Real time and historic data collection in a blender Scott ... TIME AND HISTORIC DA… · Real time and historic data collection in a blender Scott Benjamin AITPM National Conference

Real time and historic data collection in a blender

Scott BenjaminAITPM National Conference 2013

Presentation Outline

• Data Requirements• Matrix of solutions• Discussion of some existing technologies

• SCATS loop detection• Discussion of new technologies

• Camera based technologies• Bluetooth and WiFi

• Discussion of data blending

Austraffic – Blended Data Solutions 2

Survey Types

Main traffic engineering and transport network planning surveys• Link counts• Intersection counts• Origin / Destination Surveys• Queuing surveys• Road Use Analysis• Travel Time Survey


Origin & Destination Data

• Why is it important?• Reflects behaviour: Strategic• Allows tracking of weaving behaviour: Operational

• Why is it so difficult?• High sample rate required• Absolute count & understanding of sample rate• (Easily biased)


Collection Methods

There are a wide range of options, there is a need to tailor survey solutions based on the constraints of:

• Sample or absolute count required• Accuracy required• Safety and practicalities of collection, eg privacy• Timescales for collection, processing and presentation• Budget

Resulting in many survey options…


Collection Methods

However the list of constraints will often be shortened to:

• Budget• Timescales for collection, processing and presentation

The client may say…

“I just want something to give me a bit of an indication….”

Where is this data going to end up and will it be qualified ?It is incumbent on us as professionals to present best value.


Collection Methods


Survey Method

Lin

k C

ount

Lin

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ifica

tion

Turn

ing

Cou

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Vehi

cle

Pres

ence

Que

uing

Trav

el T

ime

or

Del

ay

Spee

d

Hea

dway

OD

& T

rack

ing

Surv

eys

Beh

avio

ural

St

udie

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Pede

stri

an O

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ATC Tube or Piezobased Loggers

••• ••• ••• •••Loop Based loggers ••• ••• ••• ••Magnetometers •• • ••• •• ••SCATS inductive loops •• • ••• •Beam based Sensors (eg Infrared)

•• •• •• ••Floating Vehicle (GPS) •• ••• •• •Lidar •• •• •• • ••• •••Radar •• ••• •Camera/s (automatic or manual) ••• •• ••• •• •• ••• •• ••• ••• ••Mobile Phone Data • •• •• •• •• ••Bluetooth (BT) Sensors ••• ••• •• •• ••Manual Staff •• •• ••• ••• •• • •• ••• ••

Collection Methods – Scats Loops

• Primary function is determining presence of vehicles• Inappropriate position of sensor for count information (would not position tubes or other inductive loop counters at stopline).


Collection Methods – SCATS Loops

• Can give some indication of flow if well calibrated HOWEVER

accuracy decreases significantly as headway decreases i.e. in congested conditions.

• Can undercount light vehicles by 30 to 50%• Commonly breaks up heavy vehicle axle sets • With no secondary survey method there is no way of seeing any abnormalities in the data collected• Blending of data highly recommended


Bluetooth and other RF Technologies

Urban (traffic surveyor) Myth:• BT technology can completely replace a number

of survey types

• All devices have similar sample rates

• All devices work reliably and produce repeatable results

• It is a cheaper form of survey


?


Some Positives:• Operate for long periods with little maintenance required• Near real time data feed from site from some devices• Some devices allow remote configuration• MAC addresses (or encrypted strings) are almost unique

identifiers, giving high certainty of a match

HOWEVER



Some Questions:• Privacy and surveillance issues?• Sample rate? (over page)• How repeatable is the measurement and why is this

important?(over page)Key limitations:

1. Validation 2. Classification


State and National Guidelines and LegislationSURVEILLANCE DEVICES ACT

• Do you know what the situation is in your state?• What does this technology offer that is unique (audit)?• Must pass the privacy test before we consider issues of

security i.e. should we be collecting this piece of data regardless of how you will protect it once collected?




Degradation of Bluetooth Reliability



• Sample Rate (5% 35%) • Devices per vehicle ? • Repeatability (10% 95%) • Mix of BT and WiFi devices?• Vehicle class?

Bluetooth and other RF Technologies –Number of Devices?


iOS Android


How bad can it be? Real world example with validation against video and ATC data…



Origin:



Origin – Camera Target Area:



Origin – Possible BT Target Area:


Note extraneous and unintended vehicle capture in red – very difficult to know this is happening without secondary forms of survey / validation


Destination A




Destination A – Camera Target Area:



Destination A – Possible BT Target Area:



Destination B




Destination B – Camera Target Area:



Destination B – Possible BT Target Area:


Bluetooth and other RF Technologies: Dest. A


Statistics 101 – What is a Z Score?

• Standard Error

• Z Statistic

Bluetooth and other RF TechnologiesHow bad can it be?


Z=0.35

Z=4.37

Z=0.21


Video Results (Approx. 97% sample)


31% (168)

2% (12)

67% (355)


BT Results (Approx. 30% sample).

Compare results withprevious video slide

Results that serveas a validation

& calibration


36% (121)

27% (89)

37% (122)

Guess what ! A massive survey bias identified. What happens if you can not validate??


Why is this happening? Clever sensor arrays allow us to mitigate…



Why is this happening and can we mitigate… Filters!?



Why is this happening and can we mitigate… Filters!?


Trav

el T

ime

Time of DayReal world validation built up over many years can provide a significant advantage


• Possible to validate and factor using accurate camera or ATC (V.B.V.) data.

• Some devices have the intelligence to provide automated data cleansing.

• Directional and other antennae and filtering functionality assist greatly in ensuring targeted data collection.

• Exclusive Partnership between BLIP Systems and Austraffic in Australia, However…

Still a need for blended approach to data provision


Other Potential Future Data Sources

• Mobile Phone Data• Beyond passive polling…• Understand potential• Understand cost sensitivity• Respect privacy

• Cooperative ITS• It will happen, but how and when will determine what

data is available• BT is a stepping stone in understanding how to prove

the case for significant changes in traffic control


The Blender (1of 2)

• Firstly what do you want to do with the data?• Mix of coverage and accuracy:• Common mix is 2 or 3 hour peaks (TMC) plus tube data• What is the new equivalent?


The Blender (2 of 2)

• Bluetooth options for classification and counts:• Second Infrared Sensor • Tubes or is it possible to validate with camera data for

portion of the survey OR do we have absolute certainty about overlapping read issues??

• NEXT STEP: BT queuing proxy, unique to Austraffic


Conclusion

• Wide range of possible survey solutions• Survey results are the basis for much of the work we do in

Traffic Engineering and Transport Planning• New technologies continue to develop and will continue to

offer new potential benefits• Universal truths still hold – best value is vitally important


Many thanks – Any Questions?


Paper is available at: www.austraffic.com.au/news

Contact me: [email protected]

OR in other states:

WA: [email protected]: [email protected] & ACT: [email protected]: [email protected] & TAS: [email protected]

Documents

Real time and historic data collection in a blender Scott ... TIME AND HISTORIC DA… · Real time and historic data collection in a blender Scott Benjamin AITPM National Conference