Vertical Transportation Design and Traffic Calculations – Part Four


In Article “Vertical Transportation Design and Traffic Calculations – Part Two”, we indicated that the Principles of Interior Building Circulation are:

  1. Efficiency of Interior Circulation,
  2. Human Factors,
  3. Circulation and Handling Capacity Factors,
  4. Location and Arrangement of Transportation Facilities.
We explained the first principle in above article and explained the human factors in article “Vertical Transportation Design and Traffic Calculations – Part Three”.

Today we will continue explaining other Principles of Interior Building Circulation.


Principles of Interior Building Circulation

  

Third: Circulation and Handling Capacity Factors

The handling capacity of a vertical transportation system is the total number of passengers that a vertical transportation system can transport in a certain period as per certain conditions. In the next sections we will study how to calculate the handling capacities for the following items:
  1. Corridor handling capacity,
  2. Portal handling capacity,
  3. Stairway handling capacity,
  4. Escalator handling capacity,
  5. Passenger Conveyors (Moving Walkways and Ramps) handling capacity,
  6. Lifts Handling Capacity.


1- Corridor handling capacity



The term ‘corridor’ is defined as the areas whose main function is to provide a connection between major spaces or operational areas. it include passage ways, walkways, subways etc. They do not include areas where waiting can occur, such as shopping malls. The capacity of a straight corridor can be given as:
Cc = 60VDW               Equation (1)
Where:
Cc is the corridor handling capacity (persons/minute)
V is average pedestrian speed (m/s),
D is the average pedestrian density (persons/m2),
W is the effective corridor width (m).
Table-1 shows the Density of persons in Person/ m2 in a corridor and its effect on design.
Density Person/ m2
Effect on design
below 0.3 P/ m2
free flow design: pedestrians can walk freely (see fig.1)
above 0.5 P/ m2
linear decrease of average walking speed
1.4 P/ m2
full flow design (see fig.1)
Table-1
Fig.1: Free and Full Flow Designs for Corridor
The Walking speeds vary systematically with respect to:
  1. Type of population (age, gender, grouping, purpose),
  2. Ability (fitness, handicap),
  3. Flow direction,
  4. Gradient,
  5. Air temperature and humidity,
  6. Floor finish.
Table-2 indicates empirically derived average Pedestrian speed values as guidance. The table shows the typical pedestrian horizontal speeds (in m/s) and pedestrian flows in persons per minute (persons/minute) for a free flow design density of 0.3 person/m2 and a full flow design density of 1.4 person/m2. The flows assume a corridor width of 1.0 m.
Type of traffic
Pedestrian speed and flow for stated pedestrian design density
Free flow design density (0.3 person/m2)
Full flow design density (1.4 person/m2)
Speed (m/s)
Flow rate
(person/min)
Flow rate
(person/h)
Speed (m/s)
Flow rate
(person/min)
Flow rate
(person/h)
Commuters, working
persons
1.5
27
1620
1.0
84
5040
Individual shoppers
1.3
23
1380
0,8
67
4020
Family groups, tourists
1.0
18
1080
0.6
50
3000
School children
1.1-1.8
18-32
1080-1920
0.7-1.1
59-92
3540-5520
Table-2
The width of corridor is not specific, but must be at least 900 mm and is assumed to be 1.0 m. Equation (1) allows for the flow rate to increase/decrease as the corridor width increases/decreases. This factor must be used with care, as small changes in corridor width will have little or no effect.
Table-3 shows Minimum width for corridors to accommodate various types of traffic. A (3) meter wide corridor would allow most traffic types to be accommodated.
Type of traffic
Minimum corridor width (m)
One-way traffic flow
1.0
Two-way traffic flow
2.0
Two men abreast
1.2
Man with bag
1.0
Porter with trolley
1.0
Woman with pram
0.8
Woman with pram with child alongside
1.2
Man on crutches
0.9
Wheelchair
0.8*
* Wheeled vehicles require extra width in order to turn at junctions, especially if they are very long, e.g, hospital trolleys.
Table-3
Traffic can flow freely only along unrestricted routes. Corridors are rarely free of obstructions. For example, a row of seated persons will reduce the effective width of a corridor by 1.0 m. Table-4 indicates the effect of a number of obstructions.
Table-4 shows Reductions in corridor width due to obstructions.
Obstruction
Reduction in width (m)
Ordered queue
0*6
Unordered single queue
1.2-1.5
Row of seated persons
1.0
Coin operated machine:
— one person
0.6
— queue
1.0
Person waiting with bag
0.6
Window shoppers
0.5-0.8
Small fire appliance
0.2-0.4
Wall-mounted radiator
0.2
Rough or dirty wall surface
0.2
Table-4
Example#1:
In a hospital corridor it is necessary for two trolleys to pass each other. Each trolley is pushed by one porter and another person with a bag of equipment walks alongside.
1- What width should the corridor be?
2- If a row of seated persons is encountered what effect would this have?
3-Indicate the probable flow rates at free flow design levels.
Solution:
1- From Table-3:
For one way traffic; a trolley and porter occupies 1.0 m width, a man with a bag occupies 1.0 m width.
If the traffic is two way, the minimum clear corridor width will need to be at least 4.0 m.
2- From Table-4:
If a large obstruction, such as a row of seated persons, is encountered, the corridor width would need to be increased by as much as 1.0 m. so, the total width of the corridor will be 5.0 meters.
3- The circulation mix would comprise most people moving slowly and a few others on urgent tasks moving very fast (comparatively). The slow people have a low speed, perhaps 0.6 m/s and the other would probably have a higher speed, perhaps 1.5 m/s. A reasonable average would be 1.1 m/s. Using Equation (1) the free flow design rate would be:
Cc = 60VDW = 60 x 1.1 x 0.3 x 60 = 99 person/minute

  

2- Portal handling capacity


Portals, which are called by various names (i.e. gate, door, entrance, turnstile etc), form a division between two areas for reasons of privacy, security, access control etc. They represent a special restriction in corridor width. Their main effect is to reduce pedestrian flow rates. Table-5 Portal handling capacities in persons per minute and persons per hour through an opening of 1m width.
Portal type
Flow rate
(person/min)
Flow rate
(person/h)
Gateway
60-110
3600-6600
Clear opening
60-110
3600-6600
Swing door
40-60
2400-3600
Swing door (fastened back)
60-90
3600-5400
Revolving door
25-35
1500-2100
Waist-high turnstile:
— free admission
40-60
2400-3600
— cashier
12-18
720-1080
— single coin operation
25-50
1200-1800
Table-5
Note:
Most domestic doors are less than 1m wide (e.g. approximately 750 mm) and the flow rates would be likely to be the lower values in the range. Doors in non-domestic buildings may be slightly wider than 1.0 m and would permit the higher values in the range to be possible.


3- Stairway handling capacity


The differences between the movement on stairways and on flat floor are given in below table-6.
movement on stairways
movement on flat floor
The movement on stairways is more regular as disciplined by the stair steps.
Depend on the pedestrian direction, age, gender and health status.
A stair walker needs only to perceive two vacant treads ahead (and room for body sway) and occupies an area of some 0.7 m2.
A pedestrian requires an area of some 2.3 m2 (to account for body sway etc.)
The speed along the slope is about half that on the flat
Higher pedestrian speed
higher density is permitted
Less density
free flow design is possible at a density of 0.6 person/m2
free flow design is possible at a lower density (see fig.2)
Full flow design is possible at a density of 2.0 person/m2.
Full flow design is possible at a lower density. (see fig.2)
Table-6
Fig.2: Free and Full Flow Designs for Stairway
Speed of pedestrian movement on stairway is affected by:
  1. The angle of inclination of the stairway,
  2. Step riser height of the stairway,
  3. Human behavior: slowest stair walker, greater care in the down direction.
To enable comfortable walking on a stair, a rule of thumb has been to match the average adult stride (on a stairway) of about 600 mm with the sum of twice the riser height (‘rise’) plus the tread depth (‘going’). This results in the following ranges for efficient design:
  • A range of riser heights of 100 mm to 180 mm
  • A range of treads of 360 mm to 280 mm,
  • A range of possible inclinations from 15° to 33°.
An empirical formula for stairway handling capacity is:
Cs = 0.83 (60 VDW)                    Equation (2)
Where:
Cs is the stairway handling capacity (person/min),
V is average pedestrian speed on the slope (m/s),
D is the average pedestrian density (person/m2)
W is the effective stair width (m).
Table-7 shows Stairway pedestrian flows; possible pedestrian flow rates in persons per minute (person/min) and persons per hour (person/h), and typical pedestrian stairway speeds along the slope in meters per second (m/s) for a free flow design density of 0.6 person/m2 and a full flow design density of 2.0 person/m2 for each1m width of stairway.
Type of traffic
Pedestrian speed and flow for stated pedestrian design density
Free flow design density (0.6 person/m2)
Full flow design density (2.0 person/m2)
Speed (m/s)
Flow rate
(person/min)
Flow rate
(person/h)
Speed (m/s)
Flow rate
(person/min)
Flow rate
(person/h)
Young/middle aged
men
0,9
27
1620
0.6
60
3600
Young/middle aged 3600
women
0,7
21
1260
0.6
60
3600
Elderly people,
family groups
0,5
15
900
0.4
40
2400
Table-7

  

4- Escalator Handling Capacity


(4) Factors affect the Escalator handling capacity as follows:
A- Speed:
The speed is measured in the direction of the movement of the steps. Most escalators run at one speed only, although some heavy duty escalators can switch-over to the higher speed during heavy traffic. Escalator s’ available speeds are:
Common speeds
0.5 m/s and 0.65 m/s
Other speeds
0.75 m/s and 0.9–1.0 m/s
B- Step Width:
The available widths are:
600 mm
Carry One passenger
800 mm
Carry One and half passengers
1000 mm
Carry two passengers
Note:
The hip widths, which are measured between the skirting panels are typically 200 mm wider than the step.
C- Inclination:
The available escalator s’ inclination is:
30°
Common inclination
27° to 35°
Only available at a maximum speed of 0.5 m/s and a maximum rise of 6 m
The step tread (going) and the step rise of an escalator are given in below table:
the step tread (going)
step rise
Actual  escalator
400 mm
up to 240 mm
Typical escalator
400 mm
210 mm
escalator for an emergency exit
400 mm
not exceed 210 mm
D- Boarding And Alighting Areas
These areas must encourage pedestrian confidence and assist the efficient and safe boarding of escalators. It is recommended that at least 1 1/3 flat step (light duty) to 2 1/3 flat steps (heavy duty) be provided for passengers when boarding/alighting an escalator. The average pedestrian boarding/alighting stride can be assumed to be 750 mm.
The theoretical handling capacity of an escalator (Ce) in person/minute is given by:
Ce =60Vks       Equation (3)
Where:
V is speed along the incline (m/s)
k is average density of people (people/escalator step)
s is number of escalator steps/m.
For the case where the step depth is 400 mm, s becomes 2.5 = 1000/400 and Equation (3) is:
Ce = 150 Vk    Equation (4)
The density factor (k) allows for occupation densities and is taken to be:
Escalators Width mm
Assumed Person Per Step
K
600
1
1.0
800
1.5
1.5
1000
2
2.0
Table-8
Table-9 gives escalator handling capacity in persons per minute and persons per hour for an assumed occupancy of two persons per 1000mm step and three persons per two 800 mm steps and one person per 600 mm step. The horizontal speed is given in meters per second (m/s)
Speed (m/s)
Step Width (mm)
1000
800
600
Handling capacities (person/min)
Handling capacities (person/Hr)
Handling capacities (person/min)
Handling capacities (person/Hr)
Handling capacities (person/min)
Handling capacities (person/Hr)
0.50
150
(9000)
113
(6750)
75
(4500)
0.65
195
(11700)
146
(8775)
98
(5850)
0.75
225
(13500)
169
(10125)
113
(6750)
Table-9
Notes:
The actual passenger density on an escalator is likely to be half this value. Observations showed that every other step is occupied on a moving escalator. This gives a standing person an area of two steps, i.e. a space of some 800 mm by 600 mm in which to stand, which is about 0.5 m2. This is the ‘dense* level of occupancy of 2.0 person/m2 (see fig.3)
Fig.3
Example#2:
On the London Underground it was observed, during peak periods, that passengers stood stationary on the right hand side of the 1000 mm escalator at a density of one passenger on every other step. The left hand side was occupied by a walking column of passengers at a density of one person every third step. Assuming the escalator was running at 0.75 m/s and the speed of the walking passengers was 0.65 m/s, what is the passenger theoretical and actual flow rate of the escalator? Noting that step depth is 400 mm.
Solution:
First: The theoretical handling capacity (flow rate):
1- From Table-9 for speed 0.75 m/s and 1000 mm escalator step width is 13500 persons/hour.
2- For step depth 400 mm (S = 2.5) and one passenger/ two steps (K =0.5), the flow rate for the right hand side stationary column from equation (4) will be:
Ce =150 Vk = 150x0.75x0.5 = 56.25 persons/minute = 56.25x60 persons/hour = 3375 persons/hour
3- for the walking passengers on the left side:
One person for every three steps, so K = 1/3
And the effective (relative) speed of the passengers = 0.75+0.65 = 1.4 m/s.
Then the flow rate using Equation (4) will be:
Ce =150 Vk = 150x1.4x1/3 = 70 persons/minute = 70x60 persons/hour = 4200 persons/hour
So, the total passenger flow rate = 3375 + 4200 = 7575 persons/hour.
Second: for the actual flow rate
We can represent the escalator case as follows:
Escalator steps
one passenger on every other step
one person every third step
1st step
1
1
2nd step
-
-
3rd step
1
-
4th step
-
1
5th step
1
-
6th step
-
-
Then we have (5) passengers each (6) steps giving a value for K = 5/6 = 0.83 and the actual handling capacity of the escalator will be:
Ce =150 Vk = 150x0.75x0.83 = 93.375 persons/minute = 93.375x60 persons/hour = 5603 persons/hour

In the next article, we will continue explaining other Principles of Interior Building Circulation. 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

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