Green infrastructure, or blue-green infrastructure, is a system that helps solve problems in cities and with the climate by working with nature. This system includes managing rainwater runoff, adapting to climate changes, reducing heat in urban areas, increasing plant and animal life, growing food, improving air quality, creating energy from renewable sources, providing clean water, and maintaining healthy soil. It also offers benefits for people, such as better quality of life through places to play, shade, and shelter in and around cities. Green infrastructure helps support the health of the environment, economy, and communities. Recently, experts and activists have also focused on creating green infrastructure that ensures fair access to natural resources for all people, not just some.

Green infrastructure is part of a larger category called "Sustainable and Resilient Infrastructure," which is described in guidelines like SuRe, the Standard for Sustainable and Resilient Infrastructure. It can also refer to "low-carbon infrastructure," such as systems for renewable energy and public transportation. Blue-green infrastructure is sometimes included in "sustainable drainage systems" or "sustainable urban drainage systems" (SuDS or SUDS), which help manage water quality and quantity while also improving biodiversity and making urban areas more pleasant.

Introduction

Nature can help protect communities from problems like flooding, extreme heat, and poor air, soil, and water quality. When people use natural systems, such as prairies, to manage these issues, it is called "green infrastructure." Prairies have soil that soaks up water, reducing runoff, and plants that clean water by removing pollutants. Green infrastructure works at all sizes, but it is most often linked to green stormwater management systems, which are smart and cost-effective ways to handle water. These systems support the health of communities, the environment, and the economy.

"Blue infrastructure" refers to urban systems that involve water, such as rivers, streams, ponds, and lakes. These water features can be natural parts of cities or added during urban planning. Coastal areas may also use natural coastline features in their designs, such as harbors, piers, and quays, to benefit from the ocean environment. Blue infrastructure helps support aquatic life, including insects, amphibians, and birds. It also improves the health and well-being of people who live near these water areas. Accessible blue infrastructure in cities is often called "blue spaces."

Terminology

Green urban structures began in the 1870s with ideas about growing food in cities and giving people small plots of land to grow gardens. Other names for these ideas include stormwater best management practices, source controls, and low impact development (LID) practices.

Green infrastructure ideas started in the mid-1980s with plans to manage stormwater in a way that reduces runoff, prevents erosion, and helps recharge underground water sources. In 1987, changes to the U.S. Clean Water Act required new ways to manage pollution from cities, emphasizing practices that handle runoff at its source instead of using traditional drainage systems. In 1990, the U.S. Environmental Protection Agency (EPA) created rules for municipal separate storm sewer systems ("MS4"), requiring large systems to develop plans to prevent stormwater pollution and use "source control practices." An EPA handbook from 1993 listed best management practices, such as using plants, filters, and porous pavement to manage stormwater. Rules for smaller cities were added in 1999. MS4 systems serve over 80% of the U.S. population and drain 4% of the country’s land area.

Green infrastructure focuses on using natural environments in land-use planning decisions. However, the term does not have a single clear definition. It is also called "blue-green infrastructure" or "green-blue urban grids" and is used by many fields, including design, conservation, and planning. These terms often involve stormwater management, adapting to climate changes, and creating green spaces that serve multiple purposes.

Sometimes, the term "green infrastructure" is expanded to "multifunctional" green infrastructure. This means combining different uses, like managing stormwater and creating green spaces, on the same piece of land.

The EPA later used "green infrastructure" to describe managing stormwater runoff locally using natural systems or systems that copy natural processes to treat polluted water. This approach helps natural ecosystems, even though it is not the main focus of the broader concept.

The term "blue-green infrastructure" is often used in cities to highlight stormwater management as a key part of creating sustainable, multifunctional urban areas. At the building level, "blue-green architecture" applies similar ideas on a smaller scale, focusing on using water from sources like grey water and rainwater for building greening.

As noted, the term Green Infrastructure (GI) now includes topics like walking and cycling paths and renewable energy, which has caused confusion for stormwater experts. To address this, the term Green Stormwater Infrastructure (GSI) was created in the 2010s to specifically focus on stormwater management and distinguish it from other GI topics. GSI often refers to small-scale features like stormwater curb extensions, tree well filters, and pervious pavement, but it can also describe large projects that manage runoff across hundreds of acres. Many U.S. cities and regions have developed guides, such as the GSI Handbook from the Santa Clara Valley Urban Runoff Pollution Prevention Program in California.

History

The term "green infrastructure" was first used in the early 1990s, even though the idea of using nature to support communities existed long before. In 1994, Buddy MacKay, who led the Florida Greenways Commission, used the term in a report to Florida’s governor about a project started in 1991 called the Florida Greenways Project. He explained, "Just as we plan roads, water, and electricity for our communities, we must also plan and manage green spaces to support people and the environment."

In ancient China, gardens were designed to show natural beauty in cities. These gardens, which began during the Shang Dynasty (1600–1046 BC), allowed native plants to grow naturally without human interference. This helped create safe places for wildlife in urban areas.

In ancient Greece, the concept of green spaces was used with the creation of agoras. Agoras were public spaces where people met and talked. Many were built across Greece, and some included natural elements like trees and plants to bring nature into public life.

A common feature in cities is the lawn, which is usually short grass and sometimes other plants. While modern artificial lawns can harm the environment, historical lawns helped support plant and animal life. These older lawns inspired modern designs that aim to be more eco-friendly.

During the Middle Ages in Europe, lawns filled with flowers and plants, called "flower meads," were used to create sustainable green spaces. Later, in the Edwardian Era, lawns with thyme helped attract insects and support biodiversity. In the 20th century, England used a type of lawn called "enamelled meads" for both beauty and to help manage rainwater.

During the Renaissance, cities began creating public areas like parks and gardens for people to gather and relax. These spaces also improved the look of cities and helped reduce heat and improve air quality.

Green infrastructure can be traced back to the 17th century in France, where nature was used to organize towns and provide social spaces. Plants were grown in these areas to provide food and create peaceful places. French elites used large open spaces to display wealth and power, such as promenades—lush gardens where people could relax away from crowded cities. These areas, like the Allée du Cours-la-Reine, were lined with trees and helped improve air quality.

French city planners focused on blending nature with urban design to show how cities and the environment could coexist. In the 18th century, citizens asked to remove old city walls to make room for new gardens and green walkways. Town halls and city centers were decorated with rare plants and trees to make cities more beautiful.

In 1847, George Perkins Marsh spoke about the harm of deforestation and later wrote Man and Nature in 1864, promoting forest conservation. Around the same time, Henry David Thoreau wrote Walden in 1854, arguing that cities should have parks to protect nature. Frederick Law Olmsted, a landscape architect, supported these ideas and designed parks like Boston’s Emerald Necklace, which connects public spaces and helps protect wildlife and manage water.

In Europe, Ebenezer Howard promoted the "garden city" movement, which balanced urban development with nature. He designed cities with greenbelts and tree-lined roads to connect towns and countryside.

In the late 1800s, the U.S. government began protecting land and nature. This included the 1864 law to preserve Yosemite Valley as a public park and the creation of the first U.S. national park in 1872.

In the 19th century, industrial leaders aimed to improve workers’ lives by creating clean environments and outdoor spaces, which helped increase productivity. These ideas influenced 20th-century efforts like green spaces in industrial areas and suburban gardens.

The Anaconda Copper Mining Company caused environmental harm in Montana, but a refinery in Great Falls used the land around it to create a green space for recreation. This area included a golf course, flower beds, picnic spots, a pond, and walking paths.

The role of water: blue spaces and blue infrastructure

Water has always been important for where people live. It helps with moving goods, trading, and making energy. Water also gives people things like drinking water, food, and chances to enjoy activities like swimming or boating. Many of the world’s biggest cities are near rivers, lakes, or oceans. Cities have built water-related structures, such as canals and harbors, to use water’s benefits and reduce dangers. However, cities now face serious water problems, like floods, dry periods, and activities on rivers that cross country borders. As cities grow quickly, many water structures are disappearing. More people are living near coasts, and old industrial areas near water, like canals and docks, are being changed because of new trade patterns. Scientists recently studied how these changes affect people’s health and found that being near water areas, called "blue space," can improve mental health and encourage physical activity.

One out of every five people on Earth, about 1.2 billion, live in places with not enough water. Climate change and water-related disasters will make cities need more water and cause more people to move to cities. Cities use a lot of fresh water and greatly affect water systems. By 2050, water use for cities and industry is expected to double.

In 2010, the United Nations said that clean water and sanitation are basic human rights. Scientists are looking for new ways to help cities use water more wisely. Managing water in cities is complicated. It needs not only systems for water and waste, but also ways to control pollution and stop floods. It also needs teamwork between different groups and changes in how cities are managed to use water more fairly and sustainably.

Types of green infrastructure

Urban forests are forests found in cities. They are an important part of city green spaces. These forests use tree and plant types that are not harmful or invasive, which helps reduce the need for care and watering. Native plants also look nice and lower costs. Using a variety of plant types in urban forests is important to avoid having only one type of plant, which makes the forests stronger and better at handling pests and other problems.

• Energy Use: A study by the Lawrence Berkeley National Laboratory and Sacramento Municipal Utility District showed that shade trees placed near homes can save up to 47% of energy used for heating and cooling.
• Urban Heat Island Mitigation: Tree-covered areas have lower air temperatures than open areas without trees. This happens because trees cool the air through processes like water evaporation from leaves, shading from tree canopies, and changes in how air moves over the ground.
• Water Management: Urban forests help manage city water by reducing stormwater runoff. Trees catch rainwater that falls on them.
• Property Values: Adding more trees and greenery in cities can increase the value of nearby homes and businesses.
• Public Health: Green spaces in cities can improve mental health. Urban forests help reduce the negative effects of heat from city materials and structures, which can harm health. They also help ecosystems stay strong, as seen in traditional Japanese farming. Green spaces create jobs for people who do not need advanced education and support efforts to protect the environment, such as those in the 1992 Rio Declaration on Environment and Development.

Constructed wetlands are manmade wetlands that act as natural filters. They include plants and are built on land that is not near natural wetlands to protect them. There are two main types: systems where water flows through the ground and systems where water flows on the surface. Planning and managing these wetlands carefully can prevent harm caused by changing water patterns or introducing harmful plants.

• Water Efficiency: Constructed wetlands copy natural wetlands to improve water quality and use. They use plants, soil, and microorganisms to trap dirt and break down pollutants.
• Cost-Effective: Wetlands are cheap to run and maintain. They also help manage water levels and add greenery to the environment, which can reduce unpleasant smells from wastewater.

Green roofs help improve air and water quality and lower energy costs. In some areas, green roofs have been linked to cooler temperatures because they reflect more sunlight, reducing the need for cooling. Plants and soil on green roofs provide insulation and reduce runoff from rain, which helps manage stormwater in cities. Green and blue roofs also allow people to grow food on rooftops.

Green roofs trap rainwater and carbon pollution. About 40 to 80% of rain that falls on green roofs is stored. The water is released slowly, reducing how much runoff enters water systems at once.

Blue roofs are not green infrastructure but help manage rainwater. They collect and store rainwater in basins or ponds before slowly releasing it into sewers and waterways. Blue roofs can lower city temperatures when used with reflective roofing materials and save energy by reducing cooling needs.

Rain gardens are a way to manage stormwater by capturing water. They are shallow, low areas planted with shrubs and plants that collect rainwater from roofs or streets and let it slowly soak into the ground.

Regular lawn grass does not help control runoff, so alternatives are needed. Rain gardens can reduce runoff by 30% in homes. They are usually 150 to 300 square feet in size and cost $5–$25 per square foot. Plants from wetland and river areas are best for cleaning runoff.

Stormwater basins collect rainwater in vegetated areas to reduce runoff, prevent erosion, filter water, and stop flooding. New designs use more plants instead of mowed grass for better results. These basins, called bioretention basins, are good at removing pollutants and absorbing dirt. They are important for managing floods in cities.

Downspout disconnection is a way to manage stormwater by separating roof drains from sewers and directing water to permeable surfaces. It helps reduce the amount of water entering sewers, especially in cities with combined sewer systems. During heavy rain, roof drains can send 12 gallons of water per minute into sewers, causing backups and overflows. Some cities, like Milwaukee, now require downspout disconnection in homes to reduce this problem.

Bioswales are stormwater systems that help manage rainwater. Like rain gardens, they are vegetated or mulched channels in urban areas. They absorb or carry stormwater to reduce runoff.

Planning approach

Green Infrastructure looks at the natural environment to understand how it works and then creates rules or plans to protect important natural areas. If natural areas are not working well, plans may suggest ways to improve them using natural or man-made methods.

In cities, this can mean bringing back natural waterways and making cities able to manage water on their own. For example, cities can collect water locally, reuse it, and include stormwater management in everyday structures.

This method has many uses, which helps use land efficiently, especially in crowded places like England where land is in high demand. An example is a river floodplain near a city. This area can hold floodwater, act as a nature reserve, provide space for people to enjoy, and even be used for farming. Research shows that nature can also improve people's health.

In the United Kingdom, Green Infrastructure planning is now included in national, regional, and local plans. For example, it is part of the Milton Keynes and South Midlands Growth area.

In 2009, Natural England published guidance on Green Infrastructure planning. This guidance explains how Green Infrastructure helps shape the character of places, especially when new buildings are planned.

In North West England, a past plan included a Green Infrastructure Policy that also appeared in other land use rules. This policy was supported by a guide called the North West Green Infrastructure Guide. A group called the Green Infrastructure Think Tank (GrITT) helps create policies and manages a website with information about Green Infrastructure.

A program called Natural Economy Northwest helped create projects to study how Green Infrastructure works in the region. These projects looked at the economic value of Green Infrastructure, how it connects with traditional water systems, and where it can help with problems like flooding or poor air quality.

In 2011, a tool called the Green Infrastructure Valuation Toolkit was created. This tool is free to use and helps calculate the economic value of Green Infrastructure projects. It was tested in places like Liverpool.

In 2012, the Greater London Authority created a plan called the All London Green Grid. This plan includes a network of green spaces and waterways to help with travel, flood control, health, and economic growth.

Green Infrastructure is being used to help cities prepare for climate change.

Green Infrastructure can also include goals to protect natural land features.

In the United States, programs managed by the EPA and other groups aim to improve water quality by managing stormwater better. These efforts reduce pressure on traditional drainage systems, like storm sewers and combined sewers, which are underground pipes in cities. Better stormwater management can reduce flooding and improve the environment.

Although Green Infrastructure is not yet widely used, many U.S. cities are starting to use it to meet requirements for managing stormwater. Cities encourage this by offering programs that help people improve their properties. There are about 555 such programs across the country. For example, Philadelphia has built permeable pavement in parks and parking lots, rain gardens at schools, and wetlands to manage stormwater. These improvements help reduce the amount of water that flows into the city’s old sewer system during rainstorms.

In Maryland, a program called "GreenPrint" uses maps to show which areas of land are most important for the environment. This tool helps people make better decisions about land use and supports long-term plans to protect natural resources.

In 2011, the EPA chose ten communities to work with on Green Infrastructure projects. These communities include Austin, Texas; Chelsea, Massachusetts; and others.

The Federal Emergency Management Agency (FEMA) also uses Green Infrastructure to manage urban flooding.

Since 2009, Singapore has published two versions of the ABC (Active, Beautiful, Clean) Waters Design Guidelines. These guidelines help plan and design water systems that work with the environment. The Public Utilities Board encourages landowners and developers to use these designs in their projects and invites the public to use them for recreation and learning.

The benefits of the ABC Waters Concept include:
– Treating stormwater naturally near where it falls, using plants and soil to clean water before it enters rivers and reservoirs.
– Improving wildlife habitats and making areas more attractive.
– Bringing people closer to water and creating spaces for recreation and education.

Examples

A good example of green infrastructure being used on a large scale is the Beijing Olympic site. First built for the 2008 Summer Olympics and later used for the 2022 Winter Olympics, the site covers a large area of old industrial land being turned into new spaces in the northern part of the city between the 4th and 5th ring roads. The main green feature at the site is the "Dragon-shaped river," a system of water storage areas and wetlands covering more than 500,000 square meters. From above, the system looks like a traditional Chinese dragon.

This system not only reflects Chinese culture but also helps reduce pollutants in water that comes from a nearby wastewater recycling facility.

Farmers said that flooding on their farmland happened because of development upstream. The water flowed quickly into storm drains from hard surfaces, such as roads and buildings, and then into their farmland. The farmers received an undisclosed amount of money in the tens of millions as compensation. Areas with low population density and many paved surfaces send stormwater into streams at faster speeds than before development. These practices harm the environment and can be expensive to manage. In response, the city of Surrey, British Columbia, chose a 250-hectare area called East Clayton for a green infrastructure project. This approach reduced the amount of stormwater flowing downstream and allowed rainwater to soak into the ground near where it fell. The system at East Clayton could hold one inch of rainfall each day, which covers 90% of the yearly rainfall. The use of green infrastructure in Surrey helped create a sustainable environment that reduced runoff and saved about $12,000 per household.

The former factory site of Nya Krokslätt is located between a mountain and a stream. Danish engineers, Ramboll, designed a system to slow and guide stormwater using methods like plants, ponds, streams, and soak-away pits. The design also includes glazed green-blue areas around buildings that delay and clean water from roofs and greywater. This plan created a place that serves many purposes and is lively, including energy-efficient buildings and blue-green infrastructure that supports nature in an urban area.

Since 1991, the city of Zürich has required that all flat roofs (unless used as terraces) be covered with greenery. This policy has helped increase biodiversity, store rainwater, and delay water flow. It also helps balance temperatures and improve air quality. Green roofs act as stepping stones for plants and animals, connecting with natural areas and helping spread seeds through wind and birds.

In the old industrial area of the Ruhr District in Germany, Duisburg-Nord is a landscape park that includes former industrial buildings and natural life. Architects Latz + Partner created a water park using the old River Emscher, divided into five sections: Klarwasserkanal (Clear Water Canal), Emschergraben (Dyke), Emscherrinne (Channel), Emscherschlucht (Gorge), and Emscherbach (Stream). The old wastewater canal of the "Old Emscher" river is now filled with water from rain collection systems through barriers and water channels. This gradual water supply ensures that even during dry periods, water can be added to the river to help oxygen levels. This has allowed the riverbed to become a natural area for wildlife and recreation. The plan included overgrown areas with diverse plant and animal life, including species listed as threatened. Another goal was to make the water system visible to help people connect with it.

The Greenhouse Project began in 2008 when a group of parents and teachers wanted to teach children about food, the environment, and sustainability. The project uses greenhouses on school rooftops to create urban farms and science labs. These greenhouses include solar panels, hydroponic growing systems, rainwater collection, weather stations, and composting. Topics taught include nutrition, water management, land use, climate change, biodiversity, and waste reduction. Students learn how humans and the environment are connected and gain a better understanding of sustainability and its relationship to cultural diversity.

In the early 1990s, Hammarby Sjöstad was a polluted and unsafe area in Stockholm. Now, it is a new district with strict environmental rules for buildings, utilities, and transportation. A system called the Hammarby Model, developed by Fortum, Stockholm Water Company, and Stockholm Waste Management, helps manage energy, waste, and water for homes and offices. This model uses waste heat from treated wastewater for heating, returns rainwater to nature through green roofs and pools, and recycles sludge from wastewater as fertilizer. This model has inspired projects in cities like Toronto, London, and China.

The Environmental Protection Agency (EPA) helped the city of Emeryville, California, create "Stormwater Guidelines for Green, Dense Redevelopment." Emeryville, near San Francisco, started in the 1990s to clean up old industrial areas and turn them into new spaces. This effort helped the city’s economy grow. In the 2000s, the city wanted to improve environmental outcomes, especially for stormwater, by requiring green infrastructure practices in all new private developments. The city faced challenges like high water tables, tidal flows, clay soil, and limited natural areas. The guidelines and a spreadsheet model were created to use redevelopment sites for stormwater management. Key strategies included:

• Reducing the need for parking by increasing building density, using shared parking spaces, and promoting public transit, biking, and car-sharing.
• Using green roofs and treatment pools to return rainwater to nature.
• Recycling waste materials into fertilizers for farming and forestry.

Geographic information system applications

A geographic information system (GIS) is a computer tool that helps people collect, save, show, and study different types of Earth data. GIS can combine many types of information on one map, such as streets, buildings, soil kinds, plants, and more. Planners can mix or calculate useful details, like the percentage of surfaces that don’t absorb water or how much greenery covers an area, to design or study green infrastructure projects. These systems can also include public participation GIS (PPGIS), which adds input from the public to traditional data, giving more context beyond just environmental details for specific projects. The ongoing growth and use of GIS are very important for creating Green Infrastructure plans. These plans often rely on GIS analysis of many layers of geographic data. GIS tools used for urban green projects now include methods from many fields, considering social, economic, environmental, and cultural factors of areas. This helps planners create more complete plans for projects.

According to the "Green Infrastructure Master Plan" by Hawkins Partners, civil engineers use GIS to study models of surfaces that don’t absorb water, along with past rainfall data in Nashville, within the city’s combined sewer system. This helps them find current runoff rates. GIS systems can also help planning teams study how much water could be reduced in a specific area through green infrastructure projects, such as water collection systems, green roofs, city trees, and structures that control water flow.

Implementation

Lack of money is often a problem when trying to build green infrastructure. However, green infrastructure projects can be helpful because they offer many benefits that make them eligible for different types of funding. Some tax incentive programs managed by federal agencies can help attract money for these projects. Here are two examples of programs that can support green infrastructure:

• The U.S. Department of Energy offers tax incentives for energy efficiency. Green infrastructure can be included in project designs to qualify for these incentives. For example, in Eugene, Oregon, a new biofuel station built on an old gas station site included a green roof, bioswales, and rain gardens. This project received about $250,000 in tax credits, which reduced income and sales taxes for the company that built it.
• The U.S. Department of Treasury manages the New Markets Tax Credit Program, which encourages private investment in projects like real estate or business development in areas that need help. Awards are given to non-profit and private groups based on their plans for using these tax benefits.

Some people may think that green spaces are expensive or hard to maintain, but well-designed green spaces can provide real economic, environmental, and social benefits. For example:

• Urban trees can help manage stormwater and lower energy costs.
• Bioretention systems can be used to create green transportation systems.
• Lawn grass is not a good solution for runoff, so alternatives like rain gardens are needed. Rain gardens can reduce water runoff by about 30% in homes. A typical rain garden for a private home is between 150 and 300 square feet. The cost per square foot is about $5–$25, depending on the plants used and the slope of the land. Native trees, shrubs, and wetland plants are especially helpful for reducing harmful runoff.

Well-designed green spaces help balance natural and built environments. More green spaces in neighborhoods have been linked to increased physical activity among older men and better mental health for people living near them.

Recent studies show that people value the experiences green infrastructure provides, such as beauty, health, and a sense of belonging. This means that green infrastructure should focus on these elements to improve how communities view its value and quality of life.

A 2012 study of 479 green infrastructure projects in the U.S. found that 44% of projects reduced costs, compared to 31% that increased costs. The biggest savings came from less stormwater runoff and lower heating and cooling expenses. Green infrastructure is often cheaper than traditional water management methods. For example, Philadelphia’s green infrastructure plan would cost $1.2 billion over 25 years, compared to $6 billion for a traditional plan using concrete tunnels.

Philadelphia’s green plan is expected to:
• Create 250 green jobs each year.
• Avoid or absorb up to 1.5 billion pounds of carbon dioxide yearly, similar to removing 3,400 cars from roads.
• Improve air quality through new trees, green roofs, and parks.
• Help communities with health and social benefits.
• Prevent about 20 asthma-related deaths and reduce missed work or school days by 250.
• Cut deaths from extreme heat by 250 over 20 years.
• Increase property values by $390 million over 45 years, raising city tax revenue.

In New York City, a green infrastructure plan would cost $1.5 billion less than a traditional plan. Green stormwater systems alone would save $1 billion, costing about $0.15 less per gallon. Over 20 years, sustainability benefits in New York are estimated at $139–$418 million. Each fully vegetated acre of green infrastructure is expected to provide $8.522 in reduced energy costs, $166 in lower carbon emissions, $1,044 in better air quality, and $4,725 in higher property values.

A 2016 study in the United Kingdom found that residents are more willing to pay for green infrastructure that is visibly green, accessible, and provides multiple benefits. This shows that green spaces that combine beauty and function can increase community support and investment.

In cities like Chicago, green infrastructure projects aim to improve the environment and quality of life. However, these projects sometimes cause social issues, such as gentrification, when new green spaces in low-income areas raise property values and push out current residents. Studies show that these projects often improve air quality and reduce heat in neighborhoods, but the benefits are uneven. Wealthier, whiter neighborhoods typically gain more advantages than lower-income or minority communities. In Los Angeles, research found that green infrastructure can lead to "green climate gentrification," where the gap between quality green spaces, housing prices, air pollution, and heat exposure grows for minority communities. The effects of gentrification vary by area, depending on the types of infrastructure, like parks or transportation, added to neighborhoods.