In article “Vertical Transportation Design and Traffic Calculations – Part Nine”, we indicated that we had two
Methods for Lift Traffic Design Calculations under the method of The FormulaBased Method,
which are:
 First Method: The Conventional Design Method,
 Second Method: The Iterative Balance Method.
We explained the First Method: The Conventional Design Method in the above
mentioned article. Today we will explain step by step the
Second
Method: The Iterative Balance Method
used for Lift Traffic design calculations with solved examples.
Let us take some examples to show when we need to use The Iterative
Balance Method.
Example#1:
This example is same to example#1 in article “Vertical Transportation Design and Traffic Calculations – Part Nine” but we
will solve it for the worst case design with no great prestige.
Design a lift system for a speculative,
regular office building having ten floors above the main terminal. Each floor
has 1500 m2 of net space. Assume an interfloor distance of 3.3 m.
Solution:
Step #

Step Description

1

Estimate the usable area
of the building
Usable area per floor
=75–80% of gross area = 80% x 1500 m2 = 1200 m2 per floor
Usable area for the
whole building = Usable area per floor x nos. of floors
= 1200 m2 x 10 = 12000 m2

2

Estimate the building’s
population
from Table1: Estimation
Of Population for regular office building
1012 m2/person – take the worst case as 10 m2/person
The estimated population
= the usable area of the building from step#1 / the area allocated per
person from Table1(in m2) = 12000 / 10
= 1200 person

3

Calculate the total daily population based on the attendance
ratio
the attendance ratio is not given, take it 80%
Total daily population = the building’s
population from step#2 x given attendance ratio = 1200 person x 80% = 960
person

4

Estimate peak Arrival Rate %
From Table2, estimate the peak arrival
rates for regular
office building
peak Arrival Rate % = 1115%
Take the worst
case value for peak Arrival Rate % = 15%.

5

Calculate the required
handling capacity in 5 minutes
the required handling capacity in 5 minutes = peak Arrival Rate % from step#4 x Total daily population from
step#3 = 15% x 960 = 144 person

6

Estimate Interval of car arrivals at the main terminal
Use Table2 to estimate the Interval of car arrivals at the
main terminal
So, the Interval of car arrivals at the main terminal = 2530
seconds
Usually take the higher
value to
save the capital expenditure of the building.
Then, Interval of car arrivals at the main terminal = 30 seconds

7

Calculate the Number of Round Trips over 5 minutes
the Number of Round Trips over 5 minutes = 5 minutes / Interval from step#6 = 300 / Interval from step#6 = 300/30 = 10

8

Calculate the Average
Number of Passengers per Trip (P)
the Average Number of
Passengers per Trip (P)= the required handling capacity in 5 minutes from
step#5 /Number of Round Trips over 5 minutes from step#7 = 144 person / 10 =
14.4 person

9

Calculate the car
capacity of the lift (CC)
the car capacity of the
lifts (CC) = P x 100/80 = 14.4 x 100/80 = 18 person

10

Select the nearest
standard car capacity
Select the rated
standard car capacity (CC) from Table3. So, the rated standard car capacity
(CC) = 21 person

11

Calculate the car load %
the car load % = the car capacity
from step#9 x 100 / standard rated car capacity from step#10 = 18 x
100 / 21 = 85.7%

12

Estimate the average
passenger waiting time AWT
From Table4, assign the
car load % from step#11 and find its related AWT/INT %.
For car load % = 85.7 %
, the related AWT/INT % = 1.01
So, the average
passenger waiting time AWT = 1.01 x 30 = 30.3 seconds

13

Calculate the Number of
Passengers per Trip P based on the nearest standard car capacity from step#10
P = CC x 80/100 = 21 x
80 / 100 = 16.8 person

14

Estimate the average
highest reversal floor (H) and expected number of stops (S)
From
Table6, assign the CC column and the Nos. of floors row, the intersection
will give H and S values.
For 10
nos. of floors and CC = 21 person:
H= 9.8, S = 8.3

15

Estimate the Interfloor distance (df) if it is not given
interfloor distance is given = 3.3 m

16

Calculate
total lift travel
Total Lift
Travel = nos. of floors x interfloor distance (df) =
10 x 3.3 m = 33 m

17

Estimate Rated Speed (V)
From Table8, assign the total lift travel value from step#16
and select the related rated speed.
For total lift travel = 33 m, the related rated speed = 1.6 m/s

18

Calculate Single Floor Transit Time (tv)
Single Floor Transit Time (tv) =
interfloor
distance (df) from step#15 / Rated Speed V from
step#17 = 3.3 / 1.6 = 2.1 second

19

Estimate single floor flight time tf(1)
From Table8 in above, assign the related single floor flight
time tf(1) with the total lift travel from step#16.
For total lift travel = 33 m, the related single floor flight time tf(1)
= 6 seconds

20

Estimate Door opening time (to) and Door
closing time (tc)
From Table9, assign the related Door opening time (to) and Door closing time (tc) based on the door operator, type and
opening.
Select center opening doors, advanced opening and
car width 1.1 meter gives
to = 0.8 second & tc = 3 seconds

21

Calculate door operating time (td)
Door Operating Time (td) = Door opening time (to) from step#20 +
Door closing
time (tc) from step#20 = 0.8 + 3 = 3.8 seconds

22

Calculate the performance time (T)
Performance Time (T) = door operating time (td) from step#21 +
single floor flight time tf(1) from
step#19 = 3.8 + 6 = 9.8 seconds

23

Calculate Time consumed when stopping (ts)
Time consumed when stopping (ts) = performance
time (T) from step#22 Single Floor Transit Time (tv) from step#18 = 9.8  2.1 = 7.7
seconds

24

Estimate Passenger transfer time (tp)
Select the passenger transfer time (tp) from the Table9 based
on the current design condition.
For car door width above 1 meter. tp = 1.2 seconds

25

Calculate the round trip
time (RTT),
The Round Trip Time
(RTT) = 2H t_{v} + (S+1)t_{s} + 2P
t_{p }= 2 (9.8) 2.1 + (8.3+1) (7.7) + 2 (16.8) 1.2 = 153.1 seconds
where:
H: the average highest
reversal floor from step#14,
tv: Single Floor Transit Time from step#18,
S: expected number of
stops from step#14,
ts: Time consumed when stopping from step#23,
P: the Number of
Passengers per Trip from step#13,
tp: Passenger transfer time from step#24.

26

Calculate the nos. of
lifts (L)
Nos. Of Lifts (L) = RTT
from step#25 / interval from step#6 = 153.1 / 30 = 5.1
Round the result to
nearest integer, then Nos. Of Lifts (L) = 5

27

Calculate the designed
interval (INT)
Actual Interval (INT) =
RTT from step#25 / L from step#26 = 153.1 / 5 = 30.62 seconds
designed
Interval (INT) 30.62 seconds nearly equals required Interval (INT) 30 seconds
 good design

28

Calculate the designed
handling capacity (HC) over 5 minutes
The Actual Handling
Capacity (HC) = P x L x 300/RTT = 16.8 x 5 x 300 / 153.1 = 164.6 person
where:
P: the Number of
Passengers per Trip from step#13,
L: Nos. Of Lifts from
step#26,
RTT: the Round Trip Time from step#25.

29

Calculate of The percentage population served (%POP)
The Percentage Population Served (%POP) = UPPHC from step#28 x
100 / total daily population from step#3 = 164.6 x 100 / 960 = 17.15%

30

Check the efficiency of
the lift system
The designed
handling capacity of the lift system over 5 minutes from step#28 ≥ the
arrival rate at morning 5 minutes uppeak period from step#5
Since 164.6 ≥ 144 with too
high margin, so this is Wasteful design and the
designer must repeat the evaluation.

31

Check the quality of the
service (grade of service)
No need since
the design is Wasteful.

Example#2:
Suppose the building of Example#1 were now
to be a prestigious building, what system would then be required?
Solution:
Step #

Step Description

1

Estimate the usable area
of the building
Usable area per floor
=75–80% of gross area = 80% x 1500 m2 = 1200 m2 per floor
Usable area for the
whole building = Usable area per floor x nos. of floors
= 1200 m2 x 10 = 12000 m2

2

Estimate the building’s
population
from Table1: Estimation
Of Population for regular office building
1012 m2/person  for prestigious building take the value
as 12 m2/person
The estimated population
= the usable area of the building from step#1 / the area allocated per
person from Table1(in m2) = 12000 / 12
= 1000 person

3

Calculate the total daily population based on the attendance
ratio
the attendance ratio is not given, take it 80%
Total daily population = the building’s
population from step#2 x given attendance ratio = 1000 person x 80% = 800
person

4

Estimate peak Arrival Rate %
From Table2, estimate the peak arrival
rates for regular
office building
peak Arrival Rate % = 1115%
Take the worst
case value for peak Arrival Rate % = 15%.

5

Calculate the required
handling capacity in 5 minutes
the required handling capacity in 5 minutes = peak Arrival Rate % from step#4 x Total daily population from
step#3 = 15% x 800 = 120 person

6

Estimate Interval of car arrivals at the main terminal
Use Table2 to estimate the Interval of car arrivals at the
main terminal
So, the Interval of car arrivals at the main terminal = 2530
seconds
take Interval of car arrivals at the main terminal = 25 seconds

7

Calculate the Number of Round Trips over 5 minutes
the Number of Round Trips over 5 minutes = 5 minutes / Interval from step#6 = 300 / Interval from step#6 = 300/25 = 12

8

Calculate the Average
Number of Passengers per Trip (P)
the Average Number of
Passengers per Trip (P)= the required handling capacity in 5 minutes from
step#5 /Number of Round Trips over 5 minutes from step#7 = 120 person / 12 = 10
person

9

Calculate the car
capacity of the lift (CC)
the car capacity of the
lifts (CC) = P x 100/80 = 10 x 100/80 = 12.5 person

10

Select the nearest
standard car capacity
Select the rated
standard car capacity (CC) from Table3. So, the rated standard car capacity
(CC) = 13 person
A 13 person car would be
considered too small for a prestige office building. A better size would be
16 person.

11

Calculate the car load %
the car load % = the car capacity
from step#9 x 100 / standard rated car capacity from step#10 = 12.5 x
100 / 16 = 78.13%

12

Estimate the average
passenger waiting time AWT
From Table4, assign the
car load % from step#11 and find its related AWT/INT %.
For car load % = 78.13 %
, the related AWT/INT % = 0.85
So, the average
passenger waiting time AWT = 0.85 x 25 = 21.25 seconds

13

Calculate the Number of
Passengers per Trip P based on the nearest standard car capacity from step#10
P = CC x 80/100 = 16 x
80 / 100 = 12.8 person

14

Estimate the average
highest reversal floor (H) and expected number of stops (S)
From Table6,
assign the CC column and the Nos. of floors row, the intersection will give H
and S values.
For 10
nos. of floors and CC = 16 person:
H= 9.7, S = 7.4

15

Estimate the Interfloor distance (df) if it is not given
interfloor distance is given = 3.3 m

16

Calculate
total lift travel
Total Lift
Travel = nos. of floors x interfloor distance (df) =
10 x 3.3 m = 33 m

17

Estimate Rated Speed (V)
From Table8, assign the total lift travel value from step#16
and select the related rated speed.
For total lift travel = 33 m, the related rated speed = 1.6 m/s

18

Calculate Single Floor Transit Time (tv)
Single Floor Transit Time (tv) =
interfloor
distance (df) from step#15 / Rated Speed V from
step#17 = 3.3 / 1.6 = 2.1 second

19

Estimate single floor flight time tf(1)
From Table8 in above, assign the related single floor flight
time tf(1) with the total lift travel from step#16.
For total lift travel = 33 m, the related single floor flight time tf(1)
= 6 seconds

20

Estimate Door opening time (to) and Door
closing time (tc)
From Table9, assign the related Door opening time (to) and Door closing time (tc) based on the door operator, type and
opening.
Select center opening doors, advanced opening and
car width 1.1 meter gives
to = 0.8 second & tc = 3 seconds

21

Calculate door operating time (td)
Door Operating Time (td) = Door opening time (to) from step#20 +
Door closing
time (tc) from step#20 = 0.8 + 3 = 3.8 seconds

22

Calculate the performance time (T)
Performance Time (T) = door operating time (td) from step#21 +
single floor flight time tf(1) from
step#19 = 3.8 + 6 = 9.8 seconds

23

Calculate Time consumed when stopping (ts)
Time consumed when stopping (ts) = performance
time (T) from step#22 Single Floor Transit Time (tv) from step#18 = 9.8  2.1 = 7.7
seconds

24

Estimate Passenger transfer time (tp)
Select the passenger transfer time (tp) from the Table9 based
on the current design condition.
For car door width above 1 meter. tp = 1.2 seconds

25

Calculate the round trip
time (RTT),
The Round Trip Time
(RTT) = 2H t_{v} + (S+1)t_{s} + 2P
t_{p }= 2 (9.7) 2.1 + (7.4+1) (7.7) + 2 (12.8) 1.2 = 136.1 seconds
where:
H: the average highest
reversal floor from step#14,
tv: Single Floor Transit Time from step#18,
S: expected number of
stops from step#14,
ts: Time consumed when stopping from step#23,
P: the Number of
Passengers per Trip from step#13,
tp: Passenger transfer time from step#24.

26

Calculate the nos. of
lifts (L)
Nos. Of Lifts (L) = RTT
from step#25 / interval from step#6 = 136.1 / 25 = 5.44
Round the result to
nearest integer, then Nos. Of Lifts (L) = 5

27

Calculate the designed
interval (INT)
designed Interval (INT)
= RTT from step#25 / L from step#26 = 136.1 / 5 = 27.22 seconds
designed
Interval (INT) 27.22 seconds ˃ required Interval (INT) 25 seconds with too
high margin

28

Calculate the designed
handling capacity (HC) over 5 minutes
The Actual Handling
Capacity (HC) = P x L x 300/RTT = 12.8 x 5 x 300 / 136.1 = 141.1 person
where:
P: the Number of
Passengers per Trip from step#13,
L: Nos. Of Lifts from
step#26,
RTT: the Round Trip Time from step#25.

29

Calculate of The percentage population served (%POP)
The Percentage Population Served (%POP) = UPPHC from step#28 x
100 / total daily population from step#3 = 141.1 x 100 / 800 = 17.64%

30

Check the efficiency of
the lift system
The designed
handling capacity of the lift system over 5 minutes from step#28 ≥ the
arrival rate at morning 5 minutes uppeak period from step#5
Since 141.1 ≥ 120 with too
high margin, so this is Wasteful design and the
designer must repeat the evaluation.

31

Check the quality of the
service (grade of service)
No need since
the design is Wasteful.

Second
Method: The Iterative Balance Method

Usually The Iterative
Balance Method is used when the Conventional Design Method calculations give nonefficient
results like:
The Iterative Balance
Method presents the idea of matching the lift handling capacity to the
desired handling capacity exactly. This is achieved by not rigidly fixing P
as a percentage of rated car capacity (80% for example) but P is allowed to
take the most appropriate value and P will be equal to Î» INT.
P = Î» INT
To obtain values for H
and S for the number of passengers to be carried in the car, use Table1
which gives values for integer values of P from five to 20 persons.
Table1.A: Values of H and S with respect to number of passengers carried in car (P)
For 5 to 12 passengers per trip
Table1.B: Values of H and S with respect to number of passengers
carried in car (P)
For 13 to 20 passengers per trip

Step By
Step Design Of Lift Systems By Using
The
Iterative Balance Method

Step #

Step Description


1

Estimate the usable area
of the building


2

Estimate the building’s
population


3

Calculate the total daily population based on the attendance
ratio


4

Estimate peak Arrival Rate %


5

calculate the required
handling capacity in 5 minutes


6

Estimate Interval of car arrivals at the main terminal


7

calculate the Number of Round Trips over 5 minutes


8 IBM

Calculate the Average
Number of Passengers per Trip (P)
calculate Î» rate of
passenger arrivals over 5 minutes
Î» in person/second = The Required Handling Capacity in 5
Minutes from step#5 / 300
Then, P = Î» x INT from step#6


9 IBM

Estimate the average
highest reversal floor (H) and expected number of stops (S) from Table1 in
above based on the intersection of number of floors (N) above main terminal
row and the Average Number of Passengers per Trip (P) column


10

Estimate
the Interfloor distance (df) if it is not given


11

Calculate total lift travel


12

Estimate Rated Speed (V)


13

calculate Single Floor Transit Time (tv)


14

Estimate single floor flight time tf(1)


15

Estimate Door opening time (to) and Door closing time (tc)


15

Calculate door operating time (td)


17

Calculate the performance time (T)


18

Calculate Time consumed when stopping (ts)


19

Estimate Passenger transfer time (tp)


20

Calculate the round trip
time (RTT),


21

calculate the nos. of
lifts (L)


22

Calculate the designed
interval (INT)


23IBM

Compare the estimated
interval in step#6 with the designed interval in step#22, if they are close
enough or matching go to step#25IBM and if significantly different, go to
step#24IBM.


24IBM

Estimate another value
for the interval. A possible new trial for (INT) could be:
New
INT=INT (step (22))+[INT (step (22))−INT (step (6))]
then iterate step#8IBM
to assign a new value of (P)
then iterate step#9IBM
to assign a new value of H and S
then iterate step#25 to
assign new value for RTT
then iterate step#21 to calculate
the nos. of lifts (L)
then iterate step#22 to Calculate
the Iterative designed interval (INT)
then iterate step#23IBM
Compare the new INT in step#24IBM with
the Iterative designed interval in calculated in step#24IBM , if they are
close enough or matching go to step#25IBM and if significantly different,
iterate step#24IBM.
Note:
iterate step#24IBM
till the estimated interval in step#6 with the designed interval in step#22
become close enough/matching to get an efficient design.


25IBM

Select a suitable standard car capacity (CC), which allows
approximately 80% average car load and same as
CC = last iterative P x 100/80
Then use Table2
to get the suitable standard car capacity (CC):
Table2: Car loading and car capacity
Notes:
Rated Car Capacity (CC)
calculated by dividing the value for Rated Load RL by 75 as EN81, Clause
8.2.3.
In step#25, it is
important to remember that, where an average car load is much greater than
80%, poor passenger service might result, ie: long waiting times and queues.
The designer must select a suitable car size to meet desired economic and
operating conditions.


26

Check the quality of the
service (grade of service)
We have many options for checking The Quality Of The
Service (Grade Of Service) as follows:
Option#1:
Check the quality of the service based on Based on The designed interval (INT)
By using Table3, assign
the related quality of service for the iterative designed interval (INT).
Table3:
Probable quality of service in office buildings
Option#2: Check the Quality of Service based
on the performance time T
For a 3.3 m interfloor
height use Table4 to assign the related quality of service for the
calculated performance time T from step# 17.
Table4:
the performance time (T) as an indicator of quality of service
Option#3: Check the Quality of Service based
on Passenger
Average Travel Time to Destination (ATT)
Use the following rule
of thumb to check the Quality of Service based on Passenger Average Travel Time to Destination
(ATT):
ATT =_{ }0.5H t_{v} + 0.5 S t_{s}
+ P t_{p}
Where:
H: the last iterative average
highest reversal floor from step#24IBM,
tv: Single Floor Transit Time from step#13,
S: last iterative expected
number of stops from step#24IBM,
ts: Time consumed when stopping from step#18,
P: the last iterative Number
of Passengers per Trip from step#24IBM,
tp: Passenger transfer time from step#19.
Then, The Quality of
Service based on Passenger Average Travel Time to Destination (ATT) is estimated as
per the below table:
Option#4: Check the Quality of Service based
on Passenger
Average Journey Time (AJT)
Use the following rule
of thumb to Check the Quality of Service based on Passenger Average Journey Time (AJT):
AJT =_{ }0.5H t_{v} + 0.5 S t_{s}
+ P t_{p }+ 0.5 INT
Where:
H: the last iterative average
highest reversal floor from step#24IBM,
tv: Single Floor Transit Time from step#13,
S: last iterative expected
number of stops from step#24IBM,
ts: Time consumed when stopping from step#18,
P: the last iterative Number
of Passengers per Trip from step#24IBM,
tp: Passenger transfer time from step#19.
INT: the last iterative designed interval (INT) from step#24IBM.
Then, The Quality of
Service based on Passenger Average Journey Time (AJT) is estimated as per the below
table:


Note:
All steps designated as
IBM step means this step is included only in the Iterative Balance Method.
Other steps are the same as explained before in the Conventional Design
Method in Article “Vertical Transportation Design and Traffic Calculations – Part Nine”.

Example#3
In Example#2 in above, there was too much
handling capacity and a poorer interval than desired. Use the Iterative Balance
Method indicated to enhance the designed lift system.
Solution:
Step #

Step Description

1

As in example#2

2


3


4


5


6


7


8 IBM

Calculate the Average
Number of Passengers per Trip (P)
calculate Î» rate of
passenger arrivals over 5 minutes
Î» in person/second = The Required Handling Capacity in 5
Minutes from step#5 / 300 = 120/300 = 0.4 person/second
Then, P = Î» x INT from step#6 = 0.4
x 25 = 10 persons

9 IBM

Estimate the average
highest reversal floor (H) and expected number of stops (S) from Table1 in
above based on the intersection of number of floors (N) above main terminal
row and the Average Number of Passengers per Trip (P) column
For N = 10 and P = 10 ,
H = 9.5 and S = 6.5

10

As in example#2

11


12


13


14


15


15


17


18


19


20

Calculate the round trip
time (RTT),
The Round Trip Time
(RTT) = 2H t_{v} + (S+1)t_{s} + 2P
t_{p }= 2 (9.5) 2.1 + (6.5+1) (7.7) + 2 (10) 1.2 = 121.7 seconds
where:
H: the average highest
reversal floor from step#9IBM,
tv: Single Floor Transit Time from step#13,
S: expected number of
stops from step#9IBM,
ts: Time consumed when stopping from step#18,
P: the Number of
Passengers per Trip from step#8IBM,
tp: Passenger transfer time from step#19.

21

calculate the nos. of
lifts (L)
Nos. Of Lifts (L) = RTT
from step#20 / interval from step#6 = 121.7 / 25 = 4.87
Round the result to
nearest integer, then Nos. Of Lifts (L) = 5

22

Calculate the designed
interval (INT)
designed Interval (INT)
= RTT from step#20 / L from step#21 = 121.7 / 5 = 24.34 seconds

23IBM

Compare the estimated
interval in step#6 with the designed interval in step#22 and if significantly
different
The estimated interval
in step#6 = 25 seconds while the designed interval in step#22 = 24.34 seconds
which are significantly different then go to step#24IBM.

24IBM

Estimate another value
for the interval. A possible new trial for (INT) could be:
New INT=INT
(step (22))+[INT (step (22))−INT (step (6))] = 24.34 + (24.34 – 25) =
23.68 seconds
then iterate step#8IBM
to assign a new value of (P)
P = Î» x INT from step#6 = 0.4 x 23.68 = 9.47 persons
then iterate step#9IBM
to assign a new value of H and S
H = (9.5 +9.4)/2 = 9.45
and S = (6.1+6.5)/2 = 6.3
then iterate step#23IBM
to assign new value for RTT
The Round Trip Time
(RTT) = 2H t_{v} + (S+1)t_{s} + 2P
t_{p }= 2 (9.45) 2.1 + (6.3+1) (7.7) + 2 (9.47) 1.2 = 118.63 seconds
Then iterate step#21 to
calculate the nos. of lifts (L)
Nos. Of Lifts (L) = 118.63
/ 23.68 = 5
Then iterate step#22 to
Calculate the Iterative designed interval (INT)
designed Interval (INT)
= 118.63 / 5 = 23.73 seconds
then iterate step#23IBM
to Compare the new INT in step#24IBM
with the Iterative designed interval in calculated in step#24IBM ,so:
the new INT in step#24IBM = 23.68 seconds and the Iterative designed interval in
calculated in step#24IBM = 23.73 seconds
Since, they are close
enough go to step#25IBM (difference is 0.05 seconds only)

25IBM

Select a suitable standard car capacity (CC), which allows
approximately 80% average car load and same as
CC = last iterative P x 100/80 = 9.47 x 100/80 = 11.84 person
Then use Table2
to get the suitable standard car capacity (CC) which will be 13 persons.
The car loading% =
11.84/13 = 91% ˃80%
So, select a bigger car
capacity like 16 person
The car loading% =
11.84/16 = 74% ˂80%

26

Option#1:
Check the quality of the service based on Based on The designed interval (INT)
For the iterative designed
interval (INT) = 23.73 seconds, the quality of the
service is very good.
Option#2: Check the Quality of Service based
on the performance time T
Use Table4 to assign the
related quality of service for the calculated performance time T from step#
22.
For performance time T =
9.8 seconds, the quality of the service is good.
Option#3: Check the Quality of Service based
on Passenger
Average Travel Time to Destination (ATT)
ATT =_{ }0.5H t_{v} + 0.5 S t_{s}
+ P t_{p}^{ }= 0.5 (9.45) 2.1 + 0.5 (6.3) 7.7 +9.47 (1.2) = 45.54
seconds
Since ATT <60s, the quality of the service is good.
Option#4: Check the Quality of Service based
on Passenger
Average Journey Time (AJT)
AJT =_{ }0.5H t_{v} + 0.5 S t_{s}
+ P t_{p }+ 0.5INT = 0.5 (9.45) 2.1 + 0.5 (6.3) 7.7 + 9.47 (1.2) +
0.5 (23.73) = 9.975+25.795+12.48+15.525 = 57.4 seconds
Since AJT <80s, the quality of the service is good.

In the next article, we will explain step
by step The Iterative Balance Method for Lift Traffic design calculations with solved examples. Please, keep
following.
The previous and related articles
are listed in below table:
Subject Of Previous
Article

Article

Applicable Standards and Codes
Used In This Course,
The Need for Lifts,
The Efficient Elevator Design Solution
Parts of Elevator System Design Process
Overview of Elevator Design and
Supply Chain Process.


The
Concept of Traffic Planning,
The (4) Methods
of Traffic Design Calculations,
Principles of
Interior Building Circulation:
A Efficiency of Interior
Circulation


B Human Factors


C Circulation and Handling Capacity
Factors:
Corridor handling capacity,
Portal handling capacity,
Stairway handling capacity,
Escalator handling capacity,


Passenger Conveyors (Moving Walkways and Ramps) handling
capacity,
Lifts Handling Capacity.
D Location And Arrangement Of Transportation Facilities


Traffic design calculations:
1 Calculation of the Number of Round Trips for a Single Car,
2 Estimation of Population,
3 Calculation of the Average Number of Passengers per Trip (P),
4 Calculation of the Uppeak Handling Capacity (UPPHC),
5 Calculation of the Waiting Interval (Passenger Waiting Time),
6 Calculation of The percentage population served (%POP),


7 Estimation of Arrival Rate,
8 Calculation of the Round Trip Time RTT,


9 Calculation of the quality of service (Grade of
Service)


Methods for Lift Traffic Design Calculations:
First Method: The Conventional Design Method

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