[Cartoweb-users] A few questions about pgdijkstra - oneway roads, optimize time ...

[Fay Du]

Hi all:
 
    With the help of many in our lists, I finally made pgdijkstra works.
Thank you all very much.
    After I start to use pgdijkstra tool, I got more questions need you
help.
 
1. How shortest path are calculated? Does it optimize the route length
(use road segment length)? Or does it optimize route cost (value of cost
column)? For example, I can put value of length/speed as cost, and
optimize route on time?
 
2. If I pass directed =true to shortest_path function, which means all
road segments have directions? Can I set highways which need to be
considerate direction (one-way), and local roads have no directions
(two-way) in one route? You know, in real life, you can drive on one-way
and two-way street in one trip. The route is a combination of one-way
and two-way roads.
 
3. Another question about direction. Do traffic directions have to match
road segment direction? For example, a road segment start node id is 4,
and end node id is 5, but traffic direction is actually from Node 5 to
Node 4. Does shortest_path function support this situation? How? Do I
have to flip one-way road segments to match traffic direction?
 
    Many, many thanks for your help.
 
Fay
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