Use of Mixed Traffic Simulation Modelling As a Decision-making Tool for the Urban Layout of Opera House Roundabout in Hanoi
Lucie Maitre-Savoldelli, AREP, Nicolas Augris, AREP, Aurore Remy, TSS
This simulation model has been used to study the feasibility of a new parking lot close to the roundabout of the Opera House in Hanoi, Vietnam.
The dominant presence of two-wheel motorised vehicles in Vietnam has generated a very intensive use of the road network, with traffic flows reaching 10 000 vehicles / hour, which do not necessarily heed to common driving rules, such as lane discipline. Moreover, car ownership is growing rapidly, which has an impact on current road traffic conditions and is also affected by dominant two-wheel traffic.
Classical simulation modelling tools are not well suited for studying mixed traffic, hence AREP decide to use the new simulation model especially suited for mixed traffic, developed by TSS. This simulation model has been used for a feasibility study of a new parking lot close to the roundabout of the Opera House in Hanoi, Vietnam.
Recent developments in the modelling of two-wheeled vehicles include the adaptation of a number of existing behavioural models such as Car-following and Lane-changing models, Cellular Automata models (Nagel K. & Schreckenberg M., 1992). The Car-following model can account for each pair of vehicle types present in the heterogeneous flow (Mathew T.V. & Ravishankar K.V.R. 2011) and may include Lateral discomfort caused by lateral friction between vehicles (Gunnay B., 2007). The problem of dealing with non lane-based lateral movements can be treated either in a discrete form, splitting the lanes into narrow strips where vehicles can occupy several strips at a time and applying some sort of lane changing from strip to strip (Mathew et al. 2013). Similarly to the strip approach, an extension of the cellular automata model with smaller cells and where vehicles can occupy several cells at a time has been proposed by different authors (e.g. Yao et al. 2009, Vasic and Ruskin 2012).
Although a number of specific models have been proposed to simulate the behaviour of two-wheeled vehicles, the vast majority of them have not been properly validated due to the lack of relevant empirical data
As with many other traffic simulation models, Aimsun has been initially developed to simulate traffic as found in a European context (low heterogeneity of vehicle types, high lane discipline, traffic priorities…). TSS has developed a new traffic behavioural model to better model traffic conditions as found in Vietnam, such as the decision-making process and the action of movement. Lateral movements are treated without lane discipline and different extents of road behaviour are simulated.
This model is based on two main ideas: drivers are mostly concerned on what is happening in front of them, and by taking into account high vehicle heterogeneity.
Computing speed and model reliability were also of main concern to ensure that large road layouts can be modelled in the future.
The simulation model developed by TSS has been calibrated using current road data from Hanoi, which included behavioural observation fieldwork. The model was then validated as the simulated traffic flows were behaving similarly to observed traffic conditions in Hanoi.
The evolving modal split which is happening in Vietnam can also be observed in other countries. The tools that were developed that were presented in this paper can become a new way to analyse road traffic and existing road layouts to re-think how a city can function.
Association for European Transport