Demand Response Transport & GTFS Flex: Filling Crucial Gaps in the Mobility World

Weston Shippy

Weston Shippy

June 11, 2026

When it comes to software innovation for public transport, demand response has long taken a backseat. Here’s what Optibus is doing about it.

The first thing that comes to people’s minds when public transportation comes up in conversation is probably a bus. If we develop this picture further, that bus is likely pulling over at a fixed stop, at a fixed time, and according to a predetermined schedule. But we in the transit industry know this picture could look quite different depending on where you are. What about all the other modes of public transportation that operate outside such parameters? Services beyond the scheduled bus/rail service can go by many names and behave in myriad ways—demand service zones, paratransit, dial-a-ride, ride-hail, etc.—but all fall under one umbrella we call Demand Response Transport.

DRT

A transit agency may choose to offer demand response instead of a fixed route for several reasons, such as:

  • Better service for low-density/rural areas covering long distances, sometimes in many directions
  • Fulfillment of first/last mile gaps in urban areas
  • More accessible, hands-on service
  • Safer transport for vulnerable communities
  • Faster adaptability to current rider population needs
  • Greater flexibility in how service is designed and operated overall

Despite common perception, DRT makes up a significant piece of the public transportation landscape. In fact, there are more demand-responsive routes in the U.S. than there are fixed routes.

And yet, DRT in large part remains an afterthought, or worse, entirely ignored, in many transit technology solutions we find today.

Planners are missing out

Information about an agency’s demand response services is not easily maintained and often not stored in a structured, future-proofed way. Instead, transit professionals are managing demand response services with loosely defined parameters and contradictory sources of truth, all siloed from how they plan and conceptualize their fixed route system. DRT also poses unique planning challenges, including:

  • Balancing simplicity with operational reality when designing the service (e.g., should zones favor easily-communicated jurisdictional boundaries or lean toward a custom boundary based on fixed route operations?)
  • Ensuring there are connections to specific transit hubs and mapping them in a way that makes sense
  • Documenting which areas are not available for pickups or drop-offs
  • Juggling multiple rule sets that change based on the time of day or day of the week
  • Defining service based on rider eligibility groups

Tools to sufficiently organize demand response information coherently, especially ones that integrate with their wider fixed network, are few and far between. Agencies need modern tools to model all their services in concrete ways so they can plan, conceptualize, and gain insights into how it fits in with the rest of their network of transit service. Having these services modeled with digital tools also makes it easier to publish service information clearly and consistently—namely with GTFS-Flex—so that riders can actually discover them in trip planners.

 

DRT Planning with Optibus

DRT Planning with Optibus is our answer to these pain points. With this new offering, Optibus users can finally create and manage their DRT routes alongside fixed routes, empowering them to manage all services in one platform. DRT Planning offers users:

  • Flexible Route Management: Import, define, and manage service zones. Build flexible routes with intuitive rule definition. Configure booking rules (e.g., prior-notice requirements) and more.
  • Comprehensive Network View: See fixed and flexible routes together in a single map view.
  • Dynamic Service Visualization: Visualize DRT service behavior, including complex multi-zone networks.

But riders are also missing out

Despite the ubiquity of DRT mentioned earlier, these services often remain undiscoverable in major commercial trip planning apps. This can give riders the impression that the area they live in is a transportation desert, when in reality, there may be a program out there tailor-made to their mobility needs. Many of these services are also commonly intended for more mobility-dependent people who may have disabilities, who are seniors, or for rural communities that lack a robust fixed transit system. So when we talk about these services being missing from the map, these are the folks who are being left out of the equation.

GTFS-Flex

Thankfully, GTFS-Flex, an official extension of GTFS, was adopted to the standard just a couple of years ago. In the same way that the core GTFS standard enables riders to discover and journey plan using fixed transit, GTFS-Flex does the same for DRT. We’ve been excited to see regional hubs pop up both across the U.S. and in Europe, where DRT service discovery and multimodal trip planning come together in a unified experience for the rider. Through direct three-way partnerships between the agency, Flex producer, and Flex consumer, agencies are guaranteeing that their riders are actually seeing their DRT routes.

And the extra good news? Optibus now has native support for both import and export of GTFS-Flex data. Users can now include flexible routes alongside existing fixed routes in their GTFS, which can then be consumed by Flex-enabled trip planning apps, allowing DRT service discovery (Note: At this time, agencies still must work directly with a GTFS consumer for these services to appear in their app).

 

The journey continues…

These new features don’t solve every challenge listed in this blog, but they do mark the first major milestone in what we hope becomes a long journey to support more and more needs of a fundamental piece of the mobility technology puzzle. Stay tuned!

 

Further Reading:

Topics: Technology, Public Transportation, Demand response