Community Research and Development Information Service - CORDIS

From road condition data collection to effective maintenance decision making

The operation of seamless intermodal door-to-door transport chains across Europe requires research to enable the cost-effective development and maintenance of infrastructures and nodal areas as well as to identify and realise promising alternative transport concepts.

The objectives of the Format project were:

- to provide better performing road pavement maintenance techniques and procedures that will reduce traffic disruption at road works, thus reducing congestion and improving safety;
- to develop an integrated cost-benefit analysis model that addresses key aspects of pavement maintenance, including road user costs;
- to produce safety strategies for road works for arranging the work site lay-out and the timing of maintenance intervention to maximise the safety of road users and workers;
- to propose methods, procedures and equipment for monitoring the condition of road pavements at traffic speeds to minimise the number of road closures currently required for acquiring pavement condition data.

The scientific achievements include:

1) Drawing up a comprehensive list of maintenance treatments and procedures used in individual European countries from which some effective and innovative treatments were selected for assessment. The treatments selected for testing were: a cement mortar grouted porous asphalt as an inlay; a binder course of steel slag asphalt concrete; two different high modulus bituminous binder courses as inlays under different thin asphalt surface layers; a high modulus bituminous binder course applied as an inlay to the wheeltracks alone under a thin asphalt surfacing; a thin asphalt overlay with geogrid over a cracked pavement.

2) The construction and evaluation of the test pavements in four accelerated loading test (ALT) facilities. The ALT showed that in terms of performance the innovative maintenance treatments trialed gave promising results. Some of the treatments tested also showed considerable benefits in terms of material consumption and environmental impact. However, the success of these techniques relies strongly on good construction practices and enhanced quality control procedures. Finally, it should be borne in mind that the results from ALT will only describe the performance of pavement structures with respect to load associated deterioration mechanisms, and that this type of experiment must always be supported by results obtained in real load tests (RLT) on road pavements, which are subjected to the effects of time and climatic variations, and where the variability of materials and construction procedures can play an important role in the pavement performance.

3) Three pilot trials on public roads were conducted with positive results to determine the ease of application and assess the efficiency of the selected maintenance techniques in improving the pavement condition, as well as to determine any disruption to road users. The treatments assessed were: the application of a new 0/6.3 porous asphalt on the ring road of Toulouse (France); the structural rehabilitation of a jointed concrete pavement on a motorway near Valencia (Spain) involving injection grouting followed by either surface grinding or the application of two different asphalt surfaces with one incorporating a geotextile; the rehabilitation of a continuously reinforced concrete pavement near Baytown (Texas, in the USA) that included various local repairs followed by the application of a bonded concrete overlay.

4) Mathematical models for project level studies were implemented into spreadsheets to calculate probabilistically the additional road user costs due to delays at road works, the associated agency costs for the works, the environmental costs in terms of fuel emissions and noise, and the costs of pavement preservation. These individual models were integrated into a single spreadsheet model that contained default values for users without specific data inputs for all elements of the model.

5) Data on accidents in general and those associated with road closures were collated from 15 countries (where data were available) and analysed to provide indications on the effect of road closures on accident rates.

6) Trials were conducted in driving simulators to explore the effects of innovative traffic management arrangements at work sites. These involved simulations on a two-lane dual carriageway using narrow lanes in England to study their effect on speed and on a two-way road in Sweden. Four different works arrangements were evaluated in each simulator.

7) Safety data were collected and evaluated from two major road works sites on the E411 and E25 in Belgium where the works are being undertaken over a three-year period and involve long-term operations on significant sections of two key routes.

8) Equipment that is able to collect road pavement condition data at normal traffic speeds was assessed. These included devices that are in current routine use for measuring transverse profile, evenness, friction, texture, geometry, layer thickness and noise and also prototype devices that are still under development. The prototype devices were evaluated on public roads and included two for measuring cracking, two for measuring ravelling and fretting and two for measuring deflection response. In addition, some innovative applications of ground penetrating radar to measure layer thickness were assessed.

Main findings are that much still needs to be done to ensure that all these new methods can be routinely used on highway networks and that they will provide robust and meaningful outputs that can be reliably used as inputs to pavement management systems thus enabling more efficient and economic management of these very valuable assets. However, some of the methods may be applied immediately, especially if any measurements are compared with those obtained using the slower conventional approaches before significant maintenance decisions are made.

The cost and benefit analysis concerning the application of high speed monitoring devices showed that in terms of monitoring cost and extra users cost, traffic speed monitoring is more beneficial than static/slow speed monitoring but the benefits are even larger with a high value of AADT (Average Annual Daily Total referring to traffic levels). The cost and benefit analysis did not only permit quantification of this likely benefit but also showed that the initiation of queues should be avoided. It was also observed that the residual capacity of the road is a dominant factor in the calculation of the extra users cost. Due to the large number of required parameters the results are extremely complex to validate. Among other things knowledge of the traffic management cost and the survey cost is very important. In addition some high speed monitoring devices are still considered as prototypes (they are not used as routine equipments) and so it is not possible, as yet, to provide reliable survey costs for such equipment.

9) Based on the findings of the fourth group of activities ('monitoring'), the highway authorities are recommended to consider the following items when dealing with road maintenance monitoring:

- consider and define aims of maintenance monitoring;
- consider monitoring frequency of different types of testing equipment;
- use high speed equipment for monitoring, especially at roads with high traffic volumes;
- continue the development of high speed monitoring equipment as well the development of new types of monitoring methods such as instrumented vehicles and instrumented (smart) roads.

Reported by

Ministerie van Verkeer en Waterstaat
2600 GA DELFT
Netherlands
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