demand responsive transport vehicle going up a hill

Mastering mobility: demand responsive transport

How can mobility providers avoid running empty or near-empty buses through rural areas but still provide public transport for the people who live or work there? And how can cities avoid private car usage during times where public transport availability is low?

Demand responsive transport, a relatively niche share of the mobility industry, could provide solutions to these common issues.

What is demand responsive transport?

Demand responsive transport (DRT) is a mode of transportation defined by its responsiveness to passenger demand. Or, to put it another way, DRT can be thought of as a mix between a bus and a taxi, in that it is characterised by flexible routing and scheduling that reacts dynamically to requests from passengers.

In practice, DRT is varied, leading it to be difficult to define. For example, Germany defines their digitally enabled DRT services as ‘on-demand ride pooling,’ while Portugal has gone deeper, explaining DRT as ‘public collective transport service with flexible features that is carried out, in part or in full, at the express request of the user and may include the use of information and communication technologies.’

Despite the difficulty in pinning down exactly what DRT is (and is not), the sector has been growing. EIT Urban Mobility’s October 2022 report Demand Responsive Transport: Recommendations for Successful Deployment notes that between 2019 and 2021 over 450 DRT projects were launched worldwide, predominantly in Europe, North America and Asia.

These 450+ DRT projects can largely fall within four different categories:

  • Hybrid: service similar to regular public transport, with a fixed schedule and stops, in which certain stops or off-peak hours operate solely on-demand
  • Semi-flexible: service that is adapted to demand, but the number of possible pick-up times and locations are limited by pre-determined design
  • Full-flexible: door-to-door, or point-to-point services, with open schedules and dynamic routing tailored to the demand
  • DRT with flexible layout and stops: the stops within this kind of service are fully adapted to the demand
Tradeoff between flexibility and demand aggregation (Source: nemi)

With numerous configurations on offer, DRT is a diverse sector that aims to tackle different challenges depending on the density or dispersion of the population it serves.

DRT in urban areas

Urban areas are typically places with high mobility demand, and therefore are already serviced by a more traditional public transport offering. However, in these areas, DRT can serve to replace private cars for less congestion and road traffic.

For example, in Helsinki, Finland; the Kutsuplus DRT service operated from 2012 to 2015 as an alternative to private car use. The city already had high adoption of public transport (with 34% of the polled population preferring the option) but 30% also preferred transport by public vehicle. Therefore, the Kutsuplus service was deployed as a stop-to-stop DRT service with ten buses operating from 9:00-17:00, with an additional five microbuses later added to the fleet and operational hours extended to 6:00-24:00.

Though the service offered end-users lower costs than a taxi, and quicker travel than traditional public transport, it was suspended in 2015. The key reasons for discontinuing the service included the high rate of use for existing public transport alternatives, the difficulty to book trips (as this was prior to the ubiquity of app-based services and the booking had to take place on a desktop), and the cost of the service for both end-users and public authorities, through subsidies.

Upon reflection, the Kutsuplus case offers numerous opportunities for improvement; especially in the realms of marketing, communication and user experience. Improvements and advancements in technology aside, Kutsuplus exemplifies the difficulties that DRT solutions face when trying to compete with private cars in dense urban areas where traditional public transport options are already available.

DRT for first and last mile in urban areas

Other DRT offerings in urban areas have taken a different approach, to serve as a connector for first- and last-mile services to link to public transport. For example, the DART GoLink in Dallas, Texas is a service targeted at high-demand areas to bridge specific zones across the city. The Dallas Public Transport Operator has worked with ride hailing and taxi companies to increase the system’s flexibility, in turn, maximising uptake.

DRT in rural areas

In rural areas, where there are typically significant geographic or temporal gaps in traditional public transport service, demand responsive transport can be a solution.

In the municipality of Sardoal, in the Médio Tejo region of Portugal, bus service frequency varies widely during the summer, Christmas and Easter holiday periods. Additionally, certain bus lines are not available at all during weekends. As a region with such variant public transport availability and demand, Médio Tejo has been a perfect case for DRT service. Pre-COVID-19 data shows that DRT has been growing in the region, jumping from 60 riders per month in October 2017 to 150 passengers per month in July 2019. Additionally, peak usage can be seen in summer months when traditional public transport service is lacking.

Age of users for Médio Tejo’s DRT service, SIT FLEXI (Source: IMT)

By replacing private cars with DRT, riders are able to bridge this distance in a more sustainable way, particularly benefiting those who may be unable to operate a private vehicle. In the case of Médio Tejo, 91% of the users in the area are 51 years or older and 50% utilised the service for healthcare reasons. Additionally, the average age of users for DRT service in Portugal’s Coimbra region was 69,6 years old, with 69% travelling for healthcare.

Thus, DRT is a valuable resource for aging populations in rural areas; offering an alternative to private car ownership which may be costly or impossible for people with specific healthcare needs. By serving ageing populations, DRT can offer mobility solutions to those who might be otherwise isolated.

DRT for first and last mile(s) in rural areas

By the very nature of rural living, residents often have to travel further in order to take part in traditional public transport mobility. In 2021, the transport on demand system Clic.cat was put into operation in Vall d’en Bas in the La Garrotxa region of northeastern Spain for this very reason, to provide first and last mile connections to main transport lines. Vall d’en Bas is a sparsely populated municipality with an average density of just 33 inhabitants per square kilometer, and previously had no bus service connecting villages in the area to the region’s urban core of Olot.

With deployment in the low-demand rural area, Clic.cat established routes and timetables that would be operable solely on request. Throughout the first nine months of service, 3628 passengers used the DRT system, connecting the rural area to the urban core of Olot; and thus, its public transport system, goods and services. The DRT system serves 30 different stops on a 45km route in the region, but only operates when at least one reservation is booked; meaning that only 80% of trips are actually undertaken. This reduced service translated to a 68% savings on emissions and fuel, while still serving the needs and demands of its ridership.

The future of DRT

The first pilots of demand responsive transport were launched in the 1970s, but the sector has heavily benefited from the development of connected, app-based technology. Such technology allows users to ‘demand’ the transport in a more seamless manner, and transport operators have benefited from partnerships with technology providers to offer more user-centric solutions to their riders.

While DRT solutions have seen mixed success historically, they are increasingly becoming more mainstream as technological uptake advances and DRT services are integrated into wider mobility systems. As one of the experts that took part in EIT Urban Mobility’s custom mobility workshop explained, “Before, DRT was a ‘nice to have,’ now it is a ‘must have’.”

In urban, or denser peri-urban areas, DRT has the capacity to extend the existing networks of public transport to provide first- and last-mile options in areas or times that are otherwise underserved. Demand responsive transport can also act as an alternative to private car usage in urban areas; reducing air and noise pollution, limiting traffic congestion and offering a more sustainable mode of transportation.

Research conducted by the International Transport Forum shows that DRT plays a role in accelerating the transition to sustainable mobility, specifically in rural and peri-urban areas. In rural areas in particular, demand responsive transport is often at the frontier of flexible shared mobility options; providing the sole alternative to car ownership for residents aiming to bridge longer distances. Additionally, the service offers valuable mobility for users who are unable to own or operate private vehicles.

To maximise the potential of future and existing DRT services, it is imperative to address the barriers that users experience when accessing the mobility system. From understanding user behaviour, to adjusting prices and availability; regions that are interested in improving uptake in their DRT services need to embrace a multifaceted approach that considers value beyond service costs and revenue.

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