Street Types & Classifications

Every pattern page in this guidebook is sorted two ways: by its Functional Classification and by its Street Typology. Those aren't everyday words, so this page explains what they mean, in plain language, before you run into them everywhere else in the guidebook.

[Image: Commonway System functional classification diagram showing four classes of streets and roadways: Freeways, Arterials, Collectors, and Local Streets, while describing their differences.]

The question every street has to answer

Every street is pulled between two competing jobs: helping people move through quickly, and helping people access the homes and businesses along it. A street can't fully do both at once. A road built for fast through-traffic works badly as a place with driveways and parked cars every few feet; a residential street built for slow, safe access to houses works badly as a high-speed route across town.

Functional Classification is just naming where a street sits on that trade-off. Commonway System uses four, the same categories used to classify roads across the US highway system:¹

There's a real-world example of what goes wrong when a street tries to do both jobs badly at once: it's called a Stroad², a road that tries to move fast traffic and serve strip-mall driveways and parking lots at the same time. It ends up dangerous for the same reason a car can't be a good boat: trying to do two very different jobs at once usually means doing neither one well. Commonway System flags Stroad as a pattern to avoid, and most of what a Collector or Arterial page in this guidebook recommends is really just a way of keeping those two jobs from colliding.

Related Media

The items below come from outside the Commonway System, external videos, podcasts, and articles related to this page's topic, not part of the guidebook itself.

Aligned

Stroads are Ugly, Expensive, and Dangerous

Not Just Bikes

The definitive explainer on stroads, and lays out the Dutch three-tier road/street classification system that CS's own Functional Classification structure closely mirrors.

Why a bike path or a bus route gets a car-sounding label

You'll run into pattern names like "Collector" attached to a bike path, or "Local" attached to a bus route, and that can look like a mistake at first. It isn't. Functional Classification isn't really about cars, it's about the job being done, and any mode of travel can do any of these jobs.

A dedicated bike path connecting one neighborhood to another is doing exactly the job a car Collector does, just for bikes instead of cars, so it's classified as a Collector. A car-free plaza that exists purely so people can walk to shops and linger is doing the same job a residential street does, just without cars, so it's classified as Local. The same logic sorts transit: a neighborhood bus loop plays a Local role, a bus route feeding a larger transit line plays a Collector role, a light-rail spine crossing a whole city plays an Arterial role, and commuter or heavy rail plays a Freeway-scale role. Once you're thinking in terms of the job rather than the vehicle, the classification makes sense for any mode.

From classification to a specific street

Knowing a street's Functional Classification tells you its general job. It doesn't tell you the specific situation it's handling. That's what a Street Typology³ is: a named, specific pattern within a classification, built for one clear purpose.

Think of it like this: Functional Classification answers "what job is this street doing?" Street Typology answers "what particular kind of street is doing that job?" An Alley and a Main Street are both Local, both are pure access with no through-traffic, but they're built for completely different situations: one is a service lane behind buildings, the other is a shopping street meant for browsing on foot. Same classification, very different street.

Every classification has a Default Typology: the standard, ordinary version of that classification, with no special situation attached. A pattern only gets its own named Typology when it's built around something specific enough to deserve a name of its own, a particular access pattern, a particular land use, or a single mode getting full priority.

Every Street Typology in the guidebook

Most of the names below aren't invented for this guidebook. Many trace to established American design guides, particularly NACTO's Urban Street Design Guide,⁴ cross-referenced against how each pattern is actually used in the field.

Local

Collector

Arterial

Freeway

Intersections & Crossings

Every classification above describes a stretch of street. Intersections & Crossings is different: it describes how two streets meet, and it applies across all four classifications rather than belonging to just one.

Why this matters once you're reading a pattern page

Every Segment/Intersection-scale pattern's ID starts with its Functional Classification (LOC, COL, ART, FRE, or INT), follows with a code for its specific Typology, and ends with a number, for example LOC-DEF-01 for the standard Local street. These five prefixes apply specifically to the Segment/Intersection scale, alongside four other flat Scale prefixes (NET, CDR, FAC, ELM) covering Network, Corridor, Facility, and Element patterns, which don't subdivide by classification. See Pattern IDs for the full nine-prefix ID scheme, Scale Hierarchy for what each Scale covers, and Density Tiers for the other axis every pattern page is sorted by, alongside classification and typology.

For readers coming from Dutch (CROW) practice

If you're familiar with Dutch road design, Duurzaam Veilig, or CROW's manuals, you'll recognize a lot of the underlying thinking here even though the categories don't map cleanly onto each other. Commonway System sorts streets by the job they do, movement versus access. Dutch practice sorts primarily by design speed and how completely different modes are physically separated. There's no perfect one-to-one translation, but most CS patterns have a close Dutch relative worth knowing.

Sourced from CROW's own categorization framework,⁸ bicycle design manual,⁹ and tram integration guideline.¹⁰

Two things this table can't capture cleanly. Vrijliggend fietspad and fiets(suggestie)strook don't get a real CS equivalent, since CS treats bike separation as a cross-section detail layered onto Local, Collector, or Arterial, while Dutch practice treats the separation level itself as the classifying feature. And tram doesn't get its own dedicated Dutch ladder the way roads do. CROW classifies the physical integration method instead, mixed, reserved, or grade-separated, which is what maps onto CS's Transit typologies here, by degree of separation rather than by a named category.

References

1. Legal / regulatory Federal Highway Administration, "Highway Functional Classification: Concepts, Criteria and Procedures," 2013 Edition, updated 2015. Available at: https://www.fhwa.dot.gov/planning/processes/statewide/related/highway_functional_classifications/section01.cfm
2. Precedent-based Charles Marohn and Asia Mieleszko, "What's a STROAD and Why Does It Matter?" Strong Towns, term coined by Marohn in 2013. Available at: https://www.strongtowns.org/journal/2018-3-1-whats-a-stroad-and-why-does-it-matter
3. Legal / regulatory City of Minneapolis, Street Design Guide, "Street Types" section, explicitly built on and crediting NACTO's street typology framework. Available at: https://sdg.minneapolismn.gov/street-types/introduction
4. Legal / regulatory National Association of City Transportation Officials (NACTO), Urban Street Design Guide, 2013. Available at: https://nacto.org/publication/urban-street-design-guide/
5. Evidence-based Annenies Kraaij et al., "Communal versus Private: The Unfinished Search for the Ideal Woonerf," DASH: Delft Architectural Studies on Housing, TU Delft. Origin credited to Niek de Boer and Joost Vahl, Delft, late 1960s/1970s. Available at: https://journals.open.tudelft.nl/dash/article/view/4579
6. Legal / regulatory National Association of City Transportation Officials (NACTO), "Yield Street," Urban Street Design Guide. Available at: https://nacto.org/publication/urban-street-design-guide/streets/yield-street/
7. Legal / regulatory Federal Highway Administration, Office of International Programs, "Turbo Roundabouts: Support Safety, Efficiency, and Increased Capacity." Origin credited to Dr. Lambertus Fortuijn, Delft University of Technology, 1996. Available at: https://international.fhwa.dot.gov/programs/tbp/docs/35976_FHWA_HPIP_Turbo_Roundabout_Factsheet_v05_Release_508.pdf
8. Legal / regulatory CROW, Basiskenmerken wegontwerp: Categorisering en inrichting van wegen (CROW-publicatie 315), Ede, 2012, updating the original 1997 Duurzaam Veilig categorization handbook. Available at: https://kennisbank.crow.nl/public/gastgebruiker/WOBU/Handboek_Verkeersveiligheid/Duurzaam_Veilig/20998
9. Legal / regulatory CROW, Ontwerpwijzer fietsverkeer (CROW-publicatie 230), 2006, revised 2016; published in English as CROW Design Manual for Bicycle Traffic, 2016. Available at: https://kennisbank.crow.nl/public/WOBI/Ontwerpwijzer_fietsverkeer/Woord_vooraf/33096
10. Legal / regulatory CROW, Richtlijn inpassing tram in stedelijke omgeving, commissioned by Expertisecentrum Rail, superseding the 2007 Leidraad inpassing tram in stedelijk gebied. Available at: https://www.crow.nl/kennisproducten/richtlijn-inpassing-tram-in-stedelijke-omgeving/