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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

From: The evaluation of safety efficiency of non-urban infrastructure improvements; a case-study

Type of infrastructure improvement In current study: change in injury accidents In current study: change in total accidents Results of previous local studies * Results from international experience **
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)
  1. Notes to Table 4: sig. - significant at 0.05 confidence level; near sig. - significant at 0.1 level; ns - not significant; n/a - not available
  2. * From Gitelman et al. [10, 12]
  3. ** Sources of international expertise
  4. (1) Elvik et al. [9] - percent of accident reduction with a 95 % confidence interval are presented
  5. (2) HSM [18] - mean estimate and standard error of accident modification factor are presented
  6. (3) Austroads [1, 2] - percent of accident reduction with a level of confidence (high, medium, low) are given
  7. From the international and previous local studies changes in injury accidents are presented