Answer: It is possible that a truck of 8 m tall and 4 m wide pass through the tunnel.
Step-by-step explanation:
Since we have given that
A highway tunnel has a shape that can be modeled by equation of a parabola:

Since the width of the tunnel is 18 m wide,
So, We consider the endpoints :

So, our equation becomes,

Now, we have given that the height of the tunnel is 16 m and the edge of tunnel is 5 m say 'y'.
so, it becomes,

so, finally, equation becomes,

Now, dimensions of truck is 8 m tall and 4 m wide.
So, y = 8
So,

By using the "Quadratic formula " , we get:

So, Now, we get hte distance between the points
and 
So, it becomes

Allowed width is given by

And the width of the truck is 4m
So , it is possible that a truck of 8 m tall and 4 m wide pass through the tunnel.