Table 4 Comparison of safety effects of road infrastructure improvements observed in the current study with values coming from international expertise and previous local studies: examples for road section treatments

Upgrading a single-carriageway to a dual-carriageway road section

−32 % sig.

−31 % sig.

−40 % sig.

(1) −51 [−65; −33]

Building a median on a road section crossing an urban area

No change

−53 % sig.

n/a

(1) Geometric realignment of urban road: −7 [−12; −1] (3) Building a median on urban road: −45 (medium)

Barrier installation - building a rigid median, on a single-carriageway road

−50 % sig.

−23 % sig.

−29 % ns

Median barrier installation: (1) −15 [−27; −1] (2) 0.61 (0.1) (3) −40 (high)

A combined treatment: barriers, road marking/signing, on a single-carriageway road

Increasing trend, ns

−13 % near sig.

−14 % sig.

(1) Change of barrier to a softer type: −32 [−42; −20]; Center-line marking: −1 [−8; +6]; Shoulder-line marking: −3 [−7;+1]; Signing: −15 [−25; −3] (2) Change of barrier to a softer type: 0.68 (0.1); Center-line marking: 0.99 (0.06); Shoulder-line marking: 0.97 (0.04); Center- and shoulder-lines' marking: 0.76 (0.1) (3) Center-line marking: −30 (low); Shoulder-line marking: −20 (low)

A combined treatment: barriers, road marking/signing, on a dual-carriageway road

No change

−14 % sig.

+24 % sig.

(1) Change of barrier to a softer type: −32 [−42; −20]; Lane marking: −18 [−51; +36]; Shoulder-line marking: −3 [−7;+1]; Signing: −15 [−25; −3] (2) Change of barrier to a softer type: 0.68 (0.1); Shoulder-line marking: 0.97 (0.04) (3) Shoulder-line marking: −20 (low)