答案：
解: $C, D$ 两地到路段 $A B$ 的距离相等.
证: $\because$ 两车同时出发, 同时到达,
$$
\begin{aligned}
& \therefore A C=B D, \\
& \because A C / / B D, \\
& \therefore \angle C A E=\angle D B F, \\
& \because C E \perp A B, D F \perp B F, \\
& \therefore \angle A E C=\angle B F D=90^{\circ} . \\
& \text { 在 } \triangle A E C \text { 和 } \triangle B F D \text { 中, } \\
& \left\{\begin{array}{l}
\angle C A E=\angle D B F, \\
\angle A E C=\angle B F D, \\
A C=B D,
\end{array}\right. \\
& \therefore \triangle A E C \cong \triangle B F D \\
& \therefore C E=B D .
\end{aligned}
$$