## 2 Methodology and Case Study  
### Site Description  
Field measures were conducted to show the effectiveness of various traffic calming measures placed in a sequence for determining the ideal spacing with regard to the established maximum speed. Speeds were measured in the city of Bialystok in Poland, with a population around 292,000 inhabitants, and in the city of Basauri, (40,000 inhabitants), in Spain, which is included in the metropolitan area of Bilbao, with a total population of one million people. Selected stretches are located in urban areas and have a succession of different vertical traffic calming measures. Middle points (MP) were selected as control section because it is assumed that the maximum speed between calming measures is achieved in the middle point [29]. After passing a TCM, drivers accelerate, but if another TCM is near, they may start decelerating to accommodate their speed to the new obstacle. Analyzed vertical TCMs included raised intersections (RI), raised crosswalks (RCW), speed humps (SH) and speed cushions (SC). The width of all the streets is 3.50 m for all the lanes and the speed limit is 50 km/h in all the cases. Measured stretches in Bialystok were the following:  
* Zachodnia Street. This street is the main street serving the housing estate with kindergartens and shops along it. The sequence of the controlled stretch has these traffic calming measures: raised intersection, raised intersection, speed cushion, raised crosswalk and raised intersections and the distances between the central point of the TCMs are 130 m, 127 m, 120 m and 190 m, respectively. Speed was measured in all the vertical TCMs (RI 1, RI 2, SC 3, RCW 4 and RI 5) and in the middle points (MP) between them (from MP 1-2 to MP 4-5) (Figure 2a). * Wschodnia Street. This street is the main street in the single-family housing estate. The controlled stretch is composed of three successive speed humps, with long distance between them, 187 m and 293 m. The speeds were measured in the central speed hump (SH 2), in the intermediate points between speed humps (MP 1-2 and MP 2-3) and before SH 1, outside the calmed area (Outside), as a control point, more than 100 m away from the first speed cushion in order to see how drivers operate in non-calmed areas (Figure 2b). * Pulaskiego Street. This street runs through the housing estate and has a collective function for nearby residents. The selected stretch is composed of three consecutive raised crosswalks, with short spaces between them of 114 m and 63 m. Speed measures were collected in the central raised crosswalk (RCW 2) and in the middle points between them (MP 1-2 and MP 2-3) (Figure 2c). * Transportowa Street. This street runs on the outskirts of a housing estate and is an access road to the city's bypass. In a part of this street there are three speed cushions in a sequence, with 150 m and 110 m between them. Measures were taken in the second and third speed cushions (SC 2 and SC 3), in the intermediate points (MP 1-2 and MP 2-3) and a point outside the calmed area (Outside) (Figure 2d). Figure 2: Schemes of traffic calming measures and measuring point in selected streets in Bialystok (Poland): (**a**) Zachodnia Street; (**b**) Wschodnia Street; (**c**) Pulaskiego Street; (**d**) Transportowa Street. Measured stretches in Basauri were the following:  
* Eluterio Villaverde Street. This street makes a bypass of the neighborhood of San Miguel to avoid crossing the center of it, where various traffic lights are placed. In order to calm the traffic in this area, four raised crosswalks were displayed, with varying spacing between them: 165 m, 126 m and 150 m between the axes of the crosswalks. Speed data were collected in the four TCMs (from RCW 1 to RCW 4), in the intermediate points (MP 1-2, MP 2-3 and MP 3-4) and before the sequence (Outside) (Figure 3a). * Gernika Street. This street is the main road of the neighborhood of San Miguel and in one extreme has two raised crosswalks.