TELKOM
NIKA Indonesia
n
Journal of
Electrical En
gineering
Vol.12, No.5, May 2014, pp
. 3313 ~ 33
2
2
DOI: http://dx.doi.org/10.11591/telkomni
ka.v12i5.4928
3313
Re
cei
v
ed O
c
t
ober 2
4
, 201
3; Revi
se
d Novem
b
e
r
28, 2013; Accept
ed De
cem
b
e
r
16, 2013
Emergency Veh
i
cle oriented Traffic Priority Control
Strategy at Intersection in Congested Urban Area
Yao Jiao
Dep
a
rtment of T
r
ansportation
S
y
stem En
gin
e
e
rin
g
, Busin
e
ss School,
Univers
i
t
y
of Shan
gh
ai for Sci
ence a
nd T
e
chnol
og
y, Sha
n
g
hai, 20
09
3, Chi
n
a
E-mail: yao
jia
o
@
12
6.com
A
b
st
r
a
ct
Efficient an
d s
a
fe traffic cont
rol strategy for
em
erg
ency v
ehicl
e ca
n re
d
u
ce its trave
l
time a
n
d
avoi
d sec
o
n
d
a
r
y accid
ent. B
a
sed
on
the
a
nalysis
of
its r
equ
ire
m
e
n
t a
n
d
o
b
ject, w
e
p
r
opos
ed
a
nov
el
control strate
g
y
at intersecti
o
n
accor
d
in
g to
the st
atus of
emerg
ency ve
hicle, w
h
ic
h ca
n be
divi
de
d i
n
to
three parts: “appr
oach
i
n
g
”
,
“passi
ng “an
d
“recoverin
g
”
,
F
u
rthermor
e
potenti
a
l safet
y
risk caused
by
emerg
ency v
e
hicle
w
a
s als
o
taken
into
ac
count w
h
e
n
makin
g
co
ntrol s
t
rategy.F
rom t
he cas
e
stu
d
y
w
e
concl
ude th
at w
i
th control strategy in th
is p
aper d
e
l
a
y of e
m
er
ge
ncy vehi
cle can b
e
sh
a
r
ply decr
ease
d
by
68.63
% w
i
th only 19.8
6
% l
o
s
s
of av
erage
d
e
lay of back
g
ro
und traffic.
Ke
y
w
ords
:
priority
contro
l
strategy, e
m
er
gency
ve
hicl
e,
cong
estio
n
j
u
d
g
e
m
e
n
t, nor
ma
l strategy
rec
o
very,
safety risk
Copy
right
©
2014 In
stitu
t
e o
f
Ad
van
ced
En
g
i
n
eerin
g and
Scien
ce. All
rig
h
t
s reser
ve
d
.
1. Introduc
tion
Emerge
ncy vehicle
s
,
whi
c
h are
carrying
out sp
ecial
t
a
sk, su
ch as am
bulan
ce,
firefighting,
crusi
n
g poli
c
e, engineering
rescue
for
water, power supply ect., are criti
c
al to
alleviate
life and
p
r
o
perty loss
in our so
ciety.
Ho
wev
e
r, eme
r
g
e
n
cy incide
nts
a
l
ways
hap
pe
n at
rand
om, with
liitle proba
bility and un
certa
i
nty, but severe re
sult
s [1]. YANG’s
re
se
arch foun
d o
u
t
that wh
en
so
me natu
r
al
or so
cial
i
n
ci
de
nts h
app
en, p
r
oba
bility of survival for
wo
unde
d is 80%
if
they can be
rescu
ed in 3
0
minute
s
, and this nu
m
ber g
oes
sh
arply do
wn t
o
40% and
10%
respe
c
tively, if the rescu
e
time are
60
minutes
a
nd
90 mi
nute
s
[
2
]. So it’s im
portant
to pl
a
n
a
“gold
en life route” b
e
twe
e
n
inci
dent
s si
te and
em
ergen
cy re
su
ce
agen
cy, and
respon
e the
s
e
emergen
cy v
ehicl
es in tim
e
at i
n
tse
c
tio
n
alo
ng th
e
route, an
d
give them
p
r
iorit
y
in g
r
ee
n tra
ffic
sign
als, e
s
pe
cially in co
ng
ested d
o
n
w
to
wn a
r
ea [3
] to
sho
r
ten thei
r travel
time. However, limited
by the fixed
point traffic i
n
formatio
n collectio
n,
traffic op
erational
mana
ger ca
n not
kno
w
t
he
status of
em
erge
ncy
vehi
cle
s
in
time,
whi
c
h
resul
t
in the
po
o
r
traffi
c
cont
rol
strate
gy
a
t
intersectio
n
s,
and
eme
r
g
e
n
cy vehi
cle
s
are
drow
ned in
c
o
nges
t traffic
flow,
which will
waste
valued re
scu
e
time meani
ngle
ssly.
In this
pape
r,
we
propo
se
d a
new traff
i
c
c
ontrol
strategy which
take
s the
em
erge
ncy
vehicle
statu
s
an
d cu
rrent
traffi
c situati
on at interse
c
tion
s into a
c
cou
n
t. The m
a
in idea
of the
control strate
gy is to pre
d
ict the arriv
a
l ti
me of emerg
e
n
c
y vehicle
s
, cle
a
r the queu
e at
intersectio
n
i
n
advan
ce, a
nd re
cove
r th
e norm
a
l cont
rol strategy a
s
so
on a
s
po
ssi
ble to reli
ef the
impact
of traf
fic in
co
nflicti
ng road
s. F
u
rtherm
o
re
, p
o
tential
safet
y
risk
cau
s
e
d
by em
erge
ncy
vehicle
wa
s a
l
so
con
s
id
ere
d
. Finally, wit
h
a case
stud
y, the benifit from the
co
ntrol strategy was
also a
nalyzed
2. Emergenc
y
Control Object Fuc
tion
Emerge
ncy t
r
affic control, t
o
some
exten
t, has
s
o
mething to do
with bus
priority
control
,
so in early st
udy, rese
archers
took two as the sam
e
probl
em
ca
lled “pri
ority and preempti
on”,
and
sep
a
rate
d them late
r
sin
c
e 1
980,
and d
e
fined
emergen
cy control a
s
pre
e
mption, whi
c
h i
s
highe
st level.
Evaluation Warning : The document was created with Spire.PDF for Python.
ISSN: 23
02-4
046
TELKOM
NI
KA
Vol. 12, No. 5, May 2014: 3313 – 33
22
3314
About its
obj
ect, mo
st re
sea
r
che
r
s be
lieved
that
minimal travel time of
e
m
erg
e
n
c
y
vehicle shoul
d be first, from Kolesa
r (1
975) to Lo
uisell (200
5), re
sea
r
che
r
s did
large predi
ctio
n
work
on it [4, 5].
Ho
wever, A
m
alia Vra
c
h
n
ou (2
003
) ‘
s
work [6]
sho
w
ed th
at at intersectio
n
there
we
re
lo
ts
o
f
po
te
n
t
ia
l sa
fe
ty r
i
sk
c
a
us
ed
b
y
eme
r
ge
nc
y vehicle,
whi
c
h
may re
sult to
severe eve
n
f
a
tal
accide
nts. So eme
r
gen
cy
traffic co
ntro
l not m
ean
s
absolute ri
gh
t of way, it should g
u
a
r
an
tee
again
s
t se
co
ndary a
cci
de
nt.
In recent years, with the in
creasi
ng congestion in urban ar
ea, on the premise of mobility
of emerg
e
n
cy vehicle, how to alleviate its di
sturba
nce a
nd imp
a
ct on
u
s
ual
soci
al vehicl
es
became the n
e
w issu
e to study [7].
Summari
zin
g
issue
s
abov
e, about the
t
r
avel time of
emergen
cy, it can
be de
scribed
as
follow:
0
0
li
e
w
s
f
l
L
TT
T
t
t
t
Vv
(1)
Where T is
t
he total trvavel time,
l
T
is travel time in links,
i
T
is the time going throu
gh
the intersecti
ons. About
l
t
,
we can get it throug
h follwi
ng formul
a:
/
l
f
e
v
TL
t
(2)
Whe
r
e
f
v
is th
e free
spee
d
of eme
r
ge
n
c
y vehi
cle,
e
t
is its delay ti
me be
ca
use
o
f
vehicle
s
(su
c
h as lan
e
ch
a
nge, ca
r follo
wing
)
in links
whi
c
h preven
t it
from free
driving.
About
i
t
, it inc
l
udes
three parts
as
follow:
00
/
w
il
Tl
v
t
t
(3)
Whe
r
e
00
/
lv
is th
e
the time e
m
erge
ncy ve
hi
cle traveling t
h
rou
gh th
e in
terse
c
tion,
w
t
is
the waiting
delay be
cau
s
e of tr
affic
sign
als at int
e
rsectio
n
,
l
t
is the loss ti
me ca
used
b
y
decelratio
n
,
acceration, q
ueue
dispe
r
si
on in f
r
ont of
intersectio
n
.
So we
can
see that
w
t
,
l
t
is
c
l
os
ely related to traffic
c
o
ntrol s
i
gnal.
About the p
o
tential safet
y
risk, two factor
s we
re taken
into a
c
count,
prob
ability
of
occuren
c
e of
accid
ent and its severity. The former
f
a
ctor i
s
mainl
y
related to traffic volume or
saturation
rat
i
o x if we
assume
that ca
pacity do
not
cha
nge,
JI’s re
sea
r
ch g
o
t the rel
a
tion
ship
[8], see a
s
f
o
rmul
a 4. Th
e later fa
cto
r
is mai
n
ly rel
a
ted to
spe
e
d
, highe
r
spe
ed me
and m
o
re
severe inju
rie
s
and d
eath
s
if accid
ent ha
ppen
s, FH
WA’s con
c
lu
sio
n
[9] was given as fo
rmula
5:
2
2
371.
1
3231
.
5
1656
.
1
Px
x
(4)
Whe
r
e P i
s
t
he p
r
oba
bility of occu
ren
c
e of accid
ent
, x is the saturation
ratio
whi
c
h e
qual
to
volume divide
d by capa
city.
4
(/
7
1
)
Lv
(5)
Whe
r
e
L is l
o
ss of a
c
cide
nts cau
s
ed
b
y
emerg
e
n
c
y re
scue vehi
cle,
v
is the
sp
eed of
vehic
l
es
. So we can get the s
a
fety risk
as
follow:
24
(
2
371.
1
323
1.
5
1656.
1
)
(
/
71
)
RP
L
x
x
v
(6)
Where R is
the s
a
fety risk
.
Evaluation Warning : The document was created with Spire.PDF for Python.
TELKOM
NIKA
ISSN:
2302-4
046
Em
ergency V
ehicl
e orie
nte
d
Traffic Prio
rity C
ont
rol Strategy at Interse
c
tion in… (Yao Jiao
)
3315
About the
effect of emerg
ency vehi
cle
to soical
traffic
(we c
a
ll “bac
kground
traffic
”
),
delay at interese
ction
wa
s sele
cted a
s
the perfo
rma
n
c
e ind
e
x.
2
1/
21
/
cg
c
d
qS
(7)
Whe
r
e
d
i
s
the averag
e del
ay of backgro
und traffic,
g
i
s
the green ti
me,
c
is the
cycle, q
is
the traffic
volume,
S
is
the satu
rated
flow. We
ca
n se
e
that when the
eme
r
gen
cy vehicl
e is
approa
chin
g,
gree
n time
of
co
nflicting
m
o
vement
i
s
sharply
shorte
n, so
the
del
a
y
will
be l
ong
er,
it’s importa
nt to compe
n
sate this gr
e
en l
o
ss in next one or several cycle
s
.
Overall, we g
e
t
the
em
erg
ency re
scue contro
l a
s
a
multi-obj
ect o
p
timization
problem,
the obje
c
t fuction is:
mi
n
(
,
,
)
TR
d
(8)
Whe
r
e
T
a
nd
d
are funci
o
sn of signal ti
ming pa
rame
ters
such as
cycle, green t
i
me, R is
the function o
f
speed a
nd volume, whi
c
h
we will ta
ke i
n
to accou
n
t whe
n
determi
ng yellow tim
e
.
3. Emergenc
y
Oriented T
r
affic Priority
Control
Con
s
id
erin
g the obj
ect a
b
o
ve, we di
cid
e
to take tim
e
se
rie
s
whe
n
maki
ng
co
ntrol of
emergen
cy vehicl
e. Wh
en
approa
chin
g
the interse
c
tion, jud
ge
the co
nge
sti
on statu
s
a
nd
disp
erse the
queu
e to make su
re that e
m
erg
e
n
c
y will
pass thro
ugh
the intersecti
on witho
u
t st
op
and
delay, de
tailed in
ch
ap
ter 3.1;
whe
n
passin
g
the
i
n
tersectio
n
,
prio
rity co
ntro
l will
be ta
ken
in
cha
p
ter 3.1, mean
while, safety
issues will
al
so be studied
in
cha
p
ter
3.4, and after
em
erg
e
n
cy
vehicle
s
’ pa
ssag
e, recovery strategy will
be carrie
d ou
t, detailed in cha
p
ter 3.4.
3.1. Conge
sted Intes
ectio
n Judgemen
t
and Disp
er
sion
In con
g
e
s
ted
con
d
ition, qu
eue le
ngth i
s
the majo
r fact
or, con
s
ide
r
in
g the sto
r
a
g
e
spa
c
e
betwe
en interse
c
tion
s, we
definite que
u
e
ratio as foll
ow:
0
q
c
Q
R
Q
(9)
Whe
r
e
q
R
the qu
eue ratio at links,
0
Q
is the nu
mber of qu
eu
e vehicle
s
,
c
Q
is the
maxim
stora
ge nu
mb
er of vehicle i
n
link. Wh
en
0
Q
appro
a
ching
to certain val
ue, the intese
ction will b
e
block
e
d or jams
, we definite this
as
j
Q
, so con
g
e
s
ted qu
eue ratio i
s
:
j
j
c
Q
R
Q
(10
)
In this way, we can g
e
t the con
g
e
s
tion ju
dgeme
n
t crite
r
ia as follo
w:
00
/
/
q
c
c
J
jc
j
R
QQ
Q
I
RQ
Q
Q
(11
)
Whe
r
e
c
I
is the Cong
estio
n
Index.
If
1
c
I
, the inte
rse
c
tion m
a
y blocke
d be
cau
s
e
of sto
c
ha
stic
oversaturation, it’
s
sug
g
e
s
ted th
at the emerg
ency vehi
cle
s
do
n’t sele
cted the ro
ut inclu
d
ing thi
s
intersectio
n
, if
unavoid
able,
it’s sug
g
e
s
te
d to interru
pt other move
m
ents imme
dia
t
ely to give th
e movement
s o
f
the emergen
cy vehicle more gree
n time to clea
r the qu
eue in adva
n
c
e.
Evaluation Warning : The document was created with Spire.PDF for Python.
ISSN: 23
02-4
046
TELKOM
NI
KA
Vol. 12, No. 5, May 2014: 3313 – 33
22
3316
If
1
th
c
II
(whe
re
th
I
is the thresh
ol
d of conge
st
ion), the sto
r
age spa
c
e is not
enou
gh fo
r q
ueuin
g
, mea
s
ure
s
sho
u
ld b
e
ca
rri
ed
out
to
re
strict th
e
irrel
a
ted m
o
vement of tra
ffic
flow from up
stream, and q
ueue
clea
ran
c
e shoul
d also start.
About the
di
spe
r
si
on
of
con
g
e
s
tion in
terse
c
tion,
we first
definit
e interse
c
tio
n
s
along
route (I
R) a
n
d
backg
ro
und
intersectio
n
s (BI), s
ee Fi
g
u
re1. And th
e
n
two metho
d
s
wa
s p
r
ovid
ed,
one is inte
rru
p
t traffic from
BI totally till
maxima
l red t
i
me whi
c
h we
call “cl
o
sure”, the other one
is giving it the minimal green time whi
c
h we call “m
inimal gre
en
transitio
n”. T
w
o condition
s are
given as follo
w to cho
o
se themetho
ds a
bove.
(1)
Dista
n
ce fro
m
eme
r
gen
cy vehicle to
con
g
e
s
ted int
e
rsectio
n
, se
e as f
o
rmul
a
12. If
the “minimal
gree
n tran
siti
on” can not cl
ear
the the q
ueue, we hav
e to close totally.
EV
lv
n
C
(12
)
W
h
er
e
l
the di
stan
ce fo
rm
emergen
cy v
ehicl
e to
inte
rse
c
tion
i
s
,
E
V
v
is
th
e s
p
ee
d
o
f
emergen
cy v
ehicl
e,
C
is the
cycl
e time
of
the
con
g
e
s
te
d inte
rsection
, and
n
is the
numbe
r
of
cycle, which is de
cide
d by cycle time an
d traffic volu
me.
(2)
Traffic volum
e
distrib
u
tion.
We definite d
i
stributio
n co
efficient D a
s
follow:
1
1
i
i
m
i
i
q
D
q
m
(13
)
Whe
r
e is
i
q
is the volume of movement
i
at the upstream interse
c
tion,
m
is
the total
numbe
r of movement
s at
the
u
p
st
ream
i
n
terse
c
tion. Ju
dge
the maximu
m
i
D
, if it’s the
movement
o
f
emergen
cy
vehicle, th
e up
stre
am
interse
c
tion
sh
ould toto
ally clo
s
e
other
movement
s except move
ment of em
erge
ncy v
ehi
cle, or give
them minimal gre
en time,
depe
nding Conge
stion
Ind
e
x
c
I
.
Figure 1. Net
w
ork an
d Interse
c
tion
Defi
n
i
tion for Emergen
cy Vehicl
e Control
3.2 Priorit
y
Passag
e Con
t
rol
Whe
n
emerg
ency vehicl
e approa
chin
g the inte
rsecti
on, we judg
e
its the arrival time,
and comp
are
it with the sig
nal display st
atus, if
the ph
ase of em
erg
ency vehi
cle i
s
not g
r
een,
we
sho
u
ld a
d
ju
st the si
gnal
timging i
n
follo
wing
way
s
: (1) g
r
ee
n exte
nsio
n, (2
) g
r
e
en a
c
tivation
in
advan
ce, (3
) pha
se jump.
(1) Gree
n
extension
Whe
n
em
erg
ency vehi
cle
arrive
s at
det
ector at time
t
, we jud
ge
the sig
nal
st
atus, if
satisfy followi
ng condition as form
ul
a 14, green duration will ex
tend
g
, which i
s
equ
al to
/
EV
LV
, to guarante
e
the passag
e
of emerg
e
n
c
y vehicle.
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Em
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ehicl
e orie
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d
Traffic Prio
rity C
ont
rol Strategy at Interse
c
tion in… (Yao Jiao
)
3317
ma
x
mi
n
E
VE
V
EV
EV
EV
n
e
xt
n
e
xt
EV
L
g
tg
V
L
gg
V
L
gg
V
(14
)
Whe
r
e
t
is the arrival time at detector,
EV
g
is the gree
n time durati
on of phase
of
emergen
cy vehicl
e,
L
is the distan
ce fro
m
detector to st
op line,
EV
V
is the spe
ed of emerg
e
n
c
y
vehicle,
n
ext
g
is the green tim
e
of next ph
ase,
mi
n
next
g
is the minimal gre
en time of n
e
xt
pha
se,
ma
x
g
is the
maximum g
r
e
en time of th
e pha
se
of e
m
erg
e
n
c
y vehicle,
whi
c
h i
s
de
cribed
as
follow:
ma
x
m
i
n
i
i
gC
L
o
s
s
g
(15
)
Whe
r
e
Lo
ss
is the total los
s
time in
one c
y
c
l
e,
mi
n
i
g
is the
mini
mal g
r
ee
n d
u
ration
of
pha
se
i
, whi
c
h inclu
de all p
hases ex
cept
phase of emerge
ncy vehi
cle.
(2)
Gree
n activat
i
on in advan
ce
If the arrival time of emerg
ency vehicl
e arri
ve
s is at end of red du
ration, it’s su
gge
ste
d
to cut
off the
the red
sig
n
a
l
, and
tran
sit
it to
green,
which
we call
”gree
n
activati
on in advance”.
Ho
wever, con
d
ition sh
ould
be sati
sfied a
s
follow:
mi
n
pr
e
p
r
e
E
VE
V
LL
gt
g
VV
(16
)
W
h
er
e
pre
g
is the
green
time o
f
previou
s
ph
ase,
mi
n
pre
g
is the
minimal
gre
e
n
time
of
previou
s
ph
a
s
e, othe
rs h
a
v
e the same
meanin
g
with
formula 14. I
f
the arrival time falls into the
minmal green of previous
phase,
the emergency vehicle has to wait till it
finish, see as formula
16.
mi
n
pr
e
s
t
p
r
e
E
V
L
tt
g
V
(17
)
Whe
r
e
pre
s
t
t
is th
e start time of previous p
h
a
se, othe
rs h
a
ve the sam
e
meanin
g
wi
th
formula 1
4
an
d 16.
(3)
Phase in
se
rti
on and jump
If the arrival time is not fa
r away from
t
he pha
se of
emerg
e
n
c
y vehicle, the
previou
s
pah
se, no
r at
the en
d of e
m
erg
e
n
c
y ph
ase
se
e
form
ula 17, t
w
o a
d
justme
nt wa
ys above
are
out
of service, we need jum
p
to the emerg
ency direct
ly, see a
s
Figu
re 2. We assu
mpe pha
se 1
as
the cu
rre
nt p
hase wh
en th
e emergen
cy
vehicle a
rriv
e
s, and
pha
se 3 as the
ph
ase
se
rvicin
g
fo
r
the emergen
cy movement (we call “em
e
rgen
cy pha
se”).
There a
r
e three ca
se
s we con
s
id
ere
d
(a) jum
p
to the emergen
cy phase 3 after pha
se 1, ingnore pha
se
2, and re
cov
e
ry next
cycle afte
r the emergen
cy
passag
e
. In this ca
se
pha
se
s igno
re
d a
r
e victimized,
so u
s
ually th
ey
are not imp
o
rtant, such a
s
minor traffi
c flow.
(b) jump
to t
he em
ergen
cy pha
se
3 af
ter p
h
a
s
e
1
and
re
cove
ry to ph
ase 2,
anothe
r
word, ch
ang
e
seq
uen
ce of
pha
se 2 a
n
d
pha
se 3. T
h
is
ca
se can
redu
ce th
e
delay of pha
se
s
ignored in case a, ho
we
ver, becau
se
of inse
rtio
n
of emerge
n
c
y pha
se, there i
s
still d
e
lay
increa
sem
ent
for these p
h
a
s
e
s
.
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22
3318
(c) if the end phase 1 is too long for e
m
erg
e
n
c
y vehicle waiting
or the situatio
n is very
seri
ou
s, at it
s arrival time,
jump to
ph
ase
3
a
fter
gre
e
n
interval
(sha
ded
area i
n
fi
gure
b
e
cause
of
safety co
nsi
d
eration
)
, an
d
then after
ph
ase
3, go
o
n
the re
st pa
rt
of pha
se 1
a
nd ph
ase2. T
h
is
ca
se i
s
mo
st efficient for e
m
erg
e
n
c
y vehicle, but
wo
rst for othe
r traffic, and be
cause pha
se
1
is
divided into t
w
o p
a
rts,
so
one g
r
ee
n int
e
rval is
add
e
d
, see
red
re
ctangl
e in Fi
gure
2 (c), th
e
cycle i
s
also extended.
o
r
pr
e
s
t
E
V
tt
t
g
(18)
Figure 2. Phase Jump Di
ag
ram (3
ca
se
s)
3.3. Normal Con
t
rol Stra
teg
y
Reco
v
e
ry
Because
of emergency phase, tr
affic fl
ow in other phases
w
ill be affected. In case of
“green
exten
s
ion
”
, all foll
owin
g ph
ase
s
a
r
e
affecte
d
, while
in
case
of “gre
e
n
a
c
tivation
in
advan
ce”, th
e previou
s
is affected, and in ca
se of “pha
se jum
p
”, the phase
s
that have been
jumped a
r
e af
fected, we all
these “affecte
d
pha
se”.
After passa
g
e
of emerge
ncy vehicl
e, co
mp
are the
summ
ation
of queue
ca
use
d
by
emergen
cy p
hase a
nd th
e a
rrival t
r
affic volu
me
wi
th its
dep
atu
r
e traffi
c
vo
lu
m
e
in
“
a
ffec
t
e
d
pha
se”,
if the
the form
er on
e is g
r
eate
r
th
en the
late
r
o
ne, see
a
s
fo
rmula
19,
whi
c
h me
an
s the
r
e
is
re
sidual
q
ueue
of
“affe
ct ph
ase” be
cau
s
e
of
e
m
erge
ncy pha
se, so green
du
ration of this
pha
se shoul
d
be extend.
i
=
1
,
2
,
3
,...n
i
i
in
it
i
i
i
gL
q
g
(19)
Whe
r
e
i
is the
number of af
fected pha
se,
i
is the arrival rate in phase
i
,
i
g
is the gree
n
duratio
n time of phase
i
,
ini
t
i
L
is the initial queue len
g
th at the beginni
ng of phase
i
,
i
q
is
the
depa
rture rat
e
in pha
se
i
.
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TELKOM
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ISSN:
2302-4
046
Em
ergency V
ehicl
e orie
nte
d
Traffic Prio
rity C
ont
rol Strategy at Interse
c
tion in… (Yao Jiao
)
3319
All affected
p
hases which
satisfy fo
rmul
a 18
(we
call
“seri
o
u
s
affe
cted
pha
se
s”) sh
ould
be extended
to certain val
ue as form
ul
a 19 theoret
ically, howeve
r
becau
se
of the limitation of
maximum g
r
een time
of p
hases
and
av
oidan
ce
of re
-affectivene
ss to oth
e
r
ph
ase
s
, we
sho
u
ld
recover to n
o
rmal
si
gnal
timing in
cre
a
sin
g
ly in
se
veral
cycle
s
,
not
sha
r
ply, be
cau
s
e
sh
arp
recovery may
lead to large
fluctuation of
traffic flow.
/(
)
je
x
t
h
i
n
i
t
j
j
j
j
g
Lq
g
(20
)
Whe
r
e
j
is th
e numbe
r of seri
ou
s affect
ed pha
se
s,
j
ex
th
g
is the green ex
tensio
n time of
pha
se j theoretically.
In the next cycle, ce
rtain p
e
rcentag
e green time of emerg
e
n
c
y ph
ase
sho
u
ld b
e
given to
other ph
ases,
the allocatio
n
prop
ortio
n
should b
e
de
ci
ded a
s
follow:
je
x
t
h
j
je
x
t
h
i
g
g
(21
)
Whe
r
e
j
is the allocatio
n
proportio
n
of affected p
h
a
s
e
j
.
Ho
wever,
green tim
e
of
emergen
cy p
hase
ca
n
not
sh
orte
ned
too m
u
ch to
affect it
s
operation in n
e
xt cycle, whi
c
h can be ex
pre
s
sed a
s
follow:
(1
)
(
)
0
E
V
EV
EV
gq
(22
)
Whe
r
e
is the percentag
e of shorte
ned
gree
n time of emerg
e
n
c
y pha
se,
EV
g
is it
s
norm
a
l g
r
ee
n
time in n
e
xt cycle,
and
EV
q
,
EV
are
dep
artu
re and
arrivial
ratio in
next
cycl
e
r
e
spec
tively.
So we ca
n ge
t that t
he shortend perce
nta
ge:
()
1
E
VE
V
EV
q
g
(23
)
Ho
wev
e
r, if
is
sm
aller than
10%, an
d 10%
is ad
opted to
co
mpen
sate
affecte
d
pha
se
s be
ca
use of p
r
iority
passag
e
co
n
t
rol of emerg
ency vehi
cle.
Finally, we ca
n get the gre
en extensio
n time
of
seriou
s af
f
e
ct
ed p
h
a
se
s in nex
t
cy
cle a
s
formula 2
4
:
j
e
xt
en
si
o
n
j
E
V
g
g
(24)
If one cy
cle
can
not reco
ver to the
no
rmal
sign
al ti
ming, re
peat
the procedu
re fro
m
formula
21 to
24 till the
affectivene
ss of
eme
r
gen
cy
pha
se di
sa
pp
ear. O
ne thi
n
g that shoul
d
be
mentione
d when doi
ng th
e rep
eat wo
rk is that we will repl
ace
j
ext
h
g
with
j
ex
t
h
j
exte
n
si
on
gg
in
formula 2
1
.
3.4. Potentia
l Safet
y
Risky
Consideration
As ch
apter 2
mentione
d, consequ
en
ce
of tr
affic acci
dent ca
used
by emerg
e
n
cy vehicle
is u
s
ually
se
riou
s,
so it
’
s
nec
es
sa
ry
t
o
t
a
ke
safety
issue
s
into
accout
whe
n
makin
g
cont
rol
strategy, e
s
p
e
cially ph
ase
transitio
n
bet
wee
n
eme
r
ge
ncy pha
se a
n
d
others.
Whe
n
ap
proa
chin
g the th
e
intersectio
n
with
hig
h
spe
ed at the
beg
inning
of yellow time,
driver ha
s
risky to tra
p
in
an a
r
ea
for
confused
d
e
ci
sion.
On o
ne
side,
with hi
g
h
speed
he
can’t
stop
safely (usu
ally wh
en
the vehicl
e
stop to
tally, it has al
re
a
d
y passe
d the sto
p
line
at
intersectio
n
, i
t
’s da
nge
rou
s
to collide
wit
h
othe
r vehi
cl
e (see
“Can
n
o
t stop
” a
r
ea
in Figu
re
3);
on
the other side, the distance i
s
so far t
hat he ha
s t
o
stop, or he will pass the stop line at
red
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22
3320
sign
al (Se
e
“Can
not pa
ss” are
a
),
when
trappi
n
g
the
overlap
area
(we
call “Dile
mma zone
”,see
“DZ
”
in Figure 3), drive do
n’t know what he will do next.
Figure 3. Dile
mma Zone
We d
e
finite that at the be
ginnin
g
of the
yellow
sign
al, distan
ce t
he eme
r
ge
ncy vehicle
from
stop line is
x
(m) an
d
speed
is
0
v
(m/s) .If the
diver
dec
ides
to pas
s
the inters
ec
tion,
we
assume he will go
with
the constant speed
0
v
in the
yel
l
ow
duration
y
T
, if he
de
cide
s to sto
p
,
we a
s
sum
e
t
hat de
cele
rati
on rate i
s
a
consta
nt va
lue
a_, an
d the
reactio
n
time f
o
r the
drive
r
t
o
stop is
.
The mini
mu
m dista
n
ce f
o
r a
vehicl
e
to st
op befo
r
e
sto
p
ba
r, can
be expressed as
follows
:
2
0
0
2
St
o
p
v
x
v
a
(25
)
If the driver
deci
de to pa
ss th
e sto
p
line befo
r
e
sig
nal turni
ng re
d, we
can d
e
f
ine the
maximum distance
P
ass
x
(m) as
:
0
P
as
s
Y
x
vT
(26
)
The ra
nge of
dilemma
zon
e
can b
e
give
n by inequalit
y 27:
0
2
0
0
2
v
a
v
x
T
v
Y
(27
)
From
form
ula
27,
we
can
see that if
P
ass
s
top
x
x
, the dilemm
a
zon
e
will
dis
a
pper. In this
ca
se, we
can
get followin
g
forlum
a:
0
Y
v
T
2a
(28)
So we can a
d
just the yell
ow du
ration
of tr
affic sign
al in pha
se transitio
n dep
e
nding o
n
spe
ed, de
cel
e
ration
rate a
nd rea
c
tion ti
me of driver.
4. Case Stud
y
In this chapte
r
, we sele
ct intersectio
n
at Jinqiao
Roa
d
and Zhan
g
y
ang Roa
d
a
s
the study
point, whi
c
h
are t
w
o
crossing
arte
rial
s at Pudo
ng
Distri
ct, Sha
n
ghai, China.
Figure 4
give
s its
lane an
d pha
se configu
r
ati
on.
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TELKOM
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ISSN:
2302-4
046
Em
ergency V
ehicl
e orie
nte
d
Traffic Prio
rity Cont
rol Strategy at Interse
c
tion in… (Yao Jiao
)
3321
(a) L
ane
confi
guratio
n
(b) Pha
s
e
co
nfiguratio
n
Figure 4. Con
f
iguration Info
rmation of Study Interse
c
ti
on
In
th
is s
t
ud
y, w
e
ass
u
me th
a
t
ph
as
e
4
is the
em
e
r
gen
cy
pha
se. Moreove
r
, we
lo
ad
different traffi
c volume
(sa
t
uration ratio
from 0.6
to 1) to s
i
mulate
diffe
rent con
g
este
d differen
t
scena
rio
s
, a
nd co
rron
spo
nding
cont
rol
strategi
es
a
r
e ge
nge
rate
d by cla
ssi
cal sign
al timing
optimizatio
n
softwa
r
e
Syncro,
ba
sed
o
n
whi
c
h
we a
d
j
u
st
sign
al timi
ng to
sati
sfy the
requi
rem
e
nt
of obje
c
t of e
m
erg
e
n
c
y vehicle i
n
ch
apt
er 2. Fin
a
lly, we
simulate
all these sce
nairo
s, with
a
nd
without emergen
cy-o
riente
d
pri
o
ri
ty con
t
rol in mi
rco
s
oft traffic si
m
u
lation
software VISSIM, and
get results in
Table 1 an
d Table 2.
We ca
n see
that
with
the control strateg
y
in
this stu
d
y
, the averag
e del
a
y of em
erge
ncy
vehicle
sha
r
p
l
y deacrea
s
e
d
by 68.63%,
while ave
r
ag
e delay of ba
ckgro
und ve
h
i
cle
s
incre
a
se
d
only 19.86%.
Furthe
rmo
r
e
,
in diffenent scena
rio
s
, the pe
rform
a
nce im
prove
m
ents a
r
e al
so
different, see
as Figu
re 5, with the incre
a
sin
g
of
s
a
turation ratio of intersec
tion, the benefit from
the cont
rol strategy in this study seem
s g
o
ing re
ce
ding
.
About the safety consid
eration a
nd strat
egy reco
very, we ca
n see that at lower
saturation
rati
o, the
effect
seem
s great, but
wh
en it’
s
nea
r
1, may
be b
e
cau
s
e
o
f
low spee
d,
no
vehicle in si
mulation trap
ped in delim
ma zon
e
. Moreove
r
, with the increa
sem
ent of saturat
i
on
ratio, the num
ber of cy
cle for re
cove
ry is also in
cre
a
si
ng sh
arply.
Figure 5. Perfomen
ce Improvement of
Control Strategy in this
Study
5. Conlusion
In this pap
er,
based on th
e study of co
ntrol
obje
c
t of emerg
e
n
c
y vehicle, we pro
p
osed a
new
sign
al control
strateg
y
for emerg
e
n
cy vehi
cl
e at intersectio
n
, which ca
n
be divided i
n
to
three pa
rts d
epen
ding on
time seri
es: “approa
chin
g”
,
“passin
g
“an
d
“re
cove
ring
”. Furthe
rmo
r
e,
from the
si
m
u
lation
and
validation
work, we
can
co
nclu
de th
at, with the
st
rat
egy in thi
s
p
aper,
delay of emerge
ncy vehi
cle can be
sha
r
ply de
creased with
relative few delay loss of
backg
rou
nd traffic. Ho
wev
e
r, with the increa
sing
of saturation rat
i
o of interse
c
tion, the benefit
‐
50.
00%
0.
00%
50.
00%
100.
00%
0.
6
0
.
7
0.
8
0
.
9
1
79.
75%
69.
95%
69.
55%
64.
32%
59.
57%
‐
20.
63%
‐
18.
75%
‐
15.
66%
‐
20.
11%
‐
24.
15%
Delay
(
s)
S
a
turation
rat
i
o
Performance improvement
Per
f
o
r
mance
improvement
of
Emergency
Vehi
cl
e
Per
f
o
r
mance
improvement
of
back
gr
o
und
traffic
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22
3322
seem
s goi
ng
recedin
g
. So it’s sug
g
e
s
te
d that w
hen
choo
sing route
for emer
gen
cy vehicle, we’d
better to avoi
d interse
c
tion
who
s
e
satu
ration ratio is
near 1.0 a
s
much
a
s
po
ssible. F
u
rthe
rmore,
the strate
gy in this p
ape
r
is only for th
e isol
ated int
e
rsectio
n
, m
a
ybe the
coo
r
dinate
d
cont
rol
strategy in a
r
terial o
r
route
of emerg
e
n
c
y vehicle
will g
i
ve more be
n
e
fit for the reductio
n
of tra
v
el
time of emergency vehi
cle, whi
c
h is al
so
the work we will go on in t
he future.
Table 1. Vehi
cle Delays at
Study Interse
c
tion
Dela
y
of em
erge
ncy vehicles (s)
Av
erage dela
y
of
background veh
i
cles
Saturation ratio a
t
intersection
Saturation ratio a
t
intersection
0.6 0.7
0.8 0.9
1
0.6 0.7 0.8
0.9
1
Control
st
r
a
t
e
gy
of
S
y
nchro
15.8 20.3
31.2 38.4
46.5
16.0 20.8 33.2
37.8 47.2
Control
strateg
y
in
this study
3.2
6.1
9.5
13.7
18.8
19.3 24.7 38.4
45.4 58.6
Performance
improvement
79.75%
69.95%
69.55%
64.32%
59.57
%
-
20.63
%
-
18.75
%
-
15.66
%
-
20.11
%
-
24.15
%
Average
Performance
improvement
68.63%
-19.86
%
Table 2. Simulation Results About Safety
Consi
deration and Strate
gy Recovery
Number of vehicles trapped in dilemma zone
Number of c
y
cle
for recover
y
Saturation ratio a
t
intersection
Saturation ratio a
t
intersection
0.6
0.7
0.8
0.9
1
0.6 0.7
0.8 0.9
1
Control strateg
y
of S
y
nchro
8
5
1
0
0
—
—
—
—
—
Control strateg
y
i
n
this study
6
4
1
0
0
1
2
2
4
6
Performance
imp
r
ovement
25.00%
20.00%
0.00%
0.00%
0.00%
—
—
—
—
—
Ackn
o
w
l
e
dg
ements
This
wo
rk wa
s supp
orte
d b
y
2012 Sh
an
ghai Yo
ung
University Te
a
c
he
r T
r
aini
ng
Subsidy
Schem
e(slg1
2009
)
，
Key
Labo
rato
ry o
f
Road
and
Traffic En
g
i
neeri
ng of t
he Mini
stry
of
Educatio
n, T
ongji
University (2011
07),
and Ph
D
st
art fund
s
of Unive
r
sity o
f
Shangh
ai for
Scien
c
e an
d Tech
nolo
g
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D
-1
0-303
-00
2
).
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