01390550

Component

The luminance of signs of two different retroreflective materials in various road situations is compared to the two performance categories dictated by driver legibility capabilities. By the use of a computer modeling program, the luminance of a sign was calculated as a function of approach distance (the supply model) for a set of parameters including sheeting type, vehicle type, headlight beam pattern, road geometry, sign position and lane position. The drivers' nighttime requirements (the demand model) were taken from the previous paper. When the demand curves are overlaid onto the supply curves, it is then apparent whether the different sheeting types can meet the requirements of the drive. From the two sheeting types that were compared, ASTM Type III (high Intensity encapsulated glass-bead material) and Type IX (very high intensity unmetalized microprismatic with high retroreflectivity at short road distances) the broad conclusions drawn are that: Type IX microprismatic sheeting has luminances that are several times that of beaded Type III sheeting over all distances and all road geometries Type IX sheeting has superior performance for vehicles that impose a large observation angle on drivers, such as trucks, buses, vans and trams. HI does not meet the minimum requirements of drivers of these types of vehicle. Consequently, it should be the sheeting of choice where there is diversity in the vehicle mix. The increased luminance provided by the Type IX sheeting over that of the beaded Type III sheeting would particularly benefit the older drivers in the legibility task.

01390545

English

18p

2004

Transportation Research Board Annual Meeting, 83rd, 2004, Washington, DC, USA

Aged drivers; Behavior; Drivers; Glass beads; Legibility; Mathematical models; Properties of materials; Retroreflectivity; Traffic signs; Visibility distance; Vision tests

Aged driver; Driver behaviour; Glass beads; Legibility; Material properties; Modelling; Retroreflectivity; Traffic sign; Visibility distance; Visual acuity

Materials

TRIS, TRB, ATRI

Aug 23 2012 4:55AM

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