End-to-End Intelligent Transportation System

AN-0005

1WX-501-0005www.wavetronix.com

End-to-End Intelligent Transportation System

This application note discusses the creation of an intelligent transportation system (ITS) from the traffic sensor to the end-use applications using commercially available ITS products. This end-to-end system includes traffic sensors with supporting traffic cabinets, the communications infrastructure, data collection and processing software resulting in traffic speed maps and travel-time calculations. Specific products and their integration into the pieces will be discussed. Figure 1 below shows the basic elements of an end-to-end transportation system.

Tra�c Sensor

Cabinet for surge protection and communication

equipment

Communications Infrastructure

TOC

Data collection and manipulation

software

End Use Applications

Figure 1 – Elements of an End-to-End Intelligent Transportation System


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Intelligent Transportation SystemsIntelligent traffic systems are used worldwide for real-time traffic flow monitoring, trip-time calculations, commuter information systems and planning.

While the equipment necessary to create an intelligent traffic system is readily available in the industry, the number of manu-facturers and suppliers of traffic detectors, surge equipment, power conversion equipment, communications equipment, database software and data collection software is substantial.

This application note will break down an entire intelligent transportation system from the traffic sensor to speed map and travel-time applications. This end-to-end system is created using commercially available products that can be integrated without custom-ization.

The key components of the intelligent transportation system described in this document are from the SmartSensor, Click and Command product lines manufactured by Wavetronix. Figure 2 illustrates these three product lines in the end-to-end system. The following sections of this document will discuss each of these system components.

Translator

SpeedMap

N

CollectorC10-FG

110 VAC

P1

L

L

P2

N

N

P3

G

G

P4

GE

GE

Circuit Breaker

Click! 220

0.5A

xOUT

xIN

UNPROTECTED

PROTECTED

120 VACSurge

Click! 240

xN

xG

xL

xRC1

xRC2

xN

xG

xL

x

DC+

x

DC-

x

485+

x

485-

x

GND

RS-2

32

SurgeProtector

Click! 200

x 485-

x 485+

xGND

xGND

xRTS

xCTS

xTD

xRD

S3 485-

S4 485+

S5GND

S0GND

S8RTS

S9CTS

S6TD

S7RD

S1DC+

S2DC-

xGND

xGND

x+DC

xGND

xGND

xGND

PROTECTED

UNPROTECTED

SmartSensor

S1

x

24V

S2

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GND

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GND

S3

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485-

S4

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S5

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GND

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TD

S7

x

RD

S8

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RTS

S9

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CTS

S0

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GND

x

x

GND

Power Supply24 VDC1 Amp

Click! 201

100-240 VAC

24 VDC Out

xN

x+

x+

x-

x-

xDCOK

x+

x-

x-

xL

C10-FG

110 VAC

P1

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P2

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G

P4

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GE

Circuit Breaker

Click! 220

0.5A

xOUT

xIN

UNPROTECTED

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120 VACSurge

Click! 240

xN

xG

xL

xRC1

xRC2

xN

xG

xL

x

DC+

x

DC-

x

485+

x

485-

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GND

RS-2

32

SurgeProtector

Click! 200

x 485-

x 485+

xGND

xGND

xRTS

xCTS

xTD

xRD

S3 485-

S4 485+

S5GND

S0GND

S8RTS

S9CTS

S6TD

S7RD

S1DC+

S2DC-

xGND

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x+DC

xGND

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SmartSensor

S1

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24V

S2

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GND

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GND

S3

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485-

S4

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485+

S5

x

GND

S6

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TD

S7

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RD

S8

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RTS

S9

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CTS

S0

x

GND

x

x

GND


Click! 201

100-240 VAC

24 VDC Out

xN

x+

x+

x-

x-

xDCOK

x+

x-

x-

xL

C10-FG

110 VAC

P1

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L

P2

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N

P3

G

G

P4

GE

GE

Circuit Breaker

Click! 220

0.5A

xOUT

xIN

UNPROTECTED

PROTECTED

120 VACSurge

Click! 240

xN

xG

xL

xRC1

xRC2

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xG

xL

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DC+

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DC-

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485+

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GND

RS-2

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SurgeProtector

Click! 200

x 485-

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xCTS

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xRD

S3 485-

S4 485+

S5GND

S0GND

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S6TD

S7RD

S1DC+

S2DC-

xGND

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xGND

xGND

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PROTECTED

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SmartSensor

S1

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24V

S2

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GND

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485-

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TD

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RD

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RTS

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CTS

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GND

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GND


Click! 201

100-240 VAC

24 VDC Out

xN

x+

x+

x-

x-

xDCOK

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x-

x-

xL

TOC

Figure 2 – Using SmartSensor, Click and Command Products in the Intelligent Transportation System

SmartSensor HDRadar traffic detectors have been the standard for non-intrusive ITS sensors for many years because of their accuracy in all weather and lighting conditions.

Figure 3 – SmartSensor HD

Among the ITS radar sensors available, the SmartSensor HD is the highest performing (see Figure 3). It shows improved accuracy over other ITS radar sensors in congested traffic, heavy truck traffic, frequent lane changes, near barriers and sound walls.


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The SmartSensor HD also provides per-vehicle speed measurements and very responsive average-speed measurements.

These performance enhancements are possible because of the following advancements in radar traffic technology that are incorpo-rated into the SmartSensor HD:

˽ High Resolution Radar – Results in a five-time increase in the bandwidth of the transmit signal. ˽ Dual-Radar – Creates two radar beams separated laterally along the roadway allowing the time delay between detection in the

two radar beams to be used to make a speed measurement, as is done in loop speed trap systems.

Preassembled Click CabinetsAt each sensor site, a cabinet is needed to provide power conversion, surge suppression and communication connectivity to the sen-sor. This functionality can be accomplished through the use of a pole-mount Click cabinet assembly that includes terminal blocks, an AC circuit breaker, AC surge suppression, AC to DC conversion, sensor cable surge suppression, serial-to-Ethernet conversion and a multimode fiber optic Ethernet switch. This cabinet assembly is shown in Figure 4.

GND

175-0094

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L

175-0095

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N

175-0099

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360-0073

360-0073

PE

GND

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175-0053

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VAC

+DC

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175-0054

-DC

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175-0055

GND

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175-0055

485-

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175-0055

485+

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175-0055

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175-0055

RTS

9

175-0055

CTS

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175-0055

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11

175-0055

RD

12

175-0055

GND

8

175-0055

GND

4

175-0056

360-0073

175-0053

SmartSensor

Click! 220

0.5A

Circuit Breaker

L

OUT

LIN

UNPROTECTED

PROTECTED

120 VACSurge

Click! 230

NN

xG

LL

xRC1

xRC2

NN

GG

LL

100-240 VAC

24 VDC Out

Power Supply 24 VDC1 Amp

Click! 201

NN

LL

x+

x+

x-

x-

xDCOK + -

x-

DC+

x

485+

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485-

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GNDDC-

RS-2

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PROTECTED

Surge Protector

UNPROTECTED

Click! 200

xRTS

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+DC+DC

GND

GNDx

GNDx

GND

9RTS

10CTS

11TD

12RD

5485-

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7GND

8GND

1+DC

2-DC

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4GND

x485-

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xGND

xGND

x485-

x485+

xGND

xGND

LED Status

RS-2

32

Mode Switch

Serial to Ethernet

Converter

Click! 301

ACSupply

Line

SmartSensorCable

FiberNetworkCable

100 Mbps Switch4/2 MM

Click! 341

US1US2

6

5

1

2

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4

xGND

xGND

xGND

xGND

xGND

xGND

xGND

xGND

FiberNetworkCable

Figure 4 – Click Cabinet Assembly

In Figure 4, the terminal blocks are mounted on the bottom DIN rail of the cabinet. These are used for terminating the AC power cable and the sensor cable.

The sensor cable terminations are color-coded the same as the sensor cable to reduce errors in the field. Insulation displacement


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terminations are available to reduce the need for stripping and to facilitate in-field wiring.

The devices on the middle DIN rail in Figure 4 from left to right are: ˽ Click 210 AC resettable circuit breaker – Opens the electric circuit if the rated amperage is exceeded and can also be used as

a switch to shut off power to the cabinet. ˽ Click 230 AC surge suppression module – Serves to protect the in-cabinet electronics and the sensor from electrostatic dis-

charge (ESD) that may enter the cabinet on the AC power line. ˽ Click 201 AC to DC converter – Provides DC power to the sensor and to the in-cabinet communication devices. ˽ Click 200 surge suppression module – Provides surge suppression on the sensor’s RS-232, RS-485 and DC lines. ˽ Click 301 serial to Ethernet converter – Converts serial communication to Ethernet. ˽ Click 341 Managed 100 Mbps Multi-mode Fiber Ethernet switch – Provides conversion between copper and fiber and makes

additional ports available for other devices that require a network connection.

Preassembled Cabinets with a Wireless LinkIn order to provide communications to sensor sites, it is sometimes necessary to provide a wireless link between the sensor site and the traffic cabinet in which the fiber bundle is located.

A wireless link is desirable in order to avoid the costs associated with trenching, which would be required for wired communica-tions. This link is implemented using two Click 400 900MHz serial radios.

The Click 301 serial to Ethernet converter and the Click 341 Ethernet switch are included in the cabinet with fiber access. 175-0094

L

L

175-0095

N

N

175-0099

G

G

360-0073

360-0073

PE

GND

X

175-0103

175-0053

110 VAC+DC

1

175-0054

-DC

2

175-0055

GND

3

175-0055

485-

5

175-0055

485+

6

175-0055

GND

7

175-0055

RTS

9

175-0055

CTS

10

175-0055

TD

11

175-0055

RD

12

175-0055

GND

8

175-0055

GND

4

175-0056

360-0073

175-0053

SmartSensor

Click! 220

0.5A

Circuit Breake

r

LOUT

LIN

UNPROTECTED

PROTECTED

120 VACSurge

Click! 230

NN

xG

LL

xRC1

xRC2

NN

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LL

100-240 VAC

24 VDC Out


Click! 201

NN

LL

x+

x+

x-

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xDCOK + -

x-

DC+

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485+

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485-

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DC-

RS-2

32

PROTECTED

Surge Protector

UNPROTECTED

Click! 200

xRTS

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xRD

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xGND

xGND

xGND

9RTS 10

CTS 11

TD12RD

5485

- 6485+ 7

GND 8

GND

1+DC 2

-DC3

GND 4

GND

x485-

x485+

xGND

xGND

AC Power

Internal Wireless Antenna

RS-2

32

PROTECTED

Surge Protector

UNPROTECTED

Click! 200

xRTS

xCTS

xTD

xRD

x+DC

xGND

xGND

xGND

9RTS 10

CTS 11

TD12RD

5485

- 6485+ 7

GND 8

GND

1+DC 2

-DC3

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GND

x485-

x485+

xGND

xGND

Fiber Cable

175-0094

L

L

175-0095

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N

175-0099

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G

360-0073

360-0073

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GND

X

175-0103

175-0053

110 VAC

Click! 220

0.5A

Circuit Breake

r

LOUT

LIN

UNPROTECTED

PROTECTED

120 VACSurge

Click! 230

NN

xG

LL

xRC1

xRC2

NN

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LL

100-240 VAC

24 VDC Out


Click! 201

NN

LL

x+

x+

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x-

xDCOK + -

x-

AC Power

Internal Wireless Antenna

RS-2

32

PROTECTED

Surge Protector

UNPROTECTED

Click! 200

xRTS

xCTS

xTD

xRD

x+DC

xGND

xGND

xGND

9RTS 10

CTS 11

TD12RD

5485

- 6485+ 7

GND 8

GND

1+DC 2

-DC3

GND 4

GND

x485-

x485+

xGND

xGND

100 Mbps Switch4/2 MM

Click! 341

US1US2

6

5

1

2

3

4

xGND

xGND

xGND

xGND

xGND

xGND

xGND

xGND

Figure 5 – Preassembled Click Cabinets with a Wireless Link from Sensor Site to Fiber Access

If AC power is not available at the sensor site, then solar power can be used to create a stand-alone sensor site that does not require trenching or any wired connections.


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Ethernet Over Fiber CommunicationsMany departments of transportation have deployed a fiber optic network for their ITS communication infrastructure. Fiber is desirable because of its high data bandwidth and long distance transmissions without repeaters. Data transmissions via fiber can occur in a number of different ways, but Ethernet over fiber is considered the state-of-the-art communication infrastructure.

Using an Ethernet backbone, multiple sensor sites can be connected to the same fiber pair resulting in efficient use of the fiber. Through the use of serial to Ethernet converters, serial protocols can be used without concern for collisions. Additionally, video over internet protocol (IP) can be implemented using a shared fiber pair utilizing the Ethernet protocol.

The Ethernet network is often implemented as a ring network to provide data path redundancy. If a fiber pair in the ring network is trenched through, the network will continue to operate because a data path is still available. Figure 6 illustrates a ring network implementation on a freeway system.

TOC

Sensor Site

Fiber Pair

Figure 6 – Ring Ethernet Network on a Freeway System

Command Data AppliancesThe Command product line provides data collection and processing functionality for many ITS applications. Figure 7 on the fol-lowing page shows the data flow between the Command products.

Command Collector is a software appliance that ships preinstalled on rack-mount servers. This appliance includes data collection drivers for a number of different traffic sensors and will collect traffic data from the SmartSensor HD network described in this document and then place the data in a database.

Collector employs a Web interface that allows you access to all Collector functionality using a Web browser from any networked workstation.

To ensure sensor functionality, the Collector Web interface lists each of the currently registered devices in a grid with a status light showing a good, warning or error status. The main page also shows a data snapshot containing the most recent data packet for an at-a-glance perusal of current data values.

The Collector Web interface also contains a record of recent sensor connection attempts (up to 100) showing successes and failures. This allows operators to see at-a-glance the recent connection history and any minor or major communication problems.


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Once the data has been collected into a database, it must be processed in order to create speed maps and travel times.

Translator

SpeedMap

N

Collector

Figure 7 – The Dataflow Between Command Products

The Command SpeedMap software appliance will interface with Collector and use the data in its database to create speed maps that update in real time.

The Command Translator software appliance allows you to create routes based on existing sensor sites to serve as the data back-bone for trip-time calculation.

Translator has the capability of throwing out data that is beyond certain ranges, and/or automatically adjusting the data based on (for example) local speed limits.

The trip-time algorithm can utilize volume counts to weight speeds based on the number of cars, and can fill in gaps in the data with speeds from adjacent sensor locations to provide as accurate picture of the current travel time as possible.

The End-to-End SolutionWhile the amount of hardware and software that is required for a complete intelligent transportation system is extensive, com-mercially available ITS hardware and software has advanced to the point that a complete end-to-end system can be designed and implemented without the need for additional development. Table 1 below contains a list of products that can be used to create an intelligent transportation system.

An ITS design that uses readily available products such as those in Table 1 reduces both design time and implementation time. Besides the specific system described in this document, Wavetronix products can be combined to create numberless systems that meet the needs of ITS, planning and intersection control applications.

Product Name Product DescriptionSmartSensor HD Creates volume, average speed, occupancy, and classification counts in up to 10 lanes of

traffic

SmartSensor Basic Preassembled Cabinet Unit Provides power conversion, surge protection, and cable termination for the sensor

Click 201 Serial to Ethernet Converter Provides Ethernet connectivity to the sensor

Click 341 Ethernet Switch Managed 100 Mbps Multi-mode Fiber Ethernet Switch for expansion of the Ethernet infrastructure and for providing fiber to copper conversion


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Click 400 Serial Wireless Radios Creates a wireless link between the sensor site and the cabinet with fiber access

Collector Collects data from the sensor network and stores the data in a database for real-time use by ITS applications such as trip time calculations

Translator Calculates trip times based on user defined routes

SpeedMap Interfaces with DataCollector and creates speed maps that update in real time

Table 1 – Products Used in Creating an End-to-End Intelligent Transportation System

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© 2011 Wavetronix LLC. All Rights Reserved. The Company shall not be liable for any errors contained herein or for any damages arising out of or re-lated to this document or the information contained therein, even if the Company has been advised of the possibility of such damages. The Com-pany reserves the right to make changes in the specifications and other information contained in this document without prior notification.

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End-to-End Intelligent Transportation System