Estimation of Year of Construction of Bridges in Cambodia by Analyzing the Landsat Normalized Difference Water Index
| Author(s): |
Eam Sovisoth
(Department of Civil Engineering, The University of Tokyo, Tokyo 113-8654, Japan)
Vikas Singh Kuntal 
(Department of Civil Engineering, The University of Tokyo, Tokyo 113-8654, Japan)
Prakhar Misra
(Institute of Industrial of Sciences, The University of Tokyo, Meguro, Tokyo 153-8505, Japan)
Wataru Takeuchi
(Institute of Industrial of Sciences, The University of Tokyo, Meguro, Tokyo 153-8505, Japan)
Kohei Nagai (Institute of Industrial of Sciences, The University of Tokyo, Meguro, Tokyo 153-8505, Japan) |
|---|---|
| Medium: | journal article |
| Language(s): | English |
| Published in: | Infrastructures, April 2023, n. 4, v. 8 |
| Page(s): | 77 |
| DOI: | 10.3390/infrastructures8040077 |
| Abstract: |
Inspection data can be used to comprehend and plan effective maintenance of bridges. In particular, the year of initial construction is one of the most important criteria for formulating maintenance plans, making budget allocations, and estimating soundness. In an initial survey of bridges in Cambodia, it was concluded that the year of construction of only 54% of 2439 bridges surveyed is known, with the remaining 46% remaining unknown. In this research, Landsat satellite data is used to estimate the year of construction of these bridges. Landsat provides spatial spectral reflectance information covering more than 30 years, and for longer bridges this can be used to estimate the year of construction by visual judgement. However, limited image resolution means this is not possible for shorter bridges. Instead, a method using the Landsat Normalized Difference Water Index (NDWI) is used to estimate the year of construction. Three pixels are selected from Landsat image data in such a way that one lies on the current location of a bridge and two other reference pixels are placed on similar terrain at a certain distance perpendicular to the bridge axis. NDWI values are plotted over time for the three pixels and the difference in value between the bridge pixel and the two reference pixels is then compared. Before the bridge is constructed, all three pixels should have similar NDWI values, but after construction the value of the target bridge pixel should differ from the other two because the NDWI value of a bridge surface is different from that of the surrounding vegetation. By looking for this change, the year of construction of a bridge can be estimated. All the bridges in the Cambodian database are classified into three categories based on length (which affects their visibility in Landsat images) and year of construction is estimated. The results show that estimated year of construction has the same accuracy in all three categories. |
| Copyright: | © 2023 the Authors. Licensee MDPI, Basel, Switzerland. |
| License: | This creative work has been published under the Creative Commons Attribution 4.0 International (CC-BY 4.0) license which allows copying, and redistribution as well as adaptation of the original work provided appropriate credit is given to the original author and the conditions of the license are met. |
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data sheet - Reference-ID
10722694 - Published on:
22/04/2023 - Last updated on:
10/05/2023
