Digital Twins @ Modelling World 2019: why do they matter for transport modellers?

The real value of a Digital Twin is in the integration of the transport system with other systems

The real value of a Digital Twin is in the integration of the transport system with other systems

Modelling World, now in its 14^th year, is the UK & Europe's best attended, longest-running and biggest conference / annual exhibition for transport and pedestrian modelling professionals, advisory and strategic modellers, data scientists and transport economists.

In 2019, we will be introducing an afternoon session, prior to the main conference, to explore the implications and potential of Digital Twins. It will be led by Mark Enzer, Chair, Digital Framework Task Group, Centre for Digital Built Britain and Chief Technical Officer, Mott MacDonald.

Join us on June 4, 14.00 – 18.00 at the Digital Twins workshop, led by Mark Enzer, Chair, Digital Framework Task Group (DFTG), Centre for Digital Built Britain and Chief Technical Officer, Mott MacDonald

Says Modelling World Chair Tom van Vuren, Mott MacDonald, transport modellers bring huge value to the development of Digital Twins. 

'I always say that I have been producing Digital Twins for over 30 years! Our transport models aim to be representations of the population living in the study area covered (zonal land use data on population, employment, retail etc), their mobility needs (physical segregation between activities), the transport system available to meet these needs (roads, junctions, bus and train lines, time tables, walking routes and cycle paths) and the choices people make (based on their observed travel behaviour and stringent theoretical R&D). Surely that is a Digital Twin of the real world out there?

Over the years we have improved our representation and visualisation of the resulting travel patterns – from all day aggregate flows based representation based on analogies in physics, to discrete choices made in small time periods by groups of people, segments of the population, to microsimulation of individual people and vehicles.

To me, a Digital Twin without explicit representation of its inhabitants, and without their travel needs reflected as movements in time and space, is just a static visualisation of assets: buildings, utilities. This is why, to me, there is huge value that we as transport modellers bring to Digital Twins. I have seen movement in such models, but these tend to be people and vehicles moving without reason or purpose, simply illustrative.

And with Activity-Based and Agent-Based Models we have the perfect evolution of transport models to interface smoothly with Digital Twins. And we benefit, too. People’s transport needs and choices affect, and are affected by utilities – be it electricity supply for electric vehicles, or delays caused by broken water pipes. The effort put by others into Digital Twins will allow us to visualise travel patterns and transport conditions so much better than through the usual tools available to us. But the real value will be more than visualisation – it’s the integration of the transport system with other systems.'

Van Vuren adds that Digital Twins may be able to give transport modelling a boost in areas where such models are commonly criticised, and outlines his responses:

Transport models are fed by poor, laggy and insufficiently granular data

Response: This depends on the model’s purpose and data sources. For example, with agent-based models we can represent individuals, and there is obviously a distinction between (virtually) real-time data from sensors incl mobile phones, that we use for traffic operations and management, and long term forecasts that we use for strategy development and business cases. The data can be more granular and faster; it all depends on the application

Transport models offer limited ability or incentive to validate the models with outcome data

Response: Models are validated against observations, but at an aggregate level. We actually take great care to validate the models, as per guidance by DfT and HE. The incentive is as with most models – if the model cannot reflect today’s reality, how can we trust it to predict the future?

Transport models offer limited transparency on the assumptions feeding the model

Response: This is a fair comment. The theoretical foundations of the model are well known, but not very well understood by practitioners. Is that any different for other fields? The assumptions about the future are critical and perhaps this is where transport models differ. In my experience the real danger / problems occur in forecasting mode as the assumptions on future population, economy, travel behaviour, have such a huge impact. The model is just a calculator; the assumptions are everything!

Transport models offer limited ability to link with other models/understand system of system impacts

Response: Probably true. We link with land use, economy, socio-demographics but at an aggregate level. There is a real opportunity when talking Digital Twins  – and of course it works the other way as well – without a transport model a Digital Twin just shows people and vehicle movement without it being linked to actual behaviour.

Join us on June 4, 14.00 – 18.00 at the Digital Twins workshop, led by Mark Enzer, Chair, Digital Framework Task Group (DFTG), Centre for Digital Built Britain and Chief Technical Officer, Mott MacDonald, to explore how to:

• Integrate national and city-scale data to improve planning and prediction

• Understand the impact of digital twins for clients, consultancies and the supply chain

• Hear case studies from pioneering digital twin developers

• Realise opportunities for clients, consultancy and suppliers

• See how Digital Twins are improving infrastructure management and maintenance