**4.2 Architecture of an Orbicity model**

Each model has a four-tiered structure which covers, from bottom up, [i] Traffic conditions and service operations, [ii] Demand in equilibrium to supply, [iii] Service management, [iv] Technology and regulation.

	- a. The regulatory regime corresponds to one of several available options – unregulated monopoly (MO), optimal system with no budget constraints (SO), optimal system with the constraint that the producer must balance their budget (S2) or return on public funds (S1).

*Towards Shared Mobility Services in Ring Shape DOI: http://dx.doi.org/10.5772/intechopen.94410*

**4.1 The Orbicity modelling family**

comprises three models:

destination [2].

and *t*R.

**172**

We have developed a family of models called Orbicity, designed to study ring-shaped mobility services in urban environments. As of early 2020 the family

*Models and Technologies for Smart, Sustainable and Safe Transportation Systems*

point and dropping them off at their destination [1].

off passengers at their requested locations [3].

Service management, [iv] Technology and regulation.

**4.2 Architecture of an Orbicity model**

• a *taxi service*: vehicles take individual clients, picking them up from their start

• a *sharing service for individual vehicles*, typically two-wheeled vehicles or small cars which do not require driving licences: users pick up the vehicle from its parking spot, make their journey and leave the vehicle at their

• a *shuttle service*: vehicles with a capacity of K circulating on a ring-shaped route, with vehicles running in both directions. They stop to pick up and drop

Each model has a four-tiered structure which covers, from bottom up, [i] Traffic

i. *The technical performance of the service*, with a fixed fleet size *N*, in order to serve a fixed level of demand *Q* which is compatible with *N*. This model gives us the mean journey time *t*<sup>R</sup> and access time *t*<sup>A</sup> for each journey, along

ii. *The balance of supply and demand*: with a fixed offer in terms of fleet size and pricing, the volume of demand *Q* can be modelled as a function of the fares charged and the waiting *t*<sup>A</sup> and journey *t*<sup>R</sup> times. But these times are themselves dependent on *Q*, as per the traffic model. These two causal systems are interlinked, and together they determine the state of

equilibrium between supply and demand in terms of volume *Q* and time *t*<sup>A</sup>

iii. *Service management*. Production of this service aims to optimise a certain objective function, which is determined by the regime of regulation. In cases involving an unregulated monopoly, the objective function will be the

iv. *Service policy depending on regulation regime*. It is at this upper level that

a. The regulatory regime corresponds to one of several available

must balance their budget (S2) or return on public funds (S1).

options – unregulated monopoly (MO), optimal system with no budget constraints (SO), optimal system with the constraint that the producer

net profit accrued by the operator, equal to the difference between commercial revenue and production costs. The producer determines the fleet size and pricing policy with a view to maximising this objective function. Maximisation is realised by taking into account both the technical

requirements of the service and elasticity in demand.

the structuring characteristics of the service are decided:

conditions and service operations, [ii] Demand in equilibrium to supply, [iii]

with indicators useful for designing the service offered.


This upper level thus determines the strategic conditions of the service. For the service operator, this is a matter of strategic marketing. For a public authority responsible for coordinating sustainable mobility, it is a matter of strategic planning.

**Figure 3** offers a schematic representation of this four-tier architecture.
