Planning for Net Zero Transport: A Road Map for Development of Operational Activity-Travel Models, a Discussion Paper in the UK Context

The UK’s Committee on Climate Change recommended a new emissions target for the UK: net-zero greenhouse gases by 2050, ending the UK's contribution to global warming. In June 2019, the UK became the first major economy in the world to pass laws to end its contribution to global warming. Transport is currently a major source of UK's greenhouse gas emissions and the transport sector is traditionally perceived as a laggard when it comes to environmental matters. Technological advances to change energy mix used by the vehicle fleet and of power generation will contribute to this change. Nevertheless, such changes will take time and may be insufficient to meet the policy. Transport planners should contribute to assist decision-makers in developing and delivering strong planning policies as well as infrastructure investment plan. This requires developing and applying appropriate transport modelling tools to forecast travel choices. As of 2020, the trip-based models, still seems to be a state-of-practice of modelling transport in most of UK applications. The application of these models has been extended to evaluate various transport policies encouraging modal shift and behavioural change (e.g. London Transport Studies Model). Although significant improvements on trip-based models have been undertaken to reduce aggregation errors, most travel demand model systems are limited in their usefulness because they fail to incorporate an adequate representation of decision behaviour. The trip-based models certainly have the basic limitation of the aggregate predictive tool and non-behaviourally realistic approach at their core. The difficulties faced in appropriately appraising clean air plans illustrate such limitations. Tour based models have been developed to correct for some of the errors that occur in the trip-based models by recognising the connection between the trips that are included in a tour. There are a number of tour- based models have been developed in the last two decades in the UK to correct for some of the errors that occur in the trip- based models by recognising the connection between the trips that are included in a tour such as mode choice and park-and-ride modelling (e.g. LLITM, PRISM West Midlands, MoTiON, NTM). Tour-based models are not comprehensive enough to capture the dynamics of activity and travel behaviour. The key weaknesses are the lack of an overarching pattern connecting the day's tours and the failure to integrate the time-of-day dimension into the model structure. Tour-based models cannot recognise the connection between the tours completed by the same person in a day. These models generally ignore in-home activities and their impact on out-of-home activities and travel and interactions between household members, such as access to household cars. Operational activity-based models (ABMs) have been developed for policy analysis elsewhere; in the UK the practical application of activity-based modelling is much more limited, despite the fact that available sources of travel and activity data exist to enable such models to be developed. A survey of operational ABMs indicates that not much effort is being put into enhancing the behavioural aspects of the models in the last decade. Recent advances in collection of transport demand data (e.g. Mobile Network Data, GPS-oriented data, Smart ticketing, various travel related APIs and mobile apps) and advances in agent-based modelling enable transport modellers to overcome some conventional challenges of developing ABMs, data collection and computation. This paper intends to introduce a conceptual modelling framework and potential data sources for activity generation modelling. This study firstly defines the role of activity generation component in the activity-based travel demand models and how the conventional trip-based approach in the UK could be replaced by an activity generation model. The proposed conceptual model recognises that the activity participation is influenced by physiological constraints as well as socio-economic characteristics. Also, it considers time availability and overall time budget as a further constraining factor. The inter-personal linkages and trade-off between in-home and out-of-home activity time allocation are also incorporated in the activity-based modelling framework proposal. Moreover, the model structure proposes an appropriate approach for modelling household’s and individual’s decision making about new mobility concepts as well as use of autonomous vehicles. Appropriate mathematical and statistical modelling techniques will be proposed for various sub-models. Secondly, the paper discusses relevant conventional and new data sources for model development and validation. This study will introduce a validation framework for activity generation models will be introduced. Finally, drawing on current applications in the UK the paper summarises the scenario and policy drivers and appraisal metrics that trip and tour-based models cannot adequately represent and thus the value that actor or ABM would bring.


  • English

Media Info

  • Media Type: Digital/other
  • Features: Bibliography; Figures; Tables;
  • Pagination: 26p
  • Monograph Title: European Transport Conference 2020

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Filing Info

  • Accession Number: 01765166
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Feb 16 2021 2:57PM