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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 %