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Table 1 Examples of estimating efficiency indices for selected treatment types
From: The evaluation of safety efficiency of non-urban infrastructure improvements; a case-study
(a) Upgrading a single-carriageway to a dual-carriageway road section | ||
Accident type | Efficiency index, 95 % confidence interval | Meaning |
Injury accidents | −34 % [−49 %; −13 %] | Reduction |
Severe accidents | −22 % [−62 %; +63 %] | Reduction trend |
Total accidents | −31 % [−41 %; −19 %] | Reduction |
Injury accidents, accounting for selection bias | −32 % [−48 %; −11 %] | Reduction |
Severe accidents, accounting for selection bias | −17 % [−60 %; +74 %] | Reduction trend |
(b) Barrier installation - building a rigid median, on a single-carriageway road section | ||
Accident type | Efficiency index, CI | Meaning |
Injury accidents | −61 % [−74 %; −42 %] | Reduction |
Severe accidents | −71 % [−89 %; −20 %] | Reduction |
Total accidents | −23 % [−40 %; −2 %] | Reduction |
Injury accidents, accounting for selection bias | −50 % [−68 %; −24 %] | Reduction |
Severe accidents, accounting for selection bias | −49 % [−83 %; +53 %] | Reduction trend |
(c) Resurfacing and replacing lenses by LEDs, at a signalized junction | ||
Accident type | Efficiency index, CI | Meaning |
Injury accidents | +8 % [−32 %; +72 %] | Increasing trend |
Severe accidents | +17 % [−86 %; +868 %] | -- a |
Total accidents | +7 % [−22 %; +46 %] | Increasing trend |