We will allow more people to live in areas that are already developed, which will slow construction over wilderness and farmland.

The current zoning code limits population density by restricting the number of dwellings that can be built on each lot of land. A dwelling is an apartment or house for one “family,” which is usually defined as four unrelated people. Some zones only allow one dwelling per lot. There are minimum lot sizes, which means that there is a maximum number of dwellings that can be built on each acre. For example, the R1A zone allows only one dwelling per lot, and lots must be at least 20,000 square ft. This means there can only be eight unrelated residents per acre.

Since many people want to live in Ann Arbor, and the supply of housing is limited , housing is more expensive than in nearby communities. Developers respond by building houses in nearby townships. Between 2000 and 2010, Washtenaw County’s population increased by 22,021, but Ann Arbor’s population decreased by 90.

Advertisements for these developments emphasize how close the subdivisions are to Ann Arbor. A website for “The Ravines” states “Residents pay lower Scio Township taxes but benefit from city water & utilities and by sending their children to Ann Arbor Schools.” The same page later claims: “Located in popular Ann Arbor and offers great access to the expressway to get to Detroit or beyond quickly. A hop skip and a jump away is Zingerman’s Deli, Kerrytown, Kerrytown Farmers Market, U of M campus, Medical Center and University of Michigan football games.

Our zoning plan will allow smaller lots, and more dwellings on each. The only limit on the number of people per dwelling will come from safety rules in the state construction codes which prevent fire hazards and other dangers. More people will be able to live in areas which are already developed, which will slow construction over wilderness and farm land.

We will reduce travel distances by allowing more people to live near businesses. This will reduce air pollution from vehicles.

Our zoning plan will allow a mixture of land uses in every part of the city with rules to prevent noise and other nuisances. Apartments, houses, and businesses will be permitted in the same area. This will make it easier to reach destinations on foot. It will also be easier to run busses and other forms of public transportation, because more people will be allowed to live close to transit stops. Research shows that increased population density is linked to decreased car use and more generally, decreased transport energy use.

Even though our zoning plan will likely decrease car use and pollution, it may make remaining car travel more convenient. If population density increases, traffic density will increase, but  destinations will be closer together. Research suggests that having destinations closer together speeds travel more than traffic density slows it.

Our zoning plan will also reduce traffic congestion and air pollution by abolishing off-street parking minimums. Currently, when someone builds a new structure, they must include a minimum number of parking spaces. The number depends on the size of the structure and the type of land use. These minimums exist so that people who drive to the new structure do not take up parking spaces on the street, but there are studied negative consequences. Houses and stores are spread apart by parking lots, which makes walking and public transport difficult. Commercial and residential space is more expensive, because every new development site is partially filled by parking spaces. Traffic congestion increases, because more people drive when they can park for free.

Reforming the zoning code to allow compact arrangements will slow urban sprawl, reduce vehicle use, and make all forms of transportation more convenient. Our zoning plan does this while better protecting residents from nuisances.

Traditional zoning is supposed to separate incompatible land uses to prevent nuisances.

In theory, zoning provides isolated spaces for irritating land uses like noisy factories, which would otherwise bother nearby people.

The problem is that the zones for irritating land uses have to border the other zones somewhere. A nuisance that is allowed in an industrial zone can bother people in a nearby residential zone. A small town with a few zones might use a river or lake as a barrier between districts, but in Ann Arbor today, land uses are not separate. Industrial zones touch residential zones all over the map.

The light purple is M1 Limited Industrial. The dark purple is M2 Heavy Industrial. The yellow shapes are residential zones. The pink shapes are commercial zones, which allow stores and houses. The circle contains Lotus Engineering and houses across the street.

Lotus Engineering at 1254 North Main Street in the M2 Heavy Industrial zone.

A house across the street in the R4A residential zone

Performance standards, not zoning, prevent severe nuisances.

So what is stopping industrial uses from sending dust and noise to nearby houses? City laws like the Noise Ordinance and Air Quality Control Ordinance. These performance standards forbid dangers and serious nuisances in all zones, but they do not solve the problem of how to isolate moderately disturbing land uses. Some people prefer areas that have strict rules for nuisances like noisy truck deliveries and loud businesses open late, but other people prefer areas with more lenient rules. Separating the areas is currently not possible, because people in the lenient zones can bother people in nearby restrictive zones. It is also not possible to ban moderate irritations from the whole city. It is illegal for cities in Michigan to completely exclude needed land uses, so necessary irritations must go somewhere.

Currently, residents can only avoid moderate nuisances if they push harms away from themselves.

The D1 district borders the R4C downtown near Huron and Division. The D1 allows 150-180 ft. buildings. The R4C allows 30 ft. buildings. This year, city council approved a 140 ft. building at Huron and Division in the D1 zone.

 
The red is D1 Downtown. The dark yellow is R4 Residential. The circle contains a planned 14 story building.

Many nearby residents are angry, and one of their complaints is that shade from tall buildings is a nuisance. However, tall buildings create space for people to live and work, so city council is not willing to ban all structures taller than 30 ft. The D2 district, which allows 60 ft. buildings, is supposed to solve this problem by providing a buffer between the D1 and other zones. However, the D2 district does not fully circle the D1, and even if it is expanded, there are people just outside the D2 who feel that a six story building is a nuisance. In 2010, neighbors successfully opposed The Moravian, a six story apartment built near the border of the D2. Wherever there is a line between two zones that allow different degrees of harm, people in the restrictive zone will have to live with the higher degree of harm. This buffering problem will reoccur as long as traditional zoning exists.

City council recognizes that each district’s zoning rules affect people in nearby zones, and they invite people to give their opinions on each zoning change. When people help make zoning rules for their neighbors, they sometimes act in their own self interest. Some residents would rather have fewer people and less traffic in their neighborhood, even if they know that people must live somewhere. Neighbors argue for density restrictions that make housing more expensive, and force people to live outside the city, often in subdivisions built over fields and forests. Traditional zoning creates new problems without protecting residents from nuisances.

Our zoning plan isolates moderate irritations.

Instead of regulating what irritations can be sent from properties in each zone, our plan regulates what irritations can be received by properties in each zone. This means that no one can disturb a property in a restricted area of the city, even if the disruption is coming from a property in a less restrictive zone.

The height limit for a building in an unrestricted zone depends on its distance from a restricted zone. For example, the rule could be:

“The maximum height of a structure is either 35 feet, or one half the distance between the structure and the nearest property in a restricted zone–whichever value is greater.”

This plan allows tall buildings in the center of downtown, but not the edges. No building casts a shadow on a restricted property until roughly one hour before sunset, when shadows are about twice as long as buildings. Residents are better protected, and there is more space for stores and apartments. Similar controls for noise and other irritations protect people in restricted zones from nuisances, regardless of nearby zoning changes.

The new zones are arranged to protect areas that the current zoning code intends to protect. The Restricted Mixed Use zone covers areas currently zoned residential. The Mixed Use Zone covers commercial and industrial areas.

Property owners may request a rezoning from Restricted Mixed Use to Mixed Use at any time. City council and the planning commission do not have to debate each zoning change, because Restricted Mixed Use properties are protected regardless of nearby zoning. For example, if a developer purchases a large Restricted Mixed Use tract and rezones it to be Mixed Use, the developer can build a tall building in the center of his property, but only a 35 foot building at the edge of his property. Before building, the developer must pay impact fees for water and sewer expansions that are necessary because of the development, but the rezoning can be immediate.

The plan will better protect residents and create more space for dwellings and businesses. Housing and commercial space will be more affordable, fewer people will build over farms and fields, and land use changes will occur with fewer expensive and unpleasant disputes.