# Commonway System > A Pattern Language for Roads and Streets. One system, grounded in what's proven. The Commonway System (CS) organizes established transportation design knowledge, from NACTO's guides to Dutch Sustainable Safety and Vision Zero research, into a single, cross-referenced pattern language. Every claim traces back to a cited source rather than a credential, and each page opens with a plain-language answer before the technical depth beneath it. Every link below is the markdown version of a page. Any page's HTML URL has the same content as markdown at the same path with `.md` appended (`/patterns/foo/` becomes `/patterns/foo.md`; the homepage is `/index.md`), and each HTML page advertises it with ``. The whole guidebook as one markdown file, for loading in a single request: https://commonwaysystem.org/llms-full.txt - [Commonway System](https://commonwaysystem.org/index.md): Home page for the Commonway System Guidebook, a cross-referenced pattern language for road and street design grounded in cited evidence. ## About - [About](https://commonwaysystem.org/about.md): Landing page for the About section, linking to what the Commonway System is, its brand guide, contributing, governance, and reporting. - [Accessibility Policy](https://commonwaysystem.org/about/accessibility-policy.md): Describes the publication's accessibility goal (WCAG 2.2 Level AA), states plainly that it has not been independently audited, lists known limitations and planned improvements, and explains how to report an accessibility barrier. - [Acknowledgments](https://commonwaysystem.org/about/acknowledgments.md): Credits everyone who has helped correct, source, or build the Commonway System, or explains that no contributions have landed yet. - [AI Policy](https://commonwaysystem.org/about/ai-policy.md): Explains how AI tools were used in building the Commonway System, how human review stays in the loop for every classification and citation, and what AI does not do on the site. - [Brand Guide](https://commonwaysystem.org/about/brand-guide.md): The Commonway System's full visual and editorial system, colors, typography, voice and editorial rules, illustration rules, citation format, and logo usage. - [The Commonway System](https://commonwaysystem.org/about/commonway-system.md): Explains what the Commonway System is, who compiled it, how it relates to NACTO, Complete Streets, and Strong Towns, and how the guidebook is organized. - [Submit a Change](https://commonwaysystem.org/about/contributing.md): Explains how to contribute to the Commonway System, what counts as a contribution, how a pull request is reviewed, the terms of contributing, and how contributors are credited. - [Project Governance](https://commonwaysystem.org/about/governance.md): Explains who has final say on the Commonway System, how classification decisions and evidence disputes are resolved, how project direction is set, and why participation isn't a vote. - [Privacy Policy](https://commonwaysystem.org/about/privacy-policy.md): Explains what data the Commonway System website collects through Google Analytics, GitHub, and Netlify hosting logs, and what choices visitors have. - [Release History & Roadmap](https://commonwaysystem.org/about/release-history.md): Explains the Commonway System's CalVer versioning, the current version, the changelog, and the public roadmap of work not yet built. - [Report a Problem](https://commonwaysystem.org/about/reporting.md): Explains how to report a factual error, an unsourced claim, a dead citation link, or an accessibility issue in the Commonway System, and how a report is handled after it's filed. - [Site Map](https://commonwaysystem.org/about/sitemap.md): A human-readable list of every page in the guidebook, grouped by section, plus the other ways to browse it (search, text-only pages, the XML sitemap, and the llms files). - [Terms and Conditions](https://commonwaysystem.org/about/terms-and-conditions.md): The terms governing use of the Commonway System website and guide, covering professional-advice disclaimers, warranty and liability limits, brand and licensing terms, and governing law. ## Blog - [Blog](https://commonwaysystem.org/blog.md): Chronological blog covering research notes, structural decisions, and updates on how the Commonway System guide gets built. Separate from the guide's prescriptive content and from the Release History changelog. - [Welcome to the Commonway System](https://commonwaysystem.org/blog/welcome.md): The first blog post, introducing what this blog is for and how it differs from the guide and the changelog. ## Guide - [Introduction](https://commonwaysystem.org/guide.md): Introduces the Commonway System guide and how its three sections (Foundations, Find Your Pattern, Make It Happen) fit together. - [Construction Methodology & The Build Spectrum](https://commonwaysystem.org/guide/construction-methodology-spectrum.md): Explains the four-stage build spectrum (demonstration, pilot, quick-build, permanent) used across the tactical urbanism field, states CS's position that a retrofit strategy should move through this spectrum where it can rather than skip straight to permanent construction, and notes that some strategies genuinely cannot be piloted. - [Decision & Evaluation Processes](https://commonwaysystem.org/guide/decision-evaluation-processes.md): Covers Intersection Control Evaluation (ICE) and the Road Safety Audit (RSA), two procedural, staged processes for choosing an intersection design or checking a road's safety, distinct from a Retrofit Strategy itself or a legal or funding mechanism. - [Density Tiers](https://commonwaysystem.org/guide/density-tiers.md): Explains the six Commonway System density tiers (Undeveloped, Rural, Suburban, Compact, Urban, Core), their ITE/CNU transect equivalents, units-per-acre ranges, and how they're used across pattern pages. - [Design Speed & Speed Limits](https://commonwaysystem.org/guide/design-speed.md): Explains the difference between design speed, 85th-percentile operating speed, and posted speed limit; the 1985-to-2001 FHWA/AASHTO history behind why they diverge; and the Commonway System rule that design speed always equals posted speed limit, with its Local/Collector/Arterial/Freeway application. - [Find Your Pattern](https://commonwaysystem.org/guide/find-your-pattern.md): Describes the planned Find Your Pattern diagnostic, not yet built, and points readers to Street Types & Classifications and the Pattern Index in the meantime. - [Funding & Financing Mechanisms](https://commonwaysystem.org/guide/funding-financing-mechanisms.md): Catalogs eight funding and financing mechanisms, special assessment district, tax increment financing, development impact fee, transportation utility fee, joint development, parking benefit district, transportation reinvestment zone, and naming rights and sponsorship, each described by its purpose, revenue potential, use of funds, and leveraging capacity. - [How the Transportation Ecosystem Fits Together](https://commonwaysystem.org/guide/how-the-transportation-ecosystem-fits-together.md): Explains the difference between binding regulation (MUTCD, PROWAG, EPA stormwater rules), professional guidance (NACTO, AASHTO, ITE), advocacy movements (Strong Towns, CNU, Vision Zero Network, PPS, Complete Streets, Create Streets), and international frameworks (CROW, SWOV, ITDP), and where Commonway System fits relative to all of them. - [How to Read a Pattern](https://commonwaysystem.org/guide/how-to-read-a-pattern.md): Explains how to read a Commonway System pattern entry, Pattern ID cards, classification colors and status badges, density tier chips, the Speed & Modal Hierarchy card, admonitions, and the citation and unsourced-claim system. - [How to Read a Retrofit Strategy](https://commonwaysystem.org/guide/how-to-read-a-retrofit-strategy.md): Explains how to read a Commonway System Retrofit Strategy entry, the RFT ID card, the Where this leads and Applicability and thresholds sections, Getting it built and Who can move this, and how Retrofit Strategies relate to Patterns. - [Legal & Planning Mechanisms](https://commonwaysystem.org/guide/legal-planning-mechanisms.md): Catalogs the right-of-way control tools (official map, option to purchase, comprehensive plan corridor designation, concurrency ordinance, voluntary developer reservation, density transfer, setback and building-line reservation) and policy mechanisms (Complete Streets policy, arterial retrofit ordinance, functional classification reclassification, context classification) that make retrofit strategies possible in the first place. - [How Road Changes Actually Happen](https://commonwaysystem.org/guide/make-it-happen.md): A four-question method for figuring out who has authority over a specific road and how that government processes a request, covering restoring vs. adding vs. changing a standard everywhere, public vs. private roads, splits in jurisdiction, and the seven ways a request actually gets processed once the right authority is found. - [When Jurisdiction Doesn't Follow the Pattern](https://commonwaysystem.org/guide/make-it-happen/jurisdiction-variants.md): Catalogs documented exceptions to the general jurisdiction-finding method in How Road Changes Actually Happen, including consolidated city-county governments, independent cities, Dillon's Rule states, tribal land overlaps, special districts, interstate compact authorities, states without a county layer, Michigan-style road commissions, federal-agency-embedded roads, and Puerto Rico. - [Pattern IDs](https://commonwaysystem.org/guide/pattern-ids.md): Explains the Commonway System Pattern ID format (PREFIX-CTXCODE-##), the nine Scale prefixes, and the Recommended/Situational/Avoid status badges. - [Scale Hierarchy](https://commonwaysystem.org/guide/scale-hierarchy.md): Explains the five-level Commonway System scale hierarchy (Network, Corridor, Segment/Intersection, Facility, Element) and how a pattern's scale relates to its Pattern ID. - [Street Types & Classifications](https://commonwaysystem.org/guide/street-types.md): Explains what a Functional Classification and a Street Typology are, why the Commonway System is organized around both, and indexes every Street Typology in the guide by classification. ## Media - [Media Gallery](https://commonwaysystem.org/media.md): Index of every external media item (video, podcast, article) the Commonway System references, filterable by media type, source, and topic. Each item is also cross-linked to the Pattern, Retrofit Strategy, or Guide page it relates to. ## Patterns - [Pattern Index](https://commonwaysystem.org/patterns.md): Index of every pattern in the Commonway System guidebook, grouped by Scale (Network, Corridor, Segment/Intersection by Functional Classification, Facility, Element). - [Arterial Transit (BRT/LRT)](https://commonwaysystem.org/patterns/arterials/arterial-transit.md): An Arterial street typology with dedicated bus rapid transit or light rail treatment, reinforcing rather than overriding the Arterial base modal hierarchy. - [Boulevard](https://commonwaysystem.org/patterns/arterials/boulevard.md): An Arterial street typology combining through traffic with a pedestrian-first frontage, including the Multiway Boulevard variant, which separates frontage roads from through lanes with planted medians. - [Default (No Parking, No Direct Property Access)](https://commonwaysystem.org/patterns/arterials/default.md): The baseline Arterial street typology, defined by never mixing on-street parking or direct property access with through traffic, the rule that distinguishes it from a Stroad. - [One-Way Street](https://commonwaysystem.org/patterns/arterials/one-way-street.md): An Arterial street typology marked Situational/Discouraged, since one-way operation tends to encourage speeding even though it retains the Arterial base modal hierarchy on paper. - [Parkway](https://commonwaysystem.org/patterns/arterials/parkway.md): A roadway historically designed as a scenic, landscaped route, typically featuring a planted median and limited access, whose modern implementations vary widely between two distinct traditions: a limited-access, freeway-like facility, and a slower, arterial-scale boulevard-like facility running through or alongside parkland. - [Scenic Highway / Byway](https://commonwaysystem.org/patterns/arterials/scenic-highway-byway.md): A low-density, low-development-pressure Arterial street typology, the norm at Undeveloped and Rural density, an unlikely pairing past Compact density. - [Stroad (Commercial Arterial)](https://commonwaysystem.org/patterns/arterials/stroad.md): An Arterial anti-pattern marked Avoid, formed by mixing on-street parking or direct property access with through traffic. This page exists to help identify and replace it with Boulevard or Default Arterial. - [Bike Highway / Greenway](https://commonwaysystem.org/patterns/collectors/bike-highway-greenway.md): A Collector-scale street typology providing a dedicated, physically separated bicycle path, distinct from Local's shared-roadway Bicycle Boulevard. - [Collector Transit](https://commonwaysystem.org/patterns/collectors/collector-transit.md): A Collector street typology carrying a dedicated transit route, with transit elevated above the rest of the Collector base modal hierarchy. - [Default (Standard Collector)](https://commonwaysystem.org/patterns/collectors/default.md): The baseline Collector street, applying the base modal hierarchy and 30 mph standard speed with no named override. - [Downtown Thoroughfare](https://commonwaysystem.org/patterns/collectors/downtown-thoroughfare.md): A collector-scale street running through a dense downtown or town-center context, carrying meaningful through-traffic volume while also serving frequent pedestrian activity, on-street parking, and ground-floor commercial frontage along its length. - [Industrial Collector](https://commonwaysystem.org/patterns/collectors/industrial-collector.md): A Collector street typology serving industrial land use, where freight movement is prioritized above vehicle, pedestrian, bicycle, and transit use. - [Multi-Use Trail / Greenway](https://commonwaysystem.org/patterns/collectors/multi-use-trail-greenway.md): A Collector street typology for an off-street path shared by pedestrians and bicyclists under roughly equal priority, longer-distance and often a destination in its own right, such as a rail-trail or linear park path. - [Rural Collector / Farm-to-Market Road](https://commonwaysystem.org/patterns/collectors/rural-collector.md): A Collector street typology serving vehicle and freight movement through low-density agricultural or undeveloped land, the norm at Undeveloped and Rural density and effectively absent past Suburban. - [Character Transect](https://commonwaysystem.org/patterns/corridors/character-transect.md): A corridor that deliberately passes through multiple Movement/Place contexts by design, for example a route that functions as a Highway at one end and a Main Street at the other, and the practice of sequencing the transitions between those contexts rather than treating the corridor as one uniform typology end to end. - [Density Step-Down / Step-Up](https://commonwaysystem.org/patterns/corridors/density-step-down-step-up.md): The pattern governing how a road’s cross-section, speed, and character adjust where the surrounding density tier changes along its length. - [Rail-With-Trail Corridor](https://commonwaysystem.org/patterns/corridors/rail-with-trail-corridor.md): A road or trail corridor running alongside an active rail line for some or all of its length, addressing crossing frequency, setback distance, and shared right-of-way concerns created by the parallel rail operation. - [Road-Adjacent Greenway](https://commonwaysystem.org/patterns/corridors/road-adjacent-greenway.md): A corridor where a multi-use trail or linear park runs parallel to, but physically separated from, a road for some or all of its length, without an active rail line involved, addressing connection points and crossing treatment between the two. - [Rural-to-Town Gateway](https://commonwaysystem.org/patterns/corridors/rural-to-town-gateway.md): The specific transition zone where a highway or rural road enters a town, village, or settlement edge, marked by deliberate physical cues (narrowing, street trees, lighting change, surface texture) that signal to drivers that the road’s character and behavior expectations have changed. - [Transit Alignment Corridor](https://commonwaysystem.org/patterns/corridors/transit-alignment-corridor.md): A corridor built around a fixed transit line (light rail, streetcar, or dedicated BRT) running parallel to or within the roadway, addressing how the transit alignment shapes the corridor’s whole cross-section for its full length. - [Advisory Bike Lane](https://commonwaysystem.org/patterns/elements/advisory-bike-lane.md): A dashed-line bike lane marked on each side of a narrow, typically two-way, roadway with no dedicated centerline, where vehicles are expected to cross into the bike lane space temporarily to pass oncoming traffic, yielding to any cyclist present. - [Bench](https://commonwaysystem.org/patterns/elements/bench.md): A fixed or semi-fixed seating element installed along a sidewalk, plaza, or transit stop, providing a place to rest independent of any specific transit or commercial function. - [Bicycle Signal](https://commonwaysystem.org/patterns/elements/bicycle-signal.md): A signal indication, typically a bicycle-shaped symbol in red, yellow, and green, giving cyclists their own dedicated phase or right-of-way instruction distinct from vehicle and pedestrian signals. - [Bike Box](https://commonwaysystem.org/patterns/elements/bike-box.md): A designated waiting area marked at the head of a signalized intersection, positioned ahead of the vehicle stop line, allowing cyclists to position themselves in front of queued vehicles during a red signal for improved visibility and to enable a safer left turn or through movement. - [Bike Parking / Rack](https://commonwaysystem.org/patterns/elements/bike-parking-rack.md): A fixed rack or set of racks, most commonly an inverted-U or similar design, providing a place to lock a bicycle, typically installed on a sidewalk or in a dedicated on-street corral. - [Bioswale](https://commonwaysystem.org/patterns/elements/bioswale.md): A vegetated, shallow channel designed to collect, convey, and filter stormwater runoff from an adjacent roadway or hard surface, using soil and plant material to slow flow and remove pollutants before water reaches a storm drain or waterway. - [Bollard](https://commonwaysystem.org/patterns/elements/bollard.md): A short, sturdy vertical post installed to block or control vehicle access to a specific area, protect pedestrians or infrastructure from vehicle intrusion, or delineate a boundary, ranging from fixed to removable or retractable designs. - [Buffered Bike Lane](https://commonwaysystem.org/patterns/elements/buffered-bike-lane.md): A striped bike lane with an additional painted buffer zone, typically hatched or cross-hatched markings, separating it from the adjacent vehicle travel lane or parking lane by more distance than a conventional bike lane alone provides. - [Conventional Bike Lane](https://commonwaysystem.org/patterns/elements/conventional-bike-lane.md): A striped, dedicated on-street lane for bicycle travel, separated from the adjacent vehicle travel lane by paint markings alone, with no physical buffer or barrier. - [Crash Cushion / End Terminal](https://commonwaysystem.org/patterns/elements/crash-cushion-end-terminal.md): An energy-absorbing device installed at the exposed end of a traffic barrier or in front of a fixed hazard, designed to decelerate an impacting vehicle gradually rather than presenting a rigid, unshielded end or face. - [Crosswalk](https://commonwaysystem.org/patterns/elements/crosswalk.md): A marked pedestrian crossing point, located at an intersection or midblock, delineated with pavement markings ranging from a simple two-line crosswalk to high-visibility continental or ladder striping. - [Curb Cut / Driveway Apron](https://commonwaysystem.org/patterns/elements/curb-cut-driveway-apron.md): The break in a curb allowing vehicle access from the roadway to an adjacent driveway, typically formed with a sloped apron transitioning between street grade and driveway grade. - [Curb Extension](https://commonwaysystem.org/patterns/elements/curb-extension.md): A widened curb that narrows the roadway at a crossing or parking zone, taking gateway, pinchpoint, chicane, bus bulb, or conventional form depending on its purpose and location. - [Curb Ramp](https://commonwaysystem.org/patterns/elements/curb-ramp.md): A sloped transition cut into a curb, providing an accessible path between the sidewalk and street surface for wheelchair users, strollers, and anyone unable to step up or down a vertical curb face. - [Curb](https://commonwaysystem.org/patterns/elements/curb.md): The raised edge separating the roadway from the sidewalk or shoulder, marking the physical boundary between space allocated to vehicles and space allocated to pedestrians or the roadway edge condition. - [Detectable Warning Surface](https://commonwaysystem.org/patterns/elements/detectable-warning-surface.md): A textured ground surface, typically a grid of truncated domes, installed at the edge of a curb ramp or platform to alert pedestrians with vision impairments to an approaching street edge or crossing point through underfoot texture. - [Drinking Fountain](https://commonwaysystem.org/patterns/elements/drinking-fountain.md): A fixed water fountain installed in the public right-of-way or an adjacent public space, providing free public access to drinking water, sometimes paired with a lower-height accessible basin or a pet-watering feature. - [Flow-Through Planter](https://commonwaysystem.org/patterns/elements/flow-through-planter.md): A contained, structured planting box with an engineered soil and drainage layer that captures and filters stormwater runoff before releasing it through an underdrain, used where space or soil conditions do not allow for an open bioswale. - [Green Pavement / Conflict Marking](https://commonwaysystem.org/patterns/elements/green-pavement-conflict-marking.md): A colored pavement treatment, typically green, applied at a bike facility’s conflict point with a driveway, turn lane, or intersection, to increase driver awareness that a cyclist may be present or crossing through that space. - [Guide Sign](https://commonwaysystem.org/patterns/elements/guide-sign.md): A sign providing wayfinding or informational content, such as destination names, distances, route numbers, or facility identification, helping travelers navigate rather than regulating or warning them. - [Landscaped Buffer Strip](https://commonwaysystem.org/patterns/elements/landscaped-buffer-strip.md): A planted zone running between the roadway and the sidewalk, providing separation, stormwater treatment opportunity, and space for street trees and other plantings, distinct from a hardscaped or paved separation. - [Median Island](https://commonwaysystem.org/patterns/elements/median-island.md): A raised or landscaped island placed along the center of a roadway to narrow the effective travel width and separate opposing traffic, without a pedestrian crossing function, distinct from Pedestrian Safety Island/Refuge's crossing-assistance role. - [Modal Filter / Point Closure](https://commonwaysystem.org/patterns/elements/modal-filter-point-closure.md): A physical closure placed mid-block or at an intersection leg that blocks through motor vehicle travel while preserving passage for pedestrians and bicyclists, using bollards, planters, partial curb extensions, or a similar barrier. - [Neighborhood Traffic Circle / Mini-Roundabout](https://commonwaysystem.org/patterns/elements/neighborhood-traffic-circle-mini-roundabout.md): A small raised or landscaped island placed at the center of a Local-to-Local intersection, around which traffic circulates at low speed, used for calming rather than volume control, distinct from the sized, engineered Roundabout pattern. - [Pedestrian Hybrid Beacon](https://commonwaysystem.org/patterns/elements/pedestrian-hybrid-beacon.md): A pedestrian-activated signal, sometimes called a HAWK beacon, that remains dark until activated, then displays a sequence progressing through flashing and solid indications to stop traffic and allow a pedestrian to cross, before returning to dark. - [Pedestrian Safety Island / Refuge](https://commonwaysystem.org/patterns/elements/pedestrian-safety-island-refuge.md): A protected median space within a roadway allowing a pedestrian to cross in two stages, stopping partway across to wait for a gap in the second direction of traffic rather than crossing the full width in one movement. - [Pedestrian-scale Lighting](https://commonwaysystem.org/patterns/elements/pedestrian-scale-lighting.md): A lower-mounted luminaire, typically 10-15 feet in height, providing illumination calibrated to serve pedestrians on a sidewalk, sized and spaced to support the pedestrian visual task rather than the vehicle-oriented task a standard street light serves. - [Pedestrian Signal](https://commonwaysystem.org/patterns/elements/pedestrian-signal.md): A signal indication, typically a walking figure and countdown display, informing pedestrians when it is their turn to cross and how much time remains to do so at a signalized intersection or crossing. - [Pervious Pavement](https://commonwaysystem.org/patterns/elements/pervious-pavement.md): A load-bearing paving surface (permeable concrete, porous asphalt, or permeable interlocking pavers) engineered to allow stormwater to infiltrate directly through the pavement surface into a stone reservoir base below, rather than running off. - [Pervious Strip](https://commonwaysystem.org/patterns/elements/pervious-strip.md): A linear strip of permeable surface (gravel, permeable pavers, or open-graded aggregate), allowing stormwater to infiltrate directly into the ground rather than running off to a drain, typically installed within a parking lane, shoulder, or buffer zone. - [Protected Bike Lane / Cycle Track](https://commonwaysystem.org/patterns/elements/protected-bike-lane-cycle-track.md): A bike facility physically separated from adjacent vehicle traffic by a barrier, curb, parked cars, bollards, or planters, rather than paint markings alone, providing the highest level of separation among on-street bike facility types. - [Regulatory Sign](https://commonwaysystem.org/patterns/elements/regulatory-sign.md): A sign conveying a legally enforceable traffic rule, such as a stop sign, yield sign, speed limit sign, or turn restriction, whose message carries the force of law rather than merely advising or informing. - [RRFB](https://commonwaysystem.org/patterns/elements/rrfb.md): A Rectangular Rapid Flashing Beacon, a pedestrian- or cyclist-activated warning device using bright, irregularly-flashing LED lights mounted near a crosswalk sign to increase driver yielding at an uncontrolled crossing. - [Rumble Strip](https://commonwaysystem.org/patterns/elements/rumble-strip.md): A textured roadway surface, typically a series of shallow grooves or raised bars, that alerts drivers through vibration and sound when a vehicle crosses it. - [Sharrow](https://commonwaysystem.org/patterns/elements/sharrow.md): A shared-lane marking, a painted symbol combining a bicycle icon and chevron arrows, placed within a shared vehicle travel lane to indicate that cyclists may use the full lane and to suggest proper positioning within it. - [Street Light](https://commonwaysystem.org/patterns/elements/street-light.md): A pole-mounted luminaire providing illumination for the roadway, typically mounted at a height and spacing designed primarily to serve vehicle visibility and drivers, though its light also reaches the surrounding sidewalk and public realm. - [Street Tree](https://commonwaysystem.org/patterns/elements/street-tree.md): A tree planted along a street, typically within the sidewalk zone or a landscaped buffer, providing shade, stormwater interception, visual buffering from traffic, and streetscape character. - [Traffic Barrier](https://commonwaysystem.org/patterns/elements/traffic-barrier.md): A longitudinal barrier (guardrail, concrete barrier, or similar rigid or semi-rigid structure) installed to redirect an errant vehicle away from a roadside hazard or opposing traffic, rather than allowing the vehicle to travel further off-course. - [Traffic Signal](https://commonwaysystem.org/patterns/elements/traffic-signal.md): A signal-controlled device using red, yellow, and green indications to assign right-of-way among conflicting vehicle movements at an intersection. - [Transit Boarding Island](https://commonwaysystem.org/patterns/elements/transit-boarding-island.md): A raised platform positioned between a bike lane and the vehicle travel lane at a transit stop, allowing bus or streetcar passengers to board and alight without crossing the bike lane at grade, and without the transit vehicle needing to merge across the bike lane to reach the curb. - [Trash / Recycling Receptacle](https://commonwaysystem.org/patterns/elements/trash-recycling-receptacle.md): A fixed waste and recycling container installed in the public right-of-way or an adjacent public space, providing a designated disposal point for pedestrians and street users. - [Tree Pit / Tree Trench](https://commonwaysystem.org/patterns/elements/tree-pit-tree-trench.md): The below-grade excavated and engineered soil volume, either an individual pit or a shared linear trench connecting multiple planting locations, providing root space and often structural soil to support street tree growth beneath a sidewalk or paved surface. - [Two-Stage Turn Queue Box](https://commonwaysystem.org/patterns/elements/two-stage-turn-queue-box.md): A designated waiting area positioned in the far corner of an intersection, allowing a cyclist making a left turn (or right turn in left-driving contexts) to cross the intersection in two separate straight-through movements rather than merging across vehicle traffic to execute a conventional turn. - [Vertical Speed Control](https://commonwaysystem.org/patterns/elements/vertical-speed-control.md): A raised roadway feature (speed hump, speed table, or speed cushion) that slows vehicles through vertical deflection, forcing a driver to reduce speed to avoid an uncomfortable jolt. - [Warning Sign](https://commonwaysystem.org/patterns/elements/warning-sign.md): A sign alerting drivers to an upcoming hazard or changed condition, such as a curve, a crossing, a narrowing roadway, or a stop ahead, advising caution without carrying the direct legal force of a regulatory sign. - [Wheel Stop](https://commonwaysystem.org/patterns/elements/wheel-stop.md): A small barrier, typically a short raised block or bumper, placed at the end of a parking space to prevent a parked vehicle from overrunning a curb, sidewalk, or space limit. - [Bike Parking Corral](https://commonwaysystem.org/patterns/facilities/bike-parking-corral.md): An on-street, curbside cluster of bike racks, typically installed in place of a single car parking space, providing multiple bike parking spots in the footprint one vehicle would otherwise occupy. - [Bike-Share Station](https://commonwaysystem.org/patterns/facilities/bike-share-station.md): A docking location for a shared-bike program, where users check out and return bikes from a fixed station, either dock-based (physical docking points) or hybrid/dockless with a designated parking zone. - [Park-and-Ride](https://commonwaysystem.org/patterns/facilities/park-and-ride.md): A parking facility, surface or structured, designed specifically for commuters to leave a personal vehicle and transfer to transit for the remainder of their trip. - [Parking Garage / Structure](https://commonwaysystem.org/patterns/facilities/parking-garage-structure.md): A multi-level parking structure, above-grade or underground, using ramp or helix circulation to move vehicles between levels. - [Plaza / Parklet](https://commonwaysystem.org/patterns/facilities/plaza-parklet.md): A public gathering space reclaimed from roadway or parking space, ranging from a single parking-space-sized parklet to a full intersection-corner plaza. - [Secure Bike Parking / Bike Station](https://commonwaysystem.org/patterns/facilities/secure-bike-parking-bike-station.md): An enclosed or attended facility offering higher-security, longer-term bike parking than an open-air rack or corral, ranging from a lockable cage to a staffed bike station with additional services. - [Surface Parking Lot](https://commonwaysystem.org/patterns/facilities/surface-parking-lot.md): An at-grade, open-air parking area serving adjacent land uses, ranging from a small business lot to a large-format shared or municipal lot. - [Transit Hub / Station](https://commonwaysystem.org/patterns/facilities/transit-hub-station.md): A compound facility where multiple transit patterns (platforms, shelters, wayfinding, sometimes multiple routes or modes) converge into a single coordinated site, documenting intermodal transfer and placemaking rather than a single boarding point. - [Transit Platform](https://commonwaysystem.org/patterns/facilities/transit-platform.md): The boarding surface at a transit stop where passengers board and alight, varying by platform height (level or low), length (accommodating one or multiple vehicles), and configuration (island platform serving two directions, or side platforms serving one direction each). - [Transit Shelter](https://commonwaysystem.org/patterns/facilities/transit-shelter.md): A small- or large-format weather shelter installed at a transit stop, protecting waiting passengers from sun, rain, and wind, ranging from a simple lean-to canopy to a fully enclosed structure with seating and lighting. - [Beltway / Ring Road](https://commonwaysystem.org/patterns/freeways/beltway-ring-road.md): A Freeway street typology circling a city or metro area rather than passing through its core. Out of the Commonway System's detailed design scope. - [Default (Freeway)](https://commonwaysystem.org/patterns/freeways/default.md): The baseline Freeway typology, a limited-access road, listed for completeness but intentionally out of the Commonway System's detailed design scope. - [Expressway](https://commonwaysystem.org/patterns/freeways/expressway.md): A Freeway street typology with partial access control, between a full Freeway and an Arterial in character. Out of the Commonway System's detailed design scope. - [Freeway-scale Transit (Commuter / Heavy Rail)](https://commonwaysystem.org/patterns/freeways/freeway-transit.md): A Freeway-scale transit typology, commuter or heavy rail, the one Freeway-scale pattern that becomes more typical as density rises rather than less. - [All-Way Stop](https://commonwaysystem.org/patterns/intersections/all-way-stop.md): A stop-controlled intersection where every approach stops, tapering off past Compact and Urban density as intersection volumes exceed what stop control can safely handle. - [Continuous Sidewalk / Raised Junction](https://commonwaysystem.org/patterns/intersections/continuous-sidewalk.md): The Commonway System's locked default for Local-to-Collector intersections, where the sidewalk and bike path stay uninterrupted and the roadway ramps up to meet them. - [Displaced Left-Turn (DLT)](https://commonwaysystem.org/patterns/intersections/displaced-left-turn.md): An intersection, also known as a continuous flow intersection, where the left-turn lane is shifted to the opposing side of oncoming traffic upstream, letting left-turning and opposing through traffic move concurrently, Situational at high-volume urban and suburban intersections. - [Driveway / Curb Cut](https://commonwaysystem.org/patterns/intersections/driveway-curb-cut.md): A minor access-point junction connecting a driveway or parking entrance to the street, realistic across nearly the full density range but dropping off at Core density. - [Grade-Separated Interchange](https://commonwaysystem.org/patterns/intersections/grade-separated-interchange.md): Freeway-scale grade-separated intersection treatment, an acknowledged fallback for genuinely freeway-scale volume or speed beyond what a turbo-roundabout can manage. - [Median U-Turn (MUT)](https://commonwaysystem.org/patterns/intersections/median-u-turn.md): An intersection where left-turn movements from both approaches are removed from the main crossing and rerouted through a downstream median crossover, Situational on wide, higher-speed divided roads. - [Midblock Pedestrian Crossing](https://commonwaysystem.org/patterns/intersections/midblock-crossing.md): A dedicated pedestrian crossing placed between intersections, used where block length or destination demand makes waiting for the corner impractical. - [Protected Intersection](https://commonwaysystem.org/patterns/intersections/protected-intersection.md): A Dutch-style intersection treatment using corner refuge islands and setback bicycle/pedestrian crossings to reduce conflict between turning vehicles and people walking or biking through the intersection. - [Railroad Grade Crossing](https://commonwaysystem.org/patterns/intersections/railroad-grade-crossing.md): An at-grade crossing where any street type meets an active rail line, with its own geometry standard, required warning devices, sight-distance rules, and low-clearance-vehicle risk distinct from any road-to-road intersection. - [Restricted Crossing U-Turn (RCUT)](https://commonwaysystem.org/patterns/intersections/restricted-crossing-u-turn.md): An at-grade intersection design, also known as a J-turn or superstreet, that removes minor-road through and left-turn movements entirely, redirecting them via a right turn and a U-turn at a median crossover, Situational on high-speed divided highways. - [Roundabout (Single / Multi-Lane)](https://commonwaysystem.org/patterns/intersections/roundabout.md): The default intersection control wherever two Collector-or-higher streets meet, single or multi-lane, per the Commonway System's locked intersection philosophy. - [Signal](https://commonwaysystem.org/patterns/intersections/signal.md): Traffic signal control, available within the Commonway System only as a documented last resort against the safer roundabout default, never the presumed choice. - [Stop / Yield (Two-Way)](https://commonwaysystem.org/patterns/intersections/stop-yield.md): Two-way stop or yield intersection control, common from Undeveloped through Compact density and tapering off past that point as volumes rise. - [Turbo-Roundabout](https://commonwaysystem.org/patterns/intersections/turbo-roundabout.md): A higher-capacity roundabout variant, using spiral lane markings to guide traffic, reserved for the highest-volume Arterial-to-Arterial junctions. - [Uncontrolled](https://commonwaysystem.org/patterns/intersections/uncontrolled.md): An uncontrolled intersection with no assigned right-of-way control, realistic only at the lowest density and traffic volume tiers. - [Alley](https://commonwaysystem.org/patterns/local-streets/alley.md): A narrow Local street typology for service and driveway access, where vehicle and freight movement outrank pedestrian and bicycle through-traffic. - [Bicycle Boulevard / Neighborhood Greenway](https://commonwaysystem.org/patterns/local-streets/bicycle-boulevard.md): A Local street typology using traffic calming and diversion to discourage through car traffic while prioritizing bicycle through-movement in the shared roadway, distinguished from Bike Highway/Greenway's full physical separation. - [Cul-de-sac](https://commonwaysystem.org/patterns/local-streets/cul-de-sac.md): A dead-end Local street typology, marked Situational, that peaks at Suburban density and becomes incompatible with Urban and Core connectivity. - [Default (Standard Local Street)](https://commonwaysystem.org/patterns/local-streets/default.md): The baseline Local street, applying the base modal hierarchy and 20 mph design speed with no named override. - [Festival Street](https://commonwaysystem.org/patterns/local-streets/festival-street.md): A Local street typology that closes to vehicle traffic during scheduled events and reverts to the base Local modal hierarchy off-hours. - [Frontage / Service Road](https://commonwaysystem.org/patterns/local-streets/frontage-service-road.md): A Local street typology running parallel to a faster Arterial or Freeway, separating pedestrians and cyclists from the higher-speed roadway. - [Living Street / Woonerf](https://commonwaysystem.org/patterns/local-streets/living-street-woonerf.md): A Local street typology, including NACTO's Home Zone, where pedestrians and cyclists share the full street width and vehicles move as guests at walking pace. - [Local Transit](https://commonwaysystem.org/patterns/local-streets/local-transit.md): A Local street typology carrying a dedicated transit route, with transit elevated above the rest of the Local base modal hierarchy. - [Main Street](https://commonwaysystem.org/patterns/local-streets/main-street.md): A Local street typology built around retail frontage and pedestrian priority, the small-town pattern at Rural density and the defining Local pattern at Compact and Urban density. - [Pedestrian-only Street / Plaza](https://commonwaysystem.org/patterns/local-streets/pedestrian-plaza.md): A Local street typology, marked Situational, that excludes vehicle traffic entirely in favor of pedestrians and, where permitted, bicycles. - [School Street](https://commonwaysystem.org/patterns/local-streets/school-street.md): A Local street typology that closes or restricts vehicle traffic during active school hours to protect pedestrian and bicycle arrival and dismissal. - [Shared-Use Path](https://commonwaysystem.org/patterns/local-streets/shared-use-path.md): A Local street typology for an off-street path physically separated from the roadway, shared by pedestrians and bicyclists under roughly equal priority, connecting local-scale destinations. - [Yield Street](https://commonwaysystem.org/patterns/local-streets/yield-street.md): A narrow Local street typology where opposing vehicles yield to each other by design, viable only at genuinely low traffic volumes. - [Dendritic / Hierarchical](https://commonwaysystem.org/patterns/network/dendritic-hierarchical.md): A tree-like network topology where local streets feed into collectors, which feed into arterials, minimizing through-connections at lower tiers and concentrating traffic onto a smaller number of higher-order routes. Historically progressed through increasingly branch-heavy, cul-de-sac-dominated forms over the 20th century, documented as an internal four-stage spectrum: Fragmented Parallel (c. 1950), Warped Parallel (c. 1960), Loops and Lollipops (c. 1970), and Lollipops on a Stick (c. 1980). - [Grid](https://commonwaysystem.org/patterns/network/grid.md): A network topology in which streets form a continuous, evenly spaced pattern of parallel and perpendicular routes intersecting at right angles, producing rectangular blocks and multiple direct route options between any two points. - [Organic / Irregular](https://commonwaysystem.org/patterns/network/organic-irregular.md): An unplanned, irregular network shaped incrementally over time by terrain, property lines, and historical settlement patterns rather than a deliberate overall layout, typically found in historic or pre-industrial city cores. - [Radial](https://commonwaysystem.org/patterns/network/radial.md): A network topology in which routes converge toward and radiate outward from a central point, frequently supplemented by circumferential (ring) routes connecting the radial spokes at varying distances from the center. ## Reference - [Reference](https://commonwaysystem.org/references.md): Explains the Reference section, the technical detail layer beneath a pattern page's plain-language description, organized by Pattern ID, distinct from a page's numbered citations. ## Retrofits - [Retrofit Strategy Index](https://commonwaysystem.org/retrofits.md): Index of every Retrofit Strategy in the Commonway System, grouped by scale (Network, Corridor, Intersection). A Retrofit Strategy describes how to move an existing street toward a Pattern. - [Depaving / pavement-to-gravel conversion](https://commonwaysystem.org/retrofits/corridor/depaving-pavement-to-gravel.md): Converts a paved roadway to a gravel or unpaved surface on a low-volume rural or exurban road, reducing maintenance cost and naturally discouraging high speeds. - [Five-plus lane reallocation](https://commonwaysystem.org/retrofits/corridor/five-plus-lane-reallocation.md): Reduces the through-lane count on a roadway of five or more lanes, applying road diet principles at a larger scale, adding or widening a center turn lane and requiring more careful traffic analysis than a standard four-to-three conversion. - [Four-to-three lane road diet](https://commonwaysystem.org/retrofits/corridor/four-to-three-lane-road-diet.md): Converts a four-lane undivided roadway into three lanes, one through lane each direction plus a center two-way left-turn lane, the classic road diet, reclaiming freed width for bike lanes, wider sidewalks, or parking. - [Lane diet](https://commonwaysystem.org/retrofits/corridor/lane-diet.md): Narrows existing travel lane widths, typically to 10-10.5 feet, without removing a lane, reclaiming the width difference for a bike lane, wider sidewalk, or buffer. A lighter-touch alternative to a road diet. - [One-way to two-way conversion](https://commonwaysystem.org/retrofits/corridor/one-way-to-two-way-conversion.md): Converts a one-way street back to two-way operation, typically reducing lane width and count, slowing traffic and restoring each direction's visibility to passing traffic. - [Parking-lane reallocation](https://commonwaysystem.org/retrofits/corridor/parking-lane-reallocation.md): Converts an existing on-street parking lane to another use, a bike lane, a transit lane, a parklet, or public plaza space, changing the curb's function rather than the roadway's through capacity. - [Protected bike lane retrofit via lane removal](https://commonwaysystem.org/retrofits/corridor/protected-bike-lane-lane-removal.md): Installs a physically separated bike lane by removing an entire travel lane, effectively a road diet whose primary purpose is the bike lane it creates, following the same volume thresholds as a standard road diet. - [Protected bike lane retrofit via parking reduction](https://commonwaysystem.org/retrofits/corridor/protected-bike-lane-parking-reduction.md): Installs a physically separated bike lane by removing or reconfiguring on-street parking, often shifting retained parking outside a physical buffer so parked cars help protect the bike lane. - [Protected bike lane retrofit via lane-width reallocation](https://commonwaysystem.org/retrofits/corridor/protected-bike-lane-width-reallocation.md): Installs a physically separated bike lane by narrowing existing travel lanes and reallocating the recovered width, without removing a lane or on-street parking, the lightest-touch of the three protected bike lane retrofits. - [Transit priority lane retrofit](https://commonwaysystem.org/retrofits/corridor/transit-priority-lane-retrofit.md): Converts an existing general travel lane or on-street parking lane into a lane dedicated to bus travel, curbside or center-running, removing the mixed-traffic conflict that erodes transit reliability. - [2+1 road with cable median barrier](https://commonwaysystem.org/retrofits/corridor/two-plus-one-road-cable-barrier.md): Converts an undivided rural two-lane road into a continuous three-lane cross section: a center lane that alternates as a passing lane in each direction, with a cable median barrier separating opposing traffic between passing sections. Built inside the existing right-of-way. Applies where design speed, terrain, or posted speed exceeds roughly 45 mph, where head-on and run-off crashes dominate fatalities. - [Displaced Left-Turn (DLT) retrofit](https://commonwaysystem.org/retrofits/intersection/displaced-left-turn-dlt-retrofit.md): Also known as a continuous flow intersection, shifts the left-turn lane to the opposing side of oncoming traffic upstream, letting left-turning and through traffic move simultaneously, a lower-cost alternative to a grade-separated interchange. - [Median U-Turn (MUT) retrofit](https://commonwaysystem.org/retrofits/intersection/median-u-turn-mut-retrofit.md): Also known as a Michigan U-turn, reroutes left-turn and through movements from a minor approach away from the main intersection to a median crossover downstream, reducing conflict points and signal complexity. - [Restricted Crossing U-Turn (RCUT) retrofit](https://commonwaysystem.org/retrofits/intersection/restricted-crossing-u-turn-rcut-retrofit.md): Also known as a J-turn or superstreet, reroutes both left-turn and through movements from the minor road to a right turn plus U-turn at a median crossover, letting the main intersection focus on major-road through traffic. - [Signal-to-roundabout conversion](https://commonwaysystem.org/retrofits/intersection/signal-to-roundabout-conversion.md): Replaces an existing signalized intersection with a roundabout, removing signal equipment and phasing in favor of continuous yield-controlled circulation, the concrete mechanism behind CS's roundabouts-first philosophy. - [Barrier-crossing / network reconnection retrofit](https://commonwaysystem.org/retrofits/network/barrier-crossing-network-reconnection-retrofit.md): Adds a new pedestrian and bicycle connection, a bridge, tunnel, or path linkage, across a highway, rail line, or disconnected cul-de-sac pattern that currently severs an otherwise walkable or bikeable network. - [Modal filtering / Low Traffic Neighborhood retrofit](https://commonwaysystem.org/retrofits/network/modal-filtering-low-traffic-neighborhood-retrofit.md): Installs a scattered set of point closures across a residential area, restricting motor vehicle through-traffic on interior streets while preserving full local access and full pedestrian/bicycle passage, a Low Traffic Neighborhood. - [Superblock retrofit](https://commonwaysystem.org/retrofits/network/superblock-retrofit.md): Groups several existing blocks into a single traffic cell, routing through-traffic around the perimeter while reclaiming interior streets for pedestrians, bicyclists, and local access only, a top-down area-wide planning model.