Table 2. Road and network characteristics for a regular square grid with a length of L kilometres and different levels of traffic calming.

Variable Original network
(Fig. 1)
Level 1
(Fig. 2a)
Level 2
(Fig. 2b)
Level 3
(Fig. 2c)
Level n
Scale factor S 1 2 3 4 n
Length of roads with flow function surrounding traffic-calmed area L 2L 3L 4L nL
Number of grid cells in traffic-calmed area 4 9 16 n²
Length of roads with flow function† 2L 4L 6L 8L 4nL/2 = 2nL
Length of roads with access function 0 4L 12L 24L 2n(n − 1)L
Ratio of access roads to flow roads R 0 1 2 3 n − 1
Volume on access roads λa λ§ 0.1λ 0.1λ 0.1λ γλ
Volume on flow roads λf ¦ λ 1.9λ 2.8λ 3.7λ [1 + (1 − γ)R]λ

†The actual number is divided by two because all roads surrounding the grid cell also serve its adjacent grid cells.
‡Calculated with a value of γ = 0.1.
§In the original situation, all roads have both a flow and access function.
¦Roads with a flow function also serve the local access of adjacent grid cells.