mraross
commented
4 years ago Greg Kolesniak said:
Regarding Card #210 (bcgov/ols-router#210 (comment)), it would be helpful to discuss how the TRP is going to handle route exceptions (edge cases) such as Front Street vs Royal Ave (New West), Haney Bypass vs Lougheed (Maple Ridge), Port access via Commissioner Street vs Clark Drive (Vancouver).
--- Excerpt from Card #210 ---
All of the exceptions are captured in the table ‘exceptions’ in the PostGIS database. There is a python script that I believe I passed on earlier that calculates the ‘default cost’ of all segments based on their truck route status and road type. The ‘final costs’ of any exception segments are calculated from the information captured in the ‘exceptions’ table.
During a follow-up conversation re. this ticket, @al-tabb aptly pointed out exceptions are needed given there will always be edge cases where we need to calculate costs differently from our general classification scheme (i.e. opening up a small number of private, restricted, etc. roads for truck travel).
An exceptions table would address the Royal Ave vs Front Street route and any other "fine tuning" needed to generate routes consistent with user expectations that don't fit the general classification scheme.
Suggest @al-tabb and @mraross discuss this further.
cmhodgson
In New Westminster, there are two designated truck routes:
New Westminster would like trucks to prefer option 2 over option 1.
This requires an additional truck route preference factor (aka local distortion field) which, when combined with other truck route multipliers, guides the route planner toward the preferred truck route.
Local distortion fields can also be used to keep commuter vehicles off of particular residential streets that are being used as short-cuts.
Support this feature with an additional input file to routable bc maker that contains a set of road (segment id, truck distortion factor, car distortion factor) triples.
In the future, each road authority should be able to define their own local distortion fields. These fields are necessary because its been empirically verified that no global setting of truck route attraction factors will work in all areas of the province.