sketch wrote:In Detroit I saw a much bigger difference (because Detroit's much bigger and has way more roads to choose from); basically where it used to make me backtrack to get on the nearest freeway entrance, it now sends me along a Principal Arterial (Major Highway) or two for a few miles to get to the next useful freeway entrance downstream. It actually saves a couple minutes.
I think that it is key to reinforce that having a glut of principal arterials classed as MH still helps direct or funnel longer distance routes to a freeway. Even when presented with numerous principal arterials, as long as the freeway truly is the fastest route, Waze will opt for freeway even if it is way out of the way (assuming "fastest route" intended). To one of PhantomSoul's points, I agree that most urban principal arterials are meant for more local use (i.e. non-freeway suburb to suburb or even intra-city) and and not long distance trips, but those are also mixed with US and some major state routes that also have the principal arterial designation and would be more suitable long distance routes. In any case, you still normally get "sucked" onto a freeway as long as your "avoid major highways" option is disabled, but you also have legitimate alternatives at a lower road type if appropriate from the start--not just mid-route as a detour or in the first or last few kilometers.
As an example, entering downtown Detroit from the east side of Ann Arbor/Ypsilanti (about 40 miles), there were only two initial routes suggested pre-NFC: 1) I-94 all the way, and 2) backtracking to get to US-23 to M-14 to I-96 (all freeways). Looking at my routes now from the same location, my primary route is still I-94 (purple in the image), but look at the two alternatives. The green is a bypass off of I-94 using state highway M-39 (previously mH in that stretch, now MH/principal arterial) for about three miles to join I-75. This was not even an option before but it is only three minutes more than the direct I-94 route. The blue alternative is part of the pre-NFC suggested route, but instead of backtracking to take US-23 to M-14 to I-96, Waze now suggests a road straight north to get to M-14 (previously primary street, now mH/minor arterial).
Another consideration is that people should look at how their state DOT actually classifies the roads in your state if you have not. You will find that some states fit the traditional Waze road types well, and others are nowhere close. sketch references the links on each state's mapping resources page, but since those are not altogether complete, here is a link to current FC maps.
russblau wrote:Comment: in general, I think FC is a good basis for assigning road type; I think the references to route numbering should be removed. In practice, there is a fairly high degree of correlation between route numbering and road function, but it is definitely not 100%. In those cases where a US highway serves the function of a minor highway because it travels along a narrow street with traffic lights and driveways, or where a state highway serves the function of a major highway because it has few intersections and permits high-speed through travel, the road's function should take precedence over its numbering.
Agreed, but this is an area where different DOTs may treat things differently, so it's worth looking at this in more detail. Some may lower the functional classification of a road such as US-XX through a lower-speed, full-access urban stretch while others (including Michigan) typically do not. We have some state highways at mH and plain city-controlled roads as MH in numerous cases when applying FC. Politics, funding, etc. may come into play with a designation too as sketch mentioned.
dbraughlr wrote:I would like to see the rationale documented for the exception for ramps to be used for at-grade connectors.
I believe that dbraughlr may be referencing the bit about jughandles and Michigan lefts specifically. In the case of Michigan Lefts, sketch tested and tweaked the exception for a signed but unnumbered at-grade exit from a roadway. It has to meet specific signage criteria and be at an actual major intersection, not just a standard median crossover. By the way, as GizmoGuy411 and I built that section of the Michigan wiki explaining Michigan Lefts (a colloquial term), we settled on the term "Median U-Turn Intersection" as the best documented naming convention, especially as these are employed under numerous names throughout the US, and they are increasing. If the exception part stays on the revised Road Types page, I believe it should go toward the more or less "official" name for these styles of intersections. Drop "Michigan Left" in favor of MUTI... It should be an at-grade exception in more than a few people's opinions. I think this is mostly because an instruction like "to Telegraph Rd S / US-24 S / to Grand River Ave W / M-16 W" is a bit much to see on a 10-15m segment and pollutes the visual. "Ramps" don't have street names--they carry instructions. The same goes for jughandles and MUTIs.
dbraughlr wrote:I believe that primary street should be used for the main road linking two rural towns (and presumably thus the main street through the town) when no higher classification applies (which is often the case). This could well require local knowledge of the editor rather than a published document. Functionally the street is the primary route even though there isn't much traffic.
Perhaps this page does not go into enough detail about how to apply FC in certain circumstances, or perhaps that should be somewhere else, but the guideline as adopted in Michigan when we went FC statewide was to never downgrade a road type just to match functional classification, but it would be okay to maintain or upgrade based on local editor knowledge. Also, we had another one such as what to do with dirt roads, particularly since a number of minor collectors in our state are dirt.