Between July 2004 and February 2006, research was carried out on the safety implications of flush medians in Auckland City, New Zealand. A site-by-site benefit/cost analysis found that 38 per cent of the 50 studied sites achieved a negative benefit/cost ratio, and that the introduction of flush medians could sometimes increase accident occurrences, indicating that separate analysis is required for every proposed flush median site. Crash types that increased as a result of installing a flush median were investigated. It was concluded that turning and overtaking crashes increased because installing a flush median reduces visibility. Alternatively, rear end/cornering and right turn/head on crashes increased as the installation of flush medians meant existing road lanes were narrowed, resulting in more congestion, resulting in longer queue lengths and longer peak periods. A methodology was formed to predict crash patterns at proposed flush median sites. Preliminary guidelines for safer flush medians were updated to include findings from this research. The use of these guidelines should ensure increased safety and crash savings at all flush median sites. (a) For the covering entry of this conference, please see ITRD abstract no. 0612AR242E.
Samenvatting