Exploring Relationships Between Travel Time Based Performance Measures
Analytics
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Abstract
Traffic congestion is a common problem on transportation networks in many urban areas. It causes delay, effecting the road users and their behavior. The road users always look to reduce their travel time and reach their destination on-time. Hence, travel time and travel time reliability are important performance measures in transportation research. Travel time variations are often observed and effected by various factors such as day-of-the-week (DoW), time-of-the-day (ToD), week-of-the-year (WoY), and speed limit. In the past, several researchers have explored the concept of reliability and proposed various measures for assessing transportation system performance and making informed decisions. However, they did not categorize and explore the relationships comprehensively by DoW, ToD, WoY, and speed limit. Therefore, the primary objective of this research is to categorize and explore the relationships between travel time based performance measures by DoW, ToD, WoY, and speed.Raw time travel time data was obtained from the Regional Integrated Transportation Information System (RITIS) website at one-minute interval. The data for the years 2014 and 2015 was collected and processed to compute performance measures such as minimum, maximum, and average travel times; 10th, 15th, 50th, 85th, 90th, and 95th percentile travel times; buffer time (BT); buffer time index (BTI); planning time index (PTI); travel time index (TTI); and travel time variations based on 90th and 80th percentile travel times. The selected measures were computed using Microsoft SQL and were joined using Traffic Message Channel (TMC) ID with network data, to obtain the link length and speed limit. The data was then sorted into 46 separate datasets to develop Pearson correlation matrices.The results from the Pearson correlation coefficient analysis when the year was considered indicate that not much of variation in relationship between performance measures was observed. The relationship between travel time measures was same but slight variations were observed in the case of travel time reliability indices when analyzed by DoW. When analyzed by ToD, no variations were observed in case of travel time measures while variations were observed in case of travel time reliability indices. Likewise, when speed limit was considered, it can be observed that there are variations in relationships in case of travel time and reliability indices. Only a few variations were observed in case of travel time measures, while major variations were observed in case of travel time reliability indices.