ClearviewHwy® Buy ClearviewHwy
Home
What is ClearviewHwy®?

Typeface Display

Research & Design

 
Original Study:
Pennsylvania Transportation Institute In two PTI studies intended for conventional road guide signs (Figure 1), use of an early version of the Clearview-Bold (left position, original version of typeface) improved nighttime sign reading distance by up to 16 percent when compared with the E-modified road sign typeface (right position). For drivers traveling at 45 mph, that legibility enhancement could easily translate into 80 extra feet of reading distance, or a substantial 1.2 seconds of additional reading time. On a road with a posted speed of 45 mph, a driver is traveling at 66 feet per second. With Clearview-Bold, the desired destination legend is recognized 1.3 seconds earlier (84 feet) and with greater accuracy, giving the person significantly more time to react to the information displayed.

Figure 1.


By allowing a viewer to read the unique footprint of the word when displayed in upper/lowercase letters, there is an increase in accuracy, viewing distance, and reaction time. The research (Figure 2) revealed that when the upper/lowercase Clearview-Condensed (upper position, original version of typeface) is compared to the most commonly used all-capital-letter typeface (FHWA Series D, lower position), there was a 14 percent increase in recognition when viewed by older drivers at night, with no loss of legibility. When the size of Clearview-Condensed was increased by 12 percent to equal the overall footprint of the uppercase display, the recognition gain doubled to 29 percent with little change in overall sign size.

Figure 2.


Clearview for Freeways:
Based on the Pennsylvania Transportation Institute (PTI) research, the Texas Transportation Institute (TTI) elected to compare Clearview-Bold to E-modified for full-scale side-mounted and overhead-mounted freeway guide signs. In a preliminary field review (Figure 3), Meeker, Chrysler, and Garvey found significant differences in viewing Clearview-Bold at 16 inch capital letter height as proposed for study by TTI compared to Clearview-Bold at 5 to 8 inches as used in the PTI tests. In essence, scale and viewing distance affect legibility, and the typeface needs to be designed around the worst case requirements. As a result, proportional refinements were made to the typeface before testing to expand the counters and reduce the massing at points of convergent strokes. The first TTI study using beaded Type II sheeting showed that Clearview performed no worse than Series E-modified, and, in some cases Clearview outperformed E-modified. A follow-up study at TTI using microprismatic Types VIII sheeting showed a 12 percent increase in legibility for overhead and shoulder-mounted guide signs. In this follow-up study, the largest legibility distance improvements of the Clearview-Bold were associated with older drivers.

Figure 3.Clearview-Bold (left position, original version of typeface) vs Highway Gothic Series E-modified (right)



Strokewidth and Lettershape are Critical
One of the problems with E-modified was that the heavy stroke width to height ratio (1:5) of the letterforms made the letters read as a dense mass when viewed from a distance. Although the original Clearview-Bold designs (Figure 4) tested much better than existing FHWA typefaces, we did not believe that the letterform design would accommodate a stroke width to height ratio beyond 1:5.5 with out beginning to replicate some of the deficiencies that existed in E-modified. After viewing the test signs on Pennsylvania freeways, it was confirmed that a 1:5.1 stroke width to height ratio (8 percent increase, or an additional 1/8 inch for a 16 inch letter) with added visual arc subtended to the retina would improve viewing from long distances.


Figure 4. High ay Gothic Series E-modified (top) v . Clearview-Bold (bottom)


The method for adding weight without bulk came as a result of another project to develop a new road guide sign typeface for the National Park Service (Figure 5). This typeface, named NPS Roadway, was developed by Terminal Design, with Meeker & Associates, and validated by Pietrucha and Garvey at the Pennsylvania Transportation Institute. The goal was to design a Roman typeface to replace the Clarendon typeface used on NPS guide signs. This new typeface would occupy less width on the sign, while improving legibility and recognition for older drivers. To optimize the typeface for viewing on signs, the height of the lowercase was increased, and the width of the letterforms was compressed. Based on a these modifications, the letterforms could be made slightly bolder without increasing the overall footprint of the word. This change resulted in an 1 percent increase in legibility while requiring 11.5 percent less length for words used in the field study when compared to the original Clarendon.


Figure 5. NPS Roadway (top) compared to Clarendon (bottom). The NPS Roadway reduces legend length between 10-15 percent while increasing readability by 11 percent


Final Design of ClearviewHwy
Based on the findings from the NPS study, the same design concepts, which included a taller lowercase, were incorporated into the ClearviewHwy Type System design (Figure 6). The new proportions allowed refinements that were heretofore not possible, including an increase of the stroke width by nearly 8 percent to 1:5.1 for the version of ClearviewHwy being compared to E-modified. The performance of the new ClearviewHwy when compared to Clearview-Bold was very positive. Based on this result, the system was developed into six weights in both positive and negative contrast versions for a review by a panel of experts. The new designs of the ClearviewHwy typeface were viewed (May 2002) by federal and state traffic engineers and vision specialists in a full-scale demonstration at the Pennsylvania Transportation Institute test track. This review compared the new ClearviewHwy Type System to E-modified and included field reviews of the other weights in comparison to the comparable weights of the FHWA Standard Alphabets. The displays were in both positive and negative contrast and used all standard FHWA color combinations on high brightness sheeting materials (Figure 7). Although the amount of improvement had not been validated in a research program, the twenty members of the viewing committee concurred that the performance of each display as significantly better than the control samples. Research programs are currently being planned by both PTI and TTI to empirically validate the findings of the panel of experts. Use of the new ClearviewHwy Type System by the Federal Highway Administration was requested by the Pennsylvania Department of Transportation, which has used Clearview on an experimental basis for freeway signs.



Figure 6. The evolution of the ClearviewHwy typeface design is illustrated in this example with the comparison to Highway Gothic E-modified


 
Figure 7. Observation rack at PTI Test Track (May 2002). E-modified panel in upper left. ClearviewHwy 5-W and 5-B in the middle and lower left positions respectively. ClearviewHwy 3-W and 3-B in middle and lower right positions respectively.