JRTT has a YouTube channel

[miyakoji]

I appreciate the value of YT when it comes to hosting obscure stuff like this.  Construction of the western part of the Keiyo Line.  The look and sound of the video seems early 80s, but the Tokyo to Shin-Kiba section opened in March 1990.  Much newer than I had guessed.

 

Be advised, there are dudes wearing only fundoshi around 9:00.

 

 

 

Other interesting videos on the channel as well.

 

JRTT: https://en.wikipedia.org/wiki/Japan_Railway_Construction,_Transport_and_Technology_Agency

Keiyo Line: https://en.wikipedia.org/wiki/Keiyō_Line