Commingling: Making public transit truly demand-responsive

As demand-response transit (DRT) evolves, commingling has emerged as a powerful strategy to help transit agencies create more responsive, cost-effective, and rider-centered services. By allowing agencies to integrate trips from different transit programs into a single, shared operation, commingling optimizes fleet usage, lowers operational costs, and helps improve the rider experience. At its foundation, commingling is about making transit services truly adaptable—a core goal of demand-response systems.

However, the flexibility of commingling also comes with choices. What kind of commingling setup will bring the most value to your operations? And how can you tell if commingling is right for your service in the first place? 

To make things even more nuanced, not all commingling approaches are created equal. While many software providers claim they support commingling, the reality is far more layered. Commingling can be as simple or as sophisticated as your agency requires—because no two transit systems are alike. That’s why we use a sliding scale to make commingling less daunting, helping agencies understand the full spectrum of possibilities and tailor a solution that works for them.

This guide will break down the basics of commingling, present scenarios to help you envision its application, and outline common use cases to help you unlock the full potential of commingling for your operations.

What is commingling: a flexible, demand-responsive approach

Commingling scenario

Commingling integrates trips from various transit programs using a shared fleet and infrastructure, enabling agencies to pool resources and adapt to fluctuating demand more effectively. 

Imagine an agency that runs three transit programs: microtransit, ADA paratransit, and non-emergency medical transportation (NEMT). On a typical day, each program might receive 100 trip requests, and the agency has allocated five vehicles per program, making resources evenly distributed.

Scenario #1: An even distribution of supply vs. demand on a given day.

But on a different day, demand shifts: perhaps microtransit has only 50 trips, paratransit 100, and NEMT 150. Without commingling, each program must rely on its own limited fleet, leading to inefficiencies like underutilized vehicles in paratransit and potential delays in NEMT. 

Scenario #2: Demand shifts, leading to gaps in fleet productivity and delays.

With a commingling approach, however, the entire fleet can dynamically respond to real-time demand, using resources where they’re needed most and ensuring efficient use of the agency’s dedicated fleets across its programs.

Scenario #3: Commingling: a dynamic, real-time response approach to match the right supply to demand. 

This adaptability makes commingling an essential tool for transit agencies striving for truly demand-responsive service.

The benefits of Commingling: lower costs and better rider experiences

By integrating paratransit, microtransit, or any other type of demand response programs under a commingled model, agencies gain flexibility and efficiency while enhancing the overall rider experience. Here’s how commingling benefits both riders and agencies:

Enhanced service and rider experience

With a more flexible fleet, agencies can provide quicker pickups, fewer delays, and greater service coverage. Riders benefit from more responsive services, which is particularly valuable for time-sensitive trips, such as those for medical appointments.

• Greater booking flexibility: Riders benefit from more immediate and flexible booking options, such as same-day and on-demand trips through a unified, accessible microtransit platform.
• Unified service branding: Blending paratransit and microtransit services under one brand reduces the perception of separation, creating a more inclusive transit experience.
• More rides for everyone: A shared platform allows paratransit riders to adapt and take microtransit and app-based services when able to, building confidence in a low-pressure setting.

Lowering cost per trip

By sharing resources across services, agencies can reduce deadhead trips, lower fuel expenses, and minimize labor costs per trip. Fleet utilization increases through increased productivity, leading to better cost efficiency without compromising service quality.

• Maximized fleet utilization: Using a shared fleet for different programs helps agencies meet fluctuating demand across services, reducing the number of idle vehicles and improving resource efficiency.
• Reduced deadhead miles: By allowing drivers to serve multiple trip types in a single shift, commingling reduces non-revenue-generating miles, cutting fuel costs and increasing productive vehicle use.
• Optimized driver and vehicle resources: A commingled model enables transit agencies to deploy fewer resources to achieve the same or even improved service levels, lowering overall operational costs per trip.

Common use cases for Commingling

Transit agencies frequently choose to commingle services to improve operational efficiency, reduce costs, and enhance the rider experience. Here are key scenarios where commingling proves particularly valuable:

Maximizing fleet utilization

By combining trips from various transit programs—such as paratransit, microtransit, and NEMT—agencies can optimize fleet usage, reducing deadhead miles and making better use of each vehicle.

The Pinellas Suncoast Transit Authority (PSTA) has effectively integrated its ADA paratransit service with its Transportation Disadvantaged (TD) program through commingling, leveraging Spare's flexible platform to optimize fleet utilization. By configuring their services to allow TD riders to utilize available ambulatory seats, PSTA ensures that every seat in their vehicles is utilized to its maximum capacity. This strategic approach not only enhances service efficiency but also maximizes the value of each trip taken.

Addressing driver shortages

Commingling is a powerful tool for transit agencies facing driver shortages, enabling them to make the most of a limited driver pool without cutting back on service. By integrating paratransit and microtransit services under a commingled model, agencies can share drivers across programs, expanding coverage and maintaining service quality. 

Managing daily service peaks and valleys

Transit demand often fluctuates throughout the day, leading to high demand during peak hours and lulls in off-peak times. A commingled model allows transit agencies to distribute their resources more flexibly across these “peaks and valleys,” balancing demand and supply throughout the day. By sharing fleets across multiple services, agencies can ensure that both paratransit and microtransit riders experience reliable, timely service no matter the time of day, maximizing vehicle and driver productivity across all hours.

Maintaining compliance and expanding access

Commingling enables agencies to meet ADA requirements while offering paratransit riders enhanced service options. Traditionally, paratransit riders have relied on pre-scheduled trips booked at least 24 hours in advance, limiting their flexibility. By commingling ADA and non-ADA programs in a single platform—and extending these same capabilities to the rider app—agencies can now provide these riders with same-day, on-demand booking options. This shift allows paratransit users to access a new level of freedom and spontaneity, choosing microtransit trips when they are available to fulfill same-day needs as appropriate.‍

Citibus, in Lubbock, Texas, demonstrates an effective model for how to integrate paratransit with microtransit while maintaining compliance with ADA standards. The agency leverages Spare’s commingling platform to unite its ADA paratransit service, CitiAccess, with its non-ADA microtransit service, Citibus On-Demand, while maintaining full compliance with ADA standards. With Spare’s technology, Citibus configures its services to respect ADA requirements by ensuring that ADA riders always have priority for accessible vehicles and guaranteed trip availability, even when sharing resources with non-ADA services. By seamlessly combining these programs, Citibus achieves greater efficiency and coverage without compromising on service standards for ADA riders.

Ensuring WAV availability

Optimizing the availability of wheelchair-accessible vehicles (WAVs) is crucial for both paratransit and microtransit services to provide equitable and inclusive transportation. A commingled fleet with sufficient WAV capacity, complemented by multiple ambulatory seats, enables agencies to meet diverse rider needs effectively. Another advantage of this approach is cost efficiency: agencies can incorporate more affordable, non-accessible vehicles like minivans into their fleets while maximizing the utility of their more expensive WAVs. By commingling WAVs across multiple service types, agencies enhance wheelchair accessibility across their network, ensuring that these critical assets are used efficiently and effectively to serve all riders.

Reducing cost per trip

By commingling, agencies can reduce the cost per trip across transit programs by sharing resources and scaling fleet availability according to demand. This model also reduces the need for separate, program-specific vehicles, allowing agencies to meet high-demand periods across services without added fleet expenses.

StarTran, in collaboration with Spare, implemented a fully integrated commingling model that allows for the integration of different rider groups and the sharing of fleet vehicles across its services. By launching two distinct services–VANLNK and Handi-Van–in the same zone and utilizing the same drivers and vehicles for both, StarTran has been able to efficiently combine its demand responsive operations. Previously, Handi-Van, StarTran’s paratransit service, struggled to scale due to manual booking and scheduling processes while riders lacked real-time trip information. By reducing the need for three additional vehicles on the road, this approach using commingling improved overall cost savings by 35%. StarTran is witnessing other benefits beyond cost savings–the service has also improved the rider experience through access to real-time trip information and better on-time performance.

Commingling flexibility: a sliding scale

Commingling as a sliding scale: Tailoring integration to your operations

For transit agencies exploring how to integrate paratransit with microtransit, starting small with introductory commingling is a proven approach before working up to the full potential of commingling.

It’s important to know that it’s not an all-or-nothing approach.

Commingling can be gradually implemented in phases, allowing for incremental adjustments based on your agency’s unique needs, fleet, and operational goals. The sliding scale of commingling provides flexibility to start small—such as integrating services in a single zone or with just a few vehicles—and work up to a fully commingled operation that dynamically adjusts resources across all services.‍

How to integrate paratransit with microtransit: a phased approach:

1. Introductory Commingling – Start by sharing a few vehicles between services in limited zones or regions, allowing your team to test and observe benefits without altering the entire operation. For example, a small zone within a city might allow microtransit and paratransit services to share vehicles when extra capacity exists on either service, or to boost the availability of wheelchair accessible resources.

Commingling can be experimented in small doses or scaled-up, and implemented across any part of the operation. To start, an agency might want to phase into commingling. This approach is ideal for agencies who are running operations at a larger scale, are new to commingling and want to test the model at a smaller scale. This hybrid approach enables the benefits of commingling, such as high vehicle utilization, and is ideal for agency members that are not yet fully familiar with commingling. – Chad Ballentine – Microtransit and Paratransit Transportation Executive

2. Expanded Resource Sharing – As confidence grows, increase commingling by expanding shared resources to multiple zones or adding additional vehicles that operate across different programs. This phase allows agencies to manage daily fluctuations in demand with greater efficiency by strategically adjusting shared fleet resources.
3. Full Integration – At full commingling, shared dispatch enables transit agencies to assign vehicles dynamically across all programs using real-time routing software–operating as a unified resource pool. Advanced software like Spare’s routing and dispatch engine can then intelligently allocate vehicles across all transit programs in real-time, matching supply to demand at every hour of the day. This level of commingling maximizes fleet utilization, reduces operational costs, and provides riders with a seamless experience.

Key Considerations:

• Vehicles and associated vehicle types are optimized for both paratransit and microtransit, ensuring sufficient wheelchair capacity and multiple ambulatory seats to facilitate high utilization.
• Service branding is unified such that vehicles are easily identifiable to both paratransit and microtransit riders.
• Routing and dispatch software continuously analyzes pre-booked paratransit trips to optimize seat capacity for ADA-mandated trips alongside general microtransit trips on a daily basis. 
• Software can be configured to either assign drivers to a specific service or allow them to operate across commingled services, depending on their training. For commingled services, drivers are trained to handle a variety of trip types, such as stop-based, door-to-door, or hand-to-hand service. This ensures that only qualified drivers, equipped to meet the unique requirements of paratransit trips, are assigned to support those riders, maintaining both service quality and rider safety.
• Advanced tools for shared dispatch ensure the seamless management of trips across services, regardless of vehicle type or rider need.

By gradually advancing through these stages, agencies can build operational flexibility and rider satisfaction, working toward an adaptable, fully commingled fleet that meets the needs of all transit programs effectively.

The software of choice should not be the factor to creating operational constraints. True software flexibility enables commingling at any scale–whether it’s for agencies who are looking to dip their toes in commingling or to take it on fully. 

‍

Is commingling right for your agency?

When evaluating commingling, ask these key questions:

• What are my current fleet usage patterns and cost drivers? If your agency faces issues with underused vehicles or varying service demands, commingling could help optimize resources.
• How critical is rider experience and privacy for different programs? If privacy or service separation is essential for certain programs, a separate rider pool model may offer the right balance.
• Do I have the software to support commingling seamlessly? The right software should support flexibility, without imposing constraints on how you organize and manage commingling.

With these considerations in mind, commingling offers a strategic way to improve efficiency and service quality. The right approach will depend on your operational goals, rider needs, and technology capabilities—but commingling is designed to make transit services as responsive as possible, aligning with the fundamental principles of demand-responsive transit.

‍

Whether you're interested in exploring a commingled, shared-fleet approach to your transit programs or looking to integrate your ADA paratransit with your existing on-demand transit service, we can help guide you through the process. Reach out to the Spare team today to learn more!