| Northern Colorado Truck Mobility/SH14 Relocation Study | Truck Origin and Destination Study, June 2001 |
Table of Contents
I. Introduction
II. Summary of Past Studies
III. Overview of Current Truck Operations
IV. Data Collection Methodology
V. Validation Efforts
VI. Truck Origin and Destination Analysis
VII. Truck Origin and Destination Survey Results
List of Figures
Figure 1 Study Area
Figure 2 Origin and Destination Survey
Figure 3 Traffic Count Locations
Figure 4 Linked Trip Patterns
Figure 5 Through Trucks as a Percent of Total Trucks
List of Tables
Table 1 – Traffic Count Data
Table 2 – License Plates Collected (Average Weekday)
Table 3 – Valid License Plates (Weekday Totals)
Table 4 – Linked Trips
Appendices
Appendix A – Traffic Count Data
The City of Fort Collins is conducting the Northern Colorado Truck Mobility/State Highway 14 (SH 14) Relocation Study to address truck issues in the City of Fort Collins and northern Larimer County. As part of the overall study, a Truck Origin and Destination Study was conducted in the study area. The intent of this study was to determine the proportion and number of through, long haul, through truck trips that could be accommodated by either a non-route based strategy or alternate route. This data collection effort addressed both traffic volumes and travel patterns. Traffic volume information helped identify how many trucks travel within the study area, while travel pattern data helped define whether truck trips are local or regional. The study area includes most of the City of Fort Collins and portions of unincorporated Larimer County as shown in Figure 1.
The purpose of this report is to document the methodology, assumptions, and results from the Truck Origin and Destination Study summarized in the following sections of the report.
Appendix B – Origin-Destination Data
Figure B–1 Station-to-Station Travel Patterns
Figure B–2 Combined Station Travel Patterns
Table B–1 – Station-to-Station Percentages
Table B–2 – Combined Station Results
- Summary of Past Studies–The issue of truck travel in Fort Collins has been debated and studied for over 25 years. This section of the report provides a synopsis of the major origin and destination survey efforts that have preceded the current study.
- Overview of Current Truck Operations –A general overview of current truck operations associated with I-25, SH 14, and US 287 is provided. This information is intended to provide the reader with a perspective on truck activity in northern Colorado, including a specific focus on the City of Fort Collins.
- Data Collection Methodologies –Methodologies were developed to guide the collection of both truck volume data and truck origin and destination data. This section of the report not only summarizes each of these methodologies, but also discusses how they were developed.
- Validation Efforts –The data collected were reviewed and adjusted to accommodate seasonal and other traffic flow variations. They were also checked to confirm that the data collected were acceptable for us in data analysis. This section documents these efforts.
- Truck Origin and Destination Survey Analysis –This section outlines the analysis of the origin and destination data collected.
- Truck Origin and Destination Survey Results –The work effort for the study is brought together to provide overall results for use elsewhere in the Northern Colorado Truck Mobility/SH 14 Relocation Study.
II. Summary of Past Studies
The issue of truck travel in Fort Collins has been debated and analyzed for over 30 years. During this timeframe, numerous transportation studies have been completed that addressed truck travel in and around Fort Collins. Several of these studies specifically focused on trucking operations, while other studies have investigated truck travel as part of a broader overall transportation context. Truck travel pattern data has been collected and analyzed as part of several more recent studies. The results from these past quantitative efforts provide points of comparison for the current origin and destination effort. The following information summarizes the results from those past studies that included a data collection and analysis effort focused on truck travel. Detailed documentation was not available from these past studies. As a result, the following descriptions were developed based solely on review of summary materials. Western Highway Institute Assessment (1999) The Western Highway Institute (WHI) conducted an assessment of truck volume along SH 14 and US 287 in January 1999. To conduct this assessment, WHI relied upon past CDOT traffic surveys and recent industry surveys. Based on their review of the survey data, WHI determined that commercial vehicle traffic along SH 14 and US 287 generally fell into three categories. These categories include "Local" traffic, "Regional" traffic, and "Through" traffic. The following information summarizes WHI’s findings related to each traffic category. 24-Hour Highway Truck Survey–Maurice L. Albertson, PH.D., P.E. (1999) A group of approximately 60 volunteers were assembled to collect truck counts at six locations in and around Fort Collins. Counts were collected continuously for 24-hour period. The locations analyzed were the Port of Entry along I-25, northbound I-25 at SH 14, southbound I-25 at SH 14, intersection of Jefferson Street and College Avenue, and Ted’s Place (intersection of US 287 and SH 14). Multiple traffic movements were collected at each location. Commercial trucks and buses were counted at each location. Surveyors recorded number of axles, type of carrier, color, and name (if possible). Passenger vehicles were recorded at certain locations. The survey was conducted on May 11 and 12, 1999. Numerical results and general conclusions from this survey included: SH 14 (west of I-25) Intersection of Jefferson Street & College Avenue Intersection of SH 14 & US 287 (Ted’s Place) Highway 14 (west of US 287) Estimate of Through Trips Additional study efforts have considered travel through and around Fort Collins. Although some of these projects did not focus solely on through truck travel, the following list is included for reference and a report titled History of Fort Collins Truck Route and Bypass Planning Efforts, 1966 to Present (City of Fort Collins, 2000) summarizes the recommendations of these studies: There are several distinct truck patterns in the City of Fort Collins and northern Larimer County area. Each of these is described further below. This understanding of current truck operations was based on analysis of local land use and traffic conditions, field observations, and discussions with industry and agency representatives. The goal of the origin and destination survey is to quantify the range of through trips described above and separate them from the regional and local trips.
IV. Data Collection Methodology Two separate data collection efforts were conducted as part of the Truck Origin and Destination Study. The first was a license plate and vehicle description survey conducted at six locations in the study area as shown in Figure 2. These locations were: At each location, license plate information was collected for passing trucks. For the purposes of the study, trucks were considered to be commercial vehicles with three (3) or more axles. It was assumed that 2-axle trucks are typically local delivery vehicles. Local delivery trucks and buses were not recorded in the study. The recording was conducted from early morning (7:00 a.m.) to late afternoon (4:30 p.m.) when sufficient daylight was available to read license plate data. Surveyors were given two breaks during the day. A survey was also conducted to collect nighttime data at SH 14 west of I-25, Riverside Avenue in downtown and at US 287 at the Forks at Livermore. Data was recorded from 7:00 p.m. to 1:00 a.m., with one surveyor break in that time period. Since it was difficult to collect license plate data due to poor lighting, basic identifying information was recorded, such as truck color and number of axles. The second data collection effort performed by PBS&J in conjunction with Counter Measures included traffic volume counts providing vehicle classification information throughout the study area. Twenty-four hour vehicle classification data was collected over a five-day period in November and December 2000 to supplement the origin and destination survey data and provide an overall picture of truck traffic along specific corridors. The vehicle classification data was collected at the following locations (shown in Figure 3): The vehicle classification data was collected based on the thirteen groups typically used in classification studies. The classifications were then compiled into three general categories; passenger vehicles, larger 2 axle vehicles, and multiple axle vehicles (3 or more axles). These categories were summarized to represent percentages of vehicle types in relation to overall traffic volumes at each of the locations. Figure 2
III. Overview of Current Truck Operations
Origin and Destination Survey
Figure 3
Traffic Count Locations
Information from the Colorado Department of Transportation indicates that traffic data collected in November should be increased by two percent on urban highways (similar to SH 14) and six percent on rural highways (similar to US 287 at Owl Canyon) to reflect summer traffic volumes. Summer traffic volumes represent the highest traffic volumes that typically occur along these corridors. These factors were applied to the vehicle classification data to represent the heaviest traffic volumes. The factored vehicle classification data is summarized in Table 1 and provided in more detail in Appendix A–Traffic Count Data.
V. Validation Efforts
Several efforts were undertaken to validate the survey and count data sets prior to the analysis of origin and destination patterns. This section describes these efforts. Traffic data tends to fluctuate over the course of the year, with summer months typically experiencing higher volumes and winter months typically experiencing lower volumes. Data collected from the Colorado Department of Transportation indicates that traffic data collected in November should be increased by two percent on urban highways (similar to SH 14) and six percent on rural highways (similar to US 287 at Owl Canyon). These factors were applied to the vehicle classification data. In other words, the traffic count data collected in November are lower than an average day, so they were increased to better reflect the average. This adjustment is common in traffic studies. The first step in validating the survey data collected was to determine the "capture rate." This is the percentage of all trucks on the roadway during the survey period that were actually recorded. The calculation of a capture rate answers the question, "How many of the trucks on the roadway were included in the data collected?" As shown in Table 2, at least 87 percent of the trucks on the roadway were included during the survey. This measure only reflects data collected during the survey periods, and does not recognize trucks on the roadway that passed through the survey location during non-survey times. At some locations, there were actually more trucks captured in the survey data than captured in the count data. This could occur for several reasons, including duplicated plates, inconsistencies in time clocks between the two data sets, and inaccuracies in the tube counts. As a whole, fewer vehicles were surveyed than counted, so the adjustment for this effect tends to increase the results. The next step in calibrating the data was an evaluation of the data collected to determine how much of the data was valid for matching. The survey data collected must meet several basic criteria, including number of digits recorded, legibility of entries, duplications, etc., in order to be matched. The data set was reviewed and any entries not meeting these criteria were removed. As shown in Table 3, the number of invalid license plates did not exceed 19 percent of the overall data collected, and the average was approximately 11 percent. In other words, at least 81 percent of the data recorded were usable for matching. As an average, almost 89 percent of the data were valid. Therefore, the survey data were increased by about 11 percent to rectify this error.
Table 2 – License Plates Collected (Average Weekday)
Location |
Survey Period Truck Count |
Total Plates |
Percent Captured |
||||
Northbound |
|||||||
SH 14 west of I-25 |
376 |
326 |
87% |
||||
US 287 near Laporte Ave. |
N/A |
317 |
-- |
||||
US 287 at the Forks at Livermore |
205 |
229 |
112% |
||||
Southbound |
|||||||
SH 14 west of I-25 |
321 |
298 |
93% |
||||
US 287 near Laporte Ave. |
N/A |
287 |
-- |
||||
US 287 at the Forks at Livermore |
165 |
182 |
110% |
||||
Table 3 – Valid License Plates (Weekday Totals)
Location |
Total Plates |
Valid Plates |
Percent Valid |
Northbound |
|||
I-25 at Port of Entry |
1267 |
1166 |
92% |
SH 14 west of I-25 |
651 |
529 |
81% |
Riverside Ave./Downtown |
419 |
407 |
97% |
US 287 near Laporte Ave. |
634 |
553 |
87% |
US 287 at the Forks at Livermore |
457 |
385 |
84% |
CR 70 west of I-25 |
7 |
7 |
100% |
Southbound |
|||
I-25 at Port of Entry |
1346 |
1224 |
91% |
SH 14 west of I-25 |
596 |
499 |
84% |
Riverside Ave./Downtown |
422 |
382 |
91% |
US 287 near Laporte Ave. |
573 |
533 |
93% |
US 287 at the Forks at Livermore |
363 |
335 |
92% |
CR 70 west of I-25 |
38 |
38 |
100% |
Totals |
6773 |
6058 |
|
VI. Truck Origin and Destination Analysis
After the validation process was complete, the matching process was completed. The goal of this process was to find how many truck trips traveled between the various stations, and how many truck trips traveled through the study area without stopping. Truck trips that traveled northbound from south of the Port of Entry to US 287 at the Forks at Livermore (or southbound between these points) were considered “external-to external” trips. These trips do not have an origin or a destination in the study area, and may therefore, be subject to some of the non-route based strategies or identified alternate route being developed as part of the overall Northern Colorado Truck Mobility/SH 14 Relocation Study. A key factor in determining whether a trip is truly external-to-external is the travel time along the route. If a truck travels from US 287 at the Forks at Livermore to south of the Port of Entry in eight hours, it is likely that the vehicle stopped along the route for loading, unloading, or other purposes. For this effort, a 45-minute travel time was assumed to define an external-to-external trip, with the thought that any trip longer than 45 minutes has made a stop. To determine this time, several travel time runs were performed between the Port of Entry and US 287 at the Forks at Livermore, and most of these runs found a travel time of about 30 minutes. A detailed analysis of the origin and destination data collected was performed. Portions of this analysis are included in Appendix B. The final analysis examined the true external-to-external trip pattern, using US 287 at the Forks at Livermore as one external station and either SH 14 west of I-25 or the Port of Entry as the other external station. Vehicles leaving the system between these stations were also examined to determine where (which segment) they left the route. This analysis assumed 100percent of trucks at an external station and followed the trucks through the network, with percentages turning off of the route along each segment. The remaining percentage (at the other end of the route) is the external-to-external percentage, which is a key goal of this effort. Refer to Table 4 and Figure 4.
The traffic count and origin and destination data collected have been validated and analyzed to determine the overall number of trucks on key roadways in the study area and the percent of those truck trips that are external-to-external. This section summarizes those results and brings the traffic count data together with the origin and destination data.
As outlined in Section IV, about 10percent of the traffic on SH 14 west of I-25 is truck traffic. Approximately 9 percent of the traffic on US 287 at the Forks at Livermore is truck traffic. As outlined in Section VI, about 27 percent of the northbound truck traffic at SH 14 west of I-25 is through traffic. Similarly, about 35 percent of the truck traffic at US 287 at the Forks at Livermore is through traffic. The remaining truck traffic on surveyed roadways is local or regional in nature.
After application of the validation factors outlined in Section V, a calculation of external-to-external truck volumes can be made. The results of these calculations show that about 560-590 trucks are through trucks. These numbers have been compared with overall truck volumes in the corridor as shown in Figure 5.
As part of the detailed analyses documented in Appendix B, an evaluation of truck trips using CR 70/CR 72 to travel from US 287 at the Forks at Livermore to I-25 was conducted. Data from that analysis indicate that none of the surveyed trucks traveled from the I-25 Port of Entry to US 287 at the Forks at Livermore via this route. The percentages of trucks between the CR 70 station and the US 287 at the Forks at Livermore station were less than 20%. Based on these data and information received from Colorado Lien, it is assumed that many of the trucks along CR 70 are related to this use and the agricultural uses along CR 70.
Figure 5
Through Trucks as a Percent of Total Trucks
APPENDIX A
VEHICLE CLASSIFICATION INFORMATION
TWO-WAY
Two Way Traffic Information
SH 14 West of I-25
Two Way Traffic Information
Owl Canyon Rd West of CR 21
Two Way Traffic Information
US 287 North of Owl Canyon Rd
Two Way Traffic Information
Vine Dr East of US 287
Two Way Traffic Information
US 287 North of Vine Dr
Two Way Traffic Information
Shields St North of Harmony Rd
Two Way Traffic Information
College Ave North of Harmony Rd
APPENDIX B
As a first step in the determination of the external-to-external trips, through percentages between each of the survey stations were calculated. These percentages answer the question, "How many trucks were through trucks between survey station A and the adjacent survey station B?" With six survey stations, there are six station pairs in each direction where this analysis was performed. Refer to Table B-1 and Figure B-1. As can be seen, the only station-to-station segment with more than 50 percent through trucks is the Riverside/Laporte segment, with 64 percent northbound through trips and 51 percent southbound through trips.
Table B–1 – Station-to-Station Percentages
Figure B–1
Station-to-Station Travel Patterns
After completion of the station-to-station matches, the matching was expanded to cover multiple segments of the route. In other words, the next analysis answered the question, “How many trucks traveled along the corridor from station A, through station B, to station C?” With the survey stations defined for this study, there are seven of these scenarios in each direction. There is a possible source of error in these data, since a vehicle recorded at station A and station C may not have been recorded at station B. Therefore, two matches were performed, one which looked only at the endpoint stations (station A and station C), and a second match that included all stations (stations A, B and C). Another element that required extra attention was the Port-of-Entry/US 287 at the Forks at Livermore pair. When these stations were examined without intermediate stations, there was no way to determine if the matches were from the I-25 to CR 70/CR 72 route or the I-25/SH 14/US 287 route. This was clarified by the inclusion of intermediate stations. Refer to Table B-2 and Figure B-2 for these results.
Table B–2 – Combined Station Results
An overall summary of the truck survey data collected follows Figure B-2.
Figure B–2
Combined Station Travel Patterns
Click to view an overall summary of the truck survey data.
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