VIDEO - Raised Center Medians
I enjoy these videos by Road Guy Rob. He explains how the road structures that we use daily function in an easy to understand manner. In this video he takes on the subject of raised medians. On one hand, they prevent crashes, but on the other, they keep us from turning left where we might want to. This video explains how engineers decide how to build raised medians.
Here in Canada, engineers follow the Transportation Association of Canada (TAC) design guides. If you are not a member of TAC, it will cost you almost $800 to get a copy to read yourself. Of course, these guidelines do change over time and the province of British Columbia even has it's own supplement to the guidelines.
Even with engineering training, these are heavy reading! I'm happy to have Rob explain them instead.