Irrational Exuberance

"Irrational Exuberance" is a phrase used by the Chairman of Federal Reserve Board, Alan Greenspan, in a speech given at the American Enterprise Institute during the Dot-com bubble of the 1990s. (www.wikipedia.org). The phrase was interpreted as a warning that the market might be somewhat overvalued. Robert Shiller, the famous economist and the best seller wrote the book with the same name in 2000.

In the book of the same name, Shiller talks about several phenomena in the late 1990s. The analysts' optimistic forecasts were a typical factor which contributed to the "Irrational Exuberance". "According to data from Investment Research about the recommendations on some 6000 companies, only 1.0% of recommendations were "sells" in late 1999 (while 69.5% were "buys" and 29.9% were "holds")". This kind of over-optimistic forecasts helped created an untrue environment of investment which can be described as "Irrational Exuberance".

Sources:

Shiller, Robert J. 2005. "Precipitating Factors: The Capitalist Explosion, the Internet, and Other Events" in Irrational Exuberance. Princeton University Press. New Jersey.

the Grand Manner City

Sources: http://thebizjam.com/2010/10/26/washington-metro-ipod-maps

Grand Manner refers to "an idealized aesthetic style derived from classical art". The cities of the Grand Manner are cities usually planned in a formative way.

Washington DC is a typical Grand Manner City. Based on Spiro Kostof's study, there are three primary characteristics that can describe Washington DC's uniqueness in plans. First, it is a planned city rather than a spontaneously self-grown city with organic or disorder streets and alleys. Second, it has grand radial avenues superimposed on grid system. It might be the first city in America with the combination city structure of the grid and the diagonal. Third, the landscape is deliberately incorporated into the Grand Manner plan, not only serving as the greenery for the public, but also part of the demonstration tool for the manifestation.

Right-Sizing Detroit

Why we have to consider “Right-Sizing Detroit?”

Detroit, the depressed city, continuously finds a way to recapture its previous pride over thirty years. In the long- term fighting, why it is still failed? Normally, increasing employment rate was looked for the only antidote to renovate a city, so the government tried to input huge amount of money for local industries in recent years. The financial support would encourage the huge companies (such as GM and Ford) to invite applications for new office vacancies. As the result, it would be the main attraction for people to come back this city. However, they will not come back. Detroit has been losing its charm not only about job opportunities. The other potential issues also disturb the reborn of this city; racial confliction, class antagonism, and geographical disadvantage. Fortunately, in the few years, the urban planners and politicians began to earn and follow more new ideas. Detroit Mayor Dave Bing posted the most important concept and probably the most practical perspective for this city: Right- sizing Detroit. Pursuing more job opportunities still is the issue, but how to create a more sustainable and healthier environment for current Detroit (In fact, the smaller Detroit) is the main challenge.

What is “Right-Sizing Detroit?”

Do we all understand “Right-Sizing Detroit” is the main goal of our effort? Obviously, this concept is abstract for public masses. How many people can figure out the meaning of Detroit Size? The amount of population or the amount of buildings? “Detroit’s crisis is unique only in its scale,” Time magazine writers, Daniel Okrent and Steven Gray, said this idea in the Article ”The future of Detroit: How to shrink a city?” They provided several ideas to reach this goal such as Connecting the Clusters, The Gift of Nature, and

Yang Yu Huang

People for Homes, etc. Following above concepts, we can know that shrinking a city is a more complicated issue that it should be operated with different fields together: Ecology, Culture, Economy, Real Estate, Urban Planning. Right-sizing Detroit is not only about population density. It is about how to create ideal environment for human necessity.

Oligopoly

An oligopoly is a market form in which a market or industry is dominated by a small number of sellers. Because there are few sellers, each oligopolist is likely to be aware of the actions of the others, and the action of these few sellers will make a big influence on the whole market. There are eight characters for a oligopolistic market. 

1) Profit maximisation conditions: An oligopoly maximises profits by producing where marginal revenue equals marginal costs.

2) Ability to set price: Oligopolies are price setters rather than price takers.

3) Entry and exit: Barriers to entry are high.

4 Number of firms: There are so few firms that the actions of one firm can influence the actions of the other firms.

5) Product differentiation: Product may be homogeneous (steel) or differentiated (automobiles).

6) Perfect knowledge: Oligopolies have perfect knowledge of their own cost and demand functions but their inter-firm information may be incomplete. Buyers have only imperfect knowledge as to price, cost and product quality.

7) Interdependence: Oligopolies are typically composed of a few large firms. Each firm is so large that its actions affect market conditions. Therefore the competing firms will be aware of a firm's market actions and will respond appropriately. This means that in contemplating a market action, a firm must take into consideration the possible reactions of all competing firms and the firm's countermoves.

A good example is the bank market. As the distribution of banks shows, the four big banks: JPMorgan, Bank of America, Citibank and Goldman Sachs dominate more than 90% bank market. 

Image source: http://nightlight.typepad.com/.a/6a00d8341c892053ef01347fec5334970c-pi

Wikipedia: http://en.wikipedia.org/wiki/Oligopoly

Progressive Tax

Progressive tax is one kind of taxation. The tax rate increases with individual income or expenditure, referring to the way the rate progresses from low to high, where the average tax rate is less than the marginal tax rate. It can be applied to individual taxes or to a tax system as a whole; a year, multi-year, or lifetime. Progressive taxes attempt to reduce the tax of people with a lower ability to pay, such as low income individual, as it shifts the tax incident increasingly to those with a higher ability to pay.

The opposite of a progressive tax is a regressive tax, where the relative tax rate increases as an individual's ability to pay it decreases. Sales taxes are often criticized because low income households must pay a greater share of their disposable income to a sales tax than wealthier households. Regressive tax shifts the tax incident to those with a lower ability to pay.

Image source: http://samiseconblog.wordpress.com/2010/08/25/solution-progressive-tax/

Source: Wikipedia, http://en.wikipedia.org/wiki/Progressive_tax

Externality

"In economics, an externality (or transaction spillover) is a cost or benefit, not transmitted through prices,[1] incurred by a party who did not agree to the action causing the cost or benefit. The benefits of externalities, in this case, is called a positive externality or external benefit, while its cost is called a negative externality or external costs." (http://en.wikipedia.org/wiki/Externality)

Externality is often a great concern in economic development planning. Either positive externality or negative externality, it affects the social welfare. Therefore, planning and public policy of goverments try to internalize externality to achieve optimal social welfare status.

Cohort-Component Technique

http://en.wikipedia.org/wiki/Population_pyramid

The size and composition of a region's population and the way it will change in the future is very important for local government planning. Deaths, births, and migration are largely independent processes that change by differing amounts at varying times, affecting different segments of the poplation. The age and sex differences in the components of population change are also very important because they can interact with a regions population structure. Cohort-component models can disaggregate a population into form age, sex, and racial groups or cohorts and deal separately with the three components: fertility, mortality and migration.



This method is widely used in the projection of population by planners. The analysis of population by using cohort-component technique can account seprately for the underlying causes of population change and make the population projection for the future more close to the real situation.

Shu Yang

due process

Due process clause comes from the Fifth Amendment that “No person shall be deprived of life, liberty, or property, without due process of law; nor shall private property be taken for public use, without just compensation.” The first clause is called due process clause, and the second taking clause. The Fourteenth Amendment essentially repeats the same clause, but applies to the states and their creatures -- local governments.

According to Land Use Planning and Development Regulation Law by Julian Conrad Juergensmeyer and Thomas E. Roberts, there are two types of due process: substantive due process and procedural duo process. “Substantive due process limits the exercise of the police power by requiring that a land use regulation promote the health, safety, morals, or general welfare by a rational means. It protects against arbitrary or capricious actions.” However, compared to substantive due process which deals with “why a deprivation occurred,” procedural due process “asks how the deprivation came to be.” Procedural due process attaches to administrative and quasi-judicial decisionmaking, rather than legislation which substantive due process attached to. An example of procedural due process is a proper notice on public hearing during the rezoning process. 

Ultra Vires

According to the Merriam-Webster dictionary, ultra vires, originally Latin, means “beyond the scope or in excess of legal power or authority.” (http://www.merriam-webster.com/dictionary/ultra%20vires) Usually than not, the power/authority here refers to the Constitution. Ultra vires is a statutory claim; once the court finds a law exceeds the power granted by the Constitution, it will declare the law to be ultra vires. Two conditions can lead to ultra vires: either substantive (the law is beyond the power), or procedural (the process is not proper). Under the circumstance of zoning, the Board of Zoning Appeals (ZBA) plays the quasi-judicial role to hear the appeals on the administrative decisions. It is ZBA who judges whether a law (such as a rezoning) is ultra vires or not. 

Building insulation

(http://www.wall-lag.co.uk/wp-content/themes/walllag/images/house.jpg)

Building insulation refers broadly to any object in a building used as insulation for any purpose. The most common one is thermal insulation, which is an important factor to archive thermal comfort for its occupants. Insulation reduces unwanted heat loss or gain and can decrease the energy demand of heating and cooling systems. In a narrow sense insulation can just refer to the insulation materials employed to slow heat loss, such as glass wool, polystyrene ETC. The effectiveness of insulation is commonly evaluated by its R-value. 

(http://en.wikipedia.org/wiki/Building_insulation)

As a rule, insulating homes is important in any climate and, typically, the more insulation (i.e., the higher the R-value) the better. Properly installed, insulation decreases unwanted thermal gains or losses through the envelope throughout the year.

In general, insulating the attic or roof should be the first priority since the most extreme boundary conditions or temperature differences typically occur at or around these areas. However, other hidden areas need to be insulated by home builders and contractors. These spaces include finished and unfinished attics, all exterior walls including those between living spaces, and floors above cold spaces, even slab floors built directly on the ground. 

Urban agriculture

Urban agriculture is the growing of plants and the raising of animals for food and other uses, and related processing and marketing activities, within and around cities and towns. Urban agriculture has received increased attention in the past few years from development organizations and national and local authorities in developing countries. With its multiple functions, urban agriculture plays an important role in urban poverty alleviation and social inclusion, urban food security, urban waste management and urban greening.
The most striking feature of urban agriculture, which distinguishes it from rural agriculture, is that it is integrated into the urban economic and ecological system: urban agriculture is embedded in -and interacting with- the urban ecosystem. Such linkages include the use of urban residents as labourers, use of typical urban resources (like organic waste as compost and urban wastewater for irrigation), direct links with urban consumers, direct impacts on urban ecology (positive and negative), being part of the urban food system, competing for land with other urban functions, being influenced by urban policies and plans, etc. Urban agriculture is not a relict of the past that will fade away (urban agriculture increases when the city grows) nor brought to the city by rural immigrants that will loose their rural habits over time. It is an integral part of the urban system.
(from http://www.ruaf.org/node/512)

(picture from http://www.cityfarmer.info/2010/02/07/urban-orchard-prizing-winning-concept-for-the-growing-up-design-competition-2009/#more-3800)

Urban agriculture and urban farms benefits a lot to city and dwellers. First, they offer working opportunities for citizens. In many developed countries, cities are where poor and unemployed dwellers concentrated. Urban agriculture provides a complementary strategy to reduce urban unemployment. Second, groceries produced by urban farms can be directly sent to markets in cities without the long shipping and distributing. Growing urban farms are efficient and economic way for transporting farm products. Third, urban farms are places for citizens to gather and have fun. The activities of growing vegetables and crops involves different people to meet. And they offer opportunities for people to get in touch with earth and traditional agricultural activities and are good educations for kids.

Brownfield

Brownfield sites are abandoned or underused industrial and commercial facilities available for re-use. Expansion or redevelopment of such a facility may be complicated by real or perceived environmental contamination. Innovative remedial techniques used at distressed brownfields in recent years include bioremediation and in situ oxidation. Often, these strategies are used in conjunction with each other or with other remedial strategies such as soil vapor extraction.In this process, vapor from the soil phase is extracted from soils and treated, which has the effect of removing contaminants from the soils and groundwater beneath a site. Some brownfields with heavy metal contamination have even been cleaned up through an innovative approach called phytoremediation, which uses deep-rooted plants to soak up metals in soils into the plant structure as the plant grows. After they reach maturity, the plants – which now contain the heavy metal contaminants in their tissues – are removed and disposed of as hazardous waste.
A newer technology for remediating brownfields involves an in situ injection of an iron-embedded organosilica material that creates a permanent soft curtain barrier underground. Groundwater passes through the barrier, which absorbs toxins and solvents while the iron dechlorinates them to non-toxic
products. Research is under way to see if some brownfields can be used to grow crops, specifically for the production of biofuels.

( from wikipedia)










An excellent example of remediation of brown field is the Gasworks Park in Seattle. The site previously belongs to the former Seattle Gas Light Company. It is located on the north shore of the Lake Union, having a good view of Seattle city. Through bio-phyto-remediation techniques the soil and water is cleaned and "greened". And the old plants, structures and paths are preserved to honor the rich industrial history. Now the park holds a lot of different public activities.
(Pictures from wikipedia)

bioswale

                                                                           (http://www.lakecountyil.gov/Stormwater/LakeCountyWatersheds/BMPs/PublishingImages/bioswale.jpg)

Bioswales are vegetated open channels specifically designed to attenuate and treat stormwater runoff for a defined water volume. They consist of a swaled drainage course with gently sloped sides and filled with vegetation, compost and riprap. Depending upon the geometry of available land, a bioswale may have a meandering or almost straight channel alignment. 


A common application is around parking lots, where substantial automotive pollution is collected by the paving and then flushed by rain. Two early examples of scientifically designed bioswales for large scale applications are the bioswale for Willamette River Park in Portland, Oregon and one at Carneros Business Park, Sonoma County, California.

(http://en.wikipedia.org/wiki/Bioswale)

Even where soils have very poor hydraulic conductivity, a 4 meter swale could reduce the volume of runoff from a typical local road to about 25% of total rainfall. Also, as storm water runoff flows through bioswales, pollutants are removed through filtering by vegetation and soils. In most development situations, bioswales are well- suited because of their linear nature and because they are designed to receive storm water runoff via distributed sheet flow.

However, some researchers point out that when the slope of bioswales become too steep (up to 10%), runoff velocities become fast enough to cause erosion, and prevent adequate infiltration or filtering in the channel. Besides, bioswales also do not seem to be effective at reducing bacteria levels in storm water runoff.

Successional plan

“Succession is the change of species and ecological systems over time, and in the context of landscape architecture, the purposeful manipulation of this transformation to create stable ecosystems. It is often paired with restoration efforts to foster new and stable ecosystems where there previously were none, or that had been affected by a natural disaster or man-made construction. It relies on many sequential actions executed over a longer period of time, anywhere from 10 to 200 years, allowing the species involved to grow and stabilize. Succession planning typically takes place within the context on regional processes that form and manipulate the environment. The system is not so much constructed as it is manipulated within these parameters.”

 http://nymag.com/realestate/features/2016/17149/

Succession is a landscape architecture topic. The vegetation grow in a dynamic and constantly shifting with the environment thus create dynamic space and landscape. It is a landscape plan that use plant associations, plant growth habits and planned landscape maintains to create an environment benefiting the ecosystem.To archive a good succession plan, we should know the vegetation well and analyze the bio environment, such as soil, air, water, of the site before make the design.

materiality

"Materiality in architecture is the concept of, or applied use of, various materials or substances in the medium of building.

Material is a relative term in architectural design and so may be used to designate materials which are considered to be virtual, or other materials which are natural. Some materials may be considered as combinations of the two. Certain veneers which are composed of images printed on plastic are a good example of this. Observationally therefore, virtual materials can be said not to exist without a natural physical substrate. Therefore, what separates a virtual material from a natural one is some aspect of the mind and perception as well as a process of representation to produce them.

Indeed, materiality in architecture is not limited to theoretical positions on the perceived materiality of images, texts, or other objects of representation. It may refer to the materiality of specific projects, where one would need to consider the full range of materials used. Discussions on the materiality of architecture are usually synonymous with structural and aesthetic concerns in architectural design and are typically unique with each project."
http://en.wikipedia.org/wiki/Materiality_(architecture)

Our studio is dealing with materiality recently. For architecture, materiality is a strategy or attitude that we learn from the quality of and the attitude towards the material. How to use it- the form and the purpose is significant. Material is not a two dimension element that we use on the surface of space, but also a three dimension element that can form a space and improve the experience of the space. To be specific, most material such as dust, asphalt and mud is both time related and altering coordinate with different circumstance. So by realizing the quality of one material, we can realize its’ materiality in design better.

Ribbon Farm

Ribbon Farm along Detroit River
(http://en.wikipedia.org/wiki/File:Detroit1796.jpg)

Ribbon farms (also known as strip farms, long-lot farms, or just long lots) are long, narrow land divisions, usually lined up along a waterway. In some instances, they line a road.

The size of ribbon farms can vary from lot to lot and from place to place. In Illinois, these lots could be a quarter mile or more long and only 30–40 feet wide. Near Detroit, the ribbon farms were about 250 feet wide and up to three miles long. In Texas, lots could be as small as ten acres in area, or as large as five miles by twenty miles.

Farmers of ribbon farms typically, although not universally, built houses on the farm along the river such that the houses on a series of ribbon farms were located near each other. (http://en.wikipedia.org/wiki/Ribbon_farm)

From the map, it is easy to tell the influence of historical ribbon farm on current urban fabric in Delray. Thus when our group proposed the urban design for Delray we decided to keep this ribbon farm concept as the logic to organize our proposal. The purpose of keeping ribbon farm logic is to maximize the accessibilities to the water and infrastructure.

Decorated Shed

In Learning from Las Vegas, Robert Venturi contended that a "decorated shed" was an ordinary building which is functionally designed inside and embellished on the outside. It was better than a “duck”（ an ungainly building in which the whole form and its function are tied together).

(Sketch from Learning from Las Vegas)
Summarizing the distinction between duck and shed, the author wrote：“The duck is the special building that is a symbol; the decorated shed is the conventional building that applies symbols."
Foster & Partners' Hearst Tower, for example, the stainless cladding on the external structure is obviously ornamental. Both the chamfering and the structural detailing are executed on such an "heroic" scale to mask the fact that the tower is, for all intents and purposes, a box. This is a high-end decorated shed, to be sure, but a decorated shed nontheless.

(http://en.wikipedia.org/wiki/File:Hearstowernyc.JPG)

Organic Architecture

Organic architecture is a philosophy of architecture which promotes harmony between human habitation and the natural world through design approaches so sympathetic and well integrated with its site that buildings, furnishings, and surroundings become part of a unified, interrelated composition.
(http://en.wikipedia.org/wiki/Organic_architecture)

Organic architecture is developed by Frank Lloyd Wright. The form of organic architecture is defined by its environment and purpose. Wright believes that "a structure should be grown along with its environment, where the relationship between them is entwined--structure is nature". This synergy is the basis of organic architecture, where natural materials -"wood" must be like wood, and the building's surroundings are taken into consideration. In addition, this concept describes the need for humans to be affiliated with nature. Organic architecture must look like they sprout from the environment that they are built in. The architecture must also show the influence of its natural surroundings.

Potential uses of organic architecture could be used in high density cities like New York. Cities need to be rethought and redesigned for the sake of our future generation. We will also need to focus on how building materials, energy and monetary resources can be used in a more efficient and intelligent way.

(http://en.wikipedia.org/wiki/Fallingwater)

(http://anfalsview.wordpress.com/2011/09/27/masdar-city/)

Deadweight loss

In economics, a deadweight loss is a loss of economic efficiency that can occur when equilibrium for a good or service is not Pareto optimal. (http://en.wikipedia.org/wiki/Deadweight_loss)

(http://www.bing.com/images/search?q=deadweight+loss&view=detail&id=C0C9329EA92EC6BA484A4E5E5B60D371DBC4C3DF&first=0&FORM=IDFRIR)

A child learns early about Santa Claus, an imaginary fellow who visits the homes of good little girls and boys at Christmas, leaving them gifts. The children always look forward to the day and even after they grow up to be adults because of gifts. However, except emotional side, gift is waste of money. Because the value of a gift which measured by a receiver is different with that by a giver. In the most cases, a receiver tends to think little of a gift than a giver.  The difference is deadweight loss. To reduce deadweight loss, it is better to give money than a gift. If a giver doesn’t know which gift a receiver want to have, the differences tend to be increased. And if the gift is what the receiver doesn’t want to have, a deadweight loss is maximized. In this sense, a policy which public don’t want can create a significant deadweight loss. If public want economy development, but a government gives the public unexpected gifts such as increase of social security or development of new town, a deadweight loss occurs as a tax increase.   

Streetcar

http://www.toucanart.com/en/products/6303/

Streetcar is “a vehicle on rails used primarily for transporting passengers and typically operating on city streets”. (www.m-w.com)

When you come to the words “streetcar”, “light rail”, “trolley”, do you realize their differences or something in common? Actually most people may confuse them. Streetcar was the first to be used in public transit system in New York in 1832, which was pulled by horse and then replaced by machines. Streetcar today is featured by its rights-of-way sharing with automobiles and more localized service. In contrary, light rail has its own, reserved right-of-way. It always connects different places in larger region and was featured by its fast speed.

http://goneworleans.about.com/od/photosofneworleans/ig/Riverfront/Streetcars.htm

In many urban core revitalization strategies, streetcar has been widely used in public transit systems and successfully transformed some placed into a vibrant area of shops, grocery stores, restaurants and apartments. In some cities, such as in San Francisco, Portland, streetcars are designed in old-fashioned styles to enhance the city image and attract tourists. I believe in the future, there will be more streetcars running in American cities to bring vitality and mobility.

"Streetcars & Waterfronts: The F Market & Wharves Line"

"With a little creativity, San Francisco's F Market & Wharves historic streetcar line is the most successful vintage rail line ever opened, attracting over 20,000 riders a day. The restoration of the F-Line led to a billion dollars of redevelopment along the wharves and waterfront and has been so successful in re-energizing the economy that the city is reviewing plans to double the length of the route in order to fully redevelop the historically commercial waterfront. With developments like the Cannery and Ghirardelli square credited to historic transit lines, no one was prepared for the explosion of business and revenue that resulted from adding the vintage and often whimsical F-Line. In its wake however, the value of historic streetcars is finally beginning to be realized by planners across the planet. Can Jacksonville learn from San Francisco's experience?"

http://www.metrojacksonville.com/article/2010-aug-streetcars-waterfronts-the-f-market-wharves-line

http://www.metrojacksonville.com/article/2010-aug-streetcars-waterfronts-the-f-market-wharves-line

http://www.metrojacksonville.com/article/2010-aug-streetcars-waterfronts-the-f-market-wharves-line

Amphibious city

Amphibious city

Amphibious means “able to live both on land or in water”. (www.m-w.com)

http://radio-weblogs.com/0119080/stories/2003/08/22/galleryOnTheWaterfront.html

Normally, when we hear the word “amphibious”, we always relates it to animals, such as frogs and toad. These animals are featured by their unique abilities to live both on land and in water. Scientific research shows that amphibians have been survived for millions of years, during which time numerous species were distinguished because of climate change or some other reasons. One of the biggest challenge we are facing today is the global warming, which will leads to the sea level rising to 10 feet in future hundred years and sink many cities into water. What’s our strategy towards this disaster and how to make our cities survive in water, the answer of which may possibly be found in the characteristics of amphibians. Future buildings can be capable of breathing can be away from erosion by sea. And some cities may be able to float on water. There will be underwater streets, restaurants, exhibitions, hotels, you name it. Amphibious city will become our new habitats to bring us more exciting life.

Footloose floating housing concept - Amfibischwonen competition 

                      http://radio-weblogs.com/0119080/stories/2003/08/22/galleryOnTheWaterfront.html

"The larger the structure the wider the range of sea conditions it can tolerate thus allowing it to be located farther from shore. (though this comes with the caveat that the farther from shore the more expensive the transportation due to the limited spectrum of capability current transport technology provides) This presents an interesting possibility. One is not limited to the creation of just a single home. One can found freely expanding communities and/or businesses, moving them progressively farther out to sea as they increase in potential self-sufficiency and in the scale of transportation they can support. This capability is what compelled me to suggest structures like this as the basis of marine eco-villages which could grow into full-fledged marine colonies -polution-free self supporting cities- that could move out beyond the 200 mile national boundaries of the nations that spawned them to become new autonomous self-mobile states. That may seem fantastic but there are no longer any technological obstacles to it."

http://radio-weblogs.com/0119080/stories/2003/08/22/galleryOnTheWaterfront.html
                                

Tactical Urbanism

sources: http://myriammahiques.blogspot.com/2011/04/what-is-tactical-urbanism.html

Tactical Urbanism is a kind of urbanism that usually focuses on small scale urban improvements in the efforts to test new concepts before making final substantial changes. Compared to other branches of urbanism, it has five characteristics: planned and phased approach; local solutions; short-term commitment and realistic expectations; low-risks with a possibly high reward; and the control of social capital.

The implementing short-term, low-budget projects of Tactical Urbanism usually take the form of re-discovering and reusing lost urban spaces by turning those spaces into temporary public use,such as turning the surplus parking into resting places. A lot of these practices focus on the street and block scale, aiming to promote livable streets and neighborhood vitality. And in most cases, the leaders of these bottom-up tactics are local advocates, local businesses, non-profits or community groups. To sum up, I think Tactical Urbanism, as a more flexible, community-engaged short-term renovation strategy, can definitely be applied globally but only as the complement of other main stream of urbanism.

pigovian tax

To internalize externality(refer to the word"externality"), Pigou considers
companies that have mistakes should be punished. He proposed a classic method
to make people pay for the externality cost is to levy a Pigovian taxes which
is equal to the negative externality, as is shown in figure 1. Producers who
overproduce are the sides that have mistakes, so they should be punished in the
way of turning tax. By charging producers the tax, the externality cost is
internalized. When imposed Pigovian tax, producers have an incentive to reduce
their production because their cost is increased and profit will be decreased (http://en.wikipedia.org/wiki/Pigovian_tax).
However, in
practice, there exist difficulties to implement Pigovian tax. The amount of
Pigovian tax is determined by the equilibrium where marginal social cost equals
to marginal benefit. This requires us to know the exact monetary value of the loss.
But it is hard to calculate accurate loss because theloss
is usually very complicated and uncertain. The compromising way is to estimate an
approximate loss and make the estimated value be the tax. The closer the
estimated value is to externality cost, the better the effect of the tax will
be.

image source: Qi Shen

by Qi