Due to structural and operational impact on the HSR system, the Executive Yuan respectively ratified "Speciﬁc Solutions and Action Plans Confronting Land Subsidence in Yunlin and Changhua Areas (the 1st amendment)" in May 2013 and “Golden Agricultural Corridor Project” in Nov.2015. The projects has successfully reduced groundwater usage which effectively slowed down the land subsidence issue in Yunlin and Changhua areas and brought positive impact toward HSR structural and operational safety in that area.
To monitor the land subsidence condition alongside HSR routes and generate response measures, MOTC established the “HSR Alongside Land Subsidence Prevention Ad Hoc Group” in 2008 and the MOTC Ad Hoc Group has held meetings periodically to implement projects ratified by the Executive Yuan. The projects included monitoring the subsiding degree of HSR piers and ensuring HSR operational safety, reacting to differential subsidence issue using engineering techniques, establishing HSR alongside loading regulations in Changhua and Yunlin areas, surface measurements at the intersection of HSR and Provincial Highway 78, monitoring stratum condition and restricting HSR alongside embankment loading, etc. The loading restrictions within 150m of Changhua and Yunlin HSR routes have been added in the “Building Permit Bans and Restrictions alongside HSR System” and have been formally promulgated on Jan. 1, 2016 after confirmation of MOI and MOTC. Consequently, HSR development projects in Changhua and Yunlin areas will be effectively managed.
According to monitoring data from the Water Resources Department in 2016, the area of serious subsidence in Changhua and Yunlin is obviously smaller than that in 2015 (subsidence area in Chiayi is zero). The land subsidence phenomenon is gradually stabilizing; however, authorities should be prepared in advance regarding the influence of the station body load on the subsidence of Yunlin Station in Huwei. BOHSR has supervised THSRC to finish the 2016 Safety Checks of HSR Piers as soon as possible and the “HSR Alongside Land Subsidence Prevention Ad Hoc Group” will continue to promote well management measures and response actions in Changhua and Yunlin areas to ensure HSR structural and operational safety.