), annual growth rate, ESA/vehicle | Weigh-in-motion (WIM), traffic counts | | Climate | Mean annual rainfall, temperature, Thornthwaite moisture index | Weather stations, satellite reanalysis | | Economics | VOC per vehicle type, value of time, discount rate (typical 12% for developing nations), construction unit costs | National statistics, tender data |