County-to-County Distance Matrix

The following files contain a matrix of distances and network impedances (commonly called a "skim tree") between each pair of county centroids via highway, railroad, water, and combined highway-rail paths. The matrix is called "CtyODp4," and was calculated in 2011 Apr using the intermodal network ce07. It is designed for calibrating or estimating spatial interaction models without the need to implement a distance estimation method.

For ease of download, the matrix is divided into six parts, file "CtyODp4-1" containing paths with origin counties beginning with FIPS codes from 01 to 09 (AL to CT), and "CtyODp4-6" for origin FIPS starting 50 and above (VT through WY and Canada). Except for the initial header record, they may be concatenated to form the complete matrix. Following are the first four records of file 6:

  org, dest,"O-name  ","D-name  ",    GCD,  H-imp,H-mi-US,H-mi-oU,  R-imp,R-mi-US,R-mi-oU,  W-imp,   W-mi,HRH-imp,HRH-Hmi,HRH-Rmi,All-imp,All-Lnd,All-Wmi, 2011041715
50001,01001,"Addison ","Autauga ", 1075.1, 1207.1, 1286.6,    0.0,  625.9, 1399.4,    0.0,  700.6, 2448.5,  975.3,  142.9, 1255.8,  575.9, 1399.4,    0.0
50001,01003,"Addison ","Baldwin ", 1222.6, 1344.2, 1434.5,    0.0,  689.5, 1551.3,    0.0,  520.7, 2150.2,  980.4,  145.2, 1430.0,  520.7,    0.0, 2150.2
50001,01005,"Addison ","Barbour ", 1068.6, 1218.5, 1280.3,    0.0,  785.6, 1438.9,    0.0,  730.1, 2586.0, 1018.1,  270.0, 1101.8,  715.5, 1337.0,  118.7


Each record lists one county-to-county pair, by FIPS code, in order. Fields are both fixed column and comma delimited. The fields are:

Origin FIPS I5  
Destination FIPS I5  
Origin name A8 First 8 characters of county name
Destination name A8 plus bracketing double quotes (")
Great circle dist F7.1 miles
Highway impedance F7.1  
Highway miles (internal to US) F7.1 (explicit decimal point)
Highway miles (outside US) F7.1 "oU" = outside US boundaries
Rail impedance F7.1  
Rail miles (US) F7.1  
Rail miles (outside US) F7.1  
Water impedance F7.1  
Water miles F7.1  
HRH impedance F7.1 (Highway-rail-highway)
HRH miles (truck portion) F7.1 Truck miles at both trip ends
HRH miles (rail portion) F7.1  
All modes, impedance F7.1 All modes open for use
All modes, miles truck or rail F7.1  
All modes, miles on water F7.1  

Miscellaneous notes
The first record contains the field list, and is not data.
The matrix is not quite symmetric because of numerous one-way facilities, especially intermodal terminals.
Impossible routes (eg, highway from California to Hawaii) have a mileage of -1.0 and an impedance of 99999.9.
Canadian cities have arbitrary "FIPS" codes above 80000.
To find the total miles of an origin-destination path, you must add together the non-overlapping modal or geographic mileage components, eg, inside and outside the US.

Intermodal impedance factors. Impedance units on each modal link were chosen to be relative to the best facilities, which start out with about 1 impedance unit per mile (and 0.9 for rural Interstates). These "native" impedances are multiplied by intermodal adjustment factors to bring their approximate "costs" into common units. The intermodal factors used were: 1/1 for highway 1/3.3 for rail 1/5.0 for inland barge 1/5.8 for Great Lakes 1/6.5 for marine shipping.
Water paths. The miles/impedances for "water" trips allowed shipments to use any of the 3 water modes (inland barge, Great Lakes, and marine) and the intermodal terminals between them.
HRH trips. The only explicitly intermodal paths were forced to start on a highway, pass through a highway/rail terminal, then through another rail/highway terminal, and complete the trips by truck. Only fixed terminals were used, but they could have been of any type or commodity, not just TOFC/COFC. (The team-track model was not used.) Naturally, impedances could be greater than highway alone.
All modes. For these trips, all modes and all terminals were available, and the lowest impedance path was selected regardless of mode.
Intrazonal trips. Intracounty trip length calculated as SQRT(area/pi)*0.76 times circuity factor (= 1.2). For water, this was reduced by 20% to compensate for the probable geographic concentration of water shippers in a county. For HRH intermode, intra-county trips were declared impossible.
Centroids. CONUS county centroids are 1990 residential population centroids. (A handful are outside their boundaries.) Alaska, Hawaii, and Canada aimed for the employment centroid, but were often offset to fall on a network node. For new FIPS codes in 2000 a Census-supplied geographical centroid is used. In particular, the Miami-Dade (FIPS=12086) centroid is areal, while the old Dade Co centroid (12015) is population-weighted. Because both old and new FIPS codes are in the O-D list, the O-D matrix is slightly larger, and the user must decide which entries will be used or ignored.

Download CtyODp4 matrix portions (These files compressed by WinZip.)

  CtyODp4-1 (AL-CT) (37 MB)  go CtyODp4-4 (MT-OH) (64 MB) go
  CtyODp4-2 (DE-IA) (68 MB) go CtyODp4-5 (OK-UT) (80 MB) go
  CtyODp4-3 (KS-MO) (86 MB)  go CtyODp4-6 (VT-CN) (45 MB) go


CTA Transportation Networks - Home Page

Revised 2011 April                    WebMaster                    ORNL                    Disclaimer