Analysis of the functional quality of pavements from texture measurements

The surface texture of a pavement, including uneveness, is largely determinant of drivers’safety and comfort. It is undoubtedly a major cause of road traffic accidents all over the world. Statistics show that one million killed and 50 million injured are reported every year by Competent Authorities. The effect of traffic noise has also become a critical public issue. On the road networking the surface characteristics of pavements also contributed to nearly 80-90% of roadway traffic noise. Not only engines or exhaust systems generate noise. The impact of tire-surface at speeds above 50 km/h also needs to be added to prime offenders. Functional requirements such as roadway safety, environmental quality, driving comfort and operating costs in the road network are assessed by indicators whose limits are continuously adjusted. The roadway texture is again a main intervenient. This paper aims at describing the texture indicators that can be used for the assessment of the texture of a pavement from a network point of view, based on profiles acquired at high speeds, including megatexture. First an overview of the concepts related to texture and the effects of texture, including unevenness, on safety, driving comfort, ride quality and environmental quality is given. Then, a case study related to a highly trafficked road in the north of Portugal is presented. This study is the second phase of a broader study that started with the analysis of the structural capacity of that road. In this second phase, a high speed profilometer was used to measure the pavement profile with a sampling rate which is considered to be adequate for the analysis of longitudinal profile, macrotexture and unevenness. Indicators such as the mean profile depth, the IRI and the rutting depth and the corresponding effects were addressed

Definição e características de superfícies de baixo ruído

As superfícies de pavimentos de baixo ruído são atualmente a medida de redução do ruído preferida pela maioria dos decisores por ser uma medida relativamente barata e por estarem na génese do ruído rodoviário. No entanto, para se averiguar se uma determinada superfície pode ser classificada de “baixo ruído” é fundamental a adoção de um sistema de classificação. Os principais objetivos deste trabalho são apresentar o problema da classificação de pavimentos, discutir a seleção de um limite ou de uma superfície de referência para apoiar a seleção de superfícies com desempenho acústico melhorado e identificar as características que conduzem a níveis de ruído de contato pneu-pavimento mais baixos, abordando-se particularmente a contribuição da macro e da megatextura.FEDE

Análise da qualidade funcional e do impacto ambiental de uma estrada urbana

Este artigo tem por objectivos descrever os principais indicadores da qualidade funcional e da qualidade ambiental utilizados correntemente a nível da rede e apresentar um caso de estudo de uma estrada integrada em meio urbano reabilitada recentemente. Esta estrada contempla três camadas de desgaste diferentes, duas das quais com textura optimizada, com o objectivo de se estudar o seu efeito no ruído de contacto pneu/pavimento. Para a observação dos parâmetros técnicos de qualidade funcional (irregularidade, textura e resistência à derrapagem) foi utilizado um veículo do tipo multifunções e para a medição do ruído foram efectuadas medições junto à berma com a passagem de veículos a diversas velocidades. Com base nesses parâmetros, por um lado, prevê-se que a curto prazo seja necessário desenvolver-se actividades de conservação da qualidade funcional do pavimento. Por outro lado, verificou-se que as camadas de desgaste optimizadas reduzem consideravelmente o impacto do ruído de tráfego no ambiente

Contribution of portuguese pavement surfaces to traffic noise

This paper aims at assessing the relative effect of Portuguese pavement surfaces on traffic noise. It presents the main results obtained with two distinct experiments, originally intended for other purposes, which address a significant number of thin layers and porous layers. These experiments included nine road surfaces: three of them were gap graded, three contained rubberized asphalt, one had porous asphalt and two had dense asphalt. On these road sections the tyre-road noise generated by two-axle heavy trucks and three-axle heavy trucks and several light vehicles at three levels of speed were measured by means of pass-by tests. Surface texture tests were also performed. The results focused on noise level variation versus speed and estimated noise level for each speed level versus type of surface. The best performances were achieved by gap graded mixtures with and without rubberized binder and small grain sizes. The fair behaviour shown by the porous asphalt indicates that the surface texture determined by the grain size seems to influence the noise level more than porosity

Contribution of alternative road surfaces to noise abatement

The increase of noise due to traffic particularly in urban areas has led road administrations to look for low noise surfaces in order to reduce noise impact and to improve environmental quality. This paper aims at assessing the effect of alternative road surfaces on noise abatement. It presents the main results obtained with two distinct experiments, originally intended for other purposes, which address a significant number of non conventional road surfaces. These experiments included nine road surfaces: three of them were gap graded, three contained rubberized asphalt, one had porous asphalt and two had dense asphalt. On these road sections the tyre-road noise generated by two-axle heavy trucks and three-axle heavy trucks and several light vehicles at three levels of speed were measured by means of pass-by tests. Surface texture tests were also performed. The results focused on: i) noise level variation versus speed; ii) estimated noise level for each speed level versus type of surface; iii) the variation of estimated noise level with regards to a reference surface. The best performances were achieved by gap graded mixtures with and without rubberized binder and small grain sizes. The fair behaviour shown by the porous asphalt indicates that the surface texture determined by the grain size seems to influence the noise level more than porosity. Further research on tyre-surface noise should include wide ranges of testing speeds for heavy vehicles, tests with the surface wet, tests that can provide texture spectrum and sound absorption tests

Estudo da evolução do desempenho dos pavimentos rodoviários flexíveis

Os pavimentos rodoviários flexíveis, frequentemente, não desempenham as funções para as quais foram concebidos, observando-se uma redução prematura da sua qualidade. A partir da observação da qualidade estrutural dos pavimentos, definida pelos parâmetros de estado deflexão e estado superficial, e do cálculo da vida residual, abordou-se neste artigo o estudo do desempenho estrutural de vários pavimentos submetidos a diferentes condições de solicitação. A análise do desempenho fez-se quer quanto à sua evolução, quer quanto aos factores que o podem influenciar. Os resultados indicam que a qualidade de construção tem uma influência determinante na vida residual. Além disso, o conhecimento dos dados de projecto, a avaliação inicial da qualidade dos pavimentos, o desenvolvimento de modelos de correcção do módulo de deformabilidade e o controlo das causas de erro no cálculo da vida residual, são factores que permitem apoiar o estudo da evolução do desempenho dos pavimentos de uma forma mais fiável

Towards noise classification of road pavements

Noise classification of road surfaces has been addressed in many European countries. This paper presents the first approach towards noise classification of Portuguese road pavements. In this early stage, it aims at establishing guidelines for decision makers to support their noise reduction policies and the development of a classification system adapted to the European recommendations. A ranking to provide guidance on tire-road noise emission levels for immediate use by decision makers, road authorities, contracting parties and environmental officers will be established. This research was based on the results provided by three early studies covering more than ten different surfaces, among which, rubberized asphalt and experimental non conventional surfaces with optimized grading. On each road trial, the tire-road noise generated by light vehicles and heavy trucks at three speed levels were measured by means of the Controlled Pass-By method (CPB). Three of these runs were also tested by the Close ProXimity method (CPX). Additionally, tests to characterize texture and skid resistance were performed. The early noise classification studies of road pavements focused only on the CPB tests. Three groups with similar acoustical performance were identified. Noise level abatements of about 10 dB were achieved for the gap graded mixtures with a maximum aggregate size inferior to 10 mm

Avaliação do ruído de tráfego rodoviário em pavimentos com camadas de desgaste delgadas

O ruído produzido pelo tráfego rodoviário, sendo uma componente importante de poluição ambiental que afecta significativamente as populações, foi incluído no conjunto de indicadores de desempenho dos pavimentos. No entanto, a informação existente quanto ao impacte ambiental dos diferentes tipos de camadas de desgaste utilizadas correntemente em Portugal é escassa, de modo a não ser possível fazerem-se considerações ao nível da gestão dos pavimentos, particularmente no que respeita às estratégias de reabilitação. Neste artigo faz-se a comparação do nível de ruído (Lmax) em diversos pavimentos com camadas de desgaste delgadas adoptadas actualmente na reabilitação funcional de pavimentos. O nível de ruído dos veículos ligeiros é obtido pelos métodos da passagem controlada (CPB) e da proximidade imediata (CPX). A metodologia utilizada foi a preconizada nas normas ISO 11819-1:1997 e ISO CD 11819-2. Em ambos os métodos, as camadas delgadas apresentam níveis de ruído reduzidos relativamente às camadas convencionais

Texture and noise features for road pavement identification and classification

Road planners and road administrators frequently face the problem of insufficient knowledge of the correlation between the type of road surface and the resulting noise emission. The aim of this research is to establish the relationship between road surface characteristics, such as macrotexture, and tire/pavement noise emission, in order to identify and classify road surfaces by using statistical learning methods, which is a non-destructive approach. For this purpose, several road sections with different pavement types were selected and tested. The Close-Proximity (CPX) method was adopted, as it is commonly used to register the traffic noise in near field conditions. In its turn, macrotexture of each surface was provided by a high speed profilometer, which is one of the parameters required for the assessment of the performance and conformity of road pavements. The set of features extracted from the noise emission profile and from the surface texture was applied to a statistical classifier for evaluation. A correct identification of the road pavement leads to better data, thus enhancing the accuracy of road noise predictions. Results are presented and discussed.(undefined