Greater Manchester Travel Diary Survey 2023 - district summaries

Each year, the Greater Manchester Travel Diary Survey (TRADS) collects detailed transport and travel information from every member (aged five or older) of 2,000 Greater Manchester households. Respondents provide details about all the trips they make in a 24-hour period. TRADS focuses on the specifics of the trips and the characteristics of the people making them, rather than attitudes to, and satisfaction with, travel.

The survey sample is designed to be representative of each Greater Manchester (GM) district based on resident demographics. The survey runs throughout the year, from the beginning of February to the end of the following January. The only days surveys aren’t conducted are Christmas Day and any days following a bank holiday.

The data collected from 2,000 GM households, equates to about 4,500 residents and between 7,000 and 10,000 trips. The key information captured by the survey includes trip origins and destinations, travel times, travel methods, and journey purposes.

Surveying is carried out face-to-face by experienced interviewers. The response rate was 58% for both 2017-19 and 2023.

The survey’s annual sample - a random probability sample stratified by district - provides confidence intervals of +/- 1% to 2% at the GM household level, and +/- 7% to 8% at the district household level.

Before the pandemic, trip estimates were based on data collected over three years, providing confidence intervals of +/- 1% at the GM household level, and +/- 3% to 4% at the district household level. However, since 2020, travel habits have been too unstable for this approach, so estimates from 2021 onwards are based on single-year data.

The survey data is weighted/expanded to the GM population based on each district’s population by age, gender, and Acorn Category. The weights are small, with high weighting efficiency. Between 2019 and 2022, the weighting methodology was updated to better account for population growth. In 2019, data was expanded to the Census 2011 population levels, while 2023 data is expanded to the 2022 mid-year population estimates. This change has most notably impacted districts with significant population growth, such as Manchester and Salford, where the estimated number of trips has increased despite a decrease in the average trip rate per person.

For the 2023 survey, several changes were made to the questionnaire, including the introduction of new travel modes (eg distinguishing between electric and combustion engine car drivers), and new demographic questions (eg sexual orientation, gender identity). Changes were also made to better capture commute and business trips, reflecting the working habits of GM residents. This resulted in more commute trips and fewer business trips being recorded in 2023 compared to 2022.

The report includes data estimates for 2019 and 2023. While overall estimates at the district household level have confidence intervals of +/- 7% to 8%, caution is advised when interpreting sub-group estimates (eg commute trips, short trips, age, hour, and purpose) due to larger confidence intervals.

Before the pandemic, TRADS estimates closely aligned with key variables and other data sources (eg census data, ticket sales, Google Environment Insight Explorer). And generally, TRADS trip estimates show remarkable year-on-year stability, even for smaller modes and journey purposes. For example, the number of taxi trips has consistently been around 100,000 daily since 2017. 
However, 2023 bus trip estimates are lower than patronage data indicates they should be. This discrepancy could be due to data collection issues post-pandemic, or it could just be an extreme estimate that can occasionally occur in survey data. These figures are a reminder that while TRADS produces robust estimates, it is still subject to sampling error and confidence intervals.

At the GM level, the mode share for buses decreased from 6% in 2022 to 4% in 2023, which is within the sampling error of 2%. Thus, statistical tests find the change between the two years is not statistically significant. 

However, this change in mode share from 6% to 4%, when translated to bus trip estimates, translates to a 25% decline in bus trips, which contrasts with an 8% increase measured by the TfGM Continuous Passenger Survey (annual rolling patronage comparison Q3 2022 vs Q3 2023).

Therefore, it is better to focus on changes across multiple years rather than overinterpreting year-on-year variations.

Note: totals in tables may not sum precisely due to rounding to the nearest 1,000.

If you would like more details of the surveying methodology, our technical notes can be made available on request. For more information about TRADS or for further analysis, please contact insight@tfgm.com.


Organization: Transport for Greater Manchester