USING ANALYSIS AND VISUALIZATION VASITE TO GET YOUR …Computation and Visualization of Historic Congestion Trends On Virginia Interstates During Major Holiday Travel Periods Data

Sanhita Lahiri, P.E., PTOE

Virginia Department of Transportation [email protected]

USING ANALYSIS AND VISUALIZATION

TO GET YOUR POINT ACROSS

Simona Babiceanu,

University of Virginia [email protected]

Computation and

Visualization of Historic

Congestion Trends on

Virginia Interstates During

Major Holiday Travel Periods

VASITE

2014 - SUMMER

mailto:[email protected]



Computation and Visualization of Historic Congestion Trends

On Virginia Interstates During Major Holiday Travel Periods

Introduction

Data Analysis Methodology

Visualization – Desktop and Mobile

Challenges

Q & A

2



Data

Focus – Interstates within Virginia

Data Used – Latest 3 years from INRIX

Granularity – 1 minute aggregated to 30-

minutes

3



Data Analysis – Prepare Data for Averaging

Standard deviations (STDV) of speeds over latest 3

years were calculated at 1-minute intervals and a

threshold STDV was chosen

The 1 minute data for every Traffic Message

Channels (TMC) was averaged to 30 minute

An “STDV Test” was performed for each TMC

o Speed Data with STDV below threshold was

“Ready” to be averaged across three years

o Speed Data above threshold STDV was

considered Outlier data and several steps were

performed to get it “Ready”

4



Data Analysis – Interim Steps to Eliminate Outliers

Remaining outlier data was normal (“ready”)

for a TMC if

o All three individual yearly speeds had same

Congestion Level

o Only one of three possible yearly pairs had

STDV below threshold. The outlier speed was

eliminated and speeds from the other two years

were used.

o The outlier speed was matched with only one

incident. The speed from incident year was

eliminated.

5



Mainline Congestion Threshold

Based on experience, posted speed limits,

rural or urban area and roadway gradient,

speed thresholds were assigned to different

levels of congestion

6

Speed Limit Threshold Congestion Level

Urban (60

mph or 55

mph)

55 mph or above Little to No Congestion

between 45 and 54 mph Moderate Congestion

less than 45 mph Heavy Congestion

Rural (65

mph or 70

mph)

63 mph or above Little to No Congestion

between 45 and 62 mph Moderate Congestion

less than 45 mph Heavy Congestion



Outlier Elimination

Remaining outliers were eliminated based on

values from their neighbors.

7

Congestion Level

Little to No Congestion

Moderate Congestion

Heavy Congestion

Outliers



Outlier Elimination

Remaining outliers were eliminated based on

values from their neighbors.

8

Congestion Level


Moderate Congestion

Heavy Congestion

Outliers



Data Smoothing

Single cells completely surrounded by cells of different

congestion levels were changed to match neighbors.

9

Congestion Level


Moderate Congestion

Heavy Congestion

Outliers



Data Smoothing

Single cells completely surrounded by cells of different

congestion levels were changed to match neighbors.

10

Congestion Level


Moderate Congestion

Heavy Congestion

Outliers



Final Result

11

Congestion Level


Moderate Congestion

Heavy Congestion

Outliers



Local Feedback

Manual Adjustments based on comments and special

conditions

o RHOV lanes

o I-495 Express Lane Construction

o I-564 connecting I-64 to the Norfolk Naval Base

o I-581 in Roanoke

o I-77 (Mountainous area)

o Downtown Tunnel in Hampton Roads with

Flashing Posted Speed Limits

12



13

Outlier Stats

Percent outliers at the end of each data

processing step

Holiday

Standard Deviation Threshold

STDV> Threshold

Not the Same Congestion Level

After Elimination of Outlier Speed

After Incident Mapping

TG 2012 5 mph 12.1 10 2.9 2.8

MD 2013 3.5 mph 10.5 7.2 2.3 2.2

TG 2013 4 mph 11.7 8.6 2.6 2.5

MD 2014 4 mph (mainlines) 7 mph (ramps)

7.6 5.8 1.6 1.5



Data Analysis and Field Verification Challenges

Inadequate Ramp Data

Adjusting Map based on Field Validation

Influence of truck speed on TMC speed on

mountains

INRIX data quality, availability and coverage

Understanding Drivers Expectations amidst

various travel information available

14



Online Google Maps Website

Congestion level data and geometry KML files

were loaded into Google Fusion Tables.

Congestion level color corresponds to a

specific road segment (TMC) and time period.

Website

Custom GM JavaScript API v3 code, HTML, jQuery

Interactive, easy-to-use, time-aware (slider, Prev/Next

buttons)

Custom interstate shields

Legend

15



Website code: time-awareness, interstate shield

layer, KML selection by zoom level, map coloring

are achieved with custom code.

Shapefile pyramid: shapefiles for each level of

zoom created from basic, undistorted shapefile.

Distortion: offset between the two directions

Manual corrections necessary to remove artifacts and

achieve visually pleasing results

Ramps and RHOV only at high levels of zoom

(zoomed in)

Time consuming, laborious, trial and error process

16



Mobile Version – Goal

Website with same URL as desktop version

o Automatic detection when accessed via

mobile device

Maximizing code sharing and easy migration

o Maximizing code sharing with desktop

version

o Easy migration to work with different

datasets e.g. Memorial day weekend (4 days),

Thanksgiving (5 days)..

17



Mobile Version – Working Parameters

GUI designed to cover mainstream mobile

devices on the market and display graphics

consistently

Operating Systems: iOS, Android, Windows

(Phone)

Different versions of OSs – e.g., iOS 6, iOS 7

Browser: Safari, Chrome, IE Mobile, Firefox,

etc.

Hardware: Mobile phones, Tablets, etc.

18



Mobile Version

Design of Mobile friendly GUI functions

o Showing map on a small screen, yet

highlighting the pertinent features for the user

Cross mobile devices compatibility

o Dealing with various screen resolutions, e.g.

320 X 480 to 1920 X 1080 and higher

o Customizing web components based on the

device screen size / resolution

o Dealing with mobile OS migration issues, such

as from iOS 6 to iOS 7

19



Preview

http://people.virginia.edu/~seb4v/Thanksgiving2013 http://people.virginia.edu/~seb4v/MDW2014

20

http://people.virginia.edu/~seb4v/Thanksgiving2013

http://people.virginia.edu/~seb4v/MDW2014

Documents

USING ANALYSIS AND VISUALIZATION VASITE TO GET YOUR …Computation and Visualization of Historic Congestion Trends On Virginia Interstates During Major Holiday Travel Periods Data