I do live on said potential rat run. AFAIK said rat run will be closed off after construction although still usable for a bus route so I have no idea how that will be monitored
I did Hanoi to Saigon in 2 weeks a few years back. We flew into Hanoi had a few days there then headed to Halong bay for an overnight cruise. I totally recommend seeing Halong bay, waking up to that view was amazing.
From there we headed back to Hanoi for an overnight train to Hue, great...
I'm not totally for the development and neither am I against it, however those that continue to oppose the development due to traffic should put their time and effort into getting a proper bypass of Worthing and Lancing green lit.