I happen to have lived in a few of the notes countries (China, Djibouti, Eritrea) so I'm somewhat aware of the challenges everyone faced building the railroad between Addis and Djibouti.
While there was an existing railroad built by the French in the early 20th century, lacks of maintenance and funds kept it from being a viable means of freight and people transportation. When I was in Djibouti in the late 90s, the train only operated occasionally and was always packed for the harrowing day and half trip to Ethiopia's capital.
In the video of the Chinese built train, it's quite remarkable to see the immense and gruesome work that went into it. Knowing how China operates, much of the work must have been done by thousands of Chinese laborers shipped from China's outer provinces while locals sit and watch it all being built. Temperatures in the low lands can hit 50 to 55 degrees Celsius during the day and not drop below 40 degrees at night.
This is why westerners can no longer muster the capabilities to undertake such projects at reasonable costs. Local labor doesn't have the necessary skills while westerners don't have the necessary grits, unless they're provided by a slew of costly amenities.
I might have recalled the following in another post so I apologize if this is a repeat, while in Eritrea, because they couldn't find a US contractor to do it, the US military had outsourced to the Chinese (only bidder) the building of a secret camp in the middle of nowhere. The Chinese construction company sent Chinese laborers and materials to a God forgotten mountainous desert, far from any roads, by feet and mules. The US soldiers I had spoken with while on break in Asmara, capital of Eritrea, spoke to me of the incredibly harsh conditions these laborers worked in. All had only respect for their tenacity and courage.