Model Preparation

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 »

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 »

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 »

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 »

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 »