With the problems of narrow space, many underground and above ground obstacles leading interrupted construction work for a short period of time for design review and construction measures adjustment. Sub-contractors: Bach Dang 7 Construction Joint Stock Company, Bach Dang Import Export & Construction Joint Stock Company have overcome all difficulties and mobilized resources to push up construction progress.

Currently, the contractor is under construction of segment at S1.10- 28.5m. Up to now, the contractor has installed 468.6 m on Line 1.