As I am starting my running training again, here's a list of favourite running spots in Singapore currently. If there are other good places that you know of, let me know in your comments.
1. Southern Ridges Run
My favourite run in the city currently. It is a scenic run with 2 wooden bridges and a metal bridge. There are also enough slopes and steps to make the run difficult and interesting. The usual route I take is about 10km but can be easily extended to about 20km if you run through a section of the National University (NUS). I rate it high because I have a gym membership at Vivocity, near the start of the trail. If not, then the run will be downgraded because there are no easily accessible lockers and shower areas at the start of the trail.
2. Macritchie - Bukit Timah route
This route is not as convenient as the Southern Ridge but it is more difficult in terms of terrain. The route that I used to take goes through half of the Macritchie loop and detours to Bukit Timah mountain bike trail and the Dairy Farm loop. Then I will continue running via the mountain bike trail back to Macritchie visitor center. The complete loop is around 20km and likely the best training for mountain running around Singapore. It is a challenging run given my current state of conditioning. One problem is that the Bukit Timah area has many trails so it is easy to get lost around that area.
3. East Coast Park
The east coast park route goes along the south eastern coast of Singapore. It is a long route along a beautiful park with easily accessible shower and locker facilities. Good choice for times when I want a long and flat route. The distance can be very long as it extends all the way to Changi Village and beyond. The only downside is that the center of the park is very crowded during the weekends.