Daily Vehicle Miles Traveled on National Byways in Colorado


One way to explore whether byway designation has had an economic impact is to look at the amount of dollars spent by visitors over time. The data in the charts above suggest that byway designation has had a positive economic impact on municipal economies, as measured by per capita retail sales. Another way to look into byway designation impact is to look at traffic patterns over time on sections of each of the eight byways.


Below we show data for sections of byways over a twelve year period, from 1990 to 2002. These data were transferred to us by a representative of the Colorado Department of Transportation as very large Microsoft Access files. Each file contained traffic counts and other information for all of Colorado’s highways. To pare down the large data files, data from each file were converted into Microsoft Excel files. Then data were deleted for all highways and portions of highways that are not part of the eight national byways in Colorado. (The 1998 file was incomplete, so data for 1998 are not shown in the following charts.)

Next, segments of the highways listed that are actually parts of the eight byways were selected out from the rest of the data, leaving rows of data for segments of the highways that are parts of the scenic byways. CDOT labeled these highway segments/rows with their highway number, their beginning mile marker, and a short description of the segment in each row. The number of rows in portions of byways varied from 3 to over 150, with data for segments/rows covering sometimes part of a mile, and sometimes over thirty-plus miles.

Each row also included other information about a segment of highway. The more important information included section length and average annual daily traffic (AADT) or average daily traffic (ADT). According to CDOT representatives, the ADVT data are based on 24-hour long “hose counts” done throughout the state on byway segments. Some segments may get hose counts once every three years. Some may get hose counts every six years. CDOT then creates estimates for average annual traffic counts.

According to the Colorado Department of Transportation, the daily vehicle miles traveled (DVMT) is the best measure of traffic flow over time. Compared year by year, the DVMT can illustrate growth in local traffic over a section of highway over time. The DVMT is calculated by multiplying the segment length by the AADT/ADT. For the data files for 1990 to 2002, we calculated the DVMT for each of the segments/rows, then combined the row DVMT for each highway section on the eight byways. Data for these sections were then added to determine the daily vehicle miles traveled for each of the byways. In the charts below, data are also shown for byways and for sections of highways within byways.


The first chart shows the DVMT for the eight national byways in Colorado. Data for this chart are the combined DVMT for each section of the byway. Again, the 1998 data file from CDOT were incomplete, so the data for this year are not included in any of the charts.

Recall that each of the byways received state and national designations, but these designations do not often occur in the same year. Note also that some of the CDOT traffic data are estimates, which CDOT says should be treated literally – as if they are the actual data.

What we see in the following chart are data lines that have gradually increasing DVMT numbers from year to year for half of the byways: Grand Mesa, Frontier Pathways, Gold Belt Tour, and Trail Ridge Road. The Top of the Rockies shows an overall increase in DVMT with only a slight dip in 2000. (Please note that this may be a “true” dip in traffic numbers, or
there could be problems with the CDOT estimates. It is difficult to know for certain.)

The Santa Fe Trail generally saw an increase in DVMT over the years studied, with a slight drop in 1996 and a larger drop in 2001. Its numbers in 2002 are just a bit higher than they were in 1990. The Dinosaur Diamond DVMT count stays pretty level throughout the time period. The top line on the chart represents the San Juan Skyway, the longest of Colorado’s national byway that has all its sections within the state’s borders (Dinosaur Diamond is divided between Colorado and Utah, while the Santa Fe Trail travels through Kansas into Colorado then moves south into New Mexico.) The Skyway’s DVMT trends mostly upward, with slight dips in 1992 and 2000.


The Dinosaur Diamond is divided into four sections in the CDOT data. At the lower entrance, there are two short sections of road going into Loma, one on I-70 from Utah and one on Hwy. 6 from Grand Junction. These are the top two lines on the chart. The other two lines show the DVMT from I-70 to Rangely, and the DVMT from Rangely to Dinosaur. The counts from Utah on I-70 show the most consistency in their upward trend, but it is highly doubtful that many of those traveling the interstate are also traveling up the byway.

The two lower lines should mostly show byway traffic, and there is quite a bit of movement and variation in these lines. The traffic from Rangely to Dinosaur has similar DVMT in 1990 and 2001, with increases in 1992 and 2001, and a slight decrease in 1999. The data for the section from I-70 to Rangely show quite a bit of variation, with the numbers in 2002 lower than they were in 1990. State byway designation appears to have had an impact on DVMT along the I-70 to Rangely and on the Rangely to Dinosaur sections after state designation.


Frontier Pathways is comprised of two CDOT sections, Hwy. 96 goes from Westcliffe to Pueblo city limits, and Hwy. 165 from Wetmore to Colorado City at the I-25 junction. Both segments show pretty steady increases in DVMT over the period studied, with the road from Pueblo to Westcliffe showing higher numbers and rate of increase. Frontier Pathways state byway designation occurred in 1994, after which the Hwy. 96 DVMT increase steeply. National designation was awarded in 1998, and we see increases in DVMT on each of this byway’s sections from 1999 to 2001 -- when they start to level off. Data suggest that byway designation impacted this byway’s traffic counts.


The Gold Belt Tour’s major mileage occurs on county highways, and data for DVMT’s on these sections are not included in the data shown on this chart. Data for two sections are shown. The top line represents a section of Hwy. 115 that starts in Ca?on City at Hwy. 50 and travels east through the town of Florence. Here we see a general trend upward with a peak in 1995 and a big swing upward in 2002. The bottom line is a section of Hwy. 50 that starts in Canon City and goes west to the turn off to Hwy. 9, near the Royal Gorge. The line for this CDOT section shows DVMT trending mostly upward with a dip in 2002. The Gold Belt Tour received state scenic byway designation in 1989 and national byway designation in 2000. There are some upward trends after these dates that suggest positive impacts on traffic numbers from the two designations.


The Grand Mesa is on one CDOT highway section. From I-70 Hwy. 65 goes through Mesa and into Cedaredge. The Grand Mesa became a state byway in 1991 and a national byway in 1996. In the chart we can see peak in the line in 1993 and another good-sized jump after 1994 that pretty much levels off after 1994. The increase in DVMT after 1993 may be due to byway designation in that year. The DMVT in 2002 is 47% higher than it was in 1990, while the Cedaredge population in 2002 was 31% higher than it was in 1990.


The San Juan Skyway is comprised of six CDOT sections. The legend attached to this chart lists the segments, starting with Hwy. 145 from Cortez to county road 36 north of Dolores (the CDOT section from CR 36 to Telluride is not included here). From Telluride north to the junction with Hwy. 62 is the second CDOT section listed in the legend, followed by the section of Hwy. 62 into Ridgeway. Next is the CDOT Hwy. 550 section from Ridgway south to Silverton. Then we go from Silverton south to Durango on Hwy. 550. To complete the loop we have the section of Hwy. 160 from Durango west to Cortez. The San Juan Skyway became a state byway in 1989 and gained national designation in 1996. Patterns in the data show an overall increase in DMVT over the period studied, and it could be argued that increased travel on this byway could have been positively affected by the 1989 state byway designation.

The section from Durango traveling west to Cortez is the top line shown in the chart and has the highest DVMT of the seven Skyway sections. This section’s DVMT trends upward from 1991 until 1998, then starts to decline. The section from Durango to Silverton shows the second highest DVMT on the Skyway, mostly mirroring the line from Durango to Cortez, and showing a similar decline after 1998. The other four sections of the Skyway have lower overall DVMT numbers, but they all tend to be trending upward with the Telluride to Ridgway section showing a good-sized increase after 1999, and the section from north of Ouray to Silverton showing some interesting peaks in activity during the 1990’s.


The Santa Fe Trail is comprised of three CDOT sections. The top line shows the DVMT data for the section that starts at the Kansas State line, east of Holly, and travels west to La Junta. Here we see the DVMT numbers increasing steadily until 2000 when it drops off sharply before rebounding in 2001. The other two CDOT sections show similar trends, though some data for the short trip on Hwy. 160 from 1-25 to the junction with Hwy 350 were incomplete and so not reported here. The DVMT numbers are pretty flat on the section from Hwy. 350 from Hwy. 50 in La Junta to the Beshoar junction on the east side of Trinidad. Travel on this section is probably a better indicator of byway designation impacts than the Hwy. 50 section because travelers on Hwy. 350 would most likely be on that road because it’s on the Santa Fe Trail and/or because it’s a good shortcut to Trinidad. The Santa Fe Trail Mountain Branch became a state byway in 1992, after which we see a slight increase in DVMT, and it became a national byway in 1998, before and after which the line is flat. DVMT numbers on Hwy. 350 do not give much support to the hypothesis that byway designation positively impacts traffic counts.


The Top of the Rockies DVMT data show some pretty wild swings in traffic counts over the time period studied. There are three sections of this byway shown here, with two of them starting on I-70 and traveling south to Leadville. The Hwy. 91 section ends in Leadville at the junction with Hwy. 24, and the Hwy. 24 section starts at I-70, goes through Leadville and ends at the Hwy. 82 junction. Data for the last section, from Hwy. 24 past Twin Lakes, is spotty, and no data were available beyond 1996 except in 2001. This section is represented by the lowest line in this chart, and data available for this section show that DVMT was relatively flat along this section, with a slight decrease in DVMT after state byway designation in 1993.

DVMT’s along the other two Top of the Rockies sections show a general trend upward, with significant declines on both sections in 2000, and a decline in DVMT on the Hwy 91 section in 1996. The decline in DVMT in 2000 follows national byway designation in 1998, while increasing DVMT numbers after that year are encouraging and could have been positively impacted by the designation.


Trail Ridge Road/Beaver Meadows Road is made up of two CDOT sections. Data for an additional section, on Hwy. 34 from Grand Lake to Granby, are included here because of Granby’s proximity to the byway and Grand Lake. The other CDOT section starts east of Estes Park at county road 63 and travels into Rocky Mountain National Park, over the Continental Divide to Grand Lake. The two sections show a similar trend upward over the time period studied. Trail Ridge Road/Beaver Meadows Road received designation as a national byway in 1996 and state designation in 1999, and we see an increase in DVMT on the Granby section after national designation. The DVMT counts decrease on the byway itself (between Grand Lake and Estes Park) after 1996 with higher DVMT numbers in 1999, then a decrease in 2000. We really don’t see an indication of a positive impact of byway designation on Trail Ridge Road, but the data for Granby suggest that there was a positive impact along the adjacent stretch of Hwy. 34 after national byway designation.
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