Office of Operations Freight Management and Operations

Evaluation of Travel Time Methods to Support Mobility Performance Monitoring:
Blaine (Pacific Highway) (Page 3 of 3)

Freight Delay Analysis

The measure for the freight transportation system at international roadway border crossings is travel delay per truck trip through the first inspection point in the import country. Delay is measured relative to the travel time at low volume conditions, which will allow the processing time of the inspection to be accommodated outside of the measure. Estimating the average delay per truck for each hour where congestion is present and then applying the average hourly truck volume produces an estimate of total delay.

The average delay per truck for each hour is the difference between the travel time at low volume conditions and the travel time each hour. Travel time is also affected by the number of open inspection booths and this information was recorded on all days as it changed. To determine the average travel time for each road segment, the matched license plate data in the database is used. The number of matches are noted for statistical analysis and the travel time is noted for each hour. The travel time for each truck was assigned to the hour when they passed through the primary Customs inspection location.

The data are presented in Tables 7 through 12. The columns illustrate the key elements for estimating delay:

  • No Delay Travel Time – The time through the system at low volume conditions. For this report, the value used was that of the lowest hourly travel time in that direction for each three-day data collection period.
  • Average Number of Open Booths – The average number of primary Customs commercial vehicle inspection booths open and available for processing trucks. This figure is not used to compute delay but is useful to help understand the relationship between booths, traffic volume, and delay.
  • Number of Matched Vehicles – The number of vehicle observation used to estimate the travel time for each hour.
  • Average Travel Time – The amount of travel time from entry to exit for trucks entering the system each hour (use the time the vehicle passes the advance point as the determinant of the time period label).
  • Delay per Trip – The difference between the average travel time and the "no delay" time.
  • Average Traffic Volume – The average hourly truck volume for the period being analyzed.
  • Total Delay – The product of the hourly truck volume and delay per trip.
Table 7. Total Delay – 7/10/2001 – Outbound
Time Period (a)
"No Delay" Travel Time
(b)
Average No. of Open Booths
(c)
Number of "Matched" Vehicles
(d)
Average Travel Time
(e)
Delay Per Trip (d - a)
(f)
Average Traffic Volume
(g)
Total Delay (f x e)
7:00–8:00AM 4.75 1.00 8 6.00 1.25 49 61.25
8:00–9:00AM 4.75 1.00 44 6.35 1.60 71 113.60
9:00–10:00AM 4.75 1.00 39 10.73 5.98 70 418.60
10:00–11:00AM 4.75 1.00 33 7.25 2.50 61 152.50
11:00–12:00PM 4.75 1.00 38 11.3 6.55 65 425.75
12:00–1:00PM 4.75 1.00 48 15.8 11.05 94 1,038.70
1:00–2:00PM 4.75 1.00 45 27.37 22.62 77 1,741.74
2:00–3:00PM 4.75 1.76 68 22.37 17.62 126 2,220.12
3:00–4:00PM 4.75 1.00 55 13.85 9.10 69 627.90
4:00–5:00PM 4.75 1.30 53 14.93 10.18 46 468.28
5:00–6:00PM 4.75 1.00 39 8.2 3.45 48 165.60
6:00–7:00PM 4.75 1.00 55 15.55 10.80 69 745.20
7:00–8:00PM 4.75 1.00 22 4.75 0.00 49 0.00

Table 8. Total Delay – 7/11/2001 – Outbound
Time Period (a)
"No Delay" Travel Time
(b)
Average No. of Open Booths
(c)
Number of "Matched" Vehicles
(d)
Average Travel Time
(e)
Delay Per Trip
(d - a)
(f)
Average Traffic Volume
(g)
Total Delay
(f x e)
7:00–8:00AM 4.75 1.00 11 14.15 9.40 46 432.40
8:00–9:00AM 4.75 1.00 30 20.66 15.91 70 1,113.70
9:00–10:00AM 4.75 1.00 48 30.97 26.22 79 2,071.38
10:00–11:00AM 4.75 1.00 35 31.48 26.73 77 2,058.21
11:00–12:00PM 4.75 1.33 42 33.47 28.72 96 2,757.12
12:00–1:00PM 4.75 1.92 94 18.48 13.73 129 1,771.17
1:00–2:00PM 4.75 1.10 50 20.12 15.37 70 1,075.90
2:00–3:00PM 4.75 1.33 53 13.62 8.87 100 887.00
3:00–4:00PM 4.75 1.00 42 24.11 19.36 68 1,316.48
4:00–5:00PM 4.75 1.00 51 26.17 21.42 68 1,456.56
5:00–6:00PM 4.75 1.82 72 31.85 27.10 128 3,468.80
6:00–7:00PM 4.75 1.09 56 11.25 6.50 55 357.50
7:00–8:00PM 4.75 1.00 57 13.30 8.55 74 632.70

Table 9. Total Delay – 7/12/2001 – Outbound
Time Period (a)
"No Delay" Travel Time
(b)
Average No. of Open Booths
(c)
Number of "Matched" Vehicles
(d)
Average Travel Time
(e)
Delay Per Trip
(d - a)
(f)
Traffic Volume
(g)
Total Delay
(f x e)
6:00–7:00AM 4.75 1.00 24 5.40 0.65 55 35.75
7:00–8:00AM 4.75 1.00 53 8.42 3.67 70 256.90
8:00–9:00AM 4.75 1.00 34 6.48 1.73 49 84.77
9:00–10:00AM 4.75 1.00 42 21.92 17.17 72 1,236.24
10:00–11:00AM 4.75 1.00 45 22.87 18.12 76 1,377.12
11:00–12:00PM 4.75 1.00 47 33.27 28.52 76 2,167.52
12:00–1:00PM 4.75 1.50 71 70.00 65.25 97 6,329.25
1:00–2:00PM 4.75 1.00 50 19.42 14.67 72 1,056.24
2:00–3:00PM 4.75 1.00 57 24.77 20.02 76 1,521.52
3:00–4:00PM 4.75 1.06 49 40.85 36.10 52 1,877.20
4:00–5:00PM 4.75 1.37 79 31.12 26.37 110 2,900.70
5:00–6:00PM 4.75 1.00 75 10.30 5.55 94 521.70
6:00–7:00PM 4.75 1.00 21 12.22 7.47 49 366.03

Table 10. Total Delay – 7/10/2001 – Inbound
Time Period (a)
"No Delay" Travel Time
(b)
Average No. of Open Booths
(c)
Number of "Matched" Vehicles
(d)
Average Travel Time
(e)
Delay Per Trip
(d - a)
(f)
Average Traffic Volume
(g)
Total Delay
(f x e)
7:00–8:00AM 8.12 1.87 NA NA NA NA NA
8:00–9:00AM 8.12 2.00 13 8.12 0.00 90 0.00
9:00–10:00AM 8.12 2.00 17 14.80 6.68 85 567.80
10:00–11:00AM 8.12 2.00 20 16.30 8.18 111 907.98
11:00–12:00PM 8.12 2.00 37 16.12 8.00 123 984.00
12:00–1:00PM 8.12 2.00 22 15.77 7.65 77 589.05
1:00–2:00PM 8.12 2.00 28 15.92 7.80 101 787.80
2:00–3:00PM 8.12 2.00 21 18.12 10.00 93 930.00
3:00–4:00PM 8.12 2.00 22 15.92 7.80 74 577.20
4:00–5:00PM 8.12 2.00 17 23.79 15.67 73 1,143.91
5:00–6:00PM 8.12 2.00 35 12.43 4.31 89 383.59
6:00–7:00PM 8.12 2.00 20 11.72 3.60 73 262.80
7:00–8:00PM 4.75 2.00 14 25.03 20.28 unavailable NA

Table 11. Total Delay – 7/11/2001 – Inbound
Time Period (a)
"No Delay" Travel Time
(b)
Average No. of Open Booths
(c)
Number of "Matched" Vehicles
(d)
Average Travel Time
(e)
Delay Per Trip
(d - a)
(f)
Average Traffic Volume
(g)
Total Delay
(f x e)
7:00–8:00AM 8.12 1.47 NA NA NA NA NA
8:00–9:00AM 8.12 2.00 19 11.67 3.55 86 305.30
9:00–10:00AM 8.12 2.00 32 8.67 0.55 106 58.30
10:00–11:00AM 8.12 2.00 27 18.20 10.08 93 937.44
11:00–12:00PM 8.12 2.00 27 22.92 14.80 80 1,184.00
12:00–1:00PM 8.12 2.00 30 38.65 30.53 123 3,755.19
1:00–2:00PM 8.12 2.00 16 36.77 28.65 89 2,549.85
2:00–3:00PM 8.12 2.00 22 19.47 11.35 99 1,123.65
3:00–4:00PM 8.12 1.95 19 12.53 4.41 92 405.72
4:00–5:00PM 8.12 2.00 24 8.98 0.86 72 61.92
5:00–6:00PM 8.12 2.00 19 14.10 5.98 74 442.52
6:00–7:00PM 8.12 2.00 28 15.25 7.13 78 556.14
7:00–8:00PM 8.12 2.00 28 20.45 12.33 71 875.43

Table 12. Total Delay – 7/12/2001 – Inbound
Time Period (a)
"No Delay" Travel Time
(b)
Average No. of Open Booths
(c)
Number of "Matched" Vehicles
(d)
Average Travel Time
(e)
Delay Per Trip
(d - a)
(f)
Traffic Volume
(g)
Total Delay
(f x e)
7:00–8:00AM 8.12 1.00 26 31.72 23.60 57 1,345.20
8:00–9:00AM 8.12 1.89 46 15.48 7.36 121 890.56
9:00–10:00AM 8.12 2.00 33 13.35 5.23 107 559.61
10:00–11:00AM 8.12 2.00 31 16.45 8.33 114 949.62
11:00–12:00PM 8.12 2.00 32 21.12 13.00 94 1,222.00
12:00–1:00PM 8.12 2.00 38 17.48 9.36 115 1,076.40
1:00–2:00PM 8.12 2.00 25 13.18 5.06 73 369.38
2:00–3:00PM 8.12 2.00 23 9.95 1.83 82 150.06
3:00–4:00PM 8.12 2.00 17 15.05 6.93 70 485.10
4:00–5:00PM 8.12 2.00 17 19.82 11.70 55 643.50
5:00–6:00PM 8.12 2.00 19 14.70 6.58 70 460.60
6:00–7:00PM 8.12 2.00 13 10.48 2.36 76 179.36

Statistics

Table 13 shows the baseline or "no delay" travel time, the average travel time, and three other measures that indicate the reliability of the travel time estimates. The baseline time (in minutes) is the time needed to travel the study distance (between the starting point in the exporting country and the initial inspection point in the importing country) in free-flow traffic conditions. The average time is computed from all vehicles measured during the data collection period over the study distance. The 95th percentile time is the time (in minutes) within which 95 percent of all trucks can cross the border. The buffer time is the additional time above the average crossing time (in minutes) that it takes for 95 percent of all trucks to cross. The buffer index expresses the buffer time in terms of the average time and is the percentage of extra time that must be budgeted to cross the border within the 95th percentile time. For example, if the average time was 10 minutes and the buffer time was 5 minutes, the buffer index would be 50 percent.

Table 13. Crossing Times
empty cell Baseline
Time
Average Crossing Time 95th Percentile Time Buffer Time Buffer Index
Outbound 4.8 21.0 9.1 14.3 66.5
Inbound 8.1 17.3 80.3 18.3 105.8

From the table, it is apparent that while the average travel time is slightly lower for inbound traffic, the reliability is much more favorable for outbound traffic.

Figure 9 illustrates the average travel time experienced for different truck volumes per lane per hour in each direction.

Scatter plot showing the inbound and outbound travel time in minutes for Blaine traffic volumes per hour per lane. Inbound traffic volume remains steady, with delays of 10 to 40 minutes. As outbound traffic volume increases, delays increase from 10 to 35 minutes.
Figure 9. Average Travel Time for Different Hourly Volumes

Figures 10 and 11 show typical average hourly traffic volumes per booth for the study period as well as the measured average hourly travel times. In addition, the average number of open primary Customs booths in each direction is shown.

Graph showing the average hourly inbound traffic volume and travel time in minutes per booth for Blaine from 7AM to 8PM, showing travel time, volume per booth, and number of open booths. No delay travel time is 8.12 minutes. Travel time and volume per booth increase sharply between 12 and 2PM. Open booths increase after 8AM and remain steady all day.
Figure 10. Typical Inbound Traffic

Graph showing the average hourly outbound traffic volume and travel time in minutes per booth for Blaine from 6AM to 6PM, showing travel time, volume per booth, and number of open booths. No delay travel time is 4.75 minutes. Travel time increases sharply at 1 and 4PM. Open booths increases at 1 and 5PM. Volume per booth decreases at 9AM and 4PM.
Figure 11. Typical Outbound Traffic

Conclusions

Lessons learned during data collection activities in this project at the Blaine Border Crossing and at others along the Canadian and Mexican borders with the U.S. have identified several issues that should be taken into consideration to assist future data collection efforts. Some apply to advance planning and the initial site visit and others apply more specifically to the data collection activities themselves.

Planning and Site Visits

  • Prior to conducting any data collection project, all jurisdictional and cooperating agencies should be made explicitly aware of the purpose and objectives of the study as well as all the details associated with the data collection project (e.g. dates, times, procedures to be followed during the data collection period, etc.). Failure to do so may result in confusion and possible delay of the study. This has been very time-consuming at some ports and should be adequately accounted for in the schedule. For some agencies, including U.S. Customs, it is important to contact both the federal and local levels. Some entities that should be contacted might not be readily apparent and can include construction companies working on public rights-of-way, state police and city officials. Some agencies provide verbal approval for the data collection and may even provide supporting documentation to their field staff, yet are reluctant to provide documentation for the data collectors to carry. Every effort should be made to obtain written authorization that can be carried by the data collectors. For example, Canadian immigration officials at the Blaine Crossing provided work permit documents that ensured smooth data collection operations in Canada.
  • Prior to data collection activities, a general idea of traffic peak periods and conditions should be understood to optimize collection of appropriate traffic data and coverage of the appropriate times. This information should be obtained from discussions with knowledgeable officials and by examining historical traffic data.
  • Any additional data needs should be discussed explicitly with the appropriate officials. Canadian Customs at the Blaine Crossings, for example, does not normally record and maintain average hourly truck volumes, but will do so if special arrangements are made in advance. Alternatively, it may be appropriate to use other means to measure truck volumes, such as roadway counters or having the data collectors indicate the vehicles that pass without their license plates being recorded (assuming continuous data collection during each day). These additional traffic volumes could be used to corroborate data provided by the local authorities or used if their planned data collection did not occur or there was some other problem in providing the data.
  • It is also important to be aware of special federal or local holidays on both sides of the border when scheduling data collections as these could affect traffic flows. Some minor holidays that occur on Mondays and Fridays, might not significantly affect traffic for a Tuesday through Thursday data collection period, but may increase the likelihood that key local officials will be on vacation and unavailable should any problems arise.
  • Photographs of the border facilities and data collection locations should be taken during the site visits to assist in documenting the collection effort and to better inform the data collectors prior to their arrival on-site.
  • Processing, data quality, and analysis of all traffic data require the largest portion of the study time.

Data Collection Activities

  • Prior to data collection activities, an explanation and understanding of the procedures to be followed and logistics should be made clear to all members of the study team (e.g., number and location of license plate characters to be recorded, all commercial vehicles should be recorded, when and how to contact the on-site supervisor, etc.).
  • Proper identification for all survey members and written documentation of authorization from all jurisdictional agencies should be carried at all times by all members of the study team, especially when conducting business in a foreign country.
  • The supervisor should assess all conditions upon arrival for data collection to note any changes from the site visit or prior collection activities. Sometimes unplanned construction or other events may alter the preferred data collector locations or the truck flow patterns.
  • The supervisor should be used to maintain nearly constant data collection during breaks. This improves data quality by ensuring the supervisor observe each collector and can identify and correct any problems they might be having. Further, this improves the number of trucks matched at both the #1 and #2 locations, improving the sample size for analysis.
  • It is important to ensure that the data collectors are safe and comfortable during their long periods of collection. If their data collection locations cannot provide adequate cover from severe rains or heat, additional vehicles should be considered. Comfortable sport chairs with attachable beach umbrellas served to protect the collectors well during light rain and moderate sun. Ensure that the collectors have an adequate supply of water and that facilities are conveniently accessible. This becomes more difficult for the remote locations upstream from the border crossing.

References

Turner, S. M., W. L. Eisele, R. J. Benz, and D. J. Holdener. Travel Time Data Collection Handbook. Report No. FHWA-PL-98-035. Federal Highway Administration, Texas Transportation Institute, March 1998

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