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INTRODUCTION
The 'Signals New Zealand User Group' (SNUG) identified a need to achieve better consistency with the design and operation of traffic signals throughout the country. Transfund (now part of Land Transport NZ) funded the development of a signal audit methodology, where safety and efficiency of traffic signals are examined. A representative number of signal installations, in the area covered by nine territorial local authorities (TLAs), were audited by April 2004. All audits included signals administered by the TLAs on behalf of Transit New Zealand (Transit NZ), the road controlling authority (RCA) for State Highways.
The findings of the audit reports have been published in a booklet prepared by Axel Wilke, City Solutions, Christchurch City Council (Transfund 2004). The purpose of the booklet is to draw attention to those elements of traffic signals that the auditors have found frequently compromise safety and /or efficiency, and to present ways in which these deficiencies could be addressed. The ultimate aim is to contribute to safer and more efficient installations and operations of traffic signals inNZ. Engineers who design, construct, install, manage and maintain traffic signals comprise the target audience group for the booklet.
The main sections of the booklet cover:
* Crashes at traffic signals.
* Intersection and lane layout.
* Signal post and display location.
* Phasing and operational issues.
* Pedestrian issues.
* Cyclist issues.
Under each heading, aspects for consideration are discussed, and potential safety and efficiency issues are noted. Then a series of recommended treatments and actions are listed. These recommendations are summarised below, after a brief overview of crashes at traffic signals in New Zealand.
CRASHES AT TRAFFIC SIGNALS
An analysis undertaken by Tim Hughes from the Land Transport Safety Authority (now part of Land Transport NZ) identified the main safety issues at traffic signals in New Zealand as follows:
Right-turn-against crashes 32%
Failed to stop for red 30%
Pedestrians 14%
Cyclists 8%
Factors contributing to right-turnagainst crashes
The following factors can contribute to right-turnagainst crashes:
* Compromised visibility due to geometry.
* Misjudging speed, especially on multilane roads.
* Turning on yellow when one lane has stopped, but drivers in adjacent lanes proceed.
* Misjudging intentions of opposing traffic through or turning left?
* Use of phasing and arrows.
Compared...