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The Department of Transport and Main Roads in Queensland is moving the patchwork of current models into standardised frameworks, leaning on and developing open source software where possible

Open source transport models –not a free ride

Many of the original transport modelling software packages emerged from individual efforts at a time that commercial tools did not exist, and when computing power was very limited and expensive. Says Tom van Vuren, VLC’s Regional Director UK & Europe: “I started modelling in the early 1980s with what was at the time known as the FHWA suite of models, originating from the United States, delivered on magnetic tapes and run on the mainframe of Delft University. Later, this software morphed to TRIPS, which itself became the starting point for CUBE. The SATURN ME2 matrix estimation from counts subroutines stem from Luis Willumsen’s PhD dissertation, and some of SATURN’s capabilities in signal control optimisation are the results of mine. AIMSUN, EMME and many of the PTV products also have their origins in universities, and were only later commercialised.”

It wasn’t surprising that models contained bugs, had poor or no user support, were updated infrequently and in some cases disappeared altogether – which Millennial has heard of, let alone used, CONTRAM or TRAFFICQ? And woe be the organisation that relied on such tools that became obsolete through often a single point of failure; this is where commercial vendors have played a key role in establishing confidence in practice, providing quality-controlled, documented software supported by sizable teams of experts that we can trust will still exist in years to come. It’s not unreasonable to require and also pay for that support, considering the decisions that rely on the numbers that we produce with these software tools. (As an aside, even bug-free software leaves enough latitude for quite different errors, in network coding, other base year input data such as counts or demand matrices, and particularly future year representations – but that’s a different story.)

Inevitably, these commercial solutions are less agile (development costs time and money, and introduces risk to both vendors and users). And there are further impacts on practical innovation, including the problem of organisations and locations ‘locking in’ to software products, associated training and ending up with staff resources skilled in the application of tools rather than development and understanding. Says van Vuren: “Although there are exceptions, a further frustration to me has been the slow transfer of new academic insights to practice, and even a lack of attractiveness of modelling as a career to mathematical modellers and data scientists, compounding the reliance on what commercial products can do – no more and no less.”

Recently, and certainly in academic circles, Free and Open Source Software (FOSS) has been mooted as the way ahead – often supported by arguments not dissimilar to these above – increased agility and wider ownership. The “free” part relates to unfettered access to use and modify software (rather than there being no costs), whilst the “open” part articulates the values of a joint and collaborative development effort.

Robin Lovelace, John Parkin and Tom Cohen go a step further and argue in a recent Transport Policy paper for what they call open access models, which they define as models that are both developed using open source software and are available to be used by the public without the need for specialist training or the purchase of software licences. This would encourage the questioning and sensitivity testing of model assumptions and ‘hardcoded’ parameters; and support public participation in the planning system.

“FOSS provides more room for enterprise,” says Alex Dawn of CityScience. “Red Hat Inc, for example, make billions in revenue from providing support for their ‘free’ software. FOSS provides insight within the black box and allows you to customise it to work for your needs, rather than your talented employees working around the limitations of your software licences”.

One question often pondered is whether open source models can be trusted. Key to trust is development of software that is bug-free, well documented and works as expected. This does not happen without structure and organisation. Whilst tools like GitHub have made it easier to introduce good software development practice, to collaborate with others and share code, it is ultimately the people that are the key. Crowdsourced, altruistic and parttime software developers can only get you so far.

Funding is a serious issue, Pedro

Camargo, lead developer of the AequilibraE open source modelling platform, says: “FOSS has grown tremendously since Linux’s early days, and tools like Python, R, QGIS and Biogeme have become essential tools in any modeller’s tool-belt. A few things still hinder the use of FOSS and the technical development of our professionals, however. The two most important are: we think we are special, so our tools are kept under wraps and unchecked; and we are free-riders, as we believe that we do not need to fund FOSS even if it serves us well. I believe it will be up to government bodies to start funding the relevant projects.”

Most serious efforts (like the MATSIM and ActivitySim activity based modelling frameworks) have one of two key sources of funding. The first, as in the case of MATSim, is through very strong links to academia, with plenty of research funding across multiple universities powering development of the software. The second, as in the case of ActivitySim, is through investment in open source projects from public authorities. The platform has secured long-term funding through a consortium which pools funding from a number of Metropolitan Planning Organisations in the USA. This trend of moving away from volunteer developers alone, with other organisations supporting and funding development, is termed “Community Source”. This a direction which VLC is also increasingly seeing in Australia. Says Jamie Cook, a Principal Consultant at VLC: “A good

A good example of modularity is work recently completed in Sydney, where VLC’s own public transport assignment algorithm was built into an operational public transport planning tool

Most serious open source efforts have very strong links to academia, with plenty of research funding across multiple universities powering development of the software

example is the Department of Transport and Main Roads in Queensland, where the patchwork of current models developed using different standards for coding and sometimes software is being moved into standardised frameworks, leaning on and developing open source software where possible.”

Of course, the benefits of joining forces to increase the availability of both funds and skills are not restricted to open source development. The most successful commercial software vendors already effectively pool funds from a wide base of thousands of end users to invest in new functionality and to drive innovation. And those users also benefit from the widespread testing taking place by others using this software around the world, identifying bugs early, and establishing and sharing good practice. Market forces, when working correctly, have acted to create value for the community of users.

Open source is also not a cheap option, especially if we want good outcomes. It can, however, be a way to harness pooled funding to achieve goals that are more directly related to the exact needs of those funding software improvements, who rely on their outputs.

Taking a step back, however, what about those organisations that do not have deep pools of specialist expertise to manage the more complex projects or the time to wait for development? Open source could prove to be a poisoned chalice for local authorities and smaller transport organisations that are expecting too much, too soon. MATSIM, for example, has

Making outputs from transport models far more accessible is most likely through tools like VLC’s web-based visualisation platform, Planwisely, developed specifically for that purpose

been in development since 2006 and only recently has become more widely used after features and ease of use reached a critical mass point.

Says Ali Inayathusein, VLC’s National Director Future Transport: “To me, it is clear that open source, whilst offering huge opportunities, is neither a free beer nor a silver bullet. My guess is that from a software perspective we will benefit from a continued role for commercial software providers, where increasing competition from open source alternatives will drive innovation and retain a focus on what each tool does best. Increasing modularity and better access to software functionality through APIs (already a trend that all the major software providers are embracing) will allow modellers to pick and choose the best bits of software to combine, whilst adding bespoke elements as needed themselves.

“One great example of modularity (if not open source) in action is work VLC recently completed in Sydney, where our own public transport assignment algorithm was modularised and built into a tool for operational public transport planning.”

We can expect to see an increasing number of community source projects and, alongside that, crossfertilisation and funding of ideas across cities and countries that turn good ideas into practical software at more regular intervals. Open source software will exist alongside, interface with and enhance the commercial packages we are familiar with. Will transport modelling become more accessible to non-modellers, as Lovelace, Parkin and Cohen advocate? “This is not just a question of access to open source software, but also one of understanding of the complexities of transport and travel”, says van Vuren. “I am adamant that some basic understanding of the theory is essential, how that is represented in any model, plus an awareness of the importance and impact of assumptions, buried in parameters or hardwired in the functionality. Simplified modelling interfaces will enable access (although masking complexity and uncertainty could cause more issues than it solves). More likely this can be achieved through making outputs from transport models far more accessible, through tools like VLC’s web-based visualisation platform, Planwisely, developed specifically for that purpose.”

“The discussion about open source software is also incomplete without mentioning open data, says Inayathusein in conclusion. Despite the early promises of Big Data, the costs of data supporting transport modelling still generally outstrip the costs of the actual software products. I am disappointed that access to data sources generated by the general travelling public, such as by using mobile phones, ride-hailing services like Uber, travel apps or map services has not improved markedly. Here’s probably where the real opportunities lie for opening up.” n

Ali Inayathusein is National Director Future Transport at Veitch Lister Consulting and Tom van Vuren is Regional Director UK & Europe at VLC Europe, and Visiting Professor at the University of Leeds.

Veitch Lister Consulting was founded in 1986 with one objective: to provide tools and insights that help our clients plan the cities of the future. This remains our purpose, driven by a culture grounded in transparency, the pursuit of excellence and the desire to innovate. In 2021 we extended this purpose to the UK and Europe, opening up a London office and making VLCʼs expertise available to a wider market.

Today we are one of the largest specialist transport planning consultancies in Australia. We have a reputation for providing high quality work, focusing on solutions that are both practical and technically robust. Our team of transport planners, engineers, modellers, software developers, economists and analysts deliver solutions that facilitate sustainable growth and prosperity for our clients and communities.

We work with a clientʼs models using our expertise to help develop their capabilities and tools - or we use our in-house Zenith models, covering all major metropolitan areas in Australia and transferable worldwide. Our Future Transport Lab provides research, analytics and expert advice to clients seeking to inform their decisions with data-driven insights and solutions.

Contact Tom van Vuren tom.vanvuren@veitchlister.com www.veitchlister.com

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