1. WIFI Data Collection and the Effectiveness of Various Survey Expansion Techniques- A Case Study on I-95 Corridor in Palm Beach County, FL Presented to TRB National Transportation Planning Applications Conference Raleigh, NC Presented by Srin Varanasi The Corradino Group
05/16/2017

2. Acknowledgements Cesar Martinez, PE Concept Development Supervisor
FDOT District 4- PLEM
Fort Lauderdale, FL
Sheng Yang, PE
President
CTS Engineering, Inc.
Fort Lauderdale, FL
Aditya Katragadda
Transportation Planner, The Corradino Group, Fort Lauderdale, FL
Ken Kaltenbach, PE
Senior Vice President
The Corradino Group, Louisville, KY

3. Presentation Overview
I-95 Express Palm Beach Planning Study overview
Corridor description
Bluetooth/WIFI data collection process
OD expansion methods considered
OD expansion using CUBE Analyst
Results discussion

4. Study Overview Traffic data collection Traffic balancing, OD expansion
Corridor travel demand forecasts development
Integration to VISSIM Microsimulation
Develop feasible and viable concepts

5. Corridor Description I-95 Express Master Plan
Study the corridor improvements, including Express Lanes
Northern Palm Beach County
-about 60 miles north of Miami
8-10L Typical with an existing HOV lane

6. Bluetooth/WIFI Data Collection Process (1)
Acyclica Bluetooth/WIFI equipment
Detects anonymous MAC addresses
Targeted at Bluetooth/WIFI technologies of vehicles/mobile devices
May 10-12th 2016 data collection- 3 consecutive weekdays (Tuesday-Thursday)

7. Bluetooth/WiFi Data Collection Process (2)
48 OD locations E and W of I-95 on cross streets
16 interim locations of I-95 mainline to validate the data
Simultaneous 48-hour traffic count data collection at the OD locations

8. Bluetooth/WIFI Data Collection Results- Seed OD Matrix Development
Three sets of OD matrices
AM peak hour
PM peak hour
Daily
In most locations 15-25% detection rate
A few outliers 5-15%; 25-40%
Pros-
Local OD detection
High detection rate
Cons
Detects MAC IDs not vehicles
Possibility of bias with more than one MAC ID presence
Capture of parallel corridor traffic, when close by

9. OD Expansion Methods Considered (1)
CUBE Analyst Drive OD Expansion
Use of feedback loop with highway assignment
Tests using matrix cell confidences
Close to 2% RMSE between assigned volumes and counts
Similar trends in OD patterns to the raw BT/WIFI OD
Null Test- A matrix of ones used as input instead of the BT/WIFI data.
%RMSE between Null Test OD and BT/WIFI Daily Expanded OD: 135%

10. OD Expansion Methods Considered (2)
Iterative Proportional Fitting Method
Use of a small value (0.1) for cells with zero values
Row and column based doubly- constrained balancing process
Resulted in large RMSE ~ 28 % when assigned
TLFD and average TL statistics results similar to the raw BT/WIFI OD
Travel Demand Seed Matrix and expand using CUBE Analyst Drive
3% RMSE when assigned
RMSE ~35% between BT/WIFI expanded OD and travel demand model based OD
Sensitive to land use changes in travel demand

11. BT/WIFI OD Expansion (1)
CUBE Analyst Drive Method
A matrix estimation program that optimizes OD matrices for a given traffic assignment and input traffic count data
Setup a feedback loop between highway assignment and Analyst Drive
Logged %RMSE
Monitored Avg. Trip Length TLFD

12. BT/WIFI OD Expansion (2)
Inputs
BT/WIFI seed matrices with confidence levels
ICP file analogous to the highway path file
Traffic count targets/screenlines
Trip end controls (in this case disabled)
Turn penalties/prohibitions for the highway assignment
Outputs
Matrix output
Assigned loaded network via highway assignment
%RMSE measures

13. BT/WIFI OD Expansion Results (1)
Iterative Feedback RMSE and Volume/Count Ratio Logs

14. BT/WIFI OD Expansion Results (2) Origin-based “Heat” Maps for Managed Lanes Access Points Determination
Raw WIFI/BT OD grouped by Logical Destinations
Expanded WIFI/BT OD grouped by Logical Destinations

15. BT/WIFI OD Expansion Results (3) Total Trips by Interchange
Raw Origin and Destination Data
Expanded Origin and Destination Data

16. BT/WIFI OD Expansion Results (4) Total Trips by City
Raw Origin and Destination Data
Expanded Origin and Destination Data

17. Conclusions & Recommendations
BT/WIFI method of OD data collection results in reasonable sample rates
CUBE Analyst Drive method, using a feedback loop between highway assignment and matrix estimation process, is an effective matrix expansion technique
The null test and BT/WI expanded matrix differences prove that OD data collection is important. Null test travel patterns are different than OD expanded data
Simple iterative proportional fitting may not be an effective method of OD expansion process

18. Questions/Discussion
Thank You!
Questions/Discussion