The table below shows the results of a survey of the average number of cars travelling through three suburban roads during working hours in a 10 year pollution monitoring programme Traffic calming was introduced in Harper Lane at the beginning of 1999

The table demonstrates the mean result in one working hour of how many cars traveling through three suburban roads Harper Lane, Great York Way, Long Lan, using a 10-year pollution monitoring programme and how the traffic calming method affected those numbers after being introduced in Harper Lane in early 1999.
In short, while the number of cars per hour passing Great York Way and Long Lane had slightly fluctuated between 450 to 800, Harper Lane had witnessed a surge to nearly 12 times from 82 to 915 the period between 1993 and 1998.
In early 1999, after presenting Trafficalm, the result in Harper Lane dropped sharply to 204 then decrease softly to 173 before staying remains within the range 170 to 200 in the following years. Otherwise, Great York Way and Long Lance rose dramatically to 900 and 1000 respectively.
Though Great York Way then stabilized, Long Lane hit 1400 in 2001 before reaching a plateau.