Optimal Count Locator (OCL) for Visum

i2 - Intelligent-infrastructure is proud to present its newest Visum add-on which tells you where to place counting locations in the transport model to get best results. Lets see how it works.

Idea

The quality of transport modeling depends, among others, on counting data. But who cares about quality of counting itself? We set up counting locations willing to catch as much flow as we can, yet how can we be sure that our location is best possible. Knowledge, and experience seems to be a good hint, but here we propose something more refined. Our tool employs acknowledged optimization technique to specify set of optimal counting locations catching as much flow and as many OD pairs as possible.

Study Case

We asked transport planning professionals to specify 10 best nodes to be counted in the city that they know very well (Kraków - PL). We compared their solutions to our algorithm results, and that’s what we got:

	modeler 5yrs exp	modeler 10yrs exp	Optimal Count Locator by i2
Flow detected	45.7%	50.6%	56.3%
OD pairs detected	37.2%	45.1%	57.0%

We see that even experienced transport planners, who know the city didn’t manage to cover as much flow and OD pairs as OCL. They detected almost as many flows as OCL, but OD pairs coverage was much lower. This experiment can give you a hint about what are benefits from using OCL

Product

We introduce the optimization procedure wrapped in intuitive, user friendly interface(see fig below), which can quickly find optimal solution even for complex networks.

User can define his budget (number of points that can be placed) and detectors which are already installed. It’s also available to determine what kind of detectors we want to install: junction, link, directed link, (it soon will be extended to cover also turns).

Additional technical parameter is algorithm depth, being number of paths between origin and destination that are taken into calculation process. For assignment generating numerous routes per OD pair setting this parameter low can make procedure faster.

We propose various strategies of optimization. In our opinion, and due to our tests, the most useful is mixed maximization of both OD pairs coverage and flow coverage, however you can choose to maximize only flow, or only OD pairs.

fig. intuitive user interface

Running time

Calculation time depends on size of the network. On the average up-to-date PC it takes about 1 minute to download 300 000 of paths (model for Kraków, Poland  of ca. 350 zones), and then time of optimization itself depends on number of connectors and takes roughly 5s per detector.

Results

Results are saved in your Visum network as Boolean, User-Defined-Attribute “i2_OCL_Detectors”, which equals 1 if it’s an object that should be detected

To see results visually, you can import prepared .gpa file. Additionally you can use our flow bundle generator, where you can clearly see which flows are covered with your detection.

For detailed results and statistics you can see report including OD coverage, flow coverage, keys of detected elements, calculation time, etc.

fig. input data - Visum model

fig. Statistics for obtained results

fig. graphical presentation of results: violet - counting locations, yellow - counted flow, gray - uncounted flow.

Further developments

The engine we proposed is flexible and extendable, thus it can be suited for personal needs, or extended to new functionalities:

• Transit - soon we will try to extend our functionality to cover also PuT, and define set of stop points, or lines to be surveyed.
• Plate scanning – our partners ask us to provide tool to define optimal plate scanning locations. Actually that’s on our road map, however this task is much more complicated, and we will need to spend some hours thinking on how to solve it.
• Vehicle floating data – the engine we proposed is capable to define optimal trajectory of VFD to get as much details as needed.

Sales

OCL (Optimal Count Location) is ready to buy Visum add-on, available straightaway at intelligent-infrastructure. We offer competitive price for a product that gives you significant savings in modeling. We also provide service, where you send us your visum file and we simply calculate the results that you want.

See you at: www.intelligent-infrastructure.eu

Rafał Kucharski