Transcript Lecture 6 - Offset and Delay

Topic 6
Delay and Offset
CEE 764 – Fall 2010
Delay

Delay: the most commonly used performance
measure
 Types of Intersection Delays



Stopped delay
Total delay (control delay)
Time in queue delay
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Delay Studies
Distance
Total Delay
(Control Delay)
Stopped
Delay
Deceleration
Stop Line
Acceleration
Time
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Time in Queue Delay
Distance
Stopped
Delay
Stop Line
Time in Queue
Delay
Time
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The HCM Delay Equation
d  d1PF  d 2  d3
0.5C 1  g / C 
d1 
1  min( 1, X )  g / C 
2
Uniform Delay

8klX 
2
d 2  900T ( X  1)  ( X  1) 

cT 

CEE 764 – Fall 2010
Uniform Delay
0.5C 1  g / C 
d1 
1  min( 1, X )  g / C 
Cumulative Arrival
2
V
S
r
g0
Cumulative Departure
g
C
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Uniform Delay
Cumulative Arrival
V
S
S
C
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C
Cumulative Departure
Cumulative Arrival
Random and Over-saturation Delay
V
S
S
C
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C
Cumulative Departure
Delay with Initial Queue
Cumulative Arrival
V
S
S
C
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C
Cumulative Departure
Uniform Delay with Platoon Arrival
Cumulative Arrival
(Platoon on Red)
N
S
r
g
C
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Cumulative Departure
Uniform Delay with Platoon Arrival
Cumulative Arrival
(Platoon on Green)
N
S
r
g
C
CEE 764 – Fall 2010
Cumulative Departure
Example
Assume a two-lane one-way street links two
intersections i and j, which is 800 feet apart. The oneway link flow is all through traffic and has a volume of
1000 vph. Saturation flow rate is all 1800 vphpl.
Assume vehicle travel speed is 25 mph. The system
cycle is 70 sec, and the effective arterial through greens
for the upstream (i) and downstream (j) intersections
are 35 sec and 30 sec, respectively. The offsets are 0
and 20 sec for the two intersections, referencing to the
start of green of the arterial phases (i.e., arterial phase
green at j starts 20 sec later after i).
Calculate the uniform delay at intersection j considering
(1) no platoon dispersion; (2) with platoon dispersion
(α=0.35, β=0.80); (3) What if the offset is 40 sec?
CEE 764 – Fall 2010
Flow Rate
No Platoon Dispersion
s
v
t0
ru
gu
Time
C
s
T.T
θ
v
gd
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C
rd
Time
Offset - 20
Delay = 3.7 sec/veh
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Offset - 40
Delay = 13.6 sec/veh
CEE 764 – Fall 2010