Traffic calming measures (TCM) are placed in urban areas to improve road safety, and
among them, vertical TCMs are widely employed. Many researches are focused on the influence
of the geometry of each measure on speed reduction, but it is demonstrated that drivers forget its
effect and speed up after it. Therefore, placing consecutive TCMs can help to maintain a safe area.
However, scarce literature can be found about the adequate spacing between them. Hence, the aim of
this paper is to analyze the adequate distance between TCMs. Various streets with variable distances
and different vertical TCMs were evaluated in Poland and Spain, including raised crosswalks, raised
intersections, speed humps and speed cushions. The intermediate point between two TCMs was
selected as the place where the maximum speed is achieved. Results showed that there was a
good correlation between the speeds at intermediate points and the distance between TCMs, with a
determination coefficient around 0.80. For an 85th percentile of the speed under 50 km/h, a maximum
distance of 200 m between TCMs is recommended, and for a value of 40 km/h, 75 m.
