Rehabilitation Design

Transcription

1 Pavement Performance Evaluation and Rehabilitation Design André A. A. Molenaar Delft University of Technology The Netherlands

2 Introduction Road users demand a certain level of service in terms of: - safety (geometric design, skid resistance), - driving comfort (eveness, noise in the car), - appearance of the road, - noise and air pollution, - vehicle operating costs. Road authorities are responsible for keeping the road and the pavement in such a condition that the user demands are fulfilled. User s needs must be translated in technical terms. The question is when and where should maintenance be applied and what should be done.

3 Maintenance strategies Condition Usage dependent maintenance Condition dependent maintenance Minimum acceptance level Frequency distribution of maintenance moments Time

4 Maintenance strategies Usage dependent maintenance, repair things after a certain number of hours, is only possible if service life can be predicted and variation in service life is small. Unfortunately pavement life is very difficult to predict and variation in pavement life is substantial. Therefore condition dependent maintenance is the way to go for pavements and condition monitoring is a very important issue. So measure condition,, determine what is wrong and design maintenance strategy. This is what we call pavement evaluation and rehabilitation. Usage dependent maintenance only possible if we go to pre- fabricated products?

5 Mismatch between legislators/users and technicians Technicians like to discuss things like cracks, ruts,, crack propagation, polymer modified mixtures, plasticity index etc, but they should realise that legislators and users don t talk about pavements in those terms!! They even don t understand what we mean!!! It is therefore of vital importance that we as technicians make a clear translation of the user s (legislators) needs in the technical things we are talking about and vice versa.

6 Network and project level pavement evaluation Assessing the condition of and determining the needed maintenance for an entire road network is an enormous task. Therefore it is divided in tasks on network and project level. Types of questions asked, information needed and answers to be given are different between network and project level. Network level is of importance for legislative level, network and project level is of importance for administrative/management management level and technical level.

7 Network level Questions asked: - do you really need this amount of money, - what is the effect on pavement condition and will user s complaints decrease, - what is effect of a lower budget, - what will happen if we defer maintenance or lower the standards. Network level: large amount of data should be collected and evaluated in a short period of time. High speed measuring techniques are necessary. To answer the questions it is not needed to monitor entire network. Entire network should be monitored if one wants to know where the unsatisfactory spots are.

8 Project level Questions asked: - what is going on with that pavement, - what do we need to do, - how much does it costs and how should the maintenance contract look like, Project level: quality of the data is of importance.

9 Measurements on network level About a decade ago the only measurements that could be performed at an acceptable high speed level were: - ride measurements, - skid resistance measurements. Nowadays we can measure almost anything at high speed. - road profile (e.g.. laser), - texture (laser), - thickness (radar), - deflection (laser), - skid resistance (contact measurement), - noise (sound). Unfortunately these techniques are not always applicable (costs, availability of equipment and skills, etc).

10 Measurements on project level Deflection measurements. Material testing (lab. Investigations). High speed measurement techniques quite often have an accuracy that is good enough for project level.

11 Pavement damage is due to a lot of factors Traffic Climate Subsoil Interaction between damage types; in our mechanistic designs we tend to treat various damage types as individual parameters. This is a wrong approach!

12 Damage due to settlements

13 Uneveness due to settlements

14 General pavement deterioration

15 Edge damage

16 Potholes

17 Dust problem on earth roads

18 Fatigue cracking (bottum upup or top down down?)

19 Ravelling

20 Rutting