Minimum Retroreflectivity for Overhead Guide Signs and Street Name Signs

Abstract

Research and recommendations were produced on the basis of a study on the development of minimum retroreflectivity values for overhead guide signs and street name signs. The research reviewed the literature and available photometric models. A photometric model was created to develop minimum retroreflectivity values for overhead guide signs and street name signs. One model input was the minimum luminance required for legibility. To obtain minimum luminance requirements for overhead guide signs and street name signs, a field evaluation was performed. Accommodating older drivers was specifically emphasized. After the minimum luminance values were determined, the minimum retroreflectivity model was used to study the impacts of (and determine appropriate values for) factors that affect retroreflectivity, such as distance, headlights, and vehicle speed. After the appropriate values were determined, the minimum retroreflectivity model was executed for the final runs. The recommended minimum retroreflectivity values were grouped into one table that includes overhead guide signs, postmounted street name signs, and overhead (mast-arm– or span-wire–mounted) street name signs. The values depend on type of sheeting, speed, and sign position.

Avaliação da conformidade de Sinais de Trânsito para melhorar a segurança rodoviária em meio urbano: uma aplicação no Centro de Guimarães, Portugal

“…A distância de perceção depende de fatores tais como a velocidade, o cansaço, os níveis de atenção, o consumo de álcool ou de drogas, etc. Apesar dessa multitude de fatores, as distâncias de travagem e de paragem podem ser definidas em função da velocidade dos veículos em áreas urbanas, com o pressuposto de A visibilidade dos sinais de trânsito conta com um vasto desenvolvimento na literatura, o que é elucidativo da importância do tema (Tsyganov et al, 2002;Carlson & Hawkins, 2003;Ng & Chan, 2008;Shinar & Vogelzang, 2013;Costa et al, 2014;Balali et al, 2015). Com efeito, a informação disponibilizada pelos sinais só é eficiente quando estes são devidamente visíveis (Khalilikhah et al, 2015).…”

“…Aliás, os sinais apenas são consideradas efetivos quando visíveis de dia e de noite (Khalilikhah et al, 2015). A visibilidade dos sinais resulta da combinação de cinco principais fatores: o seu estado de conservação; as condições oferecidas pelo veículo; as capacidades de perceção e reação do condutor; as condições atmosféricas; e o estado da via (Carlson & Hawkins, 2003;Costa et al, 2014). Na literatura, diversos estudos centraram-se na avaliação do estado dos sinais de trânsito, nomeadamente do impacto do seu tamanho, forma e cor na visibilidade (Ng & Chan, 2008;Stasi et al, 2012), na análise da retroreflexão (Tsyganov et al, 2002;Balali et al, 2015;Khalilikhah et al, 2015) e na inclusão de informação complementar nos sinais (Shinar & Vogelzang, 2013).…”

Model of Overhead-Sign Luminance Needed for Legibility

“…The data used to produce the luminance model were collected as part of an FHWA study (1). The objective of the study was to determine minimum in-service retroreflectivity levels for overhead guide signs and street-name signs.…”

Legibility of Urban Highway Traffic Signs Using New Retroreflective Materials

“…The relationship between luminances required for adequate legibility are dependent upon factors such as distance (which affects the apparent size of the characters) (Graham et al 1997;Carlson and Hawkins 2002;Holick and Carlson 2002), the luminance contrast between the sign background and the characters (Schnell et al 2004) the type of characters on the sign (i.e., letters versus symbols) (Zwahlen and Schnell 1999), and observer's age (Graham et al 1997).…”