	Mn/DOT Traffic Data

DataTools Index

Data Extract

1. Detectors and Stations
2. Dates
3. Data Sets
4. Times
5. File Format
6. Extracting
7. Saving/Retrieving

Run DataExtract

1. Detectors and Stations

DataExtract allows you to select either detectors or stations or a combination of the two. You can select in a variety of ways. They are:

Type a valid index number into the search box and hit enter.
Double-click the index in the available list.
Highlight multiple entries in the list by using the control or shift keys and then use the add button to add them all.
Right-click a corridor or station and choose "Select all children", then use > to select.

Detector data can be obtained by either an individual detector number or by a combination of detector numbers ( Composite Detectors ). See the DataPlot Documentation for instructions on how to use Composite Detectors. Station data can be represented by an individual station number or by creating a composite detector. If station numbers are input, they are converted to the composite detectors that represent station data. You can also select detectors and stations by creating a text input file and then importing it into DataExtract. The format for the file is quite simple. One entry per line. If it is a detector number, preface the number ( or composite ) with the letter D ( capital or lower ). If it is a station number, preface the number with S. That's all!

2. Dates

Date selection is done exactly as it is in DataPlot, but without the limitations presented by plotting data.

3. Data Sets

Data Extract can calculate many different data sets, and aggregate them accordingly. The definitions and calculations for each data set are listed here:

Volume: The number of vehicles that pass through a detector in a given time period
Occupancy: The percentage of time a detector's field is occupied by a vehicle
Flow: The number of vehicles that pass through a detector per hour (Volume * Samples per Hour)
Headway: The number of seconds between each vehicle (Seconds per Hour / Flow)
Density: The number of vehicles per mile (see the density page for calculation)
Speed: The average speed of the vehicles that pass in a sampling period (Flow / Density)
Lost/Spare Capacity: The average flow that a roadway is losing, either due to low traffic or high congestion, throughout the sampling period: Flow > 1800: 0 Density > 43: Lost Capacity: Flow - 1800 Density ≤ 43: Spare Capacity: 1800 - Flow

4. Times

You can choose to select a full days worth of data or any fractional part of a day ( down to minutes ). DataExtract expects that times are entered in 24 hour format and that you are selecting either hours or hours and minutes. If you attempt to select seconds, it will not be accepted. The entry can be of the formats:

h
h mm
hmm
hh
hhmm
hh mm

You can choose any non-numeric character if you choose to separate the hours and minutes ( e.g. hh:mm, hh mm, hh-mm etc... ).

5. File Format

The data can be extracted into a variety of file formats, hopefully versatile enough for most needs. Based on the file format that you choose, the data will be written to one or more files. When a single-file format ( composite or congestion) is chosen, you can declare the file name. The file names will automatically be generated for you when the multiple-file formats are chosen. Whether you choose a single-file format or a multiple-file format, you must select what data you want in the file(s). The options are values and a variety of aggregations of the values. Although DataExtract is not designed as a data manipulation tool, it was determined that certain aggregations of data could be useful and so, were made available. Please feel free to suggest others that you think could be useful. Additionally, you can select how you want the data oriented. Essentially, this amounts to portrait or landscape. Play around with it, you'll see what I mean.

6. Extracting

To extract the data, first make sure that you have selected at least one date, detector, data set, time frame, and the necessary file information has been provided. From the file menu, choose "Extract Data". It's that simple. This produces a CSV ( comma separated values ) file. It can then be opened with most spreadsheet and database applications as well as any text editor.

7. Saving/Retrieving

DataExtract can save and retrieve extraction settings to and from a file. You will find these options on the file menu listed as "Save Settings As..." and "Open Settings File...".