Mobility-as-a-Service, or MaaS, brings public transport, on-demand services and micromobility into one digital platform. For passengers, this means they can plan, book and pay for multimodal journeys in one place, with clearer information on routes, transfers and fares.
While the user experience should feel simple, the system behind it is more complex. The key question is: how can Demand-Responsive Transport (DRT) be connected with existing public transport systems in a way that is efficient, scalable and reliable?
This is a topic of growing interest across the industry and in multiple countries. This has become clear through industry workshops and webinars. These included sessions organised by the Saarland Ministry for Environment, Climate, Mobility, Agriculture and Consumer Protection , by the Swedish Public Transport Association as well as a side event at the IT-TRANS industry fair., where we shared key insights.
Based on years of experience with DRT and MaaS integrations, this article brings together some of the key points to consider, from open data standards and standardised interfaces to operational logic.
Mobility-as-a-Service: One App, All Mobility Options
MaaS allows passengers to search, book and pay for multimodal journeys via a single app. When on-demand transport is included, it can help close first- and last-mile gaps and make public transport more accessible.
This can support more attractive public transport, shared rides, greater accessibility and reduced reliance on private cars.
However, these benefits depend on how well the different systems work together.
Integration Architecture: What Happens Behind the App
In a MaaS integration, the app is only the visible part of the system. Behind it, different systems need to communicate reliably.
The passenger-facing MaaS app manages functions such as journey search, booking, fares, payment, ride updates and cancellations. Simdle Mobility supports the operational side of the on-demand service. This includes service areas and stops, vehicles, driving personnel, scheduling, route optimisation and passenger bundling.
This setup allows the MaaS app to offer a simple travel experience, while Simdle manages the operational complexity behind each on-demand ride. This helps ensure that different systems can communicate reliably and that on-demand services can be integrated into public transport networks in practice.
How Does the Integration Work?
In theory, a MaaS platform could call every on-demand provider’s search API for every journey request. In practice, this creates significant overhead.
Mixed journeys are especially complex. These are trips where one part uses fixed-line public transport and another part uses on-demand mobility. Without a common technical foundation, calculating and confirming these trips would require many separate API calls.
This makes one-to-one integrations difficult to scale.
The Game-Changer: Open Data Standards
Open data standards such as GTFS make integration easier.
GTFS allows fixed-line and on-demand services to be described in a single, unified format. This means a MaaS platform can use the same data foundation to plan journeys that include buses, trains and on-demand rides. If a trip requires an on-demand segment, an additional API call can then be used to check availability and confirm the ride.
This reduces complexity and helps MaaS platforms integrate different services more efficiently.
Why Standardised APIs Still Matter
GTFS supports journey planning by making transport data available in a structured format. This helps MaaS platforms understand which fixed-line and on-demand services exist and how they can be combined in one journey.
However, planning data alone is not enough for on-demand transport. Passengers also need real-time actions such as searching for availability, booking a ride, receiving updates and cancelling a trip.
This is where standardised interfaces become important. Solutions such as TRIAS and HAFAS support the exchange of journey and booking information between MaaS platforms and transport systems. In combination with GTFS, they help create compatibility with local public transport environments and reduce the need for separate proprietary integrations.
Without these interfaces, every MaaS platform would need to connect to each provider individually, making integration more complex and harder to maintain.
Anti-Cannibalisation: Making On-Demand Complement Public Transport
Integration is also an operational question. DRT should complement public transport, not compete with it. Anti-cannibalisation logic helps ensure this.
The principle is simple: an on-demand service is only offered when no reasonable fixed-line option is available. What counts as “reasonable” can be defined by the transport authority or operator according to the needs of their passengers and service area. This may include factors such as waiting time, walking distance and transfers.
This helps avoid parallel trips and supports a more efficient use of on-demand vehicles.
Key Takeaways
The integration of on-demand mobility into public transport creates new opportunities for more efficient and sustainable mobility. Three key aspects stand out:
• MaaS implementation: Anti-cannibalisation, GTFS and standardised APIs create the technical foundation for scalable integration.
• Sustainability: Integrated on-demand transport can support more sustainable operations by consolidating trips, reducing empty runs, and avoiding parallel services. It also enables a shift from purely on-demand operations to semi-flexible bus lines — combining the flexibility of demand-responsive transport with the efficiency of fixed-line services.
• Passenger experience: Centralised information, app-based booking and real-time data make it easier for passengers to plan, book and manage their journeys while supporting the optimisation of public transport.
Conclusion
MaaS is often described as one app for all mobility options. But the real value of MaaS depends on what happens behind the app. Open data standards, standardised APIs and anti-cannibalisation logic help connect on-demand mobility with fixed-line public transport in a scalable way.
When integration works, DRT does not replace public transport. It strengthens it.
At Simdle Mobility, we support transport operators and cities in integrating flexible on-demand services into existing public transport systems.
Because better integration leads to better journeys, smarter operations and more efficient public transport.