Driving change in Manchester - is better public transport enough?

For many people, owning a car isn’t just about getting from point A to B. It represents freedom, convenience, and sometimes even a status symbol. In many places, cars remain the go-to option because public transport systems are unreliable, slow, or simply don’t reach where people need to go. With car ownership on the rise globally—and its environmental and societal consequences becoming increasingly severe—understanding the potential of public transport as a solution has never been more important. Rail-based systems are often touted as effective tools for curbing car use. However, research remains inconclusive on whether they lead to a long-term reduction in car ownership, especially in the UK context.

To investigate this, I conducted a study as part of my master’s dissertation and dived deep into Manchester’s Metrolink system as it represents one of the UK’s most prominent light rail networks outside of London, offering a unique opportunity to isolate and evaluate the effects of a rail based public transport intervention on car ownership.

The Metrolink has expanded in phases since it first launched in 1992. The goal was to offer a reliable alternative to driving, reduce congestion, and improve air quality. But has it actually led to fewer people owning cars? To find out, I studied census data from 2001, 2011, and 2021, looking at how car ownership levels (car per household) changed in areas (LSOA level) where the Metrolink was introduced versus areas where it wasn’t.

How was the study conducted?

To analyse the Metrolink’s impact on car ownership, I used the Difference-in-Difference (DiD) method to compare changes in car ownership in areas affected by the Metrolink (treatment group) with areas that remained untouched by the tram expansion (control group).

The study also accounted for several confounding variables that could be impacted by the Metrolink and consequently impact car ownership rates. These included:

• Population density – More densely populated areas tend to have lower car ownership rates.
• Household size – Larger households are more likely to own multiple cars.
• Social grade – Higher-income households often have higher car ownership.
• Accommodation type – People living in apartments or rented accommodation are generally less likely to own a car.

By incorporating these variables into a linear regression model, I was able to better isolate the impact of the Metrolink itself, rather than just changes due to broader demographic trends.

What do the numbers say?

The initial analysis, which didn’t account for other variables, showed no statistically significant impact of the Metrolink on car ownership. However, when adjusting for confounding factors through the linear regression model, a different picture emerged.

After accounting for population density, household size, social grade, and accommodation type, it became clear that the Metrolink did reduce car ownership, though the effect varied across different phases:

• Phase 1: Car ownership dropped by 6% in affected areas.
• Phase 2: Car ownership dropped by 10.9% in affected areas.
• Phase 3A: Car ownership dropped by 3.8% in affected areas.

These findings indicate that while the Metrolink did help lower car ownership, the impact was not uniform across different expansion phases. The second phase, which included more densely populated areas, had the most significant reduction in car ownership. In the case of Phase 3A, its relatively recent launch could be attributed to the smaller impact it had on car ownership.

Ultimately, while better public transport is a step in the right direction, it’s not the silver bullet. However, if combined with the right policies, cities can encourage more people to leave their cars behind and embrace more sustainable travel options. If we want to create sustainable, less congested cities, it’s not just about making public transport better. It’s about making them the best choice.

ITP brings extensive expertise in delivering public transport projects and provides strategic advice to both public and private sector clients across the UK and internationally. Our work focuses on improving public transport systems to better serve local travel needs.