Guard rails are put up along roadways to help keep is safe. Safe from what? Many times they keep us safe from dangers that are easily seen.
When we drive over those high over passes, because of the guard rails we are not afraid. They also keep us safe from those dangers that we may not see. When there is a drop off, a sharp turn or a cliff; they protect us.
When we see God as our guard rail, we will find protection. Remember to keep your eyes on Him.
You make your saving help my shield,
and your right hand sustains me;
your help has made me great.
You provide a broad path for my feet,
so that my ankles do not give way.
Ps 18:35 & 36