144｜Practice

Practical optimal signal control emphasizing
pedestrian road crossing realities
1. Background and goals
Currently, pedestrians do not sufficiently understand the meaning of the signals at pedestrian crossings,
and as a result, actual pedestrian behavior is not necessarily the same as that assumed by traffic laws.
This has been noted as one factor accounting for pedestrians not completely crossing the road by thetime crossing signals turn red, affecting traffic safety and smoothness by causing complications withvehicles turning left or right.
This study is a report of an actual road experiment in which we investigate and analyze changes inpedestrian road-crossing behavior after mounting auxiliary equipment to a traffic signal that allows
pedestrians to clearly understand the amount of time remaining to cross the road.
The experiment first evaluated the effect of displays indicating time remaining for road crossing byanalyzing videos of an actual crosswalk. We then performed an experiment in which music by the composer Keiichiro Shibuya was played during road crossings as a method of promoting behavioral change
in pedestrian psychology.

2. Research content
2-1. The effect of installing crossing signals with countdown displays
We installed crossing signals with countdown displays as shown in Fig. 1 at actual pedestrian crossings,
and evaluated their effect in a pilot survey (Table 1).
Figure 2 shows changes in the ratio of pedestrians who did not complete road crossing by the time
Table 1. Evaluation by pilot survey (2005)
Item

Figure 1. Pedestrian crossing
signal with countdown display

Description

Experimental
intersections

Tokyo: Ginza 2-chome, Ginza 5-chome, Omori
Yokohama: Honcho 1-chome, MM2Experimental period

9 December 2005 (Friday) - (about 2 months)

Survey andobservation period

Before the experiment: 18, 25, 28 November 2005
During the experiment: 14, 16, 19 December 2005

Investigation methods

Videos: 3000–8000 pedestrians at each intersection
Surveys: About 100 pedestrians at each intersection

Project Leader: Masahiko Katakura
Professor Emeritus, Tokyo Metropolitan University

Practical optimal signal control emphasizing pedestrian road crossing realities｜145

Residual rate [%]Beforeexperiments

3530

Pedestrian green (PG)

Duringexperiments

2520

Pedestrian
flashinggreen (PF) Pedestrian red

15Green

1050

Ginza
2-chomeGinza
5-chome

Honcho1-chome

MM2

Figure 2. Effects of countdown display

the signal turned red (the residual rate) at eachcrossing with a countdown display. In all cases, weverified a reduction in the residual rate ranging
from a few percent to as much as 10%.

Flashing
Time traversed in 1 m/s
Figure 3. Green completion and green flashingcompletion methods

Crossing speed (m/sec)

3.5

Green completion method(during experiment)
Figure 3 shows the results for two types of2.5
Green completion methodcountdown, a “green completion method” that
(before experiment)
1.5
shows the decreasing amount of remaining timeand a “green flashing completion method” that
0.5
shows the end of the crossing period. Both had-30 -25 -20 -15 -10 -5
05Crossing
starttime(sec)
Red start time
approximately equal effects in reducing the residual rate. However, as shown in Fig. 4, the green
Figure 4. Change in crossing speed
completion method saw a rapid increase in pedestrian crossing speed during the latter half of the crossing, indicating the possibility that pedestrians feelrushed. In contrast, there is no significant difference in speed between the former and latter half ofcrossing when using the green flashing completion method. We presume that this is due to a reductionin the number of pedestrians who started crossing later than they should; therefore, we consider thegreen flashing completion method to be superior.
The results of a survey indicated that with the exception of young people (age 13 to 24 years), over
80% of pedestrians who understood the meaning of the countdown display found it helpful. We also
found that placing the countdown display and the pedestrian crossing icon on separate panels (Fig. 1)
increased the recognition rate of the display among pedestrians, as compared to when the icon and display were shown together.
In 2006, we experimentally installed these crossing signals at four intersections (Ginza 5-chome,MM2, Ginza 4-chome, and Tsurumi Keisatsusho-mae) for pedestrian crossings ranging from 13 to 38 m
in length, conducted a questionnaire, and performed video observations of approximately 16,000 pedestrians. Results of the questionnaire performed at the MM2 and Ginza 4-chome intersections were largely
positive in terms of the subjective evaluations by pedestrians. However, a statistically significant reduction in the number of pedestrians not completing road crossing by the time the signal turned red wasseen only under the green flashing completion method at the Ginza 4-chome intersection; no effect was146｜Practice

Crossing distance, 38 m (Tsurumi Keisatsusho-mae)

Average walking speed (m/sec)
3.5

Crossing distance, 24 m (Ginza 4-chome)

3.0

Crossing distance, 22 m (MM2)2.5

1.0-0.50

Pedestrian red start2-2. The effect of installing

0.5

Density: 0.0 to 0.2 people/m2-1.00

of the crossing, in the second half ofthe crossing (Fig. 5).

1.5

Gauge decrease start-1.50

increase in pedestrian walking speed,which was proportional to the length

2.0

Crossing distance, 13 m (Ginza 5-chome)

verified at the other intersections. Yet,
we were able to confirm a significant

0.00

crossing signals with
audible cues
We installed crossing signals with

0.0

Crossing start time

audible cues, which played music
when the signal was green, to investi-

Figure 5. Crossing distance and average crossing speed(during green flashing completion)gate whether the installation changed pedestrian crossing behavior by psychologically promoting anincreased crossing speed when there was little time remaining to cross, and by preventing pedestrians
from initiating crossing when the green signal was flashing. The music played was composed by
Keiichiro Shibuya, an established Japanese musician.
The three compositions respectively aimed at promoting a comfortable walking pace, increasing
crossing speed, and warning pedestrians to prevent intrusion into the crossing. The trumpet-type speakers that can be installed into pedestrian crossing signals are very limited in the range of frequencies andwaveforms they can produce, so compositions that would be easily remembered and not tiresome underthese conditions had to be produced. In other words, the compositions could not simply be sinusoidal
waves such as the loud tone played when a television station is off the air, but rather had to successfully
employ square waves for attacks and reverberations to present a rich sound that could be clearly heard.
Table 2 shows an overview of theTable 2. Overview of investigation and the acquired data
investigation and the obtained data. AsObservation
PeopleTable 3 shows, the residual rates over allMusic
Video datemeasurement times were 18.7% withoutmusic, but fell to 13.9% when the music
was played, representing a statistically significant decrease. We found no differencein the time that pedestrians initiated crossing after the light turned green based on
the presence or absence of music; however,there was a difference in the time thatpedestrians completed crossing whenmusic was played. This indicates that themusic decreased the residual rates. As Fig.
6 indicates, this is due to an increased

locationcrossing

Ginza
4-chomeNone
Yes

30 October 2007 (Tuesday)
18 March 2008 (Tuesday)

1929
1804

Table 3. Residual rate and remaining time
Music

None

Yes

Crossing count [people]

1929

1804

Residual amount [people]

361

251

Residual rate [%]

18.7

13.9

Average remaining time [sec]

5.3

4.4

Maximum remaining time [sec]

16.3

18.8

Significance0.037

Practical optimal signal control emphasizing pedestrian road crossing realities｜147

3.050%

2.540%
35%

2.030%
1.525%20%

Without music

1.015%

With music
Critical crossing speed

0.510%

Percentage of all people crossing [%] (vertical bar)

Average walking speed [m/sec] (broken line)

45%

5%
0.00%
-40

-36-32-28-24-20-16-12-8-40Crossing start time (0 = PR start time)

Figure 6. Average walking speed at crossing start timecrossing speed. Furthermore, we found that overall, the presence of music prevented approximately 40
people from prematurely starting to cross. We verified a similar effect in an investigation of an intersection at Shin-Yokohama 2-chome.

3. Conclusions
The pieces of music by Mr. Shibuya that were used in the present study were composed with the goal ofbeing easy to remember and hum along to, and were clear, distinctive, and easily heard over the soundof traffic. It is likely that pedestrian crossing signals that play such music are not only accepted more easily by pedestrians, but also exhibit tangible effects of reduced residual rate and increased walking speed,providing an effective improvement to current crosswalk walking behavior.

4. Future outlook
This research indicated that pedestrian crossing signals equipped with appropriate music-playing functionality can lead to proper pedestrian crossing behavior. We hope that future studies will verify theeffectiveness of crossing signals with audible music cues under a variety of road and traffic conditions
and in various acoustic environments, and that the installation of such equipment at many intersections
will aid efforts to improve pedestrian safety and smooth traffic.