فَسِّحُوا الْمَمَرَّ وَانْظُرُوا فِي سَبَبِ الزِّحَامِ.
Widen the passage and investigate the reason for congestion.
One command calls for immediate improvement; the other requests diagnosis of the source of the problem. They are distinct acts joined by the common purpose of helping passersby. The second is not a substitute for the first.
Widening alone may not solve the cause, and investigation alone leaves the present obstruction uncorrected. Wāw connects complementary but individually meaningful directions, rather than creating an implied question-and-answer exchange.