4. Multi-modal network planning

A network incorporates all routes that provide inter-connected pathways between multiple locations for similar traffics. Networks can be multi-modal or uni-modal—a multi-modal network typically comprises several uni-modal networks (see examples in Box 4 Transport System Elements in the Overview and in the Glossary).

Network planning in many jurisdictions has traditionally focused on planning for individual modes. The philosophy underlying the ATAP Guidelines is that this modal planning should be replaced, or preceded, by multi-modal network planning. If modal network strategies are developed, they should be inferred from, and guided by, multi-modal network strategies (and preferably by multi- modal corridor and area strategies).

Network planning involves developing a vision of how the transport network should be performing in the future (e.g. anything from 20 to 50 years ahead). The vision must be consistent with the transport system objectives and performance targets and any other government policy choices. The vision should be embodied in a multi-modal network strategy document.

The multi-modal network strategy should include consideration of funding mechanisms including likely current and future government funding levels. Explicit consideration of funding should help to manage stakeholder expectations and ensure consistency in the treatment of corridors and areas in subsequent planning and program development.

There is also a role in network planning for the identification of current system issues for shorter term resolution, consistent with the longer terms strategy.

4.1 Steps in multi-modal network planning

Figure 3 illustrates the process of multi-modal network planning as well as the links to network assessments, funding availability, corridor and area planning, and route and link planning. Note that in applying Figure 3, the sequencing of individual steps will not be strictly linear. Some jurisdictions may also find it more useful to alter the sequence of steps. The feedback loops, and therefore the iterative nature of the process, further confirms that progression through the process won’t be simply linear. The same point applies in both corridor and area planning, and route and link planning.

Figure 3: Flowchart of system planning
Flowchart of system planning

There are four steps in multi-modal network planning:

  1. Determine multi-modal network objectives, performance indicators and targets
  2. Define the multi-modal transport networks and their functions
  3. Develop multi-modal network strategies to achieve system objectives and performance targets. These should take into account the analysis contained in network assessments and any government policy settings
  4. Determine affordable, multi-modal intervention benchmarks (or standards) for infrastructure investment, ensuring that the benchmarks are consistent with system objectives and strategies. This is an optional step.

4.1.1 Step 1: Determine multi-modal network objectives, performance indicators and targets

Network objectives provide a top-down view of how the multi-modal network should perform in the future (e.g. from 20 to 50 years ahead) in order to achieve transport system objectives. They incorporate expectations about how the network should perform in order to meet the demands placed on it.

Network performance indicators and targets should be based on the same principles used to develop transport system indicators and targets (see F1). Where targets are set, they should be consistent with policy choices made, be cognisant of available funding mechanisms and achievable from a total network perspective.

Examples of long-term multi-modal network performance targets include:

  • Annual level of fatal and serious injuries in rural transport to decline by 30 per cent by 2025
  • Rural travel times not to increase until 2020
  • No more than 10 per cent variability in travel times on major interstate freight routes
  • Noise levels for residents along major urban transport routes not to increase by more than 2dB(A) before 2030
  • Emissions from transport vehicles not to increase until at least 2025.

Although the vision for the network covers a 15 to 20 year horizon, in the interim it may also be necessary to specify performance targets and deliverables for shorter periods (typically 5 years) to support funding and forward programs. For example, interim targets may be used for equity reasons, to bring the entire network to a specified minimum level of performance at an earlier date. Achieving this minimum level consistently across the network may also provide better network performance than having isolated network sections with varying levels of performance.

Multi-modal network performance targets also guide the development of multi-modal network, corridor and area strategies, and route and link plans, on a consistent basis. This top-down perspective increases the likelihood that the performance of corridors, areas, routes and links will support the achievement of multi-modal network objectives and targets.

However, not all corridors and areas will have the same multi-modal objectives and performance targets. Variations are needed to reflect local circumstances revealed in detailed corridor and area analyses. For example, the targets for a corridor or area with a poor safety record may require a certain percentage reduction in annual fatal and serious injuries by a given future year, whereas a smaller percentage reduction may be specified for a better-performing corridor or area.

4.1.2 Step 2: Define the multi-modal networks and their functions

Identifying the multi-modal networks to which funding will be directed is the next step of network planning. Networks should be specified on the basis of achieving the best overall match with transport system objectives; they should be determined from a big-picture perspective to maximise delivery of overall transport system objectives.

The National Land Transport Network is an example of multi-modal network. It is a single integrated network of land transport links of strategic national importance. It is based on specified corridors and connections that together are of critical importance to national and regional economic growth, development and connectivity. It incorporates:

  • National and inter-regional transport corridors, including connections through urban areas
  • Connections to ports and airports
  • Other rail and road inter-modal connections.

Different networks perform different functions. For example, the National Land Transport Network primarily focuses on long distance passenger and freight movements of national significance. An intrastate land transport network (i.e. the rural arterial road and regional rail networks) facilitates long distance movements of freight and passengers within a state or territory. In contrast, a transport network in a major city (urban arterial road, public transport, cycle path networks, etc) focuses on moving people to and from work and recreational activities, facilitating business activity and moving urban freight.

The relative importance of individual modes in a multi-modal network will vary across the network in response to differences in the primary function of each part of the network.

4.1.3 Step 3: Develop multi-modal network strategies

The third step in multi-modal network planning is developing multi-modal network strategies. These strategies incorporate a top-down view of how the transport network should desirably develop into the future. The strategies indicate the actions needed to contribute to achieving network objectives and performance targets.

Multi-modal network strategies should contain a description of the strategy in generic terms to enable the broad features to be clear. They may also include location-specific aspects, which are also specified in corridor and area strategies and in route and link plans. However, network strategies may make a distinction between urban and non-urban initiatives to reflect different transport contexts. For example, strategies to address congestion and transport noise are more relevant in an urban context than in a non-urban context.

Network planning can either precede corridor and area planning or be developed from the collective results of corridor and area planning and quantitative network assessments. Feedback between these two levels of planning is critical, enabling multi-modal network strategies to be reviewed and adjusted over time.

Network strategies typically incorporate a mixture of infrastructure and non-infrastructure initiatives (see F3). These strategies will need to reflect policy choices made by governments and may include a mixture of strategies that apply to all modes and strategies that are mode-specific. It is important that any associated development of modal plans reflects the multi-modal network strategies.

4.1.4 Step 4: Determine affordable, multi-modal intervention benchmarks (optional)

This is an optional step[1] in which intervention benchmarks identify specific circumstances that act as ‘warrants’ or ‘triggers’ for investment designed to achieve a particular performance standard. The circumstances usually relate to road or rail track conditions and traffic volumes. Box 1 provides examples of these benchmarks.

Benchmarks determined at the network level may subsequently need to be modified in corridor and area plans to reflect local circumstances. However, network and corridor or area intervention levels should be consistent. It may be desirable to develop interim benchmarks that align with interim objectives for the network.

Austroads has developed a comprehensive set of guides and procedures that is generally accepted as providing national benchmarks for best practice in design, construction, maintenance and user aspects of the Australian road system (www.austroads.com.au). These guides and procedures provide suitable guidance for intervention strategies. For rail, the Australasian Railway Association produces the National Code of Practice.

As intervention benchmarks apply across the entire network, they must be cognisant of likely funding mechanisms and levels from a network perspective; that is, they should be within current and expected future funding. Setting affordable benchmarks covering 15 to 20 years for a network plan can be difficult given future funding uncertainties. It may be necessary to develop different funding scenarios with different sets of benchmarks. The steps to achieve affordable benchmarks include:

  • Understanding the configuration of the existing network
  • Understanding how alternative configurations of a future network could achieve desired performance targets
  • Estimating the costs to achieve the alternative configurations
  • Forecasting future funding levels
  • Determining the configuration that optimises outcomes in terms of the performance indicators, within funding constraints.

Box 1 Examples of intervention benchmarks

  • Road widening on rural two-lane roads to 10 metres to be considered when high volume of traffic is reached (e.g. >1 000 annual average daily traffic (AADT)) or where there is a significant volume of heavy traffic (e.g. 20 per cent for 500 AADT and 5 per cent for 2 000 AADT)
  • Road duplication for rural roads to be considered when traffic volumes exceed 10 000 AADT or where there is a significant component of heavy vehicles interacting with tourism traffic
  • More, and longer, passing loops and eventually track duplication when train delays or unreliability exceed the standard accepted by the market
  • Resealing of roads to depend on a number of factors but, as a general guide, a frequency of between seven and 10 years being likely for surface seals (depending on the climatic zone) and around 14 years for thin asphalt seals
  • Pavement rehabilitation to be an option where pavement has deteriorated to a point where it no longer meets serviceability requirements such as roughness and rutting or where it is structurally inadequate for current or expected loadings, with consideration of whether a pavement is still functioning well after reaching its design life to determine the intervention time
  • Implementing initiatives to reduce transit times for rail and road when they exceed certain levels
  • Implementing initiatives to reduce fatalities and serious injuries consistent with meeting national targets
  • Rail track upgrading when the deterioration and safety risks become uneconomic or exceed acceptable levels
  • Bridge rehabilitation or replacement to be determined by structural integrity and performance of the bridge, with the time of intervention related to safety risk analyses and the score the structure receives, with the safety of the public to be paramount at all times when prioritising bridge maintenance.

[1] Use of this step will depend on each jurisdiction’s view on the usefulness of using benchmarks or standards in planning.