Routing Engine or SDM

Question

Hi I am beginning to investigate Spatial for use in generating street routing geometry and instructions.
It appears there are two ways of going about this: Routing Engine (Java-XML) or the Spatial Data Model (SDM).
If one wants instructions the Routing Engine is the way to go. But there does not appear to be anyway to restrict turns (I gather this from the description of the EDGE.DIVIDER field in the doc). The SDM model lacks instructions, but a past post indicates that restricting turns can be accomplished via adding an additional field to the LINK table (eg, a varray of restricted NODE id's).
Is there a way I can get both driving instructions and turn restrictions? I assume the solution would need to come via editing around the SDM model to add instructions.
Any thoughts? Thanks in advance.
Glen

Answer 1

David,
Here is a description of how a road is classified as a highway:
Roads come in 5 functional classes 1 through 5. We use functional class to decide two things in
the Router, 1) is the edge part of a highway and need to be in the highway partition and 2) what is the
speed classification for the edge.
We use the speed classification along with the edges length to
compute how long it should take to traverse the edge.
Function class 1 and 2 are considered highway
edges and are placed in the highway partition, the other functional classes are not.
Functional class 1 roads have consistent, typically fast speeds with limited access.
Functional class 2 roads also have consistent speeds and are used to get traffic to and from
functional class 1 roads.
Functional class 3 roads are also high volume edges used to connect functional class 2 roads.
Functional class 4 roads move volumes of traffic from neighborhood to neighborhood. Think,
busy main road in a city.
Functional class 5 roads are all other roads not accounted for above.