Vertical Transportation Design and Traffic Calculations – Part Ten

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 Formula-Based Method, which are:
1. First Method:  The Conventional Design Method,
2. 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 Table-1: Estimation Of Population for regular office building 10-12 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 Table-1(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 Table-2, estimate the peak arrival rates for regular office building peak Arrival Rate % = 11-15% 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 Table-2 to estimate the Interval of car arrivals at the main terminal So, the Interval of car arrivals at the main terminal = 25-30 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 Table-3. 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 Table-4, 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 Table-6, 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 Table-8, 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 Table-8 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 Table-9, 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 Table-9 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 tv + (S+1)ts + 2P tp = 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 Table-1: Estimation Of Population for regular office building 10-12 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 Table-1(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 Table-2, estimate the peak arrival rates for regular office building peak Arrival Rate % = 11-15% 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 Table-2 to estimate the Interval of car arrivals at the main terminal So, the Interval of car arrivals at the main terminal = 25-30 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 Table-3. 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 Table-4, 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 Table-6, 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 Table-8, 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 Table-8 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 Table-9, 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 Table-9 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 tv + (S+1)ts + 2P tp = 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 non-efficient results like: The handling capacity was larger than that required as in example#1 in above, The required interval was not achieved as in example#2 in above. 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 λ INT. P = λ INT To obtain values for H and S for the number of passengers to be carried in the car, use Table-1 which gives values for integer values of P from five to 20 persons. Table-1.A: Values of H and S with respect to number of passengers carried in car (P) For 5 to 12 passengers per trip Table-1.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 λ rate of passenger arrivals over 5 minutes
λ in person/second  = The Required Handling Capacity in 5 Minutes from step#5 / 300

Then, P = λ x  INT from step#6

9- IBM
Estimate the average highest reversal floor (H) and expected number of stops (S) from Table-1 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)
23-IBM
Compare the estimated interval in step#6 with the designed interval in step#22, if they are close enough or matching go to step#25-IBM and if significantly different, go to step#24-IBM.

24-IBM
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#8-IBM to assign a new value of (P)
then iterate step#9-IBM 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#23-IBM Compare the new INT  in step#24-IBM with the Iterative designed interval in calculated in step#24-IBM , if they are close enough or matching go to step#25-IBM and if significantly different, iterate step#24-IBM.

Note:
iterate step#24-IBM till the estimated interval in step#6 with the designed interval in step#22 become close enough/matching to get an efficient design.

25-IBM
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 Table-2 to get the suitable standard car capacity (CC):

 Rated load (kg) (RL) Max area (m2) (CA) Rated capacity (persons) (CC) Actual capacity (persons) (AC) Design capacity (persons) (DC) Capacity factor (%) (CF) Actual load (kg) (AL) 320 0.95 4 4.5 3.6 90 338 450 1.30 6 6.2 5.0 82 465 630 1.66 8 7.9 6.3 79 593 800 2.00 10 9.5 7.6 76 713 1000 2.40 13 11.4 9.1 70 855 1275 2.90 16 13.8 11.0 69 1035 1600 3.56 21 16.9 13.5 64 1268 1800 3.92 24 18.6 14.9 62 1395 2000 4.20 26 20.0 16.0 62 1500 2500 5.00 33 23.8 19.0 58 1785
Table-2: 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 Table-3, assign the related quality of service for the iterative designed interval (INT).

 Interval (s) Quality of service ≤20 Excellent 25 Very good 30 Good 40 Poor ≥ 50 Unsatisfactory

Table-3: 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 Table-4 to assign the related quality of service for the calculated performance time T from step# 17.

 Value of T (s) Quality Of Service For The Lift System 8.0-9.0 Excellent system 9.0-10.0 Good system 10.0-11.0 Average system 11.0-12.0 Poor system >12.0 Consider system replacement

Table-4: 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 tv + 0.5 S ts + P tp

Where:
H: the last iterative average highest reversal floor from step#24-IBM,
tv: Single Floor Transit Time from step#13,
S: last iterative expected number of stops from step#24-IBM,
ts: Time consumed when stopping from step#18,
P: the last iterative Number of Passengers per Trip from step#24-IBM,
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:

 Time Aim for Poor ATT <60s >70s

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 tv + 0.5 S ts + P tp + 0.5 INT

Where:
H: the last iterative average highest reversal floor from step#24-IBM,
tv: Single Floor Transit Time from step#13,
S: last iterative expected number of stops from step#24-IBM,
ts: Time consumed when stopping from step#18,
P: the last iterative Number of Passengers per Trip from step#24-IBM,
tp: Passenger transfer time from step#19.
INT: the last iterative designed interval (INT) from step#24-IBM.

Then, The Quality of Service based on Passenger Average Journey Time (AJT) is estimated as per the below table:

 Time Aim for Poor AJT <80s >90s

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 “

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 λ rate of passenger arrivals over 5 minutes λ in person/second  = The Required Handling Capacity in 5 Minutes from step#5 / 300 = 120/300 = 0.4 person/second  Then, P = λ 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 Table-1 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 tv + (S+1)ts + 2P tp = 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#9-IBM, tv: Single Floor Transit Time from step#13, S: expected number of stops from step#9-IBM, ts: Time consumed when stopping from step#18, P: the Number of Passengers per Trip from step#8-IBM, 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 23-IBM 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#24-IBM. 24-IBM 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#8-IBM to assign a new value of (P) P = λ x  INT from step#6 = 0.4 x 23.68  = 9.47 persons then iterate step#9-IBM 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#23-IBM to assign new value for RTT The Round Trip Time (RTT) = 2H tv + (S+1)ts + 2P tp = 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#23-IBM to Compare the new INT  in step#24-IBM with the Iterative designed interval in calculated in step#24-IBM ,so: the new INT  in step#24-IBM = 23.68 seconds  and the Iterative designed interval in calculated in step#24-IBM = 23.73 seconds Since, they are close enough go to step#25-IBM (difference is 0.05 seconds only) 25-IBM 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 Table-2 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 Check the quality of the service (grade of service) 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 Table-4 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 tv + 0.5 S ts + P tp = 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 tv + 0.5 S ts + P tp + 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 how to calculate the Lift Motor Size HP/KW and its Energy Consumption. 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