Urban Growth Modelling

Employment density projections

Written July 30th, 2015 by

Group of WorkersA key metric produced from an urban growth model is the future projections of employment/jobs for the region being model. These employment projections normally inform the region’s strategic plan and are often quoted by elected officials.  It is important these employment projections are realistic and the employment density assumptions utilised by the model are well documented.

What determines employment projections is the Workspace Ratios (WSR) for various land uses supported by the model. The Workspace Ratio measures the amount of floor space per Employee/Worker. There are wide disparities in these land use Workspace Ratios. It varies from industry to industry, city regions (i.e. CBD vs outer suburbs), even county to county. Read the rest of this entry »

Time for urban farming in cities to reduce obesity

Written June 26th, 2015 by

Urban FarmingIn 2005 over 40 % of the Earth’s land was given over to agriculture. This is an area of roughly 4.6 billion hectares, about the size of South America.  A further 3.2 to 3.6 billion hectares is being used to raise livestock. By 2050 up to 80% of the earth’s population will live in urban centres. If food is to be produced and consumed in the same inefficient way as is today, we will need further arable farm land the size of Brazil to support this population.

The best farming lands are already cultivated. Further increasing the agricultural land area will come with great environmental consequences, such as: destroying valuable natural ecosystems; water pollution from nutrient run-off; and soil erosion. New agricultural models are required. These models need to use new technology to improve cropping productivity while reducing the use of water and the application of fertilizer and other potentially harmful chemicals. Read the rest of this entry »

High density without occupancy

Written April 9th, 2015 by

High density apartmentsThe article High density housing’s biggest myth by Ross Elliott published on The Pulse, suggests many high-rise apartments recently constructed or being constructed contain numerous apartments that are vacant or not occupied, particularly in the inner city areas. We have observed this trend with high density residential properties when developing urban growth models.  This trend imposes the requirement for urban models to provide for properties in some locations not being fully occupied. In some cases this can be as low as 20% occupancy. These low percentages are normally seen in holiday areas such as the Gold Coast or Sunshine Coast.

With the apartments in these high-rise buildings, Ross suggests “many are vacant: simply locked up and not used by their owners (often overseas buyers)”. Whilst this will be true for some apartments, other apartments are being utilised for short-term accommodation. These apartments are available as serviced apartments or short-term rentals and this type of land use should be accounted for in your urban growth modelling. Read the rest of this entry »

Beware the faults

Written March 20th, 2015 by

Tilted HouseThe Digital Cadastral DataBase (DCDB) can be utilised to give you the number of units in building covered by group title. The cadastre can identify the common property, normally “Lot 0”, and each individual unit in the building, including the unit area and external shape. This is very useful when you have multiple floors in a building and the aerial photography or satellite view make it very difficult to identify the number of floors and number of units per floor in that building.

This method is not always reliable. We have found faults in the DCDB, when a group title property contains more than one building, that you need to be aware of. In locations were there are two or more buildings, we have seen instances of every unit “lot” within the property being assigned across multiple buildings. Let me give you an example to explain this. Read the rest of this entry »

3D city planning

Written February 17th, 2015 by

3D Modelling

Now with the latest geospatial technology and the increased processing power of computer hardware, 3D modelling is feasible and requires much less time and effort. Directions Magazine has an article that explores a 3D modelling approach: Three-dimensional City Planning Using Photogrammetry and GIS. The article describes how photogrammetric data and GIS software tools are used to produce 3D city models.

These models enable the study of complex urban environment and find solutions for various threats and challenges involved with urbanisation. Especially in Asia, where issues such has: exponential population growth and in-migration of poor people, industrial growth, inefficient and inadequate traffic corridors, lack of services and amenities and solid waste generation, are having adverse impacts on human life in city environments.   3D modelling and visualisation systems support the decision making process allowing quick evaluation and communication of ideas, leading to better urban planning and administration outcomes.

Closer to home, Brisbane City Council has developed a spatially accurate and interactive 3D model of Brisbane City’s CBD and inner 5 kilometres.  The 3D model is known as Virtual Brisbane.  It is an important strategic planning, development assessment and community engagement tool that is use by the Council. Read the rest of this entry »

Growing cities become less dense

Written January 30th, 2015 by

Cities become less denseThere is a misbelief among those in the press and some urban analysts that as cities become larger they become more densely populated. The article World Megacities: Densities fall as they become larger published by newgeography indicates the opposite is true.

newgeography builds on the groundbreaking work (such as in Planet of Cities) performed by New York University geographer, Professor Shlomo Angel. newgeography concluded population densities were falling in each of the 34 mega cities analysed.  One example was London. Even though urban sprawl is heavily constrained by greenbelts created following World War II, “London’s density is estimated to have dropped by two-thirds”. Read the rest of this entry »

50,000 new dwellings along Parramatta Road

Written December 8th, 2014 by

New Parramatta Rd Urban RenewalThe NSW Government has released the Draft Parramatta Road Urban Renewal Strategy. The Government is aiming for 50,000 new dwellings and 50,000 jobs in the Parramatta Road corridor by 2050. With eight suburbs/precincts targeted for development and jobs growth.

I am always a bit sceptical about claims made by government when comes to population and employment projections. The high level assumptions these claims are based on tend to be very optimistic.  When you start to apply them on the ground there are constraints (such as easements, property frontages and network infrastructure capacity) that apply at a property level and restrict what growth will be achieved. Read the rest of this entry »

Why flatten the cadastre

Written November 16th, 2014 by

Flatten the cadastreOne of the things you need to determine for an urban growth model is how much more development capacity is available on a property.  In some situations this can be easy to find. For example a property with a single detached house that can be demolished and replaced with multiple attached dwelling units.   The challenge comes when a property consists of common property with multiple attached dwellings or commercial units.

If you treat dwellings/units as individual properties when they are part of a larger building complex or site, there is every chance the attributes of these individual properties would not meet development density criteria that apply to that site. Thus, the model would determine no further development growth could occur at that site. In many instances these sites have further development potential.  Some examples include: an old block of units that can be demolished and replaced with a high-rise unit complex; a site that is being developed in stages over several years and is only part way through delivery of those stages.  Read the rest of this entry »

Weather and urban growth modelling

Written September 2nd, 2014 by

Gavin Schmidt presenting at TEDI came across this TED talk by Gavin Schmidt. He is a NASA climate expert and his presentation was about weather models and climate models. In his talk, Gavin explains why we can be confident about predicting how the climate will react into the long-term future.

He discusses the enormous complexities of modelling climate patterns that span a range of 14 orders of magnitude across both time and space. I though modelling urban growth was complex! We are only dealing with 2 orders of magnitude. Even at that level, there is a large body of work required to build and test an urban growth model. I certainly appreciate the mammoth effort needed to build climate models at those scales of magnitude and complexity. Read the rest of this entry »

How to establish a baseline

Written July 7th, 2014 by

Baseline image

The baseline is the most important element of an urban growth model.  Actually, this statement applies to any model. The baseline establishes the reference point from which a model will forecast future growth.  Not having an accurate baseline will result in your model either over or under allocating urban growth, especially in the early projection year cohorts.

Normally your baseline can be derived from the existing land uses of cadastral land parcels within the area that is subject to the urban growth model.  You might think establishing a baseline for a large cadastral model is a very challenging task.  Actually with today’s digital geospatial tools it is relatively easy. Although it is still time-consuming.

So how do you go about creating a baseline? Read the rest of this entry »