●A Case of Utilizing Results

Calculating Traffic Volume 24 Hours a Day/365
Days a Year through Effective Use of Vehicle
Detectors
Traffic Engineering Division, Road Department
HASHIMOTO Hiroyoshi (Research Engineer), MATSUMOTO Shunsuke (Research Engineer),MIZUKI Tomohide (Guest Research Engineer), MONMA Toshiyuki (Senior Researcher),
UESAKA Katsumi (Head)(Keywords) Vehicle detector, processing of singular/missing values, estimation of traffic volume, regular observation
traffic-data system
1. Introduction
The Ministry of Land, Infrastructure, Transport andTourism collects daily traffic volume data on aregional basis by estimating traffic flow between
adjacent road zones using vehicle detectors installedon national roads throughout Japan. An issue thathas emerged in the course of this work is how to
reduce workload required to process singular andmissing values of obtained vehicle detector data
(Figure 1).
Here, NILIM developed a method for processing
singular and missing values as well as a method for
estimating traffic volume using vehicle detector data,
and then arranged them into a set of “road traffic
survey guidelines.”
It also prepared a “trafficvolume calculation tool” that automatically processes
vehicle detector data and incorporated it into practicaloperations.

3. Conclusion
With the goal of bringing greater efficiency toRegular observation

Vehicle detector【交通量常時観測システム】
traffic-data system【車両感知器】

Visual and manual work by【職員による目視・手作業】
employee

Confirmation and processing of
特異値・欠測値の確認・処理

Traffic
flow measurement
交通量の計測singular/missing values

Fig. 1: Conventional processing of singular andmissing values

Base regular observation

point
基準常時観測点

Reference regular

Estimated

関連常時観測点
observation point

推定区間zoneObserved
観測区間zone～～

2. Method for calculating traffic volume througheffective use of vehicle detectors
For the processing singular and missing values, weutilized not only accumulated past data from vehicle
detectors but also data from adjacent vehicle detectors(reference regular observation point). In estimating
traffic volume, we observed the fact that the traffic
volume ratio between the estimated zones andadjacent vehicle detector (base regular observation
point) is roughly constant. Then we multiplied theratio of traffic volume at both points (calculated using
past actual observations in the estimation zones) bytraffic volume at the base regular observation point(Figure 2).
Characteristics of the developed method are that itrecognizes that locally generated singular values (suchas road construction-related restrictions) have aregion-wide impact in terms of estimated traffic
volume, and that it differentiates between localized
singular values (such as road construction-relatedrestrictions) and regional traffic volume fluctuations
caused by typhoons, etc. (Figure 3).

traffic volume calculation, NILIM has launchedproject research* to study specifications for a new
regular observation traffic data system that will
incorporate the developed method for calculating
traffic volume.

Observed

観測区間zone

Estimated

推定区間zone
Estimation
推定

Vehicle detector

Estimation
推定

Vehicle detector data
車両感知器データ（処理後）(after processing)

車両感知器データ
data
Singular/missing value

欠測値・特異値処理
processing

Past accumulated data
過去の蓄積データ

Figure 2. Relationship between vehicle detectors andestimation zones
START
Input of 24-hour cross-sectional traffic
volume２４時間断面交通量の入力
Step１Possible
singular value
特異値の可能性がある

Not
considered
特異値とはsingular value

Step２

考えられないRegionaltraffic
広域的なvolume
交通量変動
fluctuation

である

Not
singular value
特異値でない1: Extract
possible singular values from⇒ Stepstep１
過去の傾向から特異値のpast trends
可能性があるデータを抽出

Localized
局地的なsingular
特異値value

2: Identify
singular values from⇒ Stepstep２
関連常時観測点との比較
comparison with referenceから特異値であるかを判別
continuous observation points

である

Not
singular value
特異値でないSingular value
特異値である

台風・年末年始など
Typhoon, year-end/

事故・工事規制など
Accident,
road work, etc.

New Year’s holidays,etc.

Figure 3.Method for differentiating singular values

●A Case of Utilizing Results

Figure 4: Initial screen of the traffic volume
calculation tool
* Study on Further Development of the Collection, Analysis, and Utilizationof Regular Observation Data for Road Traffic (2011 to 2013)