The Matrix&

The NYSDOT Traffic Forecaster

By

Scott Garvey

Transportation Analyst

Traffic Monitoring Section

Highway Data Services Bureau

But what is the Matrix??

Yes. I know…It’s a Movie…

BUT…

It’s also a database!!

Red Pill = Database?? Blue Pill = Movie??

The Purpose of……The Matrix (the HDSB one)

To keep an ACCESSiblerecord of AADT’s by year for each count station in New York State.

To help determine which stations need to be counted each year when constructing the annual count schedule.

The Purpose of……The Matrix (the HDSB one)

To provide the necessary data for calculating growth factors.

To provide comedic ammunition for ridiculous on-the-nose references about a series of sci-fi movies.

The Matrix as a Record

The Matrix stores the AADT’s for the nearly 56,000 stations across New York State.

Count records currently exist for the year 2000 and beyond in the Master Matrix.

The Matrix as a Record

As changes are made to stations, these changes must be updated in the Matrix as well.

Large updates to The Matrix typically happen two to three times a year with counts from the previous year.

Plus, it is updated manually on a case-to-case basis as needed.

Count Scheduling

The records contained in The Matrix are used to determine which stations need to be added to the yearly count schedule.

The Matrix is combined with the important data from the Station Header and Off Network Station Header to start the scheduling process.

Growth Factors

The Matrix data is sent to the Traffic Forecaster to determine growth rates for the roads in New York State.

Note: The Forecaster only functions with the latest 15 years worth of data.

A Glitch in The Matrix…

A Glitch in The Matrix

A new Matrix file may be created several times a year.

A special matrix file must be designed for every significant change in counts. This might happen 3 to 5 times a year.

A Glitch in The Matrix

A new Matrix file is created once or twice in early Spring.

These Spring updates also get sent to TCE for future count processing purposes.

The Matrix file is also created for federal reporting purposes.

A Glitch in The Matrix

A Matrix file is created once in early summer for further growth factor analysis.

The Matrix file is also useful as a pre-scheduling tool to determine stations that might need to be counted early.

A Glitch in The Matrix

A new Matrix file may possibly be created once or twice a year if a data purge is deemed necessary. This may only happen

every few years or so.

Also as an occasional special request.

Does The Matrix have you??

Well?Does it…??

The NYSDOT Traffic Forecaster

Forecaster Uses

The NYSDOT Traffic Forecaster is used to calculate growth factors.

The Forecaster is also a very useful aid in “Matrix Cleanup”.

It’s difficult to fill a 30-minute time slot if I just talked about The Matrix.

How Does it Work?

Forecaster Setup

All the count data in a forecaster file comes from a Matrix file.

The Matrix file is saved as an Excel CSV file.

The Excel CSV file is then loaded into the Forecaster.

Forecaster Setup

When first setting up a Matrix file in the Forecaster, the Parameter window is encountered.

Minimum acceptable AADT values (Actuals).

Multi-year growth factor projections.

Forecaster Setup

Minimum R-squared value (percent of variance explained by the model).

Outlier detection. Detect Least-trimmed squares None

Curve options Linear Exponential

Record Selection

The Forecaster can be customized by selecting a specific type of record to be displayed. Some examples of selection

criteria include: NHS Code, Geo Code, Region, County, Functional Class, Factor Group, Route Number, Bridge ID.

For everyday general tasks, the selection criteria is just all 11 regions.

Grouping

Records can be specifically grouped. Groups consist of the

same possibilities as the Record Selection criteria.

Establishing groups can be very helpful to determine a growth factor for a station with two or less counts.

For everyday general tasks, records are grouped by Region and Functional Class.

Actuals, Estimates, and Forecasts (Oh My)

Three types of AADT value. Actual

Physical AADT count for the year

Estimate

A (count) which exists between two Actuals

Forecast

A (count) following the last Actual count

Growth Factor AnalysisStation 120460

Result Browser Record Details Window

Forecasting AnalysisStation 120460

Forecast Browser Forecast Details Window

So how does the Forecaster aid in Matrix cleanup?

Matrix Cleanup

Matrix cleanup involves analyzing suspicious stations with the NYSDOT Traffic Forecaster.

Once a station (like this one) is discovered, it is researched to determine if something is wrong.

Matrix Cleanup

If a count is found to be erroneous, it is deleted or moved in the Matrix.

A new Forecaster file is created from the revised Matrix with the changes made.

The Matrix Cleanup Reloaded

Before After

Report Not Deleted from Matrix

Before After

AADT Record Mismatch

Before After

Questions?

Scott Garvey

Email: Scott.Garvey@dot.ny.gov