ftrebien (2026-01-22 20:56:40+00:00): No, it's the criterion 2.3 indeed. It should apply in situations like these:

1. Northbound: https://www.openstreetmap.org/directions?engine=graphhopper_car&route=-29.84182%2C-51.17399%3B-29.9535%2C-50.99442#map=14/-29.85025/-51.14802

2. Southbound: https://www.openstreetmap.org/directions?engine=graphhopper_car&route=-29.95313%2C-50.99442%3B-29.84338%2C-51.1803#map=12/-29.8662/-51.0894

These short sections need to be trunk to maintain classification continuity along these routes as one is moving between the two roads (one motorway, the other trunk), there is no other route connecting them on these movements. If these sections are classified as secondary, these movements would follow an unexpected gradient:

1. motorway > motorway_link > secondary > trunk_link > trunk

2. trunk > motorway_link > secondary > motorway_link > motorway

"Trunk" is a functional way type and "motorway" is a physical design type. All motorways are also "trunk" from a functional standpoint. So, even functionally, the sequence is still unexpected:

1 and 2. trunk > trunk_link > secondary > trunk_link > trunk

The way to solve this is to raise the classification of the connecting stretch. But of course, this should only be done where intentional.

Taking inspiration from the section "The concept of topological continuity of highways", when one tries to select all roads that are either trunk or motorway (+ trunk_link or motorway_link), if these middle sections are classified as anything lower than trunk, there is no way to perform some turns on that interchange, so it would be impossible to travel continuously on them.

This would still be problematic if this stretch was classified as primary, as it was earlier in 2025 (my fault). The frontage roads along this specific road are functionally all second-level urban arterials (city plans do not assign them any class but they are useful for medium distance routes within the city, so we're filling in the gap in official sources here). For longer distances, one would prefer to simply take the central track than to navigate along the much slower parallel side ways.

These frontage roads were primary before because they are connected to the city's primary ways in a few places, thus a primary classification would reduce changes of classification along them. That is the main justification for classifying the frontage roads on the southern part of the city, despite them functioning more like secondary. In the northern part of this highway, this isn't needed. In Brazil, there isn't much of a practical difference between secondary and primary (typically similar design types, similar speeds, difference is mainly importance), so this slight upgrade made the map more readable and led to fewer edit reversals in that specific case.

Unfortunately, these situations in this particular road all due to poor design. This is the most lethal highway in the state of Rio Grande do Sul precisely because there is a lot of weaving between all those access ramps and often (as in this case) not enough distance between one ramp and the next.

It seems that this highway is being gradually redesigned, apparently by completely removing physical separation with what today are the frontage roads. If this becomes the final design, then we don't even need to argue about this anymore as the frontage road will cease to exist in OSM and the main highway will have an increased lane count and no change to its classification.