Transportation Systems In Buildings

TRANSPORTATION SYSTEMS IN BUILDINGS

Mohd Rodzi Ismail

MOVEMENT SYSTEMS

Forms of mechanical transportation may be found within, around and in general association with modern buildings and developments

LiftsEscalatorsTravolators or moving pavements

LIFTS

Introduction

A lift or an elevator is a transport device used to move goods or people verticallyConsidered a requirement in all buildings over three storeysMinimum standard of service – one lift for every four storeys with a maximum distance of 45 m to the lift lobbyFloor space estimates and car capacity can be based on an area of 0.2 m2 per person

Various speeds of lifts

Location of lift

Positioning of lift should be at locations which provide easy means of access for all building users – central entrance lobby of offices, hotels, apartments, etc.Grouping of lifts is essential for user convenience

Possibilities of lift grouping arrangements

1

2

3

The former World Trade Center's twin towers used skylobbies, located on the 44th and 78th floors of each tower.

Lift performance

Lift performance depends onAccelerationRetardationCar speedSpeed of door operation, andStability of speed and performance with variations of car load

The assessment of population may be found by allowing between one person per 9.5 m2

of floor area to 11.25 m2 of floor area.For unified starting and finishing times - 17% of population per 5 minutes may be used.For staggered starting and finishing times -12% of the population may be used.

The number of lifts will have an effect on the quality of service.

Four 18-person lifts provide the same capacity as three 24-person lifts but the waiting time will be about twice as long with the three-car group.

The quality of service may be found from the interval of the group.

23 to 35 seconds – excellent35 to 45 seconds - acceptable for offices60 seconds – acceptable for hotels90 seconds – acceptable for flats

Further criteria for the comfort and convenience of lift users:

Directional indication of location of the lift lobby for people unfamiliar with the building.Call buttons at landings and in the car positioned for ease of use with unambiguous definition for up and down directions.Call buttons to be at a level appropriate for use by people with disabilities and small children.

Call display/car location display at landings to be favourably positioned for a group of people to watch the position of all cars and for them to move efficiently to the first car arriving.Call lights and indicators with an audible facility to show which car is first available and in which direction it is traveling.Lobby space of sufficient area to avoid congestion by lift users and general pedestrian traffic in the vicinity.

A method for estimating and comparing efficiency and effectiveness of lift installation is by calculating the round trip time (RTT):

An average period of time for one lift car to circulate, incorporating statistical data for time lost due to stopsIt is measured from the time the lift doors begin to open at the main terminal to the time they reopen when the car complete its cycle

ExampleA building having five floors at 3 m floor to floor spacing, a car capacity of 6 persons and 2 ms-1

speed of travel

n

SSSSS ⎟

⎠⎞

⎜⎝⎛ −

−=1

1

1. Probable number of stops (S1):

where,• S = maximum number of stops• n = number of people or car capacity

,3.34

14446

1 =⎟⎠⎞

⎜⎝⎛ −

−=S i.e. 3 stops

⎟⎠⎞

⎜⎝⎛ += V

SVLSTu 21

2. Upward journey time (Tu):

where,• L = lift travel, 4 x 3 = 12 m• V = car speed, 2 ms-1

sxx

Tu 5.16]22[24

123 =⎟⎟⎠

⎞⎜⎜⎝

⎛+=

VVLTd 2+=

3. Downward journey time (Td):

sx 10]22[2

12=+=

sxnTp 12622 ===

4. Passenger transfer time (Tp). Allow 2 – 3 s per person to transfer, depending on the depth of car. At 2 s:

( ) sVWST

do 2.19

5.02.1)13(212 1 =+=+=

opdu TTTTRTT +++=

5. Door opening time (To). Assume door speed (Vd) = 0.5 ms-1 and door width (W) = 1.2 m:

6. Round trip time (RTT):

s7.572.1912105.16 =+++=

Estimation of the interval and quality of serviceExample

An office block with 20 storeys above ground floor having a group of four lifts with unified starting and stopping times is to have a floor area above the ground floor of 8000 m2 and floor height of 3 m. Each car of the lifts has a capacity of 20 persons and a speed of 2.5ms-1. The clear door width is to be 1.1 m and the doors are to open at a speed of 0.4 ms-1. Estimate the interval and quality of service that is to be provided.

personpersonmm 124

100/11%178000

2

2

=×

×=

1. Peak demand for a 5-minute period:

2. Car travel = 20 x 3 m = 60 m

n

SSSSS ⎟

⎠⎞

⎜⎝⎛ −

−=1

1

3. Probable number of stops (S1):

where,• S = maximum number of stops• n = number of people or car capacity

(usually approximately 80% of capacity)

1120

120202016

1 =⎟⎠⎞

⎜⎝⎛ −

−=S

⎟⎠⎞

⎜⎝⎛ += V

SVLSTu 21

4. Upward journey time (Tu):

where,• L = lift travel, 20 x 3 = 60 m• V = car speed, 2.5 ms-1

sTu 79]5.22[5.211

6011 =⎟⎠⎞

⎜⎝⎛ ×+

×=

VVLTd 2+=

5. Downward journey time (Td):

s29]5.22[5.2

60=×+=

( ) sVWST

do 66

4.01.1)111(212 1 =+=+=

6. Door operating time (To).

Door speed (Vd) = 0.4 ms-1

Door width (W) = 1.1 m:

opdu TTTT +++=

7. The average time taken for each person to get into and out of a lift car may be taken as 2 seconds.

Passenger transfer time (Tp) = 2n = 2 x 16 = 32 s

8. Round trip time (RTT)

s20632662979 =+++=

minutes 5per persons 93206

8.020460mins 5

=

××××=9. Capacity of group

s5.514

206==10. Interval for the group

The capacity of the group of lifts and the interval for the group are satisfactory (Note: Car less than 12 capacity are not satisfactory)

Electric/roped liftsIn these elevators, the car is raised and lowered by traction steel ropes rather than pushed from belowComponents:

1 - Control system2 - Electric motor3 - Sheave4 - Counterweight5 - Guide rails

Motor

Located in lift motor roomOn anti-vibrations mountings

Lift motor on motor room-less lift

Highly efficient permanent magnet (PM) motors for high-speed and super high-speed elevators (Mitsubishi)

Motor room

Roping

High tensile steel ropes driven through traction sheaves attached to the motor shaft, a system of pulleys and a counterweightAvailable in various combinations to suit different occupancy requirements

Single wrap 1 : 1The simplest but will be prone to slipage if subjected to heavy loads

Single wrap 2 : 1Improvement of single wrap 1 : 1Number of pulleys and the wrapping ratios increased to improve resistance to slipage

Single wrap 3 : 1More pulleys used

Effect of wrap ratio on car speed as the ratio increases, the car speed decreases

Alternative roping arrangements to maintain high speeds and sufficient traction

Double wrap Underslung

In very tall buildings the effect of bounce and spring from the rope load can be balanced and compensated with ropes suspended below car and counterweight

Compensating ropes

Emergency braking

While moving the car is retained upright and carried smoothly by guides and channel each side

Car guide (plan view)

In the unlikely event of rope failure, an overspeed governing mechanism will effect an immediate brake

Safety gear - alternatives

The emergency brakes are activated by a continuous rope passing over a pulley in the pit and an overspeed governor pulley in the motor room.The governor locks in response to flyweight inertia from the centrifugal force generated by excess speed, thus jerking the rope in process.

The position of the governor rope and pulleys, relative to car travel

Active Roller Guide (Mitsubishi)

This greatly reduces lateral vibration of high-speed elevator.An accelerometer detects car vibration during operation and actuators cancel the vibration with optimally controlled electromagnetic force.The result is much better ride comfort than with a conventional roller guide.

Lift doors

Required in two components:Fitted to the lift carFitted to the landing

Landing doors must be incombustible, preferably of sheet steel construction over a light steel framework of about 30 mm overall thicknessThey usually slide sideways (although vertical movement is used for some industrial applications)

Door-openersystem

Various functions of lift doors

Passenger and service lift doors

Vertical lift doors

Multi-Beam Door Sensor(Mitsubishi)

Prevents passengers from being caught by the doors, using multiple infrared light beams mounted along the entire length of car door edge. Doors reverse and open if beams are blocked during door closing

Constructional dimensions

Lifts manufactured to individual dimensional specification are possible but very expensiveBS 5655 provides standard dimensions which have been coordinated with manufacturing process and building applications to suit all but extreme clients or obscure building requirements

Section through typical small car single lift well

Normally located above the well, containing:

winding geartraction sheavecontrol paneloverspeed governor, andother components

Machine/Motor room

Section through lift motor room

Noise from motors and winding gear must be contained with adequate insulation and absorbent bedding for machineryAn overhead universal beam for raising and lowering equipment and parts during maintenance is essentialAdequate daylighting and supplementary artificial lightFan assisted ventilation to remove excess heat from electric plantA locked door (key with security staff) provides the only access to the machine room, except for a trap-door over the landing area – this is specifically for raising and lowering items of machinery

Pit

Located below the lowest landing level, containing buffersFor slower lifts – spring-type buffersFor higher-speed lifts – oil loaded buffersDepth of pit varies from 1.4 to 2.8 m, depending on lift specification

Brake

The traction sheave drive shaft is fitted with an electromechanical brakeWhen the lift is moving, the electrically operated brakes are lifted clear of the brake drum, but as the electricity switches off to disengage the motor, spring retainers activate the brakeIn addition to the overspeed governor, this provides another safety feature which would activate if the electricity supply failed

Shaft

A lift shaft should incorporate the following features:

Water tightnessMeans of drainagePlumb, vertical sidesSmooth painted finishVentilation void for emission of smokePermanent inspection lightsHave no other services except those necessary for operation of lift

Lift controls

Possibilities of control arrangements:OperatorAutomaticDown collectiveDirectional collectiveGroup collectiveProgrammed control

OperatorIn prestige buildings and hotels for the benefit of special guests.

AutomaticResponse to one call from either lift car or landing. No further calls are accepted until the car is at rest.Only suited to light occupancy and low-rise buildings up to five floors.

Down collectiveA call button is located at each landing entrance and a set of buttons in the car corresponds to each floor.Landing calls are stored and answered in sequence as the lift car descends.In upward direction, passengers are distributed in floor sequence by selection within the car.

Directional (up and down) collectiveTwo call buttons are provided at each intermediate landing, one for up and the other one for down.The lowest and the highest landings only require one button. A full set of destination buttons are provided in the car.Landing callers simply press the direction button and the call is storedOn a downward journey, the lift stops at all floors where downward callers are waiting or where passengers want to go out. Likewise upward, operating in sequence in response to stored calls.

Group collectiveApplied where groups or banks of lifts occur in large buildings, using an interconnected collective stored control systemThis permits the closest lift traveling in the desired direction to respond, rather than passengers waiting for one specific lift or having to press every lift’s button.

Programmed controlThis is an improvement of the group collective system, incorporating time-controlled functions, where demand is known to be particularly high on some floors at certain times.The lift cars can be programmed to be available at the ground floor during arrival times and at upper floors during departure times.This lends itself to routines found in office blocks, where regular hours are worked.

Elevatorbuttons

Hydraulic liftsHydraulic lift/elevator systems lift a car using a hydraulic ram, a fluid-driven piston mounted inside a cylinderFor low-rise buildings

Hydraulic lift components

Oil hydraulic lift - application

Oil hydraulic lift -principles

SINGLE SIDE OR JIGGER ACTING

DOUBLE SIDE ACTING

Oil hydraulic lift - variations

Holeless Hydraulic (Otis)The Holeless Hydraulic system eliminates the need for either a well hole or buried piping. The best application for the Holeless product is most any 2-story building with less than 14‘(4.3 m) of travel from one floor to the other.Its above-ground Holeless configuration responds effectively to the risk of soil and groundwater contamination, and greatly reduces environmental concerns. This package-type unit is most practical for those 2-story buildings where handicap access is required.

Advantages of hydraulic lifts:Capacity for very heavy loadsAccuracy in floor levellingSmooth ride characteristicsLow-level plant roomNo structural loads from winding gearPump room can be located up to 10 m from the shaft

Fire-fighting lifts

For rapid emergency accessThe original concept was a variation within conventional passenger lift, which contained a priority break-glass key switchThis was normally at the ground floor, and when activated it brought the lift to that floor immediately

Independent fire-fighting lifts are required in offices, shops and other commercial premises exceeding 18 m in height

Typical fire-fighting accommodation in a shaft located no more than 60 m from any part

of that floor level

Shared shaft fire-fighting lift – the lift must be marked for that purpose onlyRequires specific provisions:

630 kg minimum duty load to accommodate fire-fighting equipmentMinimum internal dimensions of 1100 mm width, 1400 mm depth and 2000 mm heightAn emergency hatch in the car roofManufactured from non-combustible materialA two-way intercom1 hour fire-resisting doors of 800 mm minimum width x 2 m heightA maximum of 60 s capability to run the full building heightDual power supplies, one direct mains and the other an emergencygenerator

Fire-fighting lift – shared shaft Fire-fighting lift – control diagram

Observation/panoramic/scenic lifts

“Wall climber” liftThe glass-walled cars provide a focus of interest for the casual observer, a degree of security for occupants, a mobile observation platform and floor access for the userVery popular in atrium malls, complementing the glass architectureThese lightweight structures lend themselves to hydraulic lifts, freeing the building designers from superimposed motor room loadings

Observation lift

Panoramic lift design

Panoramic lift applications

PaternosterA paternoster or paternoster liftis an elevator which consists of a chain of open compartments (each usually designed for two persons) that move slowly in a loop up and down inside a building without stoppingPassengers who are agile enough can step on or off at any floor they likeThe speed is limited to no more than 0.4 ms-1 for safety reason

Not suitable in public buildings and other locations where the elderly and infirm are likely to gain accessMost suited to single occupancy buildings such as offices, where familiarity with the system and a high degree of staff mobility is a feature

Paternoster lift

Paternoster lifts

Stair liftA means of vertical transport in homes for the elderly and disabled, hospitals and conventional homes containing physically infirm peopleDeveloped for simple application to domestic chairsThe chair moves up an inclined rail parallel with the stair gradient at about 0.15 ms-1 powered by 230 V AC electric motorThe rail is a standard steel joist bracketed to the wall and supported by the stairTransformed 24 V DC controls provide push-button directional and stop facilities

Stair lift – approximate dimensions

Other types of lifts

Double-deck elevatorsThey are elevators designed such that two elevator cars are attached one on top of the other. This allows passengers on two consecutive floors to be able to use the elevator simultaneously, significantly increasing the passenger capacity of an elevator shaft. Such a scheme can prove efficient in buildings where the volume of traffic would normally have a single elevator stopping at every floor.Example: Lifts at Menara Telekom, Taipei 101 Taipei 101

Freight elevator An elevator designed to carry goods, rather than passengers

Car elevatorAn elevator designed to carry cars (e.g. for parking)

DumbwaiterA small box elevator designed for the carriage of lightweight freight is called a dumb waiter (or dumbwaiter)

Service lift/Dumbwaiter

Platform liftFor disable

Aircratft elevator

ESCALATORS

An escalator is a conveyor transport device for transportingpeople, consisting of a staircase whose steps move up or down on tracks that keep the surfaces of the individual steps horizontalWhere large numbers of people are anticipated, such as airports and railway terminals, department stores and shopping malls, several escalators will be required and can be grouped in a number of ways to suit the building functionsThe angle of inclination is normally 30o, but may increase to 35o if the vertical rise does not exceed 6 m and the speed is limited to 0.5 ms-1

Escalator arrangements

Escalator dimensions

Escalator’s components

Step SpeedEscalator speeds vary from about 90 feet per minute to 180 feet per minute (27 to 55 meters per minute)An escalator moving 145 feet (44 m) per minute can carry more than 10,000 people an hour -- many more people than a standard elevator

The individual steps from an escalator

Long escalator in Washington MetroWestminster escalator

Spiral escalator

Conventional escalator

Escalator capacity

The following formula can be used to ascertain capacity and compare efficiencies and suitability of escalators at building design stage:

LxVxPxN θcos3600

=

Where,• N = number of persons moved per hour• P = number of persons per step• V = escalator speed (ms-1)• L = length of step (m)• θ = angle of incline

ExampleAn escalator of 30o incline, one passenger per step, a speed of 0.5 ms-1 and 400 mm tread or step length

oxxxN4.0

30cos5.013600=

= 4500 x cos 30o

= 3897 nos. persons moved per hour

The void containing escalators could encourage fire to spread rapidly through building. Therefore the following precautions could be considered:

Sprinklers, installed to provide a continuous curtain of water down the escalator voidFire curtains or shutter mechanism released by fusible link or smoke relay to seal the top of the escalator shaftCompartmentalisation or separation of escalators into a well or fire-protected enclosure

Spread of fire

TRAVELATORS

A moving walkway, moving sidewalk, or travelator is a slow conveyor belt that transports people horizontally up to the practical limitations of about 300 m.They work in a similar manner to an escalator. In both cases, riders can walk or stand. The walkways are often supplied in pairs, one for each direction.They are particularly useful in large railways and airports terminals, as well shopping complexes, and may be inclined up to about 15o where level differentials occurs.

Speed range between 0.6 and 1.3 ms-1, limitations being imposed because of the difficulty in getting off.Combine with walking, the overall pace could be about 2.5 ms-1.Materials for travelators must be flexible or elastic and include reinforced rubber or composites and interlaced steel plates or trellised steel.The latter two have the facility to deviate from the conventional straight line.

Parisian high speed walkway

Inclined travelator

REFERENCESGreeno, R.(1997). Building Services, Technology and Design. Essex: Longman.Hall, F. & Greeno, R. (2005). Building Services Handbook. Oxford: Elsevier.http://science.howstuffworks.comhttp://en.wikipedia.orghttp://www.mitsubishi-elevator.com/products/elevators/gpm_iii/index.htmlhttp://www.imem.com/en/s2/2a3.htm