25. A closed section of highway, 1 mile long and 40 feet wide. Robert rides along the route shown in Figure 5 in a semicircular path. If his speed is 5 miles per hour, then the time he needs to ride this section of the highway is ( ) hours (Note: 1 mile = 5280 feet).
(A) $\frac{\pi}{11}$
( B) $\frac{\pi}{10}$
(C) $\frac{\pi}{5}$
(D) $\frac{2 \pi}{5}$
(E) $\frac{2 \pi}{3}$
25. B.

The width of the road is 40 feet, which means each lane is 20 feet wide, so the diameter of the semicircle Robert rides is 40 feet.

The total length of the road is 1 mile, which is 5280 feet, so $\frac{5280}{40}=132$ semicircles, and the circumference of each semicircle is $\frac{1}{2} \times 2 \pi \times 20=20 \pi$.

Therefore, the total distance Robert rides is $\frac{20 \pi \times 132}{5280}=\frac{\pi}{2}$ miles, and the riding time is $\frac{\frac{\pi}{2}}{5}=\frac{\pi}{10}$ hours.