Office of Operations Freight Management and Operations

Evaluation of Travel Time Methods to Support Mobility Performance Monitoring:
Peace Bridge (Page 1 of 3)

Final Site Report

April 2002


Office of Freight Mgt. and Operations
Federal Highway Administration
U.S. Department of Transportation
Washington, DC 20590


Battelle Memorial Institute

Border Crossing Freight Delay Data Collection and Analysis
FY 2001 Data Collection – Peace Bridge

Site Description

The Peace Bridge connects Buffalo, New York with Fort Erie, Ontario and crosses the Niagara River. The bridge links the Queen Elizabeth Way (QEW) in Canada and provides with I-190 and other major roadways in the U.S. The QEW extends to Toronto, Ontario and also links with Highway 401, one of the major East-West Canadian expressways. I-190 provides a link to I-90, the main artery of the New York State Thruway, connecting the area to the major population centers on the East Coast. The bridge operates 24 hours a day, seven days a week.

The Peace Bridge contains only a single, three-lane span. The center lane is reversible and can be used to ease congestion during peak travel conditions. The bridge was built in 1927 and is 5,800 feet long. The bridge is governed by a ten-member board consisting of five members from New York State and five members from Canada. All capital improvements and operating expenses are funded by tolls and rentals of Peace Bridge-owned property and buildings, not public funds. While a single organization, the Buffalo and Fort Erie Public Bridge Authority manages two tightly linked groups of bridge operators and maintenance workers.

Area map of the Peace Bridge crossing connecting New York state and Ontario, Canada.
Figure 1. Area Map – The Peace Bridge

Data collection activities at the Peace Bridge occurred during May 22-24, 2001 and June 19-21, 2001. Truck travel times across the bridge in both directions were recorded on Tuesday through Thursday each week, for approximately 12 hours each day. The times of the data collection were staggered somewhat to obtain a broader picture of activity at the bridge.

Aerial photo of the U.S. plaza at the Peace Bridge crossing, showing the locations of Customs primary and secondard sites, inbound and outbound toll booths, and inspection stations IB-2 and OB-1.
Figure 2. U.S. Plaza

Aerial photo of the Canadian plaza at the Peace Bridge crossing, showing the locations of Customs primary and secondary site, auto primary site, and inspection stations IB-1 and OB-2.
Figure 3. Canadian Plaza

Westbound traffic (outbound to Canada) approaches the bridge either from I-190 or from Porter Avenue, a four-lane arterial. On the U.S. side, typically two toll booths are used for trucks but another is available if needed (see Figure 5). Three lanes are typically open for autos. The Duty Free Shop is located on the bridge plaza beyond the toll booths. Once across the bridge, autos are directed to the left and trucks veer off to the right to pass through one of four primary Customs inspection booths. However, the fourth is used only occasionally. Trucks are either released from primary or must continue on to secondary inspection, which could include simply completing brokerage paperwork or physical inspections of the cargo. Trucks requiring physical inspections enter an area opposite the primary inspection booths. Exiting trucks and others whose drivers must interact with their broker make a sharp left turn after the inspection booths. Those released continue straight ahead and those needing to park turn left again and park in a reserved parking area. When these trucks are finally ready to depart, they must use the same roadway that trucks released from primary must use to exit the Customs compound.

Photo of U.S. toll booths at the Peace Bridge crossing, showing vehicles in line at the booths.
Figure 4. U.S. Toll Booths

Photo of Canadian Customs primary inspection booths, showing trucks going through the OB-2 collection location.
Figure 5. Canadian Customs Primary Inspection Booths, Showing the OB-2 Collection Location

Eastbound traffic (inbound to the U.S.) approaches the bridge from the QEW. As vehicles approach the bridge, autos are directed to the left and trucks take a separate road to the right that loops around the Duty Free Shop. Beyond the Duty Free, trucks who have not yet been pre-cleared for U.S. Customs visit the Commercial Vehicle Processing Centre (CVPC). The CVPC reviews driver paperwork and, if not in order, holds the vehicle until the paperwork is complete. This reduces the number of vehicles that need to be sent to secondary inspection on the U.S. side and helps to alleviate congestion on the bridge and in the U.S. plaza.

The inbound toll booths are located immediately before the U.S. primary Customs inspection booths on the U.S. side. There are three booths to process commercial vehicles for U.S. Customs primary inspection; however, a fourth is being constructed in the near future. Any truck not released from primary must enter the same secondary inspection compound. There are areas to park for drivers who need to visit their brokers as well as docks where physical secondary inspections can be conducted. As with the Canadian side, trucks exiting from secondary must pass through the area used by trucks exiting the primary inspection booths. In addition, these truck movements intersect with those of passenger autos leaving both primary and secondary inspection.

Data Collection Process

For this study, two data collection locations were used in each direction. The "number 1" location was immediately before the toll booths and the "number 2" location was immediately after the primary inspection booths. For consistency among all border crossings visited as part of the overall project, the data collection positions were distinguished by the direction of travel that they were measuring (outbound or inbound). Westbound movement from the U.S. into Canada was referred to as outbound. Conversely, inbound was used to refer to eastbound movement from Canada to the U.S. The Outbound 1 (OB-1) position; therefore, is in the U.S. plaza, before the toll booths. The Outbound 2 (OB-2) position was after the Canadian Customs booths. The Inbound 1 (IB-1) position was located immediately after the Duty Free Shop, but before the CVPC (see Figure 6 – panel (a) shows the data collector and panel (b) shows the view toward the Duty Free Shop exit onto the truck-only roadway). Inbound 2 (IB-2) was located adjacent to the U.S. Customs booths.

Two photos of the Canadian IB-1 collection location. Photo 6a shows the data collector and a sign directing traffic to enter the Canadian Vehicle Processing Centre. Photo 6b shows a head-on view of trucks on the Canadian Duty Free Shop.
Figure 6. IB-1 Collection Location

Each data collector would use a handheld computer to record partial license plate information of all commercial vehicles that passed their location. The computer would also store the time that each license plate was entered. The data from the two locations in each direction would be combined, allowing the determination of the travel time for each vehicle that was recorded at both locations.

For the data collection, the on-site team included four data collectors and one supervisor. As previously mentioned, the hours during which data were collected were varied during each week to ensure the greatest possible coverage of conditions, including periods of low and high traffic volume. Table 1 shows the data collection hours for each day during the two site visits. As each data collector actually worked about 12 hours, the supervisor could collect data during their 30-minute meal break during the day, resulting in approximately 12-½ hours of data collection.

Table 1. Hours of Data Collection
Date Start End
5/22/01 6:00 am 6:30 pm
5/23/01 9:00 am 9:30 pm
5/24/01 9:30 am 10:00 pm
6/19/01 9:30 am 10:00 pm
6/20/01 9:30 am 10:00 pm
6/21/01 6:00 am 6:30 pm

While an extremely smooth process, it took considerable time to schedule and arrange the initial site visits to coordinate the data collection activities. Three separate meetings were held at the bridge. One meeting was held with the General Manager, the Manager of Information Technology, and a Toll/Traffic Supervisor at the U.S. side of the Buffalo and Fort Erie Public Bridge Authority. Another was held with the Chief U.S. Customs Inspector. A third meeting was held with the Divisional Program Services Officer at Canada Customs and Revenue Agency. Also in attendance at the third meeting were representatives from the headquarters office of Canada Customs who were interested in the project. It was determined that we would need to obtain visitor passes from the bridge authority shift supervisor when we arrived for the data collection.

Initial contacts with Canadian Immigration while at the bridge indicated that work permits were needed to conduct the data collection. However, consultations with Canadian Consular officials in Buffalo indicated that that would not be necessary. An e-mail was provided by the Canadian Consulate to document that they had arranged approvals for the data collection through the local Canadian Immigration office. On only one occasion was the documentation insufficient for the Customs agent at the primary auto inspection booth and Battelle's supervisor was required to briefly speak with an Immigration official prior to entering Canada on one of his frequent trips across the border.

Informal approval for data collection on the QEW, should that be necessary due to the formation of a queue, was arranged through the Canadian Customs officials. While there was no problem with data collection on the New York State Thruway (I-190), future data collection will require a work permit from the Thruway Authority.

Table 2 contains a list of the individuals who were contacted and their telephone and e-mail information. Future data collection for this project should be able to be organized and authorized with much less effort. However, any new project would require additional time to explain the data collection objectives to the involved parties and gain their approval.

Table 2. Agency Contacts
Contact Agency Phone/Fax E-mail
Anthony Braunscheidel
Manager – Info. Tech.
Buffalo and Fort Erie Public Bridge Authority 716-884-6744 ext.242
716-884-2089 (fax)
Christopher Bonn
Toll/Traffic Supervisor
Buffalo and Fort Erie Public Bridge Authority 716-884-6744 ext.269
716-884-2089 (fax)
empty cell
Stephen Mayer
General Manager/Operations
Buffalo and Fort Erie Public Bridge Authority 716-884-6744 ext.224
716-884-2089 (fax)
Mark MacVittie
Chief Inspector
U.S. Customs 716-881-4447
716-883-0582 (fax)
Ken Seebach
Div. Program Services Officer
Canada Customs 905-994-6532
905-994-6010 (fax)
Mary Keefe Canadian Consulate 716-858-9515

Data Collection Details

The Buffalo and Fort Erie Public Bridge Authority provided border crossing statistical data. This data was evaluated for an assessment of the variability in travel conditions at the Peace Bridge. The goal of this analysis process was to obtain statistically useful data with as few data collection days as possible. In order to customize the data collection activities to the Peace Bridge, the following steps were conducted:

  • Define significant "seasonal" variations,
  • Define significantly different days of the week,
  • Identify traffic streams that experience significantly different conditions, and
  • Estimate the number of days needed for the data collection survey.

As shown in Table 3, there is some variation in the commercial traffic by month. Due to project constraints, data collection needed to occur between late May and early September 2001. From Table 3, the two months with the greatest average volumes during this data collection window were May and June.

Table 3. Monthly Traffic Distribution of Commercial Vehicles
Month 1998 1999 2000 1998-2000 Average
January 109,461 101,203 118,865 109,843
February 108,576 111,860 119,572 113,336
March 121,182 130,347 138,266 129,932
April 119,711 126,059 120,066 121,945
May 118,118 127,127 130,936 125,394
June 120,477 135,313 125,779 127,190
July 107,544 116,497 119,393 114,478
August 113,480 129,938 126,537 123,318
September 119,902 128,161 117,043 121,702
October 121,235 127,332 125,772 124,780
November 113,007 128,388 112,952 118,116
December 108,803 117,812 98,148 108,254
Total 1,381,496 1,480,037 1,453,329 1,438,287

Source: Texas Transportation Institute

Tables 4 and 5 show that there is a significant difference in commercial traffic between weekdays and weekends and, further, there is a significant difference between Monday and Friday and the three mid-week days. Weekend traffic is 39 percent of typical weekday traffic and Monday/Friday traffic is 85 percent of typical Tuesday/Wednesday/Thursday traffic. In general, it was noted that inbound traffic increased from Tuesday through Thursday and outbound traffic decreased from Tuesday through Thursday. It was determined that collecting three days of data, from Tuesday through Thursday, would provide an adequate number of data samples to represent "typical" conditions.

Table 4. Sample Month – Daily Traffic Distribution of Commercial Vehicles for May 2000
Day Day of Week Outbound Inbound
1 Thursday 2010 2684
2 Friday 2737 2782
3 Saturday 2952 2930
4 Sunday 3051 2789
5 Monday 2816 1802
6 Tuesday 1174 651
7 Wednesday 465 1343
8 Thursday 2086 2831
9 Friday 2848 2868
10 Saturday 2989 2889
11 Sunday 3073 2910
12 Monday 2863 1930
13 Tuesday 1135 684
14 Wednesday 458 1277
15 Thursday 2118 2834
16 Friday 2935 2877
17 Saturday 3021 2976
18 Sunday 2879 2748
19 Monday 2683 1712
20 Tuesday 1036 576
21 Wednesday 357 1150
22 Thursday 1353 1643
23 Friday 2461 2664
24 Saturday 2902 2841
25 Sunday 2852 2795
26 Monday 2763 1696
27 Tuesday 1156 469
28 Wednesday 372 476
29 Thursday 660 1897
30 Friday 2393 2827
31 Saturday 2918 2820
Total empty cell 65,516 65,371

Source: Buffalo and Fort Erie Public Bridge Authority

Table 5. Averages for Sample Month – Daily Traffic Distribution of Export Commercial Vehicles for May 2000
Day of Week Week 1 Week 2 Week 3 Week 4 Week 5 Average
Sunday empty cell 2766 2229 2203 2210 2352
Monday empty cell 6054 5517 5619 5425 5654
Tuesday empty cell 6550 6263 6253 6020 6272
Wednesday empty cell 6643 6368 6204 6219 6359
Thursday 6520 6465 6318 6207 5640 6230
Friday 5712 5250 5211 5071 4157 5080
Saturday 2674 2208 2081 2077 empty cell 2260

Source: Buffalo and Fort Erie Public Bridge Authority

From discussions with the Buffalo and Fort Erie Public Bridge Authority, it was learned that backups typically did not occur on the U.S. side and, when they did, they did not grow very long. However, on the Canadian side, backups occurred fairly frequently and could stretch for several miles along the QEW. On the Canadian side, the backups would often occur by late afternoon and could stretch into the late evening or early morning hours.

Data Collection Procedures

The data collection stations selected for the crossing were chosen because of the particular actions that occur at each site. Segments defined by the data collection stations were used to determine the commercial vehicle travel times and freight delay. As illustrated in Figures 2 and 6, the data collection sites were located at:

  • An advance station located upstream of the commercial vehicle queue – OB-1 and IB-1.
  • The import station (primary inspection booths before detailed, or secondary, inspection) – OB-2 and IB-2.

Data collection was conducted by recording commercial vehicle license plates as vehicles crossed fixed points within the data collection sites. Survey individuals or teams, were placed at each of the four data collection sites to record commercial vehicle license plate data. Figures 2 and 3 show the facilities on both sides of the border, including station locations and major points of inspection.

Collectors at these locations would record the last five characters of the front, lower-left license plate of as many trucks as possible that passed their location. When trucking firms register many vehicles at once, they often get assigned sequential license plate numbers. Using the last five characters helps to ensure that as different trucks operated by the same firm travel across the bridge that they are uniquely identified. License plate information was entered into handheld computers with a special application designed for this project. Each entry was time-stamped with the current date and time. Prior to each day's collection, all handheld computers were synchronized to the same time. Prior experience indicated that recording the entire license plate was too time consuming and that entering only the last four characters did not provide adequate distinction between different vehicles, so the project team chose to record the last five characters.

Typically, the queue of trucks crossing the border would not extend beyond the bridge plaza. However, on occasion the queue would extend onto the highway system. When this occurred, the data collector at the #1 location would have to move further from the bridge to a point beyond the end of the queue. In this way, they could continue to record trucks before they began their wait at the end of the line. When this or any other event of interest occurred, the collectors would use an "EVENT" feature of the PDA software to record it.

For each #1 location, the supervisor would record the distance from any data collection point other than the original position (which would be in the bridge plaza). During post-processing, the data from all locations nearer to the bridge than the farthest location would be adjusted to include the additional travel time from the farthest location to the original location. The travel time would be computed at free-flow speeds, since there would have been no queue at the times that the data were collected at these closer locations. In this way, the data all would appear to be collected from the same location, the one most distant from the bridge.

The data collection team used cell phones to maintain in touch with each other. This was particularly important when the queues lengthened such that a collector had to move farther upstream. The supervisor could be kept informed without repeated trips to each data collection location. This was also useful at the end of the day when the #1 collectors would inform the #2 collectors of the last truck they recorded, so the #2 collectors would know when to stop. While cell tower locations created some problems with reception, each collector was usually able to reach whomever they needed to speak with.

Data Collection Sample Size

Sample sizes are typically not a concern with videotape or handheld data entry devices, because the data collection includes a large number of vehicles. However, minimum sample sizes should be verified with variability values from field data. Early research found that sample sizes from 25 to 100 license matches were necessary for a given roadway segment and time period (Turner, et. al.). In most cases, there were sufficient records to meet this requirement. The number of matches was significantly higher in the inbound direction as all vehicles had to travel slowly and in single file past the data collector. In addition, the use of improved data collection equipment, described in the following section, increased the number of matches during the second week of data collection.

Data Collection Equipment

As outlined in the "Data Collection Procedures" section above, handheld computers were used as the data entry device and proved adequate to the task. For the first week of data collection, Palm m100 model handheld computers were used. It was decided, however, that subsequent data collection should be done with Handspring Visors. The Handspring Visors use the same Palm OS (operating system) and have faster processing speeds (at least in side-by-side comparison with this application) and larger screen sizes than the m100 models from Palm Computing. Low-end models with 2MB of storage capacity were selected as the application and data size were projected to be well below this limit.

A custom application was developed for the Palm OS, which allowed the data collectors to identify their locations (e.g., OB-1, IB-2), the number of open booths (primarily used for the customs inspection booths), special events or other comments, and license plate information. A screen shot of the application interface is shown in Figure 7.

Photo of a Handspring Visor PDA data collection device and software application
Figure 7. Data Collection Device and Software Application

The data were downloaded via a serial cable directly from the application into a text file on the field laptop computer, which was a Dell Latitude CPx H running with a 500 MHz Pentium III processor.

After analyzing the data from the first two days of collection during the first week indicated that there might be a problem with the download process. To ensure no loss of data, it was decided to record data manually on the third and last day of collection that week. The collectors used synchronized digital watches and recorded the time in addition to the license plate information. This data was later transcribed for processing. The original Palm m100s were used as backup devices for the second week of data collection, but they did not need to be used.

Data Collection Summary

Table 6 shows the number of commercial vehicle license plates recorded for each of the stations on each of the data collection days. Table 7 shows the average daily traffic volume as recorded by the Buffalo and Fort Erie Public Bridge Authority. Hourly volumes are used in the calculation of delay; those are shown with the delay calculations in Tables 8 through 19.

Table 6. Number of Commercial Vehicle License Plates Collected
Station 5/22/01 5/23/01 5/24/01 6/19/01 6/20/01 6/21/01
OB-1 796 1133 1045 1045 1409 1342
OB-2 590 936 870 870 1533 1454
IB-1 1032 1005 1103 1309 1235 1456
IB-2 1382 1477 1388 1298 1309 1437
Total 3800 4551 4406 4522 5486 5689

Table 7. Average Daily Traffic at the Peace Bridge
Direction 5/22/01 5/23/01 5/24/01 6/19/01 6/20/01 6/21/01
Outbound 2305 2720 2783 2633 2675 2674
Inbound 2236 2852 2731 2526 2559 2641
Total 4541 5572 5514 5159 5234 5315

Data Quality Steps

At the end of each day of data collection, the supervisor would collect the PDAs and download the data into the field laptop computer where it was stored on the hard drive. The data would be examined for any anomalies and transferred across the Internet to a secondary location for backup purposes. The OB-1 and OB-2 data would be merged together and license plates from the two locations would be "matched" using a spreadsheet developed in Microsoft Excel. As it is easy to mistake certain characters, particularly letters that looked like numbers, the license plate data was pre-processed. All 'I's were replaced with '1's; all 'O's, 'D's, and 'Q's were replaced with '0's; all 'S's were replaced with '5's; and all 'Z's were replaced with '2's. In addition, the data collectors were instructed to always use '1's for 'I's and '0's for 'O's (i.e., to use the digit, rather than the letter).

Occasionally, collectors would be unsure about a license plate and would append "QQQ" to their entry. This would typically occur when several trucks passed the collector in rapid succession or if one truck blocked the license plate of another and he or she could only manage a quick glimpse. This would allow the supervisor to search the downloaded data for a potential match by using the travel times of other trucks that were recorded in the same general time frame. During this process, the supervisor could also identify the few records in which the data collector forgot to press "ENTER" after recording a license plate before recording the next one. These ten-character entries could be split into two and the time for the first interpolated from the adjacent entries if they were less than a minute or so apart.

During the first week of data collection, it was determined that a problem with the download process might preclude accessing all the data collected during the third day. It was, therefore, decided to employ a manual data collection approach for that third day. The collectors used pads of paper and synchronized wrist watches to record both the license plate information and the time of day. This data was later transcribed and double-checked. For future data collections at other locations, backup handheld computers were provided to all data collectors to use if they felt that their primary device was not functioning properly.

Data post-processing also included a step to identify any anomalies in the data, including outliers. Outliers, records that indicated travel times significantly greater than typical for that time period, were most often caused by recording the license plate of a vehicle only some of the time as it made repeated trips across the border during a single day. This is because the matching algorithm uses the most recent time at the #1 position when matching to a record from a #2 location. For example, if the vehicle was recorded as it headed from Canada to the U.S. early in the morning, later returned to Canada, was missed as it re-entered the U.S. later in the day, and then recorded on its subsequent return to Canada, the #1 time from its first trip would be matched with it #1 time from the first trip (for a valid travel time) an also matched to the #2 time from its second trip (an invalid travel time). This invalid travel time would be easily identified by manual inspection of the data, aided by highlighting those travel times above a specific, but variable, threshold.

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