Potential of Satellite Remote Sensing for Flexible Pavement Monitoring

Introduction
The functionality and safety of road networks depend on the structural integrity and surface conditions of flexible pavements. During their lifetime, pavements undergo progressive deterioration due to environmental exposure and traffic loads, requiring continuous monitoring to ensure effective maintenance planning. Traditional inspection techniques, such as visual surveys and in situ testing, are often labor-intensive, expensive, and limited to localized measurements. In the context of non-destructive testing (NDT) for structural health monitoring, satellite remote sensing offers a promising approach for large-scale assessment of pavement conditions.

Methods
This study investigates the possibility of using multispectral and hyperspectral satellite imagery to monitor the aging phenomenon of flexible pavements. The methodology is based on the analysis of surface reflectance variations in the visible (VIS), near-infrared (NIR), and shortwave infrared (SWIR) spectral regions. In fact, in these regions, variations in asphalt reflectance spectra are directly associated with material aging, oxidation, asphalt content reduction and aggregate exposure. Changes in the spectral signature were also evaluated using literature spectral indicators such as the VIS2 index (830–490 nm).

Results
The results indicate that pavement aging is associated with a general increase in surface reflectance and characteristic changes in spectral absorption features. In particular, the loss of hydrocarbons leads to the disappearance of absorption bands near 1700 nm and 2300 nm, while aggregate exposure and oxidation generate features around 520, 670, and 870 nm. Due to technical limitations related to the low spatial resolution of satellite sensors, a preliminary case study was conducted on airport pavements, confirming the capability of satellite spectral products to detect aging-related variations.

Conclusions
Despite the limited ground resolution characterizing most optical satellites, Satellite remote sensing demonstrates strong potential as a complementary NDT technique for structural health monitoring of flexible pavements, enabling large-scale, repeatable, and long-term assessment of pavement conditions.