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Browsing by Author "Yokoo, Toshihiro"

Now showing 1 - 3 of 3
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    Does poor road condition increase crashes?
    (2016-08-01) Yokoo, Toshihiro; Levinson, David M; Marasteanu, Mihai
    In a region well known for its severe weather, maintaining pavements to meet high standards remains a challenge. Changes in weather states (such as the freeze-thaw cycle) leads to distresses in the pavement materials. There exist claims that poor pavement quality reduces the ability of roads to drain and reduces the ability of vehicles to resist skidding, and is thus associated with more crashes. In order to improve road safety, several pavement maintenance treatments are carried out, such as “rout and seal cracks” and “hot-mix patching” for improving pavement roughness and distress (Tighe et al., 2000). Others have found that crash rate depends on the pavement type and pavement condition. Crash rate of tined pavement sites is larger than the rate of ground pavement sites. When the pavement condition is wet or icy, crashes are more likely than under dry conditions (Drakopoulos et al., 1998). , When the pavement condition is poor, severe crashes are more likely, but when the pavement condition is very poor, severe crashes are less likely to occur than poor pavement conditions (Li et al., 2013). In accident rate estimation models, the results indicate that most important independent variable is “AADT”, and “geometric design” (lane width and access control) and “pavement condition” (friction, serviceability index, and pavement type) are also important variables (Karlaftis and Golias, 2002). Our research proposes to statistically test such claims of a relationship between incident number and road quality, while controlling for traffic data (AADT and percent truck), segment length, crash conditions (date, road characteristics, and road surface), and pavement type. To investigate the relationship, we combine data from various sources. We then conduct a statistical analysis for ascertaining the effects of good road quality on incident number and severity. This paper de- scribes the data, methods, hypotheses, and results in turn.
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    The effect of road network structure on speeding using GPS data
    (2016-05) Yokoo, Toshihiro
    This paper analyzes the relationship between road network structure and speeding using GPS data collected from 152 individuals over a 7 day period. To investigate the relationship, we develop an algorithm and process to match the GPS data and GIS data accurately. Comparing actual travel speed from GPS data with posted speed limits, we measure where and when speeding occurs, and by whom. We posit that road network structure shapes the decision to speed. Speeding is large in both high speed limit zones (e.g. 60 mph (97 km/h)) and low speed limit zones (less than 25 mph (40 km/h)); in contrast, speeding is much lower in the 30 - 35 mph (48-56 km/h) zones. The results suggest driving patterns depend on the road type. We also find that if there are many intersections on the road, the average link speed (and speeding) drops. Long links are conducive to speeding.
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    Road network structure and speeding using GPS data
    (2016) Yokoo, Toshihiro; Levinson, David M
    This paper analyzes the relationship between road network structure and the percentage of speeding using GPS data collected from 152 individuals over a 7 day period. To investigate the relationship, we develop an algorithm and process to match the GPS data and GIS data accurately. Comparing actual travel speed from GPS data with posted speed limits we measure where and when speeding occurs, by whom. We posit that road network structure shapes the decision to speed. Our result shows that the percentage of speeding, which is calculated by travel distance, is large in high speed limit zones (e.g. 60 mph ) and low speed limit zone (less than 25 mph); in contrast, the percentage of speeding is much lower in the 30 - 50 mph zone. The results suggest driving pattern depends on the road type. We also find that if there are many intersections in the road, average link speed (and speeding) drops. Long links are conducive to speeding.