secondary main road的意思|示意

I continued northwards on a secondary road winding first through rice paddies and then through rolling hills. It was a wonderful route with very little traffic and avoided both the main highways.

接下来我待在一条次要干道持续往北，迂回过稻田和山谷，这条路很不错，交通很少且让我不用待在主要道路上。

The system default for the main road east-west direction (release 30s), secondary roads north-south direction (release 20s).

该系统默认东西方向为主干道(放行30s)，南北方向为次干道(放行20s)。