Description / objective
The Network Planning function designs the collective of services and how they relate to each other. The scope of this function varies enormously.
- At the simplest level, routes are opened, adjusted and closed in accordance with observed demand and feedback from drivers and the public. Simple calculations and estimates of revenue and cost are performed, and routes are adjusted based on experience.
- At the medium level, some effort is made to consider the collective of routes, to provide a planned level of coverage in the service area, and to gain efficiencies where there are route overlaps. A scientific approach is taken to route open/closing and service level adjustment. Surveys are carried out to understand current and potential demand, some modelling of demand and service levels is performed, and the viability of the services is forecast.
- At the higher level, network planning is based on a strategic vision and extensive modelling of demand, ridership and services. The transport planning takes the urban planning and development as its reference point. The bus network is likely to be modelled in conjunction with the other transport modes. Intensive demand analysis is conducted and complex models are used. This is an expensive process. The justification is that it is an investment, and that it costs far less to plan the network well than to engage in a ‘trial-and-error’ approach, which could lose large amounts of money on unviable or sub-optimal routes, and still not get it right.
The highest level of Network Planning is usually carried out by Transport Authorities, or by Operators who have a mandate or a Service Contract for the entire operating area. At this level of Network Planning, the network is considered as a whole. A strategic vision is developed, the structure of the network is developed, there may be a hierarchy of routes and transport services, decisions may be taken about trunk and feeder services, broad service level parameters would be developed in response to demand, and the network design would take into account future urban development and likely trends in demand. By contrast, medium and simpler levels of Network Planning focus on the more immediate term, and tend to be either responsive or opportunity-seeking.
The depth and complexity of Network Planning, and the tools that support the function, will typically depend on:
- The scale and complexity of the service area, number of potential routes, and scale of the demand
- Who is carrying out the Network Planning activity (Authority, Operator), and the objectives
- Whether a full urban area/regional (re)design is required, or whether it is adjustment to part of the network in response to changes in land-use, demand or other factors
- Availability of urban development plans, demographic and activity forecasts
- Availability of mapping data for the area
- Availability of travel demand forecasts and source data for the desired spatial and time scale
- Availability of calibrated network descriptor and modelling tools, and capacity to use them
Technologies, data and resources
Computerised Network Planning tools range from simple spreadsheet-based assistance, to extensive and complex network modelling and demand forecasting software packages. The latter require extensive data inputs, may have heavy computational requirements, and may take a lot of time and effort to set up, populate and calibrate.
For more complex network planning tools, input data requirement include urban and road network descriptors, travel times and costs by public transport and by other modes, demographic data, activity modes, travel demand information including origin-destination sets, and unit costs of the transportation supply. Less complex tools may only require network/route calibration data, current travel patterns, growth forecasts and unit revenue/cost data. AVM and Fare Collection can provide some of the required data, although it may require some manipulation for entry to the network planning tools.
Advantages and cautions
The primary advantages of ITS-supported Network Planning are:
- Extensive and advanced computations and optimisation can be performed, which are beyond the capacity of manual methods
- Large quantities of input data can be absorbed and transformed to support the modelling processes.
- Multiple scenarios can be tested
The primary cautions are:
- Complex network planning models require a long establishment period, extensive data, powerful computational platforms, and specialist expertise to use and interpret them to best effect.
- As any modelling tools, the predictive accuracy of Network Planning applications is dependent on the assumptions, accuracy of the input data, and skills of the modellers. Despite best efforts and the value of such modelling tools, the actual outturn may not match what the models predict. A critical capacity must also be brought to bear.