Add `modal split`

[lumi321]

Description of the issue

In many decriptions of the transport sector a modal split (also known as modal share or modal choice) is used. This describes the percentage of a transport modality compared to all the modalities considered.

Ideas of solution

There are several possibilities for implementation. Possibility one: modal split as subclass of fraction value and axioms 'is about' some 'vehicle' and 'has unit' some 'percent'

Possibility two: like above, but with modal split share instead of just modal split. In addition, modal split as subclass of data item with axiom 'has part' some 'modal split share'.

The latter possibility distinguishes between the "whole" modal split and single parts. In contrast, the first option simply states the share of a certain modality without having a connection to something overarching.

There is also a third option where modal split is not even a fraction value but simply a data item that 'is about' some 'vehicle'.

In my opinion, possibility 2 is the most accurate. The main question here is if that level of detail is necessary/wanted or if a simpler solution like possibilities 1 or 3 is preferred.

Definitions depend on the choice above, but are probably variations of this: A modal split (share) is a fraction value/data item that describes the share of a transport modality compared to all considered transport modalities. A modal split is a data item that represents the usage of transport modalities.

Workflow checklist

• [x] I discussed the issue with someone else than me before working on a solution
• [x] I already read the latest version of the workflow for this repository
• [x] The goal of this ontology is clear to me

I am aware that

• [x] every entry in the ontology should have a definition
• [x] classes should arise from concepts rather than from words

[l-emele]

To me, one mode of transportation (e.g. bicycles) have a modal share and the combination of all modal shares is the modal split. We can see a modal share also as an attribute of some transport process. So what about about:

• A modal share is a fraction value/process attribute that describes the share of a transport mode.
• A modal split is a data item that contains modal shares.

General remark: We should discuss the definition first, the axiom should be derived after from the definition.

[lumi321]

Sounds good. I would prefer fraction value for modal share though. Of course, a single transport process contributes with the used modality to the modal share, but the modal share itself does not existentially depend on a single process. The way I interpret the definition of process attribute that is a requirement though.

[l-emele]

Okay, I can agree to this thought.

[lumi321]

Summarisation: New classes: modal split: A modal split is a data item that contains modal shares. modal share: A modal share is a fraction value that describes the share of a transport mode. New axioms: 'modal split' 'has part' some 'modal share' 'modal share' 'is about' some 'vehicle' 'modal share' 'has unit' some 'percent'

Do we also agree on the bottom two axioms?

[l-emele]

I am unsure about the axiom 'modal share' 'is about' some 'vehicle'. Following the definition, we need here more something like 'modal split' 'is about' some 'transport mode'. If have no immediate idea how to define a transport mode. But it has subclasses like walking, public transport, cycling or driving a car. So it is a split of processes (in which vehicle can be involved, but don't necessarily need to as in the case of walking).

[lumi321]

As far my research tells me, the subclasses of transport mode can be very different depending on the subject of interest. There is a section on the german wikipedia page about modal split that shows what I mean. So, defining such subclasses could be complex. For now, I don't think that is necessary.

• Picking up your thought from earlier to add a process attribute, the transport mode could be one. At least, if we argue that every transport process has its own transport mode.
• Looking at the other classes from the BFO, it cannot be a specifically dependent continuant. In that case, transport mode can only reasonably be connected to vehicle ('vehicle' 'has quality' some 'transport mode'), but that would exclude walking again.
• I believe it is also fair to say that transport mode is not an independent continuant.
• This leaves the generically dependent continuant or more precisely the information content entity, which then would be about some transport process. (Which may or may not include a vehicle.)
• That leads my thoughts towards another, more condensed possibility: 'modal share' 'is about' some 'transport' (process), for which we would need to change the definition of modal share to ... describes share of a transport ~~mode~~ process.

I can see pros and cons for all options, so I don't have a preference here.

[lumi321]

If there is no preference, I opt for the last option, changing the definition and leaving transport mode out. From my view this adapted definition is not wrong, but limited in its expressiveness compared to a solution with transport mode. Since this expressivness may be desired in the future, I would add an editor note saying: The definition may be altered to "... transport mode" instead of "... transport process" once a definition for transport mode has been agreed on.

[lumi321]

I have one more suggestion for transport mode: A transport mode is a process attribute that describes a transport process. It is used to distinguish between transport processes by looking at certain characteristics such as propulsion type, environment, purpose, ownership, etc. Axiom: 'process attribute of' some transport

If that one doesn't suffice, I would continue with the temporary solution from my last comment.

[lumi321]

@OpenEnergyPlatform/oeo-domain-expert-energy-modelling any thoughts on the definition of transport mode?

[stap-m]

If have no immediate idea how to define a transport mode. But it has subclasses like walking, public transport, cycling or driving a car.

If these :arrow_up: are examples for transport mode, it should be classified as process. Otherwise, if classified as process attribute, what would examples of transport mode look like @lumi321 ?

If there is no preference, I opt for the last option, changing the definition and leaving transport mode out.

transport mode is rather central for the current definition of transport split. Thus, if the latter stays as is, I'd recommend to define transport mode as well.

[lumi321]

I wouldn't define transport mode itself as a transport process. At least to me, a definition like "A transport mode is a transport process that ..." doesn't make a lot of sense. However, the examples walking, cycling, driving are processes indeed. So, if all transport modes are included as transport processes, the modes would become unnecessary. Then we could take one of my previous suggestions: "A modal share is a fraction value that describes the share of a transport ~mode~ process."

If transport mode is classified as process attribute, examples would be by foot, by bicycle, by car, public, private. I have to say though that I am not convinced of this anymore.

---

Perhaps it's a good idea to discuss what transport mode actually should capture. My motivation was to find a way to represent distinctions or categories in the transport sector, aka transport mode/mode of transport. In german usually "Verkehrsträger" or "Verkehrsmittel". Examples of such categories are in the images below: [^1]

[^3]

[^2]

As can be seen, there are many different categories and some of them, like in the last picture MIV-Fahrer/private motorised transport driver and MIV-Mitfahrer/private motorised transport co-driver, are everything but handy. This one is also a good example, where I don't know how it could suitably be defined as a transport process. So, for me transport mode is a category of transport processes. Thinking about that, I wonder, if information content entity wouldn't be the better parent class, i.e. A transport mode is an information content entity that describes a category of transport processes.

[^1]:Image taken from: Energiewirtschaftliches Institut an der Universität zu Köln (EWI) (2021). dena-Leitstudie Aufbruch Klimaneutralität. Klimaneutralität 2045 - Transformation der Verbrauchssektoren und des Energiesystems. Herausgegeben von der Deutschen Energie - Agentur GmbH (dena). [^2]:Image taken from: infas, DLR, IVT und infas 360 (2018): Mobilität in Deutschland (im Auftrag des BMWI) [^3]:Image taken from: Prognos, Öko-Institut, Wuppertal-Institut (2021): Klimaneutrales Deutschland 2045. Wie Deutschland seine Klima-ziele schon vor 2050 erreichen kann. Langfassung im Auftrag von Stiftung Klimaneutralität, Agora Energiewende und Agora Verkehrswende

[l-emele]

Maybe we should try to find a definition for transport mode without a classification into an parent class first, so something: A transport mode is an X that ...

When we've settled on a definition, we probably find the classification. So let's start with the last proposal: A transport mode is a X that describes a category of a transport process.

What exactly does category mean here? Something like a type? And how does this category distinct from a simple subclass like public transport?

[lumi321]

Well, I would say a category here means a subset, which is the very definition of a subclass. As I said earlier, I wouldn't mind if we do it that way. The only "problem" I see with defining subclasses of transport is that some subclasses would be tricky to define, e.g. micromobility or the distinction driver/co-driver in private motorised transport like in the example above.

[lumi321]

I have compiled a list with terms that provide a good coverage of the transport modes used in modeling. I would like to have them included either as subclasses of transport mode itself or as subclasses of transport. The wording of the terms may be changed for better distinction.

The list is based on common distinctions of transport modes: passenger or freight public or private road, rail, air, or water national or international small, medium, or big/heavy (truck only) short, medium or long distance Not all combinations are used, though, and there are some additions like micromobility with walking and cycling, distinction between driver, co-driver, and car/ride sharing, and pipeline transport. EDIT: Added local public transport to the list because a simple conjunction of bus and rail modes may not suffice to represent the local public transport.

• micromobility
  • walking
  • cycling
• passenger
  • private
    • driver
    • co-driver
    • car/ride sharing
  • public
    • local public transport
    • road
      • city bus
      • regional bus
      • coach/long distance bus
    • rail
      • underground/subway
      • regional train
      • long distance train
    • air/avation
      • national
      • international
    • water/ship
• freight
  • road
    • small truck
    • intermediate truck
    • big/heavy truck
  • rail
  • air/aviation
    • national
    • international
  • water/ship
    • national
    • international
  • pipeline

Regarding the definition of transport mode: The function of a transport mode is to describe a type of transport, and it is used to distinguish between different types of transport. That is also what a subclass of transport does/is used for. So, from that I would say that A transport mode is a ??? that describes categories/types/subclasses of transport. Or maybe even shorter: A transport mode is a ??? that describes transport.

[lumi321]

I will add this issue to the list for the next dev meeting.

[l-emele]

From OEO dev meeting 48:

• What is a transport mode?
  • No clear definitions in literature
  • Modes used in modeling are almost unique for every model i.e. everyone defines modes depending on their own needs
    • A list of somewhat common/recurring modes is in the issue
  • Used in modeling to distinguish different types of transport. Common attributes for distinction:
    • transported "object": passenger or freight
    • organisation: public or private
    • transport medium: road, rail, air, or water
    • national or international
    • vehicle type: small, medium, or big/heavy vehicle (especially for trucks)
    • short, medium or long distance
• Is there a difference between transport modes and subclasses of transport?
  • Both characterize transport further
  • freight transport has a subclass fuel transport. Is that a transport mode as well?
    • Isn't that a special kind of freight transport? - Yes, it is.
• Analogy to sectors?
• Can we import stuff from trasport ontologies?
  • LMs search wasn't succesful for OEO purposes
• last status: propose definitions in issue and check if this is viable during dev process

[carstenhoyerklick]

As far as I know there is no such transport ontologies. I could ask some of our transport colleague to maybe come to one of the next OEO-DEV Meetings...

[lumi321]

Below are my suggestions for the definitions. I omitted driver/co-driver because they are more roles than modes. As far as I remember, we agreed on making the transport modes subclasses of transport. However, I don't recall we made a decision on what to do with transport mode itself. Perhaps it is not even necessary to include it explicitly. Instead, we could add a note to transport with something like Subclasses of transport are also referred to as 'transport modes'.

---

• micromobility: Micromobility is transport on short distances.

  • walking: Walking is micromobility without any vehicle.
  • cycling: Cycling is micromobility with a bicycle.

• passenger transport: already in the OEO

  • private transport: already in the OEO
    • car sharing: Car sharing is the private transport where people share a car.
  • public transport: already in the OEO
    • local public transport: Local public transport is public transport where the used transport networks cover a certain local area.
    • public road transport: Public road transport is public transport that takes place on roads.
      • city bus transport: City bus transport is public road transport for short distances.
      • regional bus transport: Regional bus transport is public road transport for medium distances.
      • long distance bus transport: Long distance bus transport is public road transport for long distances.
    • public rail transport: Public rail transport is public transport that takes place on rails.
      • city train transport: City train transport is public rail transport for short distances.
      • regional train transport: Regional train transport is public rail transport for medium distances.
      • long distance train transport: Long distance train transport is public rail transport for long distances.
    • public air transport: Public air transport is public transport that primarily takes place in the air.
      • national public air transport: National public air transport is public air transport that does not cross country borders.
      • international public air transport: International public air transport is public air transport that crosses the borders of one or more countries.
    • public water transport: Public water transport is public transport that takes place on water.

• freight transport: already in the OEO

  • road freight transport: Road freight transport is freight transport that takes place on roads.
    • small truck transport: Small truck transport is the road freight transport with small trucks.
    • intermediate truck transport: Intermediate truck transport is the road freight transport with intermediate trucks.
    • heavy truck transport: Hevy truck transport is the road transport with heavy trucks.
  • rail freight transport: Rail freight transport is freight transport that takes place on rails.
  • air freight transport: Air freight transport is freight transport that primarily takes place in the air.
    • national air freight transport: National air freight transport is air freight transport that does not cross country borders.
    • international air freight transport: International air freight transport is air freight transport that crosses the borders of one or more countries.
  • water freight transport: Water freight transport is freight transport that takes place on water.
    • national water freight transport: National water freight transport is water freight transport that does not cross country borders.
    • international water freight transport: International water freight transport is water freight transport that crosses the borders of one or more countries.
  • pipeline transport: Pipeline transport is freight transport that uses pipelines.

[areleu]

micromobility: Micromobility is transport on short distances.

* `walking`: Walking is micromobility without any vehicle.

* `cycling`: Cycling is micromobility with a bicycle.

I think we should avoid for now assigning classes to quantified conditions since short-long, small-large are rather relative terms mostly defined by context. So, we either assign micromobility to some other differentiator or we avoid implementing it for now. Walking and cycling are still forms of transport so I would suggest adding them as subclass of transport.

walking: Walking is transport performed by a person|being | agent | ... by means of their own body capabilities.

cycling: Cycling is transport in which a bicycle with no good role is participant.

public transport: already in the OEO

* `local public transport`: Local public transport is public transport where the used transport networks cover a certain local area.

* `public road transport`: Public road transport is public transport that takes place on roads.
  
  * `city bus transport`: City bus transport is public road transport for short distances.
  * `regional bus transport`: Regional bus transport is public road transport for medium distances.
  * `long distance bus transport`: Long distance bus transport is public road transport for long distances.

* `public rail transport`: Public rail transport is public transport that takes place on rails.
  
  * `city train transport`: City train transport is public rail transport for short distances.
  * `regional train transport`: Regional train transport is public rail transport for medium distances.
  * `long distance train transport`: Long distance train transport is public rail transport for long distances.

* `public air transport`: Public air transport is public transport that primarily takes place  in the air.
  
  * `national public air transport`: National public air transport is public air transport that does not cross country borders.
  * `international public air transport`: International public air transport is public air transport that crosses the borders of one or more countries.

* `public water transport`: Public water transport is public transport that takes place on water.

I would make the subclasses of public transport parallel to public transport instead. Unfortunately because of the mono-hierarchy we can't make composite classes but I think is safer to be able to say for example:

`transport x` a `public transport`
`transport x` a `bus transport`

Because bus transport can be private as well (companies moving employees for example).

Without the mono-hierarchy restriction we would be able to say that the previous transport x is a public bus transport. But this probably can be addressed with our composition solution.

freight transport: already in the OEO

* `road freight transport`: Road freight transport is freight transport that takes place on roads.
  
  * `small truck transport`: Small truck transport is the road freight transport with small trucks.
  * `intermediate truck transport`: Intermediate truck transport is the road freight transport with intermediate trucks.
  * `heavy truck transport`: Hevy truck transport is the road transport with heavy trucks.

Again, I would avoid size based differentiations.

I would add air transport, water transport etc and let the instances be the bearers of composition (individuals having multiple classes do not break the mono-hierarchy)

[areleu]

Just a quick thought about water transport:

• water transport: Water transport is transport that takes place on water.
  • sea transport: Sea transport is water transport that takes place on the sea.
  • river transport: River transport is water transport that takes place on a river.
    • upstream transport: Upstream transport is river transport that goes against the direction of the river flow.
    • downstream transport: Downstream transport is river transport that goes on the same direction of the river flow.

[areleu]

To keep track of the distance related information I would suggest adding a quantity value to the transport process: travel distance which represents the length of the path the transport process takes place on.

We could also add a path participant that bears this travel distance value to the transport process which would be a fiat boundary? this can be useful to annotate GIS datasets representing vehicle paths. But I would leave this to other discussion.

[areleu]

walking: Walking is transport performed by a person|being | agent | ... by means of their own body capabilities.

This one is tricky because energy service demand for pkm is realized by a passenger transport we would either have to make walking a passenger transport or we would have to create a personal transport as a parent class of passenger transport and walking and would be the process in which energy service demand for pkm is realized.

[l-emele]

This is beyond the scope of the OEO and more for a planned transport ontology.