User:Subs5/DDI exit left TIO

Virginia/Mid-Atlantic Region guidance on Divergent diamond interchanges (DDI)

DDIs are the new rage in transportation engineering. They can save a lot of room for a controlled entrances and exits from a freeway/highway and they are supposed to improve travel flow. Because a DDI has traffic flowing counter to the normal US experience, you drive on the left side of the interchange for a while, the first time can be a harrowing experience for drivers. Virginia follows the national Diverging diamond interchange (DDI) with two additional points:

1) Exit Left TIO When driving on the left side of the road add an "Exit Left" Turn Instruction Override for the second exit to the freeway/highway in both directions. Example

Exit Left TIO on second exit (driving on left side of road) in DDI

2) Elevation All elevations should be ground for at grade connections, unless there is a bridge, then make proper elevation change.

These segments are Elevation = +1 since they actually bridge across the freeway. All the rest of the segments in the DDI are Elevation = ground.