Order Without Design
01 Aug 2020 •
Chapter 2 - Cities as Labour Markets
- Firms and Households relate via the labor market. The labor market obliges firms and households to locate at ‘commute-able’ distances.
- OTOH, they compete for land use.
- Thus, there is a trade-off between land consumption and commute distance.
- The Model trip patterns in metropolitan areas take the forms of :
- Urban Village
- The efficient operation of labor markets requires mobility and affordability.
- Firms and Households have the freedom to stay put or migrate at will.
- Travel within the city remains fast and cheap.
- Real estate is affordable that it does not distort the allocation of labor.
Chapter 4 - Spatial Distribution of Land Prices and Densities
- Projections of population density is a necessary input into design; but projections should not be frozen into land use regulations.
- High land prices —> High Density; not the other way around.
- Standard Urban Model
- The SUM works for a acentric city with no CBD, since proximity to centroid provides a better access to labor market.
- The SUM can estimate the urban-agriculture boundary, and how far a city expands.
- There will develop two urban-agriculture boundaries:
- x1, where urban land price meets agricultural land prices
- x2, where urban land price meets agricultural land price + cost of infrastructure
- In the range between x2 to x1, informal development occurs. The cause of informal development is the same in developed and developing economies: poorly conceived land use regulations that do not take into account the income of poor households.
Chapter 5 - Mobility
- Mobility is the ability to choose among jobs and amenities offered in a city with commute time < 1 hour.
- Commuting (for work) forms a small fraction (14%-19%) of trips, yet provide maximum economic viability to the city. Hence, it is used as a proxy for mobility.
- Increasing population density decreases distance between any A & B points in the city, but need not reduce commute times. It can also increase congestion. Commuting time depends also on transport mode, transport speed, area under roads, etc.
- The objective of urban transport is to increase mobility to maximise the effective size of labour markets. Congestion and pollution are constraints to it (but they are not the objectives).
- Promoting the constraints of reducing congestion and pollution to the objective makes planners to fragment the city’s labour market into sectors where jobs and housing are matched (i.e. a resident of a sector works in the same sector). However, such fragmentation does not decrease average trip-length because:
- all workers in a household cannot not find employment in the same neighbourhood.
- when a worker changes employment, they do not change residence since moving homes has a high transaction cost.
- proximity to work is not the only consideration when choosing a residence.
- A measure for mobility can be computed in two stages:
- Calculating the number of jobs accessible from every census tract within a selected time limit. This is accessibility of the census tract.
- Calculating the worker-weighted average of the accessibility of all census tracts to form the mobility index of the metropolitan area.
- Commuting time = Travel time + Access time. Reducing access time, rather than improving speed of travel, should be a priority. Access time is also why public transports take longer than a private vehicle in point-to-point commute.
- Congestion is measured using TTI - Travel Time Index - ratio of travel time in peak periods vs. travel time in free-flow conditions.
The Supply Side
- Increasing Road Supply in already dense areas is not feasible: the Haussmann project in 1850s Paris is unique in this respect. The alternative of an underground rail network makes more sense for modern cities. The arithmetic depends on price per square metre of real estate vs. price per square metre of underground construction.
- In general, a planner has to act on the demand side rather than on the supply side, to improve mobility.
The Demand Side
- Consumption of Road by vehicles is almost entirely the space maintained between cars to allow for 2-second reaction time. Thus, a smaller car does not use less space than a large SUV.
- There are only two ways to decrease the consumption of street area by moving cars:
- Decrease the 2-second reaction time using self-driving technology, etc.
- Decrease the width of vehicles such that two can occupy the space of one in a lane; two bikes instead of one car.
- The total number of cars on street determines the combined speed of the traffic.
- Buses have a very low index of street area used per passenger; almost 50 times less than a car, both travelling at 40km/h.
- However, an argument for BRT based on just the above index does not factor in how commuting in a bus is different from a car. Buses cannot follow each other, even in a BRT, in a long column because of the need for headway.
- BRT street consumption is at par with cars once adjusted for realistic headways and passenger occupancy levels.
- BRT lines can be an option only along axes of the city where demand for capacity at peak hours ensures full occupancy.
- Also, BRTs focus on optimising PPHPD (passengers per hour per direction), but does not focus on speed. For large cities, speed of commute is an important factor to attain maximum mobility.
- Singapore manages to decrease congestion by managing demand via pricing.
- Charging for Road Maintainence and Capital Cost
- Gasoline taxation is the traditional way governments cover the maintainence costs of roads. It is never close to the real costs, due to lack to inflation-ties taxation and the improving fuel efficiency of cars. Also, electric cars do not pay such a toll.
- Making the consumer pay the real economic price of road usage - inclusive of shared fixed costs of construction, per-vehicle fixed costs of insurance, and negative externalities - can ensure that consumers choose better between public, shared, and private modes of transport. In the long run, this will alter urban land use for the better.
Chapter 6 - Affordability
- The level of affordability of a housing unit is comprised of the floor area, price per square meter, construction quality, and location of the unit.
- The government response to low-income housing crunch & unfavourable living conditions in low-income housing is ‘to do something’, most typically create affordable housing which improve on floor area, and price per square meter, but deteriorate the poor’s accessibility to labour markets by being situated in peripheral locations.
- The choice of housing made by low-income households is very different when provided with affordable, remote housing versus when their incomes are increased by the implicit subsidy.
- Price of housing (P) for households = (Land area) * (Price of land) + (Floor area) * (Cost of construction). Rent depends on the same variables.
Chapter 7 - Alternative Urban Shapes and Utopia
- Since a city does not have a specific purpose, it is difficult to define an objective function around which the city can be designed. We have to rely on the self-organising principle of markets to do so.
- Objects which are designed are discarded with time for better objects with improved designs. Cities however are expected to evolve, and external shocks improve cities which survive those shocks. ‘Fluctuat nec mergitur’ – it is tossed around, but never sinks.
- Objective functions for urban planning can be of four kinds:
- Aesthetics as objective function. eg. Paris historical preservation.
- Limiting externalities, or public interest as objective function
- Containing urban expansion as objective function
Aspirations as objective function