The Future is Form-Based: Zoning Code Renewal with ArcGIS Urban & CityEngine

In this blog, we will explore how ArcGIS Urban and ArcGIS CityEngine can be leveraged by planners and GIS professionals to efficiently explore three key principles of Form-Based Zoning. Here, our focus is on the former community of Dundas within the City of Hamilton, Ontario, as the site of a fictional pilot project to develop a new form-based code. 

Introduction

More and more municipalities across Canada are exploring the value of form-based zoning (FBZ) concepts to address the needs for housing affordability, walkability, and transit-oriented communities. Where conventional zoning places emphasis on enforcing the separation of uses, FBZ focuses instead on outlining built-form guidelines that will produce walkable, livable public realms. FBZ maintains and strengthens the character of individual communities and enables faster development approval, since most development is allowed by right once designs satisfy the objective standards as laid out in the code. 

But how are FBZ bylaws developed and implemented? For many municipalities, moving to FBZ represents a major departure from older zoning bylaws. Significant work must be done to identify the potential impacts of different FBZ concepts and to select what is most appropriate for an area. 

In this blog, we will explore how ArcGIS Urban and ArcGIS CityEngine can be leveraged by planners and GIS professionals to efficiently explore three key principles of FBZ. Here, our focus is on the former community of Dundas within the City of Hamilton, Ontario, as the site of a fictional pilot project to develop a new form-based code. 

Screenshot of the study area in Urban with existing buildings and trees. 

1. Focusing on the Public Realm with Street Type Standards 

A central idea in FBZ is an emphasis on the role that private sites play in shaping the public realm. Form-based codes are typically prescriptive on those elements of site design that most affect the public realm, and more flexible on secondary concerns, such as building and land uses. 

One of the techniques commonly employed to this end is a two-stage approach to zoning, where sites are assigned a “primary” zoning designation, which controls broad site design elements like maximum height and density, and a secondary “street type” designation tied to the nature of the street on which a lot fronts, which controls elements such as setbacks and the nature of desired building frontages. 

ArcGIS Urban allows us to perform an exploration of this approach. Using ArcGIS Urban’s Zoning Types, we can assign a new set of “primary” zoning types to our study area. In some places, these new zones will align with previous zoning designations - such as the Cross-Melville Heritage District, which is assigned a new zoning designation that continues to focus on maintaining the heritage character of this area. In other places, new zoning will diverge significantly. Both approaches are easy to explore in ArcGIS Urban, where planners can update zones at the click of a button. 

Screenshot of study area with old zones & new zones side-by-side. 

Alongside this work, ArcGIS Urban’s Overlay functionality is used to apply our new set of secondary “street type” standards, in accordance with an evaluation of the nature and desired character of streets within the community. 

Screenshot of study area with street overlays applied. 

We can use Zoning Types to control maximum height, density, and coverage allowance, and use Overlays to control lot line setbacks and provide visual context regarding street type differences. ArcGIS Urban is scenario-based, meaning we can explore multiple visions for this rezoning in parallel, and switch seamlessly between them for analysis and comparison. 

GIF showing re-assignment of zoning & application of overlay type, then toggling on envelopes and viewing regulation pane on a parcel. 

2. Shaping Neighbourhood Character with Building Types 

Building types are another key concept in FBZ. Building types allow for identification of desired built forms within different zones, as well as variation of key regulations (such as allowed coverage or dwelling unit density) according to the intended built form on each site. They also afford planners the ability to provide clear, detailed specifications for different typologies, such as controlling facing distances and private road access requirements for multi-building sites. 

 We can use building types directly in ArcGIS Urban to establish a hierarchy of uses within a building, and set other elements, such as maximum or minimum building dimensions, and tower-podium forms. When building types are applied to parcels, they also absorb regulations from underlying zoning and overlays, meaning that realistic, feasible development in line with the principles outlined by the FBZ bylaw can be deployed at the click of the button. 

GIF showing application of a building type in Urban. 

For more complex sites with multiple buildings, ArcGIS CityEngine can be leveraged to generate building footprints based on a totally customizable logic. Once generated, these footprints can be synced with ArcGIS Urban, to produce our 3D massing. 

For our study area, we have created a custom ArcGIS CityEngine rule designed to handle a range of multi-unit residential building types permitted in the draft Neighbourhood Low (F-NL) zone, including detached dwelling clusters, and street-facing, back-to-back, or clustered townhomes. Our custom rule is configured for a wide range of complex parameters outlined in our new draft zoning bylaw, such as maximum adjacent units, minimum townhome unit widths, facing distances and more. 

Switch between different building forms in CGA and resulting footprints.

3.  Visualizing Desired Facade Features 

Because FBZ is primarily concerned with the way in which development shapes the public realm, many form-based codes provide some guidance on the architectural design of buildings within the zone. Once a simple massing has been created in ArcGIS Urban, the plan may be brought into ArcGIS CityEngine, and custom rules can be applied to generate detailed 3D models of acceptable facade types. This modelling is not limited to buildings; ArcGIS CityEngine can also be used to create detailed landscaping and street visuals to capture a complete visualization of the target public realm for a particular area of interest. 

GIF showing sped-up application of CGA rules to accomplish the above. 

Conclusion 

Using ArcGIS Urban and ArcGIS CityEngine, we have been able to explore several key FBZ concepts and identify those most appropriate for our community.  

As we continue to work to apply these techniques across a range of zones within our study area, we will begin to develop a complete plan that visualizes these changes alongside the range of built forms enabled by them. This work will act as a powerful explanatory tool that we can share with key stakeholders and community members for feedback. We can also use this work to generate an understanding of the impact of these changes on key residential and employment capacity metrics within the community. 

ArcGIS Urban makes these workflows seamless, allowing for a collaborative and iterative process of zoning code redesign. Interested in learning more? Check out this recent webinar on the full lifecycle of a plan in ArcGIS Urban, and how the wider ArcGIS ecosystem can be used to easily engage stakeholders every step of the way.