Changing the wording of Community Speed Watch (CSW) letters does not reliably reduce speeding, according to new research funded by The Road Safety Trust.
When CSW volunteers record a speeding vehicle, the driver is often sent an outcome letter. The study shows these letters shape drivers’ intentions and perceptions of the scheme, but altering their wording alone does not consistently lower vehicle speeds.
How the letters affect driver behaviour
The study, conducted by Dr Leanne Savigar-Shaw at Staffordshire University, surveyed 785 drivers and analysed CSW speed data alongside academic research. It found that 80% of drivers intending to reduce their speed said their experience of CSW influenced this, and nearly 25% cited it as the only reason.
Drivers reported significantly lower intentions to speed in the six months after receiving a letter compared to before. Factual content in the letters—such as statistics on people killed or seriously injured (KSI) in road collisions—and warnings of possible future enforcement were the most convincing elements.
Speed data offers a mixed picture
Actual measures of vehicle speeds after letter changes varied. Some police force areas recorded decreases in speeding vehicles, while others saw little change or even rises. The research found no consistent evidence that revising letter wording alone lowers speeds.
One positive finding was that repeat offenders tended to be recorded at lower speeds on their second offence, regardless of which version of the letter they received.
Inconsistency across police force areas
The study highlights variation in how CSW schemes operate across forces. For example, whether the letter included the driver’s recorded speed affected perceptions of legitimacy and made it easier for drivers to challenge the data.
Many drivers showed limited understanding of who carries out CSW, how it works with police forces, and volunteer training. The report suggests letters represent an opportunity to improve this awareness.
Recommendations for standardisation and content
The report concludes that CSW letters should be treated as behavioural interventions, not mere administrative notices. It recommends including police branding, the recorded speed and offence details, explanations of the scheme’s partnership with police and volunteers, and ways for recipients to respond.
It also advises highlighting risks associated with both illegal and inappropriate speeds, emphasising the benefits of safe driving, and standardising data collection including traffic volumes, repeat offending, and letter numbers.
Dr Savigar-Shaw commented, "CSW letters are experienced as a point of interaction between police forces and drivers, with the potential to impact drivers’ perceptions of the police and relationships with the law." Ruth Purdie OBE, chief executive of The Road Safety Trust, urged police forces to consider updating their letters to reduce road risk.
The research does not name the police forces involved. Separate data shows speeding fines across the UK reached a four-year high in April 2026.
