Median Width

The median width is a critical factor in defining how a divided highway intersection or crossover operates. As such, it has an important impact on the signs used. Medians are classified as wide or narrow. In a wide median, the opposing left-turn paths cross each other. In a narrow median, the opposing left turns do not cross. Figure 7-1 illustrates this difference.
Difference in Operations between a Wideand Narrow Median (click in image to see full-size image)
Figure 7-1. Difference in Operations between a Wide and Narrow Median
The median width is measured between the inside of the left turn lanes, or if there is no left turn lane on an approach, from the inside through lane.
Each median opening has two width measurements, with one measurement for each approach.
 The types of medians are defined below. Figure 7-2 illustrates how to measure median width.
  • Wide Median:
     the median width is 30 ft or more
    on at least one of the approaches
    .
  • Narrow Median:
     the median width is less than 30 ft.
    on both approaches
    .
Measuring Median Width (click in image to see full-size image)
Figure 7-2. Measuring Median Width