Back to visual transport modeller On to detailed walkthroughs What is it?
Visual-tm is an integrated modelling workbench for the transport planner to create really exciting transport solutions - solutions which are more sustainable and which can move dependence away from the car for some types of trips.
The transport planner doesn't have to wait overnight to get the model's results, these are high quality tools in a fully integrated Windows environment - and they're fast, very fast.
What models can it do?
Models for trip generation, distribution, mode choice, highway and public transport assignment are controlled from simple screens with default parameters and options which you can easily change if you wish.
For the highway assignment module, you specify link speed/flow and junction delay/flow curves as simple equations or by points on the standard shaped curve for capacity restraint, set the number of iterations, press GO and (you don't have to wait...) its done. None of this 'put it on overnight' malarkey. 20 iterations of the West Midlands Model (300 nodes, 9500 links) takes 20 seconds!
The public transport model takes nodes, links, routes, fares, interchange, boarding and other generalised cost parameters, builds multi route paths and does your assignment. You can skim for in-vehicle time, walk time, fare, interchange and mode used - all in one pass ready to go into your mode choice model. Benchmark time for the West Midlands model (250 routes) takes 3 minutes!
You have some very sophisticated mode choice models at your fingertips supporting both conventional matrix mode choice and behavioural modelling needed to address sustainability and the other special issues of today. The mode choice model can be aggregate matrix based, disaggregate based on actual trips or prototypical sample enumeration, which combines the best of aggregate and disaggregate methods and allows for a much finer level of market segmentation for your behavioural models. They all fit together and are all formulated round the multinomial logit model.
The distribution models are correctly formulated and are versatile. They use the combined utility from the mode choice model to distribute using the doubly constrained distribution model. You can calibrate different distribution functions for different sector to sector movements. You can calibrate over one area and forecast over a different area. This means you don't have to start with a complete matrix, you can infill using our distribution model - and that goes for all modes. Forecasting can be applied as either incremental (for areas which don't change their pattern much), absolute (for new development areas) and using simple Furness (for external to external movements - all at once. You can combine distribution and mode split (dms) in a single logit structure.
The models are structured correctly so you don't make mistakes and the software directs you to get the correct outputs for input to the next process. For example, the skims from the assignment models are ready for the mode choice model; the logsums from the mode choice model can be put directly into the distribution model and the matrix that's come out of the distribution model goes through mode split and assignment with no messing about. Its fully integrated and its fast, very fast.
What is it like for developing models?
It can be programmed with simple macros, or using Excel spreadsheets, or if you know Delphi, Java, Visual Basic, Foxpro or other high-level languages you can program in your model yourself, with your own user interface. You can also run it on your intranet or the internet.
It is a fully integrated environment for developing models and running extensive forecasts with it. In forecasting, most models go through a central loop: through distribution, mode choice, assignment, capacity restraint and back to distribution several times until the highway speeds converge. In our software all this is fully integrated so it takes minutes rather than hours or even days to complete several cycles for this loop.
Can it connect to my other processes?
It has completely open architecture - the complete opposite of a black box. You can get reports on all calculations so you can check them with your calculator - even the public transport paths! We even provide screens to help you do this, so you can sleuth problems in your model and fix them more easily.
It connects to everything via the built-in DOS prompt where you can invoke SATURN or any other software you wish to. Data is held on simple spreadsheets or comma separated files so you can easily edit them in Excel or via the built-in editor.
Its toolkit includes polygon editing to get your zone system right, network scenario editing, connect your model up directly to your transport plan best value targets with the datawiewer, calculators for a quick answer to predict switch from car to park and ride or cycle. It is fully integrated with DfT's ERICA5 and your origin-destination database. If you have Microsoft Office and MapPoint you can develop, edit and display your networks and results on maps.
Why does Visual Transport Modeller Come in Different Editions?
Different types of user require different functionality. Visual transport modeller therefore comes in a number of editions, each aimed at a different type of user:
Visual Transport Modeller: Academic Edition
Some people want to try the software out before making a possible purchase, some may want it for teaching purposes and others may be just curious as to what transport modelling is all about. The free Academic Edition is aimed at these types of people.
Visual Transport Modeller: Professional Edition
We think that there are some transport modellers who want their own transport modelling software. They may want to develop transport models for their own purposes and can't afford the price of currently available commercial software. There may be people who could want it for a medium sized problem eg a town, city, corridor or region where there is not the data to support a large model. They may be not considering doing a model because it takes too much time/ data or because the size of the problem does not warrant a 'big' model. They may be considering doing something simple on paper or with a spreadsheet. Instead we may tempt them to considering implementing a simple transport model using Visual-tm's rapid model development capability. The Professional Edition is aimed at these types of people.
Visual Transport Modeller: Corporate Edition
With our Visual-tm and DfT's ERICA5 software, Local Authorities, Regional and National Governments have a superb way of retaining their transport data in an encapsulated transport database as a permanent resource for the future. This will enable them to develop progressively better transport plans (with or without a model). If they don't have a model and do not want to develop one, they could run tables and queries to get the transport statistics they need. If they wished to develop a model at a later date they would need to build such a database as a first step. If they had a model, they could keep it up-to-date without having a complete rebuild every 10 years or so. The model could grow as the need arose for greater detail, more market segmentation, as new types of transport solutions come along and as more is known about transport in their area. This will help them devise better solutions. If they monitor transport, it will help them monitor better and allow the results from their monitor to feed through to their transport planning to make it better still. These types of user may have a large problem size and may want other specialist tools. For example as well as producing origin-destination trip matrices by combining different data sources in a statistically more rigorous way, Visual-tm & ERICA5 also produce variance matrices which show the degree of precision of each origin-destination cell of the matrix. Visual-tm can carry this through the modelling process so that estimates of relative precision can be provided for the model results.
These types of user may also require a stated and revealed preference modelling capability (provided by our SPHINX software module) and perhaps to use disaggregate models to bring into their forecasts better models of behaviour (eg for road pricing, responses to congestion, peak spreading, park and ride and other more sustainable transport modes). These people may also need to monitor the green travel plans in their area with pd-Green. The Commercial Edition is aimed at these types of user.
Visual Transport Modeller: ERICA5 Edition
This is aimed at people who want the specialist database functionality provided by ERICA5 and who do not require the full functionality of all the transport models. The Academic Edition is included with it.
Visual Transport Modeller: Accessibility Edition
This is aimed at people who want the specialist accessibility functionality provided by Visual-tm and who do not require the full functionality of all the other transport models. The Academic Edition is included with it.
Visual Transport Modeller: pd-Green Edition
This is aimed at users who want to develop and monitor their green travel plans and who have no need of transport modelling functionality.
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