STATE HIGHWAY TRAFFIC DATA

After gathering traffic data for the national park study sample, archived traffic data collected on nearby state highways were also obtained from the states surrounding these five national parks. Before directly contacting each of the state departments of

transportation, the department websites were first visited to determine the locations where traffic data were collected continuously. While some states posted all of their hourly traffic counts online, others provided only a map of the automated traffic recorder (ATR) locations in their state. For the states that did not post the counts online, the departments of transportation were directly contacted to obtain the hourly counts for specific ATR locations. Because the hourly state highway counts were to be compared to those of the data collection station representing each national park, it was determined that the ATR located nearest to the national park data collection station was of the most

interest. Therefore, continuous traffic data for the following ATR locations were requested:

• The ATR located in Maine on State Route 3 at the north end of Thomson Island Bridge. This bridge provides access to Mount Desert Island, which is where most of Acadia National Park is situated, and is located approximately eight miles northwest of the data collection station representing this national park. A map detailing the location of this permanent count station with respect to that of Station 4701 can be seen in Fig. 9.

Fig. 9. Map of Station 4701 and Nearby ATR Location (Microsoft 2007)

ATR location

• The ATR located in Texas on Interstate 90 just west of the town of Marfa. This location was approximately 60 miles northwest of the data collection station representing Big Bend National Park. A map detailing the location of this permanent count station with respect to that of Station 5601 can be seen in Fig. 10.

Fig. 10. Map of Station 5601 and Nearby ATR Location (Microsoft 2007)

ATR location

• The ATR located in Virginia on Interstate 66 between Interstate 29 and State Route 120. Although this location was not on George Washington Memorial Parkway, it was on a nearby roadway and was no more than five miles west of the data collection station representing George Washington Memorial Parkway. A map detailing the location of this permanent count station with respect to that of Station 6009 can be seen in Fig. 11.

Fig. 11. Map of Station 6009 and Nearby ATR Location (Microsoft 2007)

ATR location

• Two ATR locations were used in Montana. One (Station A-18) was on Interstate 20 and 15 miles west of the data collection station representing Yellowstone National Park while the other (Station A-19) was on Interstate 191/287 and 20 miles northwest of the data collection station representing Yellowstone National Park. A map detailing the location of these permanent count stations with respect to that of Station 2701 can be seen in Fig. 12.

Fig. 12. Map of Station 2701 and Nearby ATR Locations (Microsoft 2007)

ATR location (A-18)

Station 2701 ATR location

• The ATR located in California on State Route 120 at Kistler Ranch Under Crossing. This location was approximately 40 miles west of the data collection station representing Yosemite National Park. A map detailing the location of this permanent count station with respect to that of Station 4808 can be seen in Fig. 13.

Fig. 13. Map of Station 4808 and Nearby ATR Location (Microsoft 2007)

Although the ATR locations listed above include only those that were located nearest to the national parks, some of these locations were much farther from the parks than others. For instance, the ATR locations corresponding to Acadia National Park, George

Washington Memorial Parkway, and Yellowstone were much closer than those of Big Bend National Park and Yosemite National Park. However, the data for each of these ATR locations were equally significant. Upon determining whether the National Park Service could coordinate such data collection efforts using nearby ATR locations, the

Station 4808 ATR Location

wide range of distances was necessary in determining how close the ATR location needs to be to the park in order to be useful.

Although each requested ATR data file included similar information for the locations listed above, it was evident that each state uses a different format when archiving continuous traffic data. Therefore, before the traffic data were analyzed, the data files were reformatted to establish consistency. Reformatted files included the description of the ATR location and name of the county in which the data were collected along with the 24 hourly counts and total count for that ATR. While the hourly counts for Virginia, Texas, and California were collected for 2002 to 2006, Maine and Montana were only able to provide continuous counts for 2003 to 2006. Additionally, it was noted that the dataset provided by Maine Department of Transportation for 2006 included a traffic volume for the 31st day of November, which is a date that does not exist. Therefore, this year was not used. In the reformatted data files, it was also noted that the counts for Maine and Montana were a combination of the counts in both directions while Virginia, Texas, and California reported the hourly count for each direction separately.

Additionally, it was noted in each file that all of the above state highways were two-lane roads with one lane in each direction except for the highway in Virginia, which was a four-lane road with two lanes in each direction.

SUMMARY

Because it was not feasible to include all 391 parks in this study, a national park sample set was created to include national parks located in both rural and urban settings where traffic monitoring improvements were most needed. Therefore, this study examined parks that had an extremely high number of annual visitors or were large in size, and the sample set included Acadia National Park, Big Bend National Park, George Washington Memorial Parkway, Yellowstone National Park and Yosemite National Park. While most of these parks contained multiple traffic data collection stations, only one station was used for each park due to limitations on data access. Big Bend National Park had only one data collection station, and therefore, this particular station was used to represent the park. For the other four parks, the data collection stations at the main entrances that consistently collected the most traffic data from 2002 to 2006 were selected to represent the parks. After determining the most appropriate national park sample set, hourly traffic data for 2002 to 2006 were obtained directly from the National Park Service for the five data collection stations representing the parks. Additionally, hourly traffic counts for the nearby state highways were collected for 2002 to 2006. These archived data were accessed either directly from the appropriate state departments of transportation or via the department websites. Because the hourly state highway counts were to be compared to those of the data collection station representing each national park, continuous traffic data were requested for the ATR located nearest to each national park data collection station.

CHAPTER IV