SECTION 6
Traffic Monitoring Data Formats

Table of Contents

1. CHAPTER 1 - INTRODUCTION
   • Traffic Data Records
   • Data Submittals to the FHWA
2. CHAPTER 2 - STATION DESCRIPTION DATA FORMATS
3. CHAPTER 3 - TRAFFIC VOLUME DATA FORMATS
4. CHAPTER 4 - VEHICLE CLASSIFICATION DATA FORMATS
5. CHAPTER 5 - TRUCK WEIGHT DATA FORMATS

TABLES

• Table 6-2-1 Station Description Record
• Table 6-3-1 Hourly Traffic Volume Record (#3 Record)
• Table 6-4-1 Vehicle Classification Record
• Table 6-5-1 Truck Weight Record

Traffic Data Records

This section contains instructions for coding data in the formats requested by the FHWA. The record formats and coding instructions have been developed to provide input to national databases maintained by the FHWA. These include the Traffic Volume Trends (TVT) system and the Vehicle Travel Information System (VTRIS).

The TVT system is used to process the continuous traffic volume data and produce the monthly Traffic Volume Trends report. The VTRIS is used to process the vehicle classification and truck weight data collected as part of the annual Truck Weight Study. Both are microcomputer database management systems that process, validate, summarize, and maintain traffic data. TVT and VTRIS may be used by anyone with data in the formats described in this section and can be retrieved from the FHWA web site at http://www.fhwa.dot.gov/ohim/tvtw/tvtwpage.htm The data collection program has been approved by the Office of Management and Budget, OMB # 2125-0587, and has a current expiration date of April 30, 2004.

The data records are divided into four types: station description data, traffic volume data, vehicle classification data, and truck weight data. Each type of data has its own individualized record format. Specific coding instructions and record layouts are discussed separately for each type of data in the following chapters.

Note that some fields are labeled "critical." This means that a record cannot be processed by TVT or VTRIS without them. All data files described here are ASCII flat files. For character fields with missing or inapplicable data, enter blanks. Numbers such as counts should be right-justified and filled with leading blanks or zeros unless noted otherwise. For numeric fields with missing or inapplicable data, enter blanks or "-1" right-justified.

Certain data items are common to all four types of records. For example, all records contain a six-character station identification. This allows States to use a common identification system for all traffic monitoring stations.

Several fields in the station description record were replaced with fields that are needed to tie traffic data to geographic information systems (GIS). This will allow traffic data to be overlaid on the National Highway Planning Network (NHPN) and similar systems.

Data Submittals to the FHWA

Copies of continuous traffic volume data collected by permanent ATRs should be submitted monthly to the FHWA within 20 days after the close of the month for which the data were collected. The station description record need only be sent annually or when there is a change. The preferred method of transmission is as an attachment to an e-mail message sent to "atrdata@fhwa.dot.gov". Alternatively, diskettes may be mailed to:

Federal Highway Administration
Travel Monitoring and Surveys Division, HPPI-30
400 Seventh Street, SW
Washington, D.C. 20590
Attention: Traffic Volume Trends

Annually, each State should submit to the FHWA the vehicle classification and truck weight data collected at WIM sites. Data for the preceding calendar year should be submitted by June 15th. More frequent submissions are also acceptable.

If continuous weigh-in-motion data are available, send up to one week of data per quarter (select any week without a holiday). The data should be addressed as follows:

Federal Highway Administration
Travel Monitoring and Surveys Division, HPPI-30
400 Seventh Street, SW
Washington, D.C. 20590
Attention: Vehicle Travel Information System

All data should be in the record formats described in this section and edited for reasonableness. If the files are large, it is preferable that a compression program such as PKZIP be used to condense them. Please provide the name of a contact person and the telephone number in case further clarification is necessary. For further information, contact the Travel Monitoring Division and Surveys Division at (202) 366-0175.

The Station Description record format is used for all traffic volume, vehicle classification, and truck weight monitoring stations. A Station Description file contains one record for each traffic monitoring station per year. All fields are considered to be character fields. The optional file naming convention is "ssyy.STA", where ss is state postal abbreviation and yy is the last two digits of the year. Table 6-2-1 summarizes the Station Description record.

Fields designated as Critical are required for entry into the VTRIS database.

1. Record Type (Column 1) - Critical

S = Station description record

2. FIPS State Codes (Columns 2-3) - Critical

Table 6-2-1: Station Description Record

3. Station Identification (Columns 4-9) - Critical

This field should contain an alphanumeric designation for the station where the survey data are collected. Station identification field entries must be identical in all records for a given station. Differences in characters, including spaces, blanks, hyphens, etc., prevent proper match. Right justify the Station ID if it is less than 6 characters. There should be no embedded blanks.

4. Direction of Travel Code (Column 10) - Critical

Do not combine directions. There should be a separate record for each direction. Whether or not lanes are combined in each direction depends on the next field.

5. Lane of Travel (Column 11) - Critical

Either each lane is considered a separate station or all lanes in each direction are combined.

Note: The Station ID, Direction of Travel, and Lane of Travel make up the Station Code. There should be one Station Description record per Station Code. Stations can be either by lane or with lanes combined by direction, but not both.

6. Year of Data (Columns 12-13) - Critical

Code the last two digits of the year in which the data were collected.

7. Functional Classification Code (Columns 14-15) - Critical

8. Number of Lanes in Direction Indicated (Column 16)

Code the number of lanes in one direction at the site. Use "9" if there are more than eight lanes.

9. Sample Type for Traffic Volume (Column 17)

T = Station used for Traffic Volume Trends
N = Station not used for Traffic Volume Trends

10. Number of Lanes Monitored for Traffic Volume (Column 18)

Code the number of lanes in one direction that are monitored at this site. Use "9" if there are more than eight lanes.

11. Method of Traffic Volume Counting (Column 19)

1 = Human observation (manual)
2 = Portable traffic recording device
3 = Permanent automatic traffic recorder (ATR)

12. Sample Type for Vehicle Classification (Column 20)

H = Station used for Heavy Vehicle Travel Information System
N = Station not used for Heavy Vehicle Travel Information System

13. Number of Lanes Monitored for Vehicle Classification (Column 21)

Code the number of lanes in one direction that are monitored for vehicle classification at this site. Use "9" if there are more than eight lanes.

14. Method of Vehicle Classification (Column 22)

1 = Human observation (manual) vehicle classification
2 = Portable vehicle classification device
3 = Permanent vehicle classification device

15. Algorithm for Vehicle Classification (Column 23)

Code the type of input and processing used to classify vehicles:

A = Human observation on site (manual)
B = Human observation of vehicle image (e.g., video)
C = Automated interpretation of vehicle image or signature (e.g., video, microwave, sonic)
D = Vehicle length classification
E = Axle spacing with ASTM Standard E1572
F = Axle spacing with Scheme F
G = Axle spacing with Scheme F modified
H = Other axle spacing algorithm
K = Axle spacing and weight algorithm
L = Axle spacing and vehicle length algorithm
M = Axle spacing, weight, and vehicle length algorithm
N = Axle spacing and other input(s) not specified above
Z = Other means not specified above

16. Classification System for Vehicle Classification (Columns 24-25)

This indicates the total number of classes in the vehicle classification system. The default value is 13 which indicates the standard FHWA 13 class system (see Appendix 4-C). The other vehicle classification systems are based on the HPMS and the Traffic Monitoring System (TMS) documentation. The value that is used will determine the number of count fields needed on the Vehicle Classification Record. In the following list the numbers in parentheses are from the FHWA 13 class system:

• 1 = One class: total volume
• 2 = Two classes: non-commercial (classes 1-3) and commercial (classes 4-13) vehicles
• 3 = Three classes: non-commercial (classes 1-3), single-unit commercial (classes 4-7), combination commercial (classes 8-13) vehicles
• 4 = Four classes: non-commercial (classes 1-3), single-unit commercial (classes 4-7), single-trailer commercial (classes 8-10), multi-trailer commercial (classes 11-13) vehicles
• 5 = Five classes as follows:
  • 1 of 5 = two-axle, two or four-tire vehicles (classes 1-3)
  • 2 of 5 = buses (class 4)
  • 3 of 5 = single-unit trucks (classes 5-7)
  • 4 of 5 = single-trailer combination trucks (classes 8-10)
  • 5 of 5 = multiple-trailer combination trucks (classes 11-13)
• 13 = FHWA's standard 13 class system (see Appendix 4-C)
• 14 = FHWA's 13 class system plus a class 14 (State or vendor defined)
• 15 = FHWA's 13 class system plus classes 14 and 15 (State or vendor defined)
• Other numbers = number of classes (unsupported)
  

• B = Station used for TMG sample and Strategic Highway Research Program (SHRP) Long Term Pavement Performance (LTPP) sample
• L = Station used for SHRP/LTPP sample (but not TMG sample)
• T = Station used for TMG sample (but not SHRP/LTPP sample)
• N = Station not used for any of the above

18. Number of Lanes Monitored for Truck Weight (Column 27)

Code the number of lanes in one direction that are monitored for truck weight at this site. Use "9" if there are more than eight lanes.

19. Method of Truck Weighing (Column 28)

• 1 = Portable static scale
• 2 = Chassis-mounted, towed static scale
• 3 = Platform or pit static scale
• 4 = Portable weigh-in-motion system
• 5 = Permanent weigh-in-motion system

20. Calibration of Weighing System (Column 29)

Code the method used to calibrate the weighing system, e.g., comparing weight-in-motion and weights from static scales.

• A = ASTM Standard E1318
• B = Subset of ASTM Standard E1318
• C = Combination of test trucks and trucks from the traffic stream (but not ASTM E1318)
• D = Other sample of trucks from the traffic stream
• M = Moving average of the steering axle of 3S2s
• S = Static calibration
• T = Test trucks only
• U = Uncalibrated
• Z = Other method

21. Method of Data Retrieval (Column 30)

• 1 = Not automated (manual)
• 2 = Automated (telemetry)
  

22. Type of Sensor (Column 31)

Code the type of sensor used for traffic detection.

• A = Automatic vehicle identification (AVI)
• B = Bending plate
• C = Capacitance strip
• D = Capacitance mat/pad
• E = Hydraulic load cells
• F = Fiber optic - NEW
• G = Strain gauge on bridge beam
• H = Human observation (manual)
• I = Infrared
• K = Laser/lidar
• L = Inductance loop
• M = Magnetometer
• P = Piezoelectric
• Q = Quartz piezoelectric - NEW
• R = Road tube
• S = Sonic/acoustic
• T = Tape switch
• U = Ultrasonic
• V = Video image
• W = Microwave
• X = Radio wave
• Z = Other

23. Second Type of Sensor (Column 32)

If there are two types of sensors at the station, code the second using the same codes as Type of Sensor. Otherwise, code "N" for none.

24. Primary Purpose (Column 33) - NEW

This field indicates the primary purpose for installing the station and hence which organization is responsible for it and supplies the data.

• E = Enforcement purposes (e.g., speed or weight enforcement)
• I = Operations purposes in support of ITS initiatives
  
• L = Load data for pavement design or pavement management purposes
  
• O = Operations purposes but not ITS
• P = Planning or traffic statistics purposes
• R = Research purposes (e.g., LTPP)

25. LRS Identification (Columns 34-45) - NEW

The LRS Identification reported in this item for the station must be the same as the LRS identification reported in the HPMS for the section of roadway where the station is located. The LRS identification is a 12-character, right justified value. The LRS ID can be alphanumeric, but must not contain blanks; leading zeros must be coded. More information concerning the LRS may be found in Chapter V of the HPMS Field Manual, Linear Referencing System Requirements.

26. LRS Location Point (Columns 46-51) - NEW

This is the LRS location point for the station. It is similar information to the LRS Beginning Point and LRS Ending Point in the HPMS. The KMPT for the station must be within the range of the LRS beginning point and LRS ending point for the roadway section upon which the station is located. It is coded in kilometers with an implied decimal in the middle: XXX.XXX.

27. Latitude (Columns 52-59) - NEW

This is the latitude of the station location with the north hemisphere assumed and decimal place understood as XX.XXX XXX.

28. Longitude (Columns 60-68) - NEW

This is the longitude of the station location with the west hemisphere assumed and decimal place understood as XXX.XXX XXX.

29. SHRP Site Identification (Columns 69-72) - NEW

If the site is used in the SHRP/LTPP sample, give the SHRP site ID.

30. Previous Station ID (Columns 73-78)

If the station replaces another station, give the station ID that was used previously.

31. Year Station Established (Columns 79-80)

Code the last two digits of the appropriate year if known.

32. Year Station Discontinued (Columns 81-82)

Code the last two digits of the appropriate year if known.

33. FIPS County Code (Columns 83-85)

Use the three-digit FIPS county code (see Federal Information Processing Standards Publication 6, "Counties of the States of the United States").

34. HPMS Sample Type (Column 86)

• N = No, not on an HPMS standard sample section
• Y = Yes, on an HPMS standard sample section

35. HPMS Sample Identifier (Columns 87-98)

If the station is on an HPMS standard sample section, code the HPMS Sample Identifier per the HPMS Field Manual (Item 47).

36. National Highway System (Column 66) - NEW

• N = No, not on National Highway System
• Y = Yes, on National Highway System

37. Posted Route Signing (Column 100)

This is the same as Route Signing in HPMS Field Manual (Item 22).

38. Posted Signed Route Number (Columns 101-108)

Code the route number of the principal route on which the station is located. If the station is located on a city street, zero-fill this field. This is the same as Signed Route Number in HPMS Field Manual (Item 24).

39. Concurrent Route Signing (Column 109)

Code same as Posted Route Signing for concurrent route if there is one.

40. Concurrent Signed Route Number (Columns 110-117)

Code same as Posted Signed Route Number for concurrent route if there is one.

41. Station Location (Columns 118-167)

For stations located on a numbered route, enter the distance and direction of the station from the nearest major intersecting route or state border or landmark on state road maps. If the station is located on a city street, enter the city and street name. Abbreviate if necessary. Left justify.

Chapter 3
TRAFFIC VOLUME DATA FORMATS

The Traffic Volume file contains one record for each day of traffic monitoring. All numeric fields should be right-justified and zero-filled. Table 6-3-1 summarizes the Hourly Traffic Volume record. The fields are as follows:

1. Record Type (Column 1) - Critical

• 3 = Traffic volume record

2. FIPS State Code (Columns 2-3) - See chapter 6-2. - Critical

3. Functional Classification Code (Columns 4-5) - See chapter 6-2. - Critical

4. Station Identification (Columns 6-11) - See chapter 6-2. - Critical

This should be right-justified and zero-filled. - Critical

5. Direction of Travel Code (Column 12) - See chapter 6-2. - Critical

6. Lane of Travel (Column 13) - See chapter 6-2. - Critical

The code for combined lanes (0) is preferred.

7. Year of Data (Columns 14-15) - See chapter 6-2. - Critical

8. Month of Data (Columns 16-17) - Critical

• 01 = January
• 02 = February
• 03 = March
• 04 = April
• 05 = May
• 06 = June
• 07 = July
• 08 = August
• 09 = September
• 10 = October
• 11 = November
• 12 = December

9. Day of Data (Columns 18-19) - Critical

Code the day of the month of data, 01-31. Must correspond to the month of data.

10. Day of Week (Column 20) - Optional

• 1 = Sunday
• 2 = Monday
• 3 = Tuesday
• 4 = Wednesday
• 5 = Thursday
• 6 = Friday
• 7 = Saturday

11-34. Traffic Volume Counted Fields (Columns 21-25, ..., 136-140)

Enter the traffic volume counted during the hour covered. If the data are missing, code a -1 or blanks.

35. Restrictions (Column 141)

• 0 = no restrictions
• 1 = construction or other activity affected traffic flow
• 2 = traffic counting device problem (e.g., malfunction or overflow) - NEW
  

Table 6-3-1: Hourly Traffic Volume Record (#3 Record)

Chapter 4
VEHICLE CLASSIFICATION DATA FORMATS

The Vehicle Classification file contains one record for each hour with the traffic volume by vehicle class. The optional file naming convention is "ssyy.CLA", where ss is state postal abbreviation and yy is the last two digits of the year. Table 6-4-1 summarizes the Vehicle Classification record.

Fields designated as Critical are required for entry into the VTRIS data base.

1. Record Type (Column 1) - Critical

• C = Vehicle classification record

2. FIPS State Code (Columns 2-3) - Critical - See chapter 6-2.

3. Station Identification (Columns 4-9) - Critical - See chapter 6-2.

4. Direction of Travel Code (Column 10) - Critical - See chapter 6-2.

5. Lane of Travel (Column 11) - Critical - See chapter 6-2.

Note: The Station ID, Direction of Travel, and Lane of Travel make up the Station Code. There should be one Station Description record per Station Code.

6. Year of Data (Columns 12-13) - Critical - See chapter 6-2.

7. Month of Data (Columns 14-15) - Critical - See chapter 6-3.

8. Day of Data (Columns 16-17) - Critical - See chapter 6-3.

9. Hour of Data (Columns 18-19) - Critical

Code the beginning of the hour in which the count was taken:

• 00 = 0:01 a.m. to 1:00 a.m.
• 01 = 1:01 a.m. to 2:00 a.m.
• ...
• ...
• 22 = 10:01 p.m. to 11:00 p.m.
• 23 = 11:01 p.m. to Midnight

10. Total Hourly Volume (Columns 20-24)

This numeric field is the total traffic volume for the hour. The total volume is needed because some vehicles might not be classified, in which case the sum of the class counts would not equal the total volume. If the total volume is not collected, leave this field blank or put "-1" (for missing data).

The following class count fields are numeric fields with the traffic volume by vehicle class for each hour of data. Field number 16 in the Station Description Record, "Classification System for Vehicle Classification," determines the number of classes expected from the station. The default classification system is the FHWA 13 class system (see Appendix 4-C).

These counts should be checked for reasonableness. For example, Class 13 should not be larger than 99. VTRIS allows users to set a limit for each class count

11. Class 1 Count (Columns 25-29) - Optional

Class 1 is for Motorcycles, which is an optional class. If motorcycles are not counted, enter "-1" or blanks in the Class 1 field.

12. Class 2 Count (Columns 30-34) - Critical

Class 2 is for Passenger Cars.

13. Class 3 Count (Columns 35-39) - Optional

Class 3 is for Other Two-Axle, Four-Tire, Single-Unit Vehicles. However, classes 2 and 3 may be combined, in which case the total for both classes should be entered in the class 2 field and "-1" or blanks in the Class 3 field.

14. Class 4 Count (Columns 40-44) - Critical

Class 4 is for Buses.

15. Class 5 Count (Columns 45-49) - Critical

Class 5 is for Two-Axle, Six-Tire, Single-Unit Trucks.

16. Class 6 Count (Columns 50-54) - Critical

Class 6 is for Three-Axle, Single-Unit Trucks.

17. Class 7 Count (Columns 55-59) - Critical

Class 7 is for Four-or-More Axle, Single-Unit Trucks.

18. Class 8 Count (Columns 60-64) - Critical

Class 8 is for Four-or-Less Axle, Single-Trailer Trucks.

19. Class 9 Count (Columns 65-69) - Critical

Class 9 is for Five-Axle, Single-Trailer Trucks.

20. Class 10 Count (Columns 70-74) - Critical

Class 10 is for Six-or-More Axle, Single-Trailer Trucks.

21. Class 11 Count (Columns 75-79) - Critical

Class 11 is for Five-or-Less Axle, Multi-Trailer Trucks.

22. Class 12 Count (Columns 80-84) - Critical

Class 12 is for Six-Axle, Multi-Trailer Trucks.

23. Class 13 Count (Columns 85-89) - Critical

Class 13 is for Seven-or-More Axle, Multi-Trailer Trucks.

The Vehicle Classification record may be ended here if exactly 13 classes are used. However, some automatic vehicle classification systems have one or two more classes usually designating "Unclassified" or "Unclassifiable" vehicles. If Class 14 and/or Class 15 are included such that the total of all the classes equals the total volume, then the Total Volume field may be left blank.

24. Class 14 Count (Columns 90-94) - Optional

If a Class 14 is used, enter the count for the hour here.

25. Class 15 Count (Columns 95-99) - Optional

If a Class 15 is used, enter the count for the hour here.

Table 6-4-1: Vehicle Classification Record

Chapter 5
TRUCK WEIGHT DATA FORMATS

The Truck Weight file contains one record for each truck with its axle weights and axle spacings. The optional file naming convention is "ssyy.WGT", where ss is the state postal abbreviation and yy is the last two digits of the year. Table 6-5-1 summarizes the Truck Weight record.

Fields designated as Critical are required for entry into the VTRIS database.

1. Record Type (Column 1) - Critical

• W = Truck weight record

2. FIPS State Code (Columns 2-3) - Critical - See chapter 6-2.

3. Station Identification (Columns 4-9) - Critical - See chapter 6-2.

4. Direction of Travel Code (Column 10) - Critical - See chapter 6-2.

5. Lane of Travel (Column 11) - Critical - See chapter 6-2.

Note: The Station ID, Direction of Travel, and Lane of Travel make up the Station Code. There should be one Station Description record per Station Code.

6. Year of Data (Columns 12-13) - Critical - See chapter 6-2.

7. Month of Data (Columns 14-15) - Critical - See chapter 6-3.

8. Day of Data (Columns 16-17) - Critical - See chapter 6-3.

9. Hour of Data (Columns 18-19) - Critical

Code the beginning of the hour in which the count was taken:

• 00 = 0:01 a.m. to 1:00 a.m.
• 01 = 1:01 a.m. to 2:00 a.m.
• ...
• ...
• ...
• 22 = 10:01 p.m. to 11:00 p.m.
• 23 = 11:01 p.m. to Midnight
  

Table 6-5-1: Truck Weight Record

Note: The number of axles determines the number of axle weight and spacing fields.

10. Vehicle Class (Columns 20-21) - Critical

Enter the class of the vehicle from FHWA Vehicle Classes 1 to 13. Classes 1 - 3 are ordinarily omitted.

A dummy vehicle class of -1 indicates that weight data for this hour are missing. A dummy vehicle class of 0 indicates that weight data for this hour are not missing, and thus if there are no Truck Weight records for the hour, then there were no trucks during that hour. Without these indications, no Truck Weight records for an hour might be interpreted to mean that the WIM system was not working.

11. Open (Columns 22-24) - Optional

This field is for special studies or State use such as for vehicle speed (kilometers per hour) or pavement temperature (degrees Celsius in the range -99 to +99).

12. Total Weight of Vehicle (Columns 25-28)

Enter the gross vehicle weight to the nearest tenth of a metric ton (100 kilograms) without a decimal point. This should equal the sum of all the axle weights except for rounding.

13. Number of Axles (Columns 29-30)

Enter the total number of axles in use by the vehicle (including any trailers).

The Number of Axles determines how many Axle Weight and Spacing fields will be expected. Axle Weight and Spacing fields that are not needed may be omitted. If a fixed-length record is desired, pad the record with blanks to the desired length.

The rest of the record alternates between axle weights and axle spacings, starting from the front of the vehicle. Axle weights are to the nearest tenth of a metric ton (100 kilograms) without a decimal point. Axle spacings are to the nearest tenth of a meter (100 millimeters) without a decimal point.

Reasonableness checks should be performed on the axle weights and spacings. The default limits in VTRIS are 200 to 20,000 kilograms for axle weights and 0.5 to 15 meters for axle spacings. The user may adjust these values.

14. A-axle Weight (Columns 31-33)

15. A-B Axle Spacing (Columns 34-36)

16. B-axle Weight (Columns 37-39)

17. B-C Axle Spacing (Columns 40-42)

18. C-axle Weight (Columns 43-45)

19. C-D Axle Spacing (Columns 46-48)

20. D-axle Weight (Columns 49-51)

21. D-E Axle Spacing (Columns 52-54)

22. E-axle Weight (Columns 55-57)

23. E-F Axle Spacing (Columns 58-60)

24. F-axle Weight (Columns 61-63)

25. F-G Axle Spacing (Columns 64-66)

26. G-axle Weight (Columns 67-69)

27. G-H Axle Spacing (Columns 70-72)

28. H-axle Weight (Columns 73-75)

29. H-I Axle Spacing (Columns 76-78)

30. I-axle Spacing (Columns 79-81)

31. I-J Axle Spacing (Columns 82-84)

32. J-axle Weight (Columns 85-87)

33. J-K Axle Spacing (Columns 88-90)

34. K-axle Weight (Columns 91-93)

35. K-L Axle Spacing (Columns 94-96)

36. L-axle Weight (Columns 97-99)

37. L-M Axle Spacing (Columns 100-102)

38. M-axle Weight (Columns 103-105)

Additional axle spacing and axle weight fields may be added in the same manner if needed.