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Table 3 Summary of evaluation results for treatments at junctions and interchanges: efficiency indices and their 95 % confidence intervals

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

Type of infrastructure improvement (#) Injury accidents Severe accidents Total accidents
At junctions
 Building a roundabout (9) −52 % [−71 %; −21 %] -- Reduction trend, ns
 Traffic lights' installation (14) −29 % [−49 %; −2 %] -- +46 % [+17 %; +81 %]
 Minor geometric realignment at a signalized junction (26) No change No change +13 % [+2 %; +25 %]
 Signing arrangement at junction (4) No change -- −36 % [−52 %; −16 %]
 Replacing lenses by LEDs, at a signalized junction (11) Reduction trend, ns -- Increasing trend, ns
 Resurfacing junction and replacing lenses by LEDs (3) Increasing trend, ns -- Increasing trend, ns
 Resurfacing and barrier treatments at a signalized junction (7) −20 % [−38 %; +2 %]* Reduction trend, ns −19 % [−28 %; −9 %]
 Shoulder treatments and replacing lenses by LEDs (2) No change -- Increasing trend, ns
 Changes in traffic signal program and replacing lenses by LEDs, at a signalized junction (2) -- -- Increasing trend, ns
 Crosswalks' arrangement and signing treatment, at a signalized junction (1) Reduction trend, ns -- Increasing trend, ns
 Barrier treatments, at a signalized junction (9) −28 % [−43 %; −9 %] Reduction trend, ns −11 % [−20 %; 0 %]*
 Pavement treatments, at a signalized junction (2) −50 % [−68 %; −20 %] Reduction trend, ns −25 % [−44 %; +2 %]*
 Installing pedestrian fences and replacing lenses by LEDs, at a signalized junction (1) Reduction trend, ns -- Increasing trend, ns
On interchanges
 Realignment of junction on the interchange (1) -- -- Increasing trend, ns
 Building roundabouts on the interchange (1) −72 % [−92 %; −5 %] -- Reduction trend, ns
 Barrier treatments (2) Increasing trend, ns -- −28 % [−42 %; −10 %]
 Traffic signal installation at a junction (1) Reduction trend, ns -- Reduction trend, ns
 Ramps' resurfacing (4) −23 % [−38 %; −5 %] Reduction trend, ns Increasing trend, ns
  1. Notes to Table 3: # number of sites treated; 91 junctions and 9 interchanges, in total. The numerical results presented are significant at 0.05 confidence level; * significant at 0.1 level; ns - not significant
  2. "--" means no result (insufficient data); "no change" indicates that average value of the efficiency index is below 5 %