Washington State Department of Transportation
WebFlow Data
The data contained in this directory [data.wsdot.wa.gov\traffic\webflow] is intended for use by the WSDOT developed and supported program called WebFlow32. The current version can be downloaded from http://www.wsdot.com/traffic/seattle/products/webflow.aspx. Third party use of the webflow data will require an agreement with the Washington State Department of Transportation.
Use Agreement Contact:
Jeremy Bertrand
360-705-7872
BertraJ@wsdot.wa.gov
Technical Contact:
Michael Forbis
forbism@wsdot.wa.gov
Other Data:
There is an established API (application programing interface) for traffic information from WSDOT. Please visit http://www.wsdot.wa.gov/traffic/api/. You are encouraged to use the API. If you need raw volume, occupancy, and speed data, you can find data in XML format located in the regional data folder, see http://data.wsdot.wa.gov/traffic/nw for look at the data or check out http://data.wsdot.wa.gov/traffic/Documentation/TrafficDataFolders.htm for more information.
Files:
NG_WebFlowNW.csv
Database file in comma separated format and updated when changes occur.
NG_WebFlowNW.dat
Data file in text and binary format and updated every minute.
NG_WebFlowNW.csv.old
This is a discard file and should not be read or processed.
NG_WebFlowNW.dat.old
This is a discard file and should not be read or processed.
Regions:
WSDOT is divided into six regions, Northwest, Olympic, Southwest, North Central, South Central, and Eastern. Not all regions are publishing traffic data. In the filenames listed above there is an NW which stands for Northwest. If there is data available from Olympic region the file will contain an OR rather than an NW.
How to Use the Data:
Each file has a version number, time stamp, and item count. The developer should read the database file on start up. Next read the data file and verify that the version and item count match the ones found in the database file. Then, check the time stamp to ensure the data is current enough for your application. Unpack and use the data. Depending on your application requirements read the data file and recheck the version, item count, and time stamp. If the version changes you must read the database again and compare the version and item counts again. If the versions do not match – do not attempt to use the data. The item count should not change unless the version changes. Do not attempt to read the file more than once per minute. This data is intended for real time applications. Do not attempt to aggregate this one minute data into larger blocks for traffic analysis.
Format of NG_WebFlowNW.csv:
The database contains four lines of text as below:
Version = 591
DateTime = 04/07/2010 11:05:10
Count = 7240
Name Location Milepost Lanes Latitude Longitude
The file should contain “Count” lines. In this case the file would contain 7240 more lines. The last line in the file is “End” which marks the end of the file.
Format of NG_WebFlowNW.dat:
The data contains four lines of text as below:
Version = 591
DateTime = 04/07/2010 11:05:10
Count = 7240
Volume (MSB LSB) Occ. (Byte) Speed (Byte w/ msb flag)
The file should contain “Count” data stations. In this case the file would contain 7240 data stations. Each data item is four bytes long. Volume is two bytes with the most significant byte (MSB) first. The occupancy is only one byte and is given as percent. Speed is one byte, but only uses the lower 7 bits (0 – 127 miles/hour). The most significant bit is a flag that indicates whether or not WSDOT believes the data is good or bad (1 = good, 0 = bad). The end of the file is marked with “End”.
Data Definitions:
Version - An integer number that relates the database and data files.
DateTime - The date and time the contents of the file were created.
Count - The number of lines or stations contained in a file.
Station - A point on a road that contains one or more lanes of traffic.
Volume - A count of all vehicles that crossed the lanes in a station.
Occupancy - The percent of time that the station sensed a car in the time period.
Speed - Average speed at the station in miles per hour.
Name - Name of the station in the form RRResMMMMM where R is the State
Route number, “es” stands for electronic sensor, and M is the milepost to the nearest 1/100 of a mile.
Location - A text description of the cross street nearest the cabinet.
Milepost - The milepost of the cabinet to the nearest 1/100 mile, not the station.
Lanes - Number of traffic lanes in the station.
Latitude - The latitude of the cabinet, not the station.
Longitude - The longitude of the cabinet, not the station.
Station name 005es13969:_MN___1 is located on I-5 northbound at milepost 139.69. The device is a single lane detector located on the I-5 mainline. _MN___1 is the device name and includes 7 characters. Characters from left (1) to right (7):
Character 1 designations of ‘D’ are for extra detectors and should not be used in most real time applications. If characters 5, 6, 7 = Stn, the station is an aggregation of multiple lanes. Usually a station contains devices of “__1”, “__2”, “__3”, “__4” to the greatest lane in the cabinet. Character 5 designations of ‘P’, ‘D’, ‘Q’, and ‘A’ are for the ramp meter systems. Data from the Passage loop is considered that most accurate for an on ramp. The ‘O’ designation is for an on ramp that is not metered. Typically, a real time application should use stations of “_Stn” for mainline roadways and ramps should be O, X, and P.