Where are you coming from? Taipei? The no.3 should be OK; it’s a big road, not to high and any damage should have been fixed already I think. Which road will you go east on? The 14 or the 16? I know there’s been some severe flooding down where the 16 is; don’t know how the road is although again as it’s a major route they should be fixing any damage quickly.
I always take the 136 to go southeast from Taichung but it’s pretty messed up at the moment. I wouldn’t really want to take a scooter up there for another few weeks anyway.
You mentioned going into the Shei-Pa (Xueba) National Park area. A quick and very pleasant detour might be the 62 to Taian hotsprings. I haven’t been there but Mucha Man’s glowing post here;
[forumosa.com/taiwan/viewtopic.ph … 462#103462](Taiwan Top 10
makes me want to go there as soon as possible.
There are the Neiwan and the Nanzhuang areas – nice especially when less crowded i.e. not weekends.
Routes that go deeper into the National Park are the 122 to Guanwu (Hsinchu County?) and the little “47” something to Daxueshan in Taichung County. I think they’d be more likely to be damaged though.
I don’t know the current states of any of the roads for the above detours. I too would be very interested in a phone number to contact the roads agency, particularly if there is an English information line.
By the way, it would be good to plan an overnight stop somewhere along the way. Taipei to Sun Moon Lake is a long long way on a scooter and I think it would be difficult to maintain alertness and safety if you do it in one day.