Pavement Management System (PMS)
Development and research
The development and adaptation of the Pavement Management System to German conditions was followed by the first successful application in 1999. Practical tests showed that the tool achieved good results for federal highways. The PMS is now being used in nearly all federal states to support the planning engineers.
The PMS has been continuously developed and improved since its first use in 1999. The goal is to improve the ability of the program to model reality in a stepwise manner and to integrate it more tightly with the requirements of daily road maintenance practice.
The research topics at the BASt for further development of road maintenance planning including PMS are varied and extend from better selection of contract sections, cost assessment, consideration of structural maintenance, updating of the behaviour functions, assessment of the residual value, improved building substance valuation, consideration of the building site management and aspects of the total economy to integration of restructuring and extension measures.
The PMS was designed as an open system with a modular structure. This module-type structure allows focused development and continuous improvement of the individual modules. Experiences in maintenance planning and research are directly used in practical applications through an appropriately revised and extended system. Updating, id est the replacement of individual modules, is performed without affecting the total system.
Data source and condition development
A condition survey for federal highways has been performed since 1992 in a four-year cycle. In many federal states, the condition of the state and regional roads is surveyed as well.
The Road Monitoring an Assessment (ZEB) takes place in four sub-projects (TP):
- Longitudinal and transversal evenness (TP 1a and 1b)
- Skid resistance (TP 2)
- Substance characteristics of the surface (TP 3)
- Evaluation of the data collected (TP 4).
The ZEB data only provide snapshots of the road condition, while plans have to be made for several years in advance. Specific maintenance planning, which is performed for federal highways for periods of four years, therefore requires an estimate of the condition development. Such network-wide estimates of the condition development can no longer be done by hand where large road networks are involved.
The application of the PMS therefore allows further optimisation of maintenance planning, which is mainly based on the consideration of different input data: inventory data, condition data, structural data, maintenance history, traffic data, traffic safety data and additional user-relevant data are included in the evaluation. In particular, the substance value of the inventory is used in the calculations of the PMS to consider the age and the thickness of the layer in addition to the substance value of the surface. This makes it possible to give higher weight to the substance during maintenance planning.
Planning of maintenance measures with PMS
PMS is able to estimate the condition development of the road surface and the road substance in the road network considered, based on known behaviour curves and current status results and as a function of the budget allocated.
PMS prediction of usage value characteristics
PMS prediction of substance characteristics
The percentage distribution over the four status classes described below can be calculated for the road network considered for each characteristic and year and as a function of the budget allocated:
- Blue: Very good
- Green: Good/satisfactory
- Yellow: Sufficient
- Red: Bad/very bad
This allows an estimate of the condition development over several years (prediction), which can be used for appropriately adjusted, network-wide optimised maintenance planning.
In essence, a PMS run involves eight modules:
- The first module combines areas with the same quality according to the condition survey (TP 1-2), into larger, homogeneous sections.
- The second module selects the sections relevant for maintenance.
- The third module analyses faults and causes of faults and the fourth module provides a prediction of the condition changes.
- The fifth module suggests structurally possible maintenance measures and the sixth module evaluates the effectiveness of these measures and provides a ranking of the various alternatives as a result.
- The seventh module optimises the alternatives for a limited budget.
- The eighth module finally derives a suggestion for the maintenance programme.
Modules of the PMS
The results can be shown in tables, maps or diagrams, e.g. the diagrams of the status distribution for a substance or usage characteristic or for different financing levels. The effectiveness of the selected strategies and measures can thus be estimated for several years and the consequences for the network can be illustrated.
Proportion of road segments with very bad conditions for various financing levels
However, PMS can only provide an objective basis for decisions to support the planning engineer; it cannot replace the engineer.