Nighttime Expert Panel and Photometric Evaluations of Unlighted Overhead Guide Signs

2003 ◽  
Vol 1844 (1) ◽  
pp. 67-78 ◽  
Author(s):  
Helmut T. Zwahlen ◽  
Andrew Russ ◽  
Şahika Vatan
Keyword(s):  
Expert Panel ◽  
Contrast Ratio ◽  
Field Evaluation ◽  
Luminance Contrast ◽  
Test Material ◽  
Department Of Transportation ◽  
Type Iii ◽  
Evaluation Scores ◽  
White Type ◽  
Ohio Department Of Transportation

A nighttime field evaluation of four different retroreflective overhead-sign sheeting combinations (ASTM D4956 beaded Type III legend on beaded Type III background, Type IX legend on beaded Type III background, Type IX legend on Type IX background, and Type VII legend on beaded Type III background) was conducted on a section of US-30 near Mansfield, Ohio. The test-material combinations were compared when lighted and unlighted (illuminated by low-beam headlights only). Twelve Ohio Department of Transportation engineers and technicians served as evaluators, riding the test loops in 2002 Dodge Caravans. The white Type IX legend on green-beaded Type III background sheeting combination received the highest evaluation scores for appearance, conspicuity, and legibility. The scores for the Type VII legend on beaded Type III background signs were only slightly lower in all three categories. The Type IX legend on Type IX background combination received slightly lower evaluation scores, and the beaded Type III legend on beaded Type III background combination received the lowest evaluation scores. The same signing material combinations were also photometrically (luminance and luminance contrast ratio) evaluated under low-beam illumination at selected approach distances from 200 to 1,000 ft (61 to 305 m) using a 1984 Peterbilt truck, a 2002 Chrysler Town and Country minivan, and a 2002 Toyota Camry sedan, both when lighted and unlighted (low beams). Unlighted overhead signs made with either the white Type VII or the Type IX legends on green-beaded Type III backgrounds provide nighttime motorists with adequate appearance, conspicuity, and legibility.

Viewing Ground-Mounted Diagrammatic Guide Signs Before Entrance Ramps at Night: Driver Eye Scanning Behavior

2003 ◽  
Vol 1843 (1) ◽  
pp. 61-69 ◽  
Author(s):  
Helmut T. Zwahlen ◽  
Andrew Russ ◽  
Thomas Schnell
Keyword(s):  
Information Acquisition ◽  
Department Of Transportation ◽  
Eye Fixations ◽  
Entrance Ramps ◽  
Ohio Department Of Transportation ◽  
Scanning Behavior ◽  
Excessive Number ◽  
Gain Access

The driver eye scanning study is part of a larger study conducted for the Ohio Department of Transportation to evaluate the effectiveness of ground-mounted diagrammatic guide signs placed before entrance ramps at highway freeway interchanges. This nighttime study investigated driver eye scanning behavior while approaching ground-mounted diagrammatic guide signs placed before entrance ramps. Six highway-freeway interchanges were selected in the Greater Columbus, Ohio, area for placement of the diagrammatic signs in the field. Subjects were six unfamiliar drivers, between the ages of 22 to 42. Two diagrammatic signs were located at each of the six interchanges, .5 mi (805 m) and .25 mi (402 m) before the last point of the gore, where a driver can still gain access to the correct freeway entrance ramp. Driver eye scanning behavior measurements were recorded at night to determine if the presence of the diagrammatic signs elicited an excessive number of eye fixations or was visually distracting to the drivers or both. The results indicate that the diagrammatic signs are not looked at excessively often or excessively long. The average look numbers and average look duration times indicate a normal and reasonable level of information acquisition processing employed by the drivers. These values agree with those previously obtained for regular traffic signing determined in previous eye scanning studies. Ground-mounted diagrammatic signs on multilane arterials in advance of highway freeway interchanges were not demonstrated to unduly distract drivers and detrimentally affect a driver’s looking behavior.

scholarly journals NON-DESTRUCTIVE EVALUATION OF IN‐PLACE REHABILITATED CONCRETE PAVEMENTS

2010 ◽  
Vol 16 (4) ◽  
pp. 552-560 ◽  
Author(s):  
Kasthurirangan Gopalakrishnan ◽  
Sunghwan Kim ◽  
Halil Ceylan
Keyword(s):  
Field Experiment ◽  
Asphalt Concrete ◽  
Field Evaluation ◽  
Structural Condition ◽  
Concrete Pavements ◽  
Test Results ◽  
Department Of Transportation ◽  
Portland Cement Concrete ◽  
Reflection Cracking ◽  
Non Destructive

Several in‐place rehabilitation techniques have been used before placing an Asphalt Concrete (AC) overlay on Portland Cement Concrete (PCC) pavements in attempts to minimize reflection cracking. Among these techniques, “rubblization” of PCC has been recognized to be the most utilized procedure for the mitigation of reflection cracking in US. This paper presents the practices on the use of rubblization in US and discusses the performance of this technique based on field evaluation. The specifications for the rubblization procedure used by state Department of Transportation (DOT) in US were reviewed. To evaluate the performance of rubblization technique, the structural and the surface conditions of AC overlaid pavements with rubblized PCC layer are compared to those with virgin PCC layer. A series of field experiment tests were carried out on six representative AC overlaid pavements with both rubblized PCC and virgin PCC in Iowa during 2007. The field experiment tests include the Nondestructive (NDT) and destructive tests, and the distress survey. Deflection Basin Parameters (DBPs) were derived from NDT test results to characterize the structural condition of pavements. The results indicate that the rubblized PCC layer has strength comparable to that of virgin PCC layer and has better performance under that structural condition. Santrauka Siekiant nustatyti asfaltbetonio (AC) sluoksnio veiksminguma, mažinant plyšiu ir itrūkiu atsiradima portlandcemenčio betono (NKK) dangose, buvo taikyti keli kelio dangu rekonstrukcijos metodai. Vertinant ivairius plyšiu susidaryma mažinančius keliu rekonstrukcijos metodus, geriausiu buvo pripažintas regeneracijos metodas (PCC rubblization), taikomas JAV. Nagrinejama mineto regeneracijos metodo taikymo patirtis JAV ir analizuojamos jo taikymo galimybes bei veiksmingumas. Ši keliu atnaujinimo metoda taiko JAV Transporto departamentas (DOT). Siekiant ivertinti nagrinejamo regeneracijos metodo veiksminguma eksploatacinemis salygomis, AC buvo padengtas pagal naujaji metoda paruoštu PCC sluoksniu, ir gauti tyrimu rezultatai palyginti su standartiškai paruošto PCC sluoksnio rezultatais. Natūriniai eksperimentiniai bandymai buvo atlikti, taikant neardomuosius (NDT) ir ardomuosius tyrimu metodus. Ilinkiai (DBPs) buvo nustatyti NDT bandymo metodais, charakterizuojančiais konstrukcines dangu salygas. Darbo rezultatai parode, kad pagal naujaji metoda paruoštas PPC sluoksnis igijo panašu stipri kaip ir PCC sluoksnis su standartine danga, tačiau regeneruota PPC danga igijo geresniu eksploataciniu charakteristiku.

Field Evaluation of Automated Flagger Assistance Devices in Work Zones on Two-Lane Roads

2013 ◽  
Vol 2337 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Melisa D. Finley
Keyword(s):  
Field Evaluation ◽  
Field Studies ◽  
Department Of Transportation ◽  
Work Zones ◽  
Right Of Way ◽  
Stop Sign ◽  
Texas Department ◽  
Research Findings ◽  
The Right ◽  
Violation Rate

Automated flagger assistance devices (AFADs) are designed to be operated remotely by a flagger positioned outside of the travel lanes and thus to reduce the flagger's exposure to vehicular traffic. There are two types of AFADs. One type uses a remote-controlled stop and slow sign to alternate the right-of-way; the other uses remote-controlled red and yellow lenses to alternate the right-of-way. A gate arm is required only with the latter. Although AFADs may have increased the safety of flaggers, there were concerns that motorists may have misunderstood AFADs and proceeded before it had been safe to do so. As part of a recent Texas Department of Transportation project, Texas A&M Transportation Institute researchers conducted field studies at lane closures on two-lane, two-way roadways in Texas to assess the operational and safety effectiveness of AFADs relative to the use of flaggers. The research findings show that the violation rate for the stop–slow AFAD without a gate arm is the highest and is significantly higher than the violation rate for the red–yellow lens AFAD (which requires a gate arm). Adding a gate arm to the stop–slow AFAD decreased the violation rate such that it was not significantly different from the red–yellow lens AFAD. In addition, alternative supplemental signs increased motorists' understanding that the stop sign would have changed to a slow sign when motorists were allowed to proceed. Overall, the research findings show that some motorists violate AFADs, especially when the queue of vehicles going in the same direction is visible to the stopped motorist.

Effectiveness of Ground-Mounted Diagrammatic Advance Guide Signs for Freeway Entrance Ramps

2003 ◽  
Vol 1843 (1) ◽  
pp. 70-80 ◽  
Author(s):  
Helmut T. Zwahlen ◽  
Andrew Russ ◽  
James M. Roth ◽  
Thomas Schnell
Keyword(s):  
Lane Change ◽  
Department Of Transportation ◽  
Before And After ◽  
Entrance Ramps ◽  
Ohio Department Of Transportation ◽  
The Cost ◽  
Primary Measure ◽  
Guidance Information

This study investigated the effectiveness of ground-mounted diagrammatic signs in the context of urban multilane arterials leading to freeways. Six highway-freeway interchanges were selected in the greater Columbus, Ohio, area for installation of the diagrammatic signs in the field. The primary measure of effectiveness was the distance at which unfamiliar drivers driving in the wrong lane changed lanes. A total of 21 and 19 test drivers unfamiliar with Columbus roads were recruited for an evaluation before and after installation of the diagrammatic guide signs. This evaluation with unfamiliar test drivers showed that drivers were able to execute a needed lane change earlier when diagrammatic signs were provided. Combining all six sites and looking at the 50th (377 m before, 819 m after) and 85th percentile (203 m before, 601 m after) lane change distances, an increase by a factor of 2.2 to 3.0 between the after and before condition was observed. In addition, a panel of 13 Ohio Department of Transportation and FHWA evaluators visited the six interchange sites and provided their input and opinions on the use of diagrammatic signs. The majority of the evaluators fully embraced the idea of diagrammatic signs. It is suggested that such signs should be used on multilane arterials in advance of highway–freeway interchanges in addition to preexisting guide signs (trailblazer assemblies), in cases in which the cost of overhead span-type sign bridges cannot be economically justified and additional advance guidance information to motorists is highly desirable.

Contrast Ratio and Masking Ability of Three Ceramic Veneering Materials

2012 ◽  
Vol 37 (4) ◽  
pp. 406-416 ◽  
Author(s):  
NN Shono ◽  
HNA Al Nahedh
Keyword(s):  
Linear Regression Analysis ◽  
Contrast Ratio ◽  
Color Difference ◽  
Clinical Situation ◽  
Test Material ◽  
White Background ◽  
Mean Values ◽  
Black Background ◽  
Multiple Comparison Test ◽  
The Mean

SUMMARY Statement of the Problem Porcelain veneer materials are translucent and are therefore affected by their thickness as well as the color of the underlying substructure, which limits their masking ability and compromises the esthetic result in heavily stained teeth. Purpose The purpose of this study was to compare the contrast ratio (CR) and masking ability of three different veneering ceramics with two thicknesses by measuring the color differences over white and black backgrounds. Correlations between CR and masking ability of these veneering ceramics were evaluated. Methods and Materials A total of 30 disc-shaped specimens (12 mm diameter × 1.0 mm or 1.5 mm) were fabricated in shade A2 from three types of all-ceramic systems: IPS e.max Press (IPSe; Ivoclar Vivadent, Schaan, Liechtensein), Vita VM7 (VM7; VITA Zahnfabrik, Bad Säckingen, Germany), and Nobel Rondo Press Alumina: Solo (NRPA; Nobel Biocare, Zürich-Flughafen, Switzerland). The CR, defined as the ratio of illuminance (Y) of the test material when placed on the black background (Yb) to the illuminance of the same material when placed over a white background (Yw), was determined (CR=Yb/Yw). The color (CIE L*a*b*) and Y of each specimen were measured over standard white and black tiles using a spectrophotometer (ColorEye 7000 A, Model C6, GretagMacbeth, New Windsor, NY, USA). Masking abilities of the specimens were determined by measuring the color difference (ΔE) over white and black backgrounds. Both CR and ΔE data were analyzed using two-way analysis of variance (ANOVA). One-way ANOVA was used to compare the mean values of CR across the three materials followed by the Duncan multiple comparison test. The correlations between CR and ΔE were determined by comparing R2 values obtained from a linear regression analysis. A Student t-test for independent samples was used to compare the mean contrast ratio and ΔE values for the two thicknesses. Results CR values of NRPA were significantly less than those of IPSe and VM7, and the CR of IPSe was higher than that of VM7. Furthermore, CR increased as the thickness of the discs increased to 1.5 mm for all three materials. Mean ΔE values were significantly higher with 1.0-mm-thick discs than with 1.5-mm discs. Among the three materials it was observed that NRPA had the highest ΔE when compared with IPSe or VM7, whereas the ΔE of the latter two were not significantly different from one another. There was a strong linear correlation between CR and masking ability. Conclusion CR and masking ability are affected by the type as well as the thickness of the ceramic used. IPSe and VM7 are similar in their masking abilities, whereas NRPA had the lowest masking ability. NRPA was the most translucent, followed by VM7; IPSe was the most opaque. None of the materials tested was able to completely mask the black background. It is therefore recommended that the type of ceramic should be chosen according to each clinical situation.

scholarly journals Unsuccessful bids: Coefficient of variation of bids as indicator of project risk

2020 ◽  
Vol 12 (1) ◽  
pp. 2193-2199
Author(s):  
Young Joo Kim ◽  
Miroslaw J. Skibniewski
Keyword(s):  
Coefficient Of Variation ◽  
Collective Intelligence ◽  
Theoretical Framework ◽  
Department Of Transportation ◽  
Project Risk ◽  
Project Cost ◽  
Sealed Bid ◽  
Coefficients Of Variation ◽  
Ohio Department Of Transportation ◽  
The Relationship

AbstractAlthough unsuccessful bids are usually discarded once the bids are opened under the typical lowest-price sealed-bid project award auction environment, considering efforts and resources expended by responsive and responsible bidders, it is likely that not only a successful bid but also unsuccessful bids can convey important information about the project at hand. This article documents an effort to answer the question that whether projects that receive more dispersed estimates at the bidding stage are more likely to experience greater project cost changes. Taking collective intelligence as the theoretical framework, a total of 210 projects conducted by the Ohio Department of Transportation between 2008 and 2018 were analyzed to investigate the relationship between the coefficients of variation of bids and project final costs. It was found that large projects with above-average coefficients of variation of bids showed greater deviations from original award amounts than large projects with below-average coefficients of variation. The finding enables project owners to study the projects before execution by recouping valuable insights from the community of bidders on the possibility of greater project cost changes faced by the planned projects without complex and mathematically rigorous models.

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