centerline

詳細解釋：

cen.ter.line

n.（名詞）
A painted line running along the center of a road or highway that divides it into two sections for traffic moving in opposite directions, or, in the case of a divided highway, for lines of traffic moving in the same direction at different speeds.
中線：沿馬路或公路中間刷的一條線，將公路分為兩部分以使車輛雙向行駛，或在分速公路上使車輛以相同的方向不同的速度行駛