A study of the base saturation flow rate at signalized intersections

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K22435
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0303:Civil engineering, social systems engineering, safety engineering, disaster prevention engineering, and related fields
• Research Institution: Nihon University (2020, 2023); National Institute for Land and Infrastructure Management (2021-2022)
• Principal Investigator: AOYAMA Eri 日本大学, 理工学部, 助手 (40874954)
• Project Period (FY): 2020-09-11 – 2024-03-31
• Keywords: 飽和交通流率 / 信号交差点 / 交通容量

Outline of Final Research Achievements

The saturation flow rate is a fundamental value for road planning and design. The base value for through lanes in Japan has been set at 2,000 pcu/ hour of green, based on observations in the 1970s and 1980s. This study clarifies the actual situation of the value corresponding to the base value of the saturation flow rate in current traffic flows in Japan. The observed values in this study show that they are below the base value and have even decreased over time. Furthermore, the study showed that elderly drivers and tourist traffic may reduce the saturation flow rates. It was noted that using the base value as 2,000 pcu/hour of green, without reflecting the actual decline in saturation flow rates and these effects, would result in low estimates of flow ratio and delay at signalized intersections.

Free Research Field

交通工学

Academic Significance and Societal Importance of the Research Achievements

わが国において飽和交通流率の基本値に関する見直しは長年行われていない。一方で、米国では、飽和交通流率の観測結果に基づく基本値の見直しだけでなく、都市部の人口により異なった飽和交通流率の基本値が設定されている。わが国においても、これらに関する知見の必要性は言及されてきているものの、実際に現状は明らかになっていない。さらには、飽和交通流率の特性上、実測に基づくべきとされているが、基本値が用いられていることが多い。そこで、現在の飽和交通流率の実態を示すことは、現在の交通流の状況における基本値の実態を示すだけでなく、実測に基づくべきという主張にもつながるものと考えている。