Cube Case Study: Victoria Integrated Transport Model: Zone Aggregation

User: The Department of Transport for Victoria
Location: Victoria, Australia
Citilabs Product: Cube

Challenge: Create a simple rezoning scheme to cover a larger geographical extent while maintaining rapid run times.

Solution: Implement Cube zone aggregation capabilities to build a model that will prioritize zone detail in the study area and remove unnecessary detail in peripheral areas.  This process will enhance model detail and enable greater flexibility for use across multiple projects without sacrificing short run times.

 

The Department of Transport (DOT) for Victoria, Australia was looking to expand the coverage of the Victorian Integrated Transport Model (VITM) from the greater Melbourne region to the entire state of Victoria. The expansion dramatically increases the number of zones, which could hamper model run time. The DOT turned to automated zone aggregation to simplify the modeling process and create a more flexible and customizable zone aggregation system. The zone aggregation techniques within Cube transportation modeling software enables a dynamic zone system that can easily be adapted to any chosen project site across the region. This model would improve detail while keeping run times low.

The original zoning system, made up of 6,973 zones, can be reduced by inputting a user-defined boundary file encompassing the study area and any other areas which require high-level definition, such as major trip generators or attractors.  This step would be the only manual processing required and careful consideration of project requirements is needed.

The next step uses fixed regions (unchanged from project to project) which are comprised of Transport Zones, Australian Bureau of Statistics units, and a new standard referred to as “MILEXMESH”. The MILEXMESH zones are created using a grid of squares at “X” miles length and width. This grid is then further split by major roads and transit corridors. The resulting set of regions then ‘gathers’ transport zones into their resulting aggregation system, with major infrastructure or geographic features that typically define land use, demographic sectors, or other characteristic features of the area remaining aligned with boundary edges.

Figure 1: Aggregation using the MILEXMESH defined boundaries using a 4-mile square grid.

 

The final step then creates new centroid connectors for zones which have been removed, with consideration given to keeping accessibility to the road network and PT services as similar to the original network as possible.

 

Figure 2: Zones set by aggregation methods for each region. MILXMESH methods were used throughout most of the study area, with the exception of the Level 5 region on the outskirts of town that used Transport Zones.

 

This new and improved process is expected to provide opportunities for smaller organizations that may benefit from lower cost model development. The DOT of Victoria continues to improve the speed of its model through testing, with the goal of reducing the total number of zones throughout the region to within the recommended range of 2500-3000 for rapid run times.

 

Figure 3: Final zone aggregation configuration for the VITM Ballarat Zone System

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