I know the route they ran well because it's at my hometown. I don't think it's suitable for marathon competition. This route is a main highway used for mass transportation and not friendly for runners. At that time, marathon in Thailand was not as popular as present. Therefore, the arrangements may not take some factors into account such as high temperature. Nowadays, marathon races in Thailand usually start earlier than 5.00am to avoid this problem.
Naoko ran a 2:21:47 marathon under 32ºC, no crowds cheering, no competition, a solo run. At the time the world record was 2:20:47 in Berlin, one minute faster, with all that rabbits, cheering crowds and 12º C. It is nonsense, unfair and an insult to the sport that Naoko Takahashi didn't get the real WR here. One of the most impressive marathons ever raced by a woman.