Q&A with Paul Mackey on Street Redesign and Traffic Calming

Q. Explain the concept of road diets. How do road diets contribute to traffic calming and what types of streets are best suited for this intervention? 

A. A road diet is the process of taking a street with multiple vehicle lanes and right-sizing it so that space can be reallocated for other uses. The most common approach is to convert a four-lane street into three lanes, with one travel lane in each direction and a centre, two-way left turning lane. The extra space is then used for things such as bike lanes, wider sidewalks, landscaping with stormwater capture or on-street parking. This design is particularly effective in improving safety because the slowest drivers regulate the flow and discourage speeding while making traffic flow more predictable. Road diets are particularly effective on medium-volume arterial or collector streets that have many driveways. They not only reduce speeding but also create more space for people walking, cycling and enjoying the street environment. Often, it is possible to incorporate traffic islands in the centre lane to improve crossing opportunities for pedestrians.

Q. In your experience, what are the most common challenges when implementing traffic calming measures and how can communities overcome resistance? 

A. Traffic calming interventions often face challenges when first introduced. Residents and business owners may be concerned about congestion, slower emergency response times, the potential for cut-through traffic on side streets or the loss of parking. Overcoming this resistance requires early and meaningful engagement with communities. Sharing local before-and-after evidence showing fewer crashes and injuries can help address concerns. Piloting interventions with quick-build materials, such as paint or planters, allows people to experience the changes before they become permanent. It is also important to listen to residents, schools and businesses and adjust designs to reflect their input. Being transparent about the goals of traffic calming – preventing injuries and making streets safer for everyone – is essential to building support. It is also essential that municipal staff have a very good grasp of traffic calming techniques, advantages and disadvantages, and that all road users are taken into consideration.

Q. Can you speak to how street redesign can reduce vehicle speeds without relying on signage or enforcement alone? 

A. Street design can be a very powerful way to reduce vehicle speeds without relying on signage or enforcement alone. When streets are designed with narrower lanes, curb extensions, raised crosswalks, chicanes, protected bike lanes, roadside trees or landscaped medians, drivers are given clear visual and physical cues that encourage slower driving. These design changes reduce the wide-open feel that often leads to speeding and make the presence of pedestrians and cyclists more obvious. Unlike enforcement, which is intermittent, design is constant: it influences every driver, every time they use the street. By creating self-enforcing streets, municipalities can lower speeds and improve safety while also making roads more welcoming and accessible for all users.

Road diets and other traffic calming measures are about designing streets that guide safe behaviour by default. When paired with strong community engagement and transparency, these interventions not only lower speeds but also build trust and support, leading to safer and healthier communities.