Assessment of spatial transferability of an activity-based model, TASHA
Spatial transferability has been recognized as a useful validation test for travel demand models. To date, however, transferability of activity-based models has not been frequently assessed. This paper assesses the spatial transferability of an activity-based model, TASHA (Travel Activity Scheduler for Household Agents), which has been developed for the Greater Toronto Area (GTA), Canada. TASHA has been transferred to the context of the Island of Montreal, Canada using the 2003 Origin–Destination (O–D) travel survey and the 2001 Canadian Census. It generates daily schedules of activities (individual and joint) for each individual in this region. The modelled activity attributes (frequency, start time, duration and distance) from TASHA and observed attributes from the 2003 O–D travel survey are compared for five different activities (i.e. work, school, shopping, other, and return to home). At the aggregate level, TASHA provides quite reasonable outcomes (in some cases – better results than for the Toronto Area) for all four attributes for work, school and return to home activities with few exceptions (for instance, school start time). The model outcomes are also promising for shopping frequency and start times; however, TASHA provides larger differences for average shopping durations and distances. Only the forecasts for all four attributes for the ‘other’ activity type differ greatly with the observed attributes for the Montreal Island. These large differences most likely indicate the differences in behaviour between the Montreal Island and the Toronto Area. In general, we conclude that re-estimation of model parameters and the use of local activity attribute distributions (frequency, start time and duration) is a desirable step in the transfer of the TASHA model from one context to another.
Microsimulation and Policy Applications of an Activity-Based Modeling System of Travel Demand
An activity-based microsimulation model is developed for the Jakarta Metropolitan Area, primarily adopting a tour-based structure. It is a system of random utility based disaggregate and fully-connected logit and nested logit models assuming a hierarchy of the model components. This paper particularly focuses on the overall microsimulation process, model validation, and application to policy analysis. Several activity scheduling decision rules are applied to adjust the simulated daily activity patterns. Intra-household interaction rules have been applied including joint tour/activity generation and household maintenance tour allocation. For model validation, the microsimulation outcomes of the base year are validated both internally and externally. The internal validation involves comparison with the expanded survey data including the activity diary survey and household travel survey data based on which the models were developed and trip length frequencies. The external validation involves comparison with the observed traffic counts surveyed on two major screen lines in the region. This paper also presents the results of the application of microsimulation model to evaluate future transportation policy scenarios including several area pricing schemes. Direct and secondary results of the policy analyses simulations are discussed including emission estimates as well as emerging effects caused by each policy scenario. Overall, it became clear that the activity-based microsimulation model presented in this study provides accurate travel estimates which are expected to serve as better inputs for evaluation of different transportation policy scenarios. This provides a powerful and practical decision-making tool that can be used for policy applications not only in Jakarta but also in other metropolitan regions.
When to Cross the Spread? Trading in Two-Sided Limit Order Books
In this paper the problem of optimal trading in illiquid markets is addressed when the deviations from a given stochastic target function describing, for instance, external aggregate client flow are penalized. Using techniques of singular stochastic control, we extend the results of [F. Naujokat and N. Westray, Math. Financ. Econ., 4 (2011), pp. 299--335] to a two-sided limit order market with temporary market impact and resilience, where the bid ask spread is now also controlled. In addition to using market orders, the trader can also submit orders to a dark pool. We first show existence and uniqueness of an optimal control. In a second step, a suitable version of the stochastic maximum principle is derived which yields a characterization of the optimal trading strategy in terms of a nonstandard coupled forward-backward stochastic differential equation (FBSDE). We show that the optimal control can be characterized via buy, sell, and no-trade regions. The new feature is that we now get a nondegenerate no-...