To use Arrows or Stripes in street signs.  Which is better ?

They are complimentary to each other.  Arrows are good for indicating the direction of a point (1 way).  Stripes are good for indicating the direction of a line (2 way).

Arrows are ideal for indicating the direction of a future point or one way location (such as a city, town, park or construction area).  They are not suited for indicating the direction of a (2-way) highway, street or road. 

Stripes are better for indicating the direction of a highway, street or road because like lines, they are two directional.