The road to the Burma border crossing at Phu Namron is north of Kanchanaburi (3229), it was finished a few years ago. M81 seems to be to prevent all the heavy traffic on the 323 every weekend when half of Bangkok drives to Kanchanaburi in their SUVs, but I do see plans to link it up on that map.
Motorway M81 opens
Re: Motorway M81 opens
Who is the happier man, he who has braved the storm of life and lived or he who has stayed securely on shore and merely existed? - Hunter S Thompson