Representation of road topology in a GIS file

Question

I'm just getting into GIS right now with a new project at my work - so I'm still kinda new at all of this. I'm using GDAL to work with the TigerLine Shape files from the previous US census land survey. Within these files you can find (among other things) polyline sets that describe lat/long position of roads and you can find the names of the roads. What I haven't been able to find are things like lanes, traffic signals, and perhaps most importantly, the topology of how it's all connected together. For instance, topology would tell me that an overpass is not directly connected to road below (even though their polylines apparently intersect), whereas intersecting roads are connected at the intersection. Topology would also be able to tell me the traffic direction.

Now I know these things must exist because Susan (my Garmin GPS) tells me in her breathy, British accent which lane to be in and how to get across town to where I'm going. She is apparently topology-aware because she never tells me to take a left at an overpass. How is this information encoded in GIS files, and better yet, where can I find example of this?

Thanks!

Answer 1

Perhaps something like this way.

Answer 2

Your best-bet for road data with the topological information you seek is private companies. NAVTEQ offers a 30-day evaluation version of their NAVSTREETS dataset which includes all of the attributes you mentioned and many more.