Electronic Parking System forSingapore
TAKAYASU OBATAHIDEKAZU ONOYOSHIHIRO MIYAZAKI
MASAKUNI ANDOAn Electronic Road Pricing (ERP) system was introduced in 1998 in Singapore to reduce the traffic congestion inthe city area, almost all vehicles in Singapore are equipped with onboard equipment called in-vehicle unit (IU). Using
these in-vehicle units and the technologies based on the ERP system, Mitsubishi Heavy Industries, Ltd. (MHI) has
developed an Electronic Parking System (EPS) that enables settlement of parking fees without parking tickets andcash. In order to keep the compatibilities of current car park system, antennas were made smaller and compact,
processing systems were integrated and devices for calculating the fees were developed, the device for calculating thefee was called charging unit (CHU). In order to meet the various needs of the car park owners and to allow freesetting of the parking fee, the devices are designed. The introduction of EPS in Singapore has brought about an
unprecedented realization of the application using the same onboard equipment in both EPS and ERP systems (application fields).

ERP system so as to allow application to undergroundparking lots with limited installation environment, anda highly universal charging unit (CHU) that can conform to the requirements of car parks with various
charging systems were developed.

1. Introduction
The spread of Automatic fee collection system for collecting the traffic charges has become a global trend. In
Japan Electronic Toll Collection (ETC) is now operatingin major toll roads. The ETC is a toll collection systemthat allows the driver to pay the toll without having tostop the vehicle. The toll is collected from the IC card
into the onboard equipment using radio frequency (RF)communication with the antenna installed on the toll
plazas.
In Singapore the excessive traffic congestion at theCentral Business District (CBD) became a social problem. This led to the adoption of a "road pricing system"in order to control the traffic volume by charging thevehicles going into the CBD area. This system is called
Electronic Road Pricing (ERP) and is used for collecting
the toll during the morning and evening traffic jam. For
this system, in-vehicle units (IU) were supplied by MHI
in 1998, more than 99% of the vehicles in Singapore are
equipped with them. As a result, IU becomes social infrastructure in Singapore. In other words, Singapore
presented an ideal environment for the application ofIU to other fields. One of such fields was the development of Electronic Parking System (EPS), a chargecollecting system in the parking lots. In EPS, the parking system has been realized by using the 10 digits
numbers, called the specific IU labels memorized for each
IU for vehicle identification.
In developing the EPS system, antennas were madesmaller on the basis of the technologies obtained through2. Outline of EPS(1) Features
The features of EPS are given below.
(a) Availability
The driver doesn't have to open the window to takea ticket or to pay the charge, and the vehicle can passthrough the entrance/exit gates without having tostop. The driver doesn't need to prepare the cash
(money) to pay.
(b) Flexibility of car park operation (management)
The car park owner or manager can flexibly change
the parking charges table depending on their demands.
(c) Reliability
The RF communication and security technologies
of ERP system have been used in ensure high reliability of the system.
(d) Service time (hours)
Since no need of handling tickets or cash at theentrance or exit gate allows non-stop operation, theprocessing capacity at exit can be drastically improved.
(The processing time per vehicle can be shortened
to 3-4 seconds against about 15 seconds needed by
the existent system.)
Mitsubishi Heavy Industries, Ltd.
Technical Review Vol.40 No.3 (Jun. 2003)1

(2) System types
There are three types of EPS system as shown below.
(a) Access control (entrance/exit control) system
This system is installed in the car park for monthly
subscribers, and is used only for checking the entrance
and exit of vehicles, not for charging.
(b) Charging system
This system is installed in private car parks wherethe vehicles are charged according to the vehicle types
and parking time.
(c) Free-flow charging system
This system utilizes the most of the EPS features,
allowing non-stop charging. As in the case of ERP, inorder to let the vehicles pass without having to stop,
image processing system using camera are requiredso as to detect and catch the invalid vehicles, and to
make the system a foul-proof system.
The developments for the aforesaid items (a) and (b)were carried out. As for item (c), the future trend inneed will be thoroughly monitored and dealt with accordingly.
2.1 Access control (entrance/exit control) system
The access control system configuration is shown inFig. 1
1.
(1) Operation at the entrance(a) When the vehicle presence detector (loop coil) at
the entrance detects a vehicle, the antenna radiates radio frequency.
(b) The antenna makes communication with the IU
installed in the vehicle, and reads the IU label tocheck whether the IU label is included in the list
pre-recorded in the antenna or host computer, andif the label is found to be included in the list, thebarrier opens. The vehicle can enter the car park.
(2) Operation at the exit
The exit is also equipped with a vehicle presence
detector (loop coil) and a barrier. The barrier opens
when the vehicle presence detector detects a vehicle.
The outside vehicles cannot enter from the exit because of the barrier.
The access control system has two modes: thestand-alone mode where the list of IU labels of theparking cars is recorded in the antenna and the online mode where the IU label list is recorded in thehost computer that may be installed in the office. In
the case of stand-alone mode, the IU labels are added
to or deleted from the list recorded in the antenna for
maintenance, according to the need, by connecting amaintenance computer. In the case of on-line mode,
however, the maintenance of IU labels can be easily
carried out using the host computer. The car park
owners and managers can select the mode according
to the scale of the car park, and can further install anantenna at the exit to allow flexible management of
the car park such as detection of detention time, etc.
2.2 Charging system
The charging system configuration is shown inFig
Fig.. 2 .
(1) Operation at the entrance(a) With a vehicle detected by the vehicle presence
detector at the entrance, the antenna radiates radio frequency.
(b) The antenna reads the IU label through communication with the IU installed in the vehicle, andtransmits the IU label to CHU before opening thebarrier.
(2) Operation at the exit(a) With a vehicle detected by the vehicle presence
detector at the exit, the antenna radiates radio frequency.
(b) The antenna reads the IU label through communication with the IU installed in the vehicle, andtransmits the label to CHU.
(c) The CHU (host computer, depending on the system) calculates the parking fee of each vehicle fromthe parking time of the vehicle on the basis of theIU label transmitted by the antenna.
(d) According to the calculated fee, CHU issues charging command and it is transmitted to IU throughthe antenna.
(e) On receiving the charging command, the IU deducts the parking fee from the IC card.

Host computer

Personal computer for
Host computer
maintenance use

CHUOrOffice

Antenna

Entrance

Optical communication
Antenna

Barrier
Barrier

Vehicle presence
detector

Vehicle presence
detector

Vehicle presence
detector

Fig. 1 Access control system

Antenna
Entrance

Exit
Barrier

Vehicle presence
Vehicle presence
detectordetector
Fig. 2 Charging system

Vehicle presence
detector

Mitsubishi Heavy Industries, Ltd.
Technical Review Vol.40 No.3 (Jun. 2003)

2(f) The IU then inform CHU through the antenna thatthe parking fee has been deducted from the IC card.

(1) Development of integral-type antenna
Antenna transmits radio waves to communicate
data with IU using radio frequency communication.
The antenna function in ERP was only RF communication. The EPS antenna, however, was designed tobe equipped with one-chip micro computer andmemory and to have a built-in communication control function to allow access control solely by theantenna. Further, it also enables to build up a system of collecting parking fee from IC card by making
connection with CHU.
(2) Development of CHU
The CHU was designed as a unit consisting of fee
calculation and security units with integrated functions of parking fee calculation, encryption anddecryption of processing data and vehicle control.
The development program for each device is described below in detail.
3.1 Development of integral-type antennaAmong the component machines of ERP system, theantenna, radio frequency communication unit (RFU) anda part of the antenna controller for preparing transmit
data were integrated to the antenna.
(1) Antenna communication area
In ERP the radio-wave emission pattern was focused to the lane width direction in order to identify
the vehicle, and a long communication area in the forwarding direction was formed as shown in Fig. 5 inorder to secure the communication time. On the otherhand, there are a number of restrictions dependingon the surrounding environment in the installationof antenna in a car park, such as the requirement of awide communication area in the direction of lane
width to cover an area equivalent to one lane by using a single antenna, the restriction in antenna

3. Development of EPS
The development of EPS equipment is based on thetechnologies achieved through ERP. The ERP system has
successfully realized the high-grade performances suchas charging at 120 km/h and identification of invalid car
at 180 km/h by advanced equipment and through complicated system configuration. Fig. 3 shows theconfiguration of ERP system.
In the development of EPS, integration and miniaturization of ERP system functions were carried out, andthe specifications required of a parking system were realized. On the other hand, compared with the low-cost
existing tag system, EPS clearly makes difference not
only in access control system but also in charging fee byusing IU.
The devices of ERP system were functionally integrated
to two types of devices, that is antenna and the other isCHU, with the devices configuration shown in Fig
Fig.. 4.
Vehicle presence detector
Antenna

Marking line
Lighting system
Antenna

In-vehicle unit

Second gantry
In-vehicle unit

Enforcement
cameraOutdoor control equipment
First gantry
Center computer station
Fig. 3 ERP system equipment configuration

To the Center

Hostcontroller

Security
unit

Radio
frequency
communication
unit

AntennaRadiofrequency
communication

Antenna

In-vehicle unit
ERP system

controller

IC cardRoad side

Vehicle side

Radio frequency
communication unit
Antenna controller
Antenna
All-in-one antenna
EPSCHU
Optical cable

Fig. 4 Relation between ERP system and EPS system
Integration of ERP system machines (devices) led to the development of EPS system.

Mitsubishi Heavy Industries, Ltd.
Technical Review Vol.40 No.3 (Jun. 2003)

3antenna

All-in-one antenna
2m

4m
6m

5m

3m
4m

2m

Fig. 6 Communication area of EPS

Fig. 5 Communication area of ERP

Fig. 7 Photograph of antenna

Fig. 8 Photograph of CHU

installation height in an underground car park andso on. Further, it is necessary to set the antenna communication area so as to secure the communication
area even under restricted environment in order tomake communication with the concerned vehicle while
making no communication with the other vehicles.
With the aforesaid conditions taken into account,the communication area shown in Fig. 6 was set, andthe beam pattern of the antenna to satisfy the conditions was simulated in order to determine theantenna installation conditions. Further, the communication area was measured using the actualequipment, with the result found to conform to thedesign values.
(2) Antenna and radio frequency communication unit
In consideration of multi-lane control, the ERP system is equipped separately with antenna unit andradio frequency communication unit, because of anexcessively large antenna in order to control the communication area. Thus, these units were miniaturized,
and had their size and structure reviewed to enable
them for indoor use.
(a) Antenna power level
Based on the simulation result of communicationarea, the transmission power level was reduced tooptimum level and the high-frequency circuit wasdownsized.

(b) Antenna element
The antenna pattern was reviewed and optimized
to satisfy the communication area in order to realize
miniaturization.
(3) Antenna controller unit
In order to develop small-size antenna unit for carparks, the antenna controller unit was miniaturized
and integrated in the following manner.
In ERP system, the antenna controller unit was a
VME bus single-board computer, and was equippedwith a large amount of RAM using a general-purpose
CPU. This was integrated into a single-chip microcomputer capable of high-speed processing, andperipheral interfaces were added, leading to reduction in size by half. As for the single-chip
microcomputer, the microcomputer with built-in flash
ROM allowing easy exchange of software was selected
to provide flexibility at the time of maintenance andalteration in specification.
Further, in the case of stand-alone mode, the allin-one antenna was equipped with the input of vehicle
presence detector and the control output of barrier toenable to build up the access control system without
the help of the host computer.
3.2 Development of CHU(1) Miniaturization
In order to realize miniaturization, the single-chip
Mitsubishi Heavy Industries, Ltd.
Technical Review Vol.40 No.3 (Jun. 2003)

4microcomputer capable of high-speed processing wasadopted. Further, the system was equipped inside witha flash ROM allowing easy exchange of software.
(2) Interface
The machines and devices are installed at different places in a car park. Especially the antenna units
installed at the entrance and exit are often locatedaway from the CHU installed at the office.
For this reason, the connection to the antenna waschanged from the conventional metal-cable communication system to optical communication to ensure
long-distance and speedy transmission.
(3) Function
The following two types of CHU function were prepared and various contrivances were made to meet
diversified requirements of car parks.
(a) Type-1
This type of CHU is equipped inside with the function of vehicle control in the car park and charging
table, and charges the vehicle driver by calculating
the parking fee from the detention time inside thepark. It can be easily introduced in a small-scale carpark. Since the entrance/exit process are carried out
only by CHU, it ensures high-speed processing.
(b) Type-2
This type of CHU charges the vehicle driver basedon the data obtained by the host computer throughvehicle control in the car park and by calculating theparking fee. This type enables different charging calculations simply by charging the host computer
software and enables to build up a highly flexible system. Further, this system can meet with various otherneeds such as the addition of EPS function in an existing car parking system, and can be easily
introduced simply by adding an interface function toEPS for the existing car park.

4. Conclusion
MHI launched the newly developed all-in-one, smallsize antenna and highly universal CHU for EPS in themarket in 2002, and various car parking systems (access control system, charging system) using these devices
are being put into practical use by a large number ofsystem integrators in Singapore. The EPS system, ahighly convenient car parking system, is expected tospread rapidly in Singapore. MHI takes full account of
the trend in market needs, and is determined to continue development on the free-flow charging system inaddition to the access control system and charging system. In the future, MHI is determined to make efforts indeveloping the car parking system in Japan using theETC on-board equipment on the basis of the ERP andEPS technologies obtained through the experiences inSingapore.

KOBE SHIPYARD & MACHINERY WORKS

Takayasu Obata

Hidekazu Ono

Yoshihiro Miyazaki

Masakuni Ando

Mitsubishi Heavy Industries, Ltd.
Technical Review Vol.40 No.3 (Jun. 2003)

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