This alteration involves raising 7.85km of track to an elevated level instead of at ground level in Ban Mai sub-district. The change, affecting Contracts 3 to 5 of the Kok Kruad-Nakhon Ratchasima section, will add 4.7 billion baht to the costs and delay the project by 28 months.

SRT Governor Nirut Maneephan revealed that phase 1, extending from Bangkok to Nakhon Ratchasima over 250.77km, is already underway. This phase includes 188.68km of elevated tracks, 54.09km of surface tracks, and 8km of tunnels, with a total investment of around 170 billion baht. Out of 14 construction contracts for phase 1, 12 have been awarded and work is in progress, though one has been finished.

Significant stations along phase 1's route are Bang Sue, Don Mueang, Ayutthaya, Saraburi, Pak Chong, and Nakhon Ratchasima. However, there are still unresolved issues concerning the Ayutthaya station, primarily due to ONREPP's heritage impact concerns. SRT has stated it will not conduct a new HIA to avoid further delays and expense, instead will discuss the issue using the existing HIA report.

Initially agreed upon by Thailand and China on December 19, 2014, the high-speed rail project aims to connect Bangkok with Nong Khai, covering 609km. Nevertheless, it has encountered numerous setbacks, leading to significant delays.