WIM #40 US 52, MP 126.8 S. ST. PAUL, MN APRIL 2010 MONTHLY REPORT
In order to understand the vehicle classes and groupings the Mn/DOT Vehicle Classification Scheme and the Vehicle Class Groupings for Forecasting are shown on the WIM Reports home page at http://www.dot.state.mn.us/traffic/data/html/wim_reports.html VOLUME For WIM #40 on US 52 at mile post 126.8 in South St. Paul, there were 1,847,243 vehicles that passed the site for the month of April. The Average Daily Traffic (ADT) and Heavy Commercial Average Daily Traffic (HCADT) for April 2010 was 61,174 and 3,892, respectively. Of the heavy commercial vehicles, the top two in volume were the Class 9 s and 5 s. Figure 1 shows the average number of vehicles, broken down by direction, versus day of the week. The average numbers of vehicles for northbound (NB) and southbound (SB) both grew throughout the work week and peaked on Fridays and were lowest on Sundays. Figure 2 shows the total vehicles, passenger vehicles (Class 1, 2, and 3), and heavy commercial vehicles (Class 4 to 13) versus hour of day. For April the total vehicles and passenger vehicles had a smaller peak between 5 am and 6 am and a larger peak between noon and 5 pm. The heavy commercial vehicles peak starting at 6 am and extended to 1 pm. The heavy commercial vehicles were reviewed for directional volume differences and it appears that there are a few more vehicles going in the NB direction. VEHICLE CLASSIFICATION The traffic volume consisted of 1,727,893 passenger vehicles (93.5%) and 119,350 heavy commercial vehicles (6.5%). Table 1 summarizes vehicle class volumes and percentages; and overweight vehicles and the percentages as compared to total overweight vehicles. OVERWEIGHT VEHICLES Without a permit, the maximum allowable weight for a single axle is 20,000 pounds; tandem axles, spaced 8 or less, can be up to 34,000 pounds; tridem axles, spaced 9 or less, can be up to 43,000 pounds; quad axles, spaced 13 or less, can be up to 51,000 pounds; and the maximum GVW is 80,000 pounds. The total volume and total heavy commercial volume for April 2010 was 1,847,243 and 119,350, respectively. The total number of vehicles that were overweight was 13,894 or 0.8% of the total traffic or 11.6% of the heavy commercial vehicles. Figure 1 shows the average number of overweight vehicles, broken down by direction, versus day of the week. The average numbers of overweight vehicles for both directions peaked on Wednesdays and were lowest on the weekends for both directions. The top two overweight violators by class were the Class 9 s and the Class 5 s. Overweight vehicles by class versus hour of the day are shown in Figure 3. The Class 9 overweight vehicles peaked between 5 am and noon. The overweight vehicles were also reviewed to determine if there is an NB and SB difference. Figure 4 shows the total, NB, and SB overweight vehicles versus hour of the day. Figure 4 shows that for April 2010, more overweight vehicles were in the NB direction.
Figure 5 shows the gross vehicle weight for Class 9 s and 10 s in both the NB and SB direction. From Figure 5 it is apparent that the Class 9 s had more full than empty vehicles in the NB direction and more empty than full vehicles moving in the SB direction. The Class 10 s had more full vehicles than empty vehicles in both directions. For weight enforcement the WIMs are a screening tool. Currently, piezo-quartz WIM systems are considered to be accurate within 5% to 10% on Gross Vehicle Weight (GVW). With an accuracy of about 10% anything over a GVW of 88,000 pounds is overweight. These may still be permitted loads. For the most efficient use of personnel and equipment, these are the vehicles that should be weighed on static scales and reviewed for permits. In the NB direction there were 112 vehicles over 88,000 pounds, 59 were Class 9 s and 22 were Class 10 s. In the SB direction there were 225 vehicles over 88,000 pounds, 93 were Class 9 s and 85 were Class 10 s. Table 2 summarizes the Top 10 Gross Vehicle Weight for Class 9 and Class 10 vehicles for the month of April 2010. SPEED The speed limit on US 52 at the WIM site is 55 mph. For April 2010, WIM #40 recorded an average speed of 61 mph, the median speed was 61 mph, and the 85 th percentile speed was 66 mph. Figure 6 shows the speed versus the normalized percentage of passenger vehicles and heavy commercial vehicles in both the NB and SB direction. Both the NB and SB heavy commercial vehicles were going slightly slower that the passenger vehicles. Figure 7 shows the speed versus the day of the week with the volumes normalized. It looks like for April 2010, there was no significant difference in speed based on day of the week. Figure 8 shows the speed versus the hour of the day with the volumes normalized. It appears that the traffic tends to move a little faster during the early part of the day, 3 am to 6 pm. As can be seen in the figures there are slight differences in speeds based on vehicle class and hour of the day but no significant difference in speed based on day of the week. BRIDGE The Lafayette Bridge No.9800 is approximately 3.9 miles north of WIM #40, and Bridge No. 19016 on the NB side and Bridge No. 19015 on the SB side are 0.7 miles south of WIM #40. For the month of April 2010, WIM #40 saw 1,847,243 vehicles with a total weight of 10,426,300 kips (1 kip = 1,000 pounds). Figure 9 summarizes the total GVW by lane and class and Figure 10 summarizes the percentages each class contributes to the total GVW. Table 3 provides details on the class breakdowns versus lane for GVW. MATERIALS For April 2010 a total of 74,742 ESALs passed over the pavement at WIM #40. Approximately 80.9% of the ESALs were in the driving lane, 42.1% NB and 38.8% SB. Figure 11 graphically depicts the total ESALs by class and lane. Figure 12 summarizes the percentages that each vehicle class contributes to the total ESALs. It is interesting to note that the Class 9 s provide 63.5% of the ESALs while they are only 25.4% of the total gross vehicle weight. Table 4 provides details on the class breakdowns versus lane
for ESALs. Table 4 also provides the flexible ESAL factors for each vehicle class using a terminal serviceability of 2.5 and a structural number of 5. For April there were 4,605 Class 9 trucks and 711 Class 10 trucks over 80,000 pounds. These 5,316 vehicles generated 14,600 ESALs. If all of these trucks weighed just 80,000 pounds they would have generated 13,273 ESALs, 1,326 ESALs lower. If you take the April ESALs of 74,742 and multiply it by 12 to get an annual ESAL number, and then multiply it by 20 to get a 20-year BESAL you get 17,938,000. If you go through the same process but start with a monthly value of 73,416, i.e. subtracting out all of the overweight Class 9 and 10 vehicles, you come up with 17,620,000 20-year BESALs. If you take the 20-year BESAL with all Class 9 s and 10 s weighing 80,000 pounds or less and divide that by 74,742, the BESALs with the overweight Class 9 s and 10 s you get 236, or the overweight Class 9 s and 10 s cause the pavement to reach its 20-year design life 4 months early. This is a quick, back of the napkin calculation, this only looks at Class 9 s and 10 s, not the other 8 heavy commercial classes. As part of a technical implementation research project we are looking at developing a report function that will perform this calculation for all heavy commercial classes. Because the heavy commercial haulers are looking to move that weight of freight we will add additional legal-weight trucks so that the total weight being shipped stays the same. CALIBRATION WIM #40 was calibrated during initial construction last fall. WIM #40 was checked on February 10, 2010. As part of the on-going monitoring to assure the performance between calibrations, front axle weights and gross vehicle weights of Class 2 s, 3 s, and 9 s are being monitored on a monthly basis. Table 5 summarizes the front axle weight of the Class 2 s, 3 s, and 9 s by lane. Table 6 summarizes the gross vehicle weight of the Class 2 s and 3 s. Currently, all Class 2 s and 3 s are included in this data. In the future, the goal would be to only monitor the Class 2 s and 3 s that are not pulling trailers. The current goal of the calibration is to first have the GVW for each class and each lane stay within a range of ±5% and then secondly to have each individual axle stay within a range of ±9%. As you can see in Table 5 the front axle weight for all three Classes and all four lanes are currently within the range. In Table 6 the GVW for all three Classes and all four lanes is within the range. Past WIM research indicates that an unloaded Class 9 should weigh 28 to 32 kips. Data from the MnROAD site indicates that this unloaded range may have moved a little higher. The range for loaded Class 9 s is generally in the 70 to 80 kip range but varies more by site and season. Figures 13 to 16 shows histograms of the monthly GVW of Class 9 s for the last three months for Lanes 1 to 4. Figure 17 is a graph of the unloaded and loaded peaks by lane versus date. There are enough Class 9 s in Lanes 1 to 4 that a weekly histogram can be developed. With only a little over three months of data, it is a little early to tell but if this site acts like the other sites, calibrating only twice a year will not provide the quality of data that is needed. Physically calibrating the 14 systems with a test truck on a weekly or monthly basis is not practical and cost prohibited. Our current
software will not allow us to adjust the raw data and then perform the overweight violations, GVW, ESALs and other calculations in a timely manner. Therefore, the adjustments will have to be done at the controller. There is a feature in the hardware that allows the system to autocalibrate. The algorithm basically adjusts the machine to bring the unloaded Class 9 s back into the range of 28 to 32 kips after a given number of Class 9 s cross the sensors. It is a moving average calculation that steps the system back into calibration, i.e. not just one big jump. We will begin to implement this change over the next few months. Please let me know if you have suggestions, comments, or concerns. SUMMARY For April 2010 the average volumes grew throughout the work week and peaked on Fridays in both directions and were lowest on Sundays. The overweight vehicles peaked in both directions on Wednesdays and were lowest on the weekends. The average numbers of overweight vehicles were higher for NB than SB. The overweight vehicles peaked from 8 am to 3 pm. For April 2010, for the Class 9 s, 17.6% of them were overweight and for the Class 10 s, 28.9% of them were overweight. The speed of the traffic varies slightly based on vehicle class and hour of the day but no significant difference in speed was observed based on day of the week. The GVW was a little higher in the NB direction 5,251,000 kips versus 5,175,000 kips SB. This agrees with the ESALs. The NB ESALs were higher 40,620 versus 34,120 SB. For April 2010, the overweight Class 9 s and 10 s were shortening the 20-year BESAL design life by 4 months. Attach: Table 1 Vehicle Classification Data Table 2 Top 10 Gross Vehicle Weight, Class 9 and Class 10 Table 3 Gross Vehicle Weight by Class and Lane Table 4 ESALs by Class and Lane and Flexible ESAL Factors Table 5 Front Axle Weight by Class and Lane Table 6 Gross Vehicle Weight by Class and Lane Figure 1 Average Volume and Average Overweight Volume vs. Day of the Week Figure 2 Total Vehicles, Passenger Vehicles, and Heavy Commercial Vehicles vs. Hour of the Day Figure 3 Overweight Vehicles by Class vs. Hour of the Day Figure 4 Overweight Vehicles by Direction vs. Hour of the Day Figure 5 Class 9 s and 10 s by Direction vs. Gross Vehicle Weight Figure 6 Speed vs. Vehicle Type and Direction of Travel Figure 7 Speed vs. Day of the Week Figure 8 Speed vs. Hour of the Day Figure 9 Total Gross Vehicle Weight by Class and Lane Figure 10 Total Gross Vehicle Weight by Class Figure 11 Total ESALs by Class and Lane Figure 12 ESALs by Class Figure 13 Monthly Class 9 GVW Histogram Lane 1 (NB Driving) Figure 14 Monthly Class 9 GVW Histogram Lane 2 (NB Passing)
Figure 15 Monthly Class 9 GVW Histogram Lane 3 (SB Passing) Figure 16 Monthly Class 9 GVW Histogram Lane 4 (SB Driving) Figure 17 Unloaded and Loaded Peaks by Lane vs. Date
TABLE 1 - VEHICLE CLASSIFICATION DATA WIM #40 - SOUTH ST. PAUL April 2010 MONTHLY MONTHLY MONTHLY MONTHLY AVERAGE MONTHLY TOTAL TOTAL TOTAL VEHICLE DAILY TOTAL VOLUME OVERWEIGHT OVERWEIGHT CLASS VOLUME VOLUME PERCENTAGE VEHICLES PERCENTAGE C1 0 0 0.0% 0 0.0% C2 47,672 1,437,199 77.8% 0 0.0% C3 9,610 290,694 15.7% 0 0.0% C4 64 1,944 0.1% 212 1.5% C5 1,155 35,460 1.9% 937 6.7% C6 394 12,071 0.7% 795 5.7% C7 33 1,015 0.1% 427 3.1% C8 258 7,893 0.4% 472 3.4% C9 1,835 56,284 3.0% 9,912 71.3% C10 89 2,747 0.1% 794 5.7% C11 37 1,133 0.1% 65 0.5% C12 13 376 0.0% 77 0.6% C13 15 427 0.0% 203 1.5% TOTAL = 61,174 1,847,243 100.0% 13,894 100.0% TABLE 2 - TOP 10 GROSS VEHICLE WEIGHT, CLASS 9 AND CLASS 10 WIM #40 - SOUTH ST. PAUL April 2010 DAY OF VEHICLE GVW DATE WEEK TIME CLASS DIRECTION LANE (lbs) 4/9/10 Friday 5:32:52 9 Northbound 1 135,000 4/20/10 Tuesday 5:43:42 9 Northbound 1 133,000 4/1/10 Thursday 6:01:52 9 Northbound 1 130,000 4/16/10 Friday 5:46:21 9 Northbound 1 127,000 4/6/10 Tuesday 5:58:51 9 Northbound 2 125,000 4/27/10 Tuesday 19:30:25 10 Southbound 4 123,000 4/13/10 Tuesday 5:24:07 9 Northbound 1 122,000 4/30/10 Friday 6:16:59 9 Northbound 1 120,000 4/20/10 Tuesday 14:28:34 9 Northbound 1 120,000 4/28/10 Wednesday 23:20:39 10 Northbound 1 113,000
TABLE 3 - GROSS VEHICLE WEIGHT BY CLASS AND LANE WIM #40 - SOUTH ST. PAUL April 2010 NB NB SB SB DRIVING PASSING PASSING DRIVING VEHICLE LANE LANE LANE LANE TOTAL CLASS (Kips) (Kips) (Kips) (Kips) (Kips) PERCENTAGE C1 239 267 218 627 1,351 0.0% C2 1,411,925 839,808 812,239 1,569,827 4,633,798 44.4% C3 551,772 253,371 269,420 554,078 1,628,641 15.6% C4 20,886 4,149 4,332 17,957 47,324 0.5% C5 233,525 44,487 40,874 228,450 547,335 5.2% C6 136,540 34,882 32,087 136,839 340,348 3.3% C7 14,276 8,234 5,080 21,182 48,772 0.5% C8 111,384 14,458 15,383 116,085 257,310 2.5% C9 1,071,246 354,869 236,582 987,372 2,650,069 25.4% C10 66,127 37,988 21,766 62,879 188,760 1.8% C11 22,431 5,519 5,677 23,812 57,439 0.6% C12 8,503 2,301 747 9,048 20,600 0.2% C13 1,938 282 406 1,900 4,525 0.0% TOTAL = 3,650,791 1,600,615 1,444,812 3,730,055 10,426,274 100.0% GVW/LANE = 35.0% 15.4% 13.9% 35.8% GVW/DIRECTION = 50.4% 49.6% TABLE 4 - ESALs BY CLASS AND LANE AND FLEXIBLE ESAL FACTOR WIM #40 - SOUTH ST. PAUL April 2010 NB NB SB SB FLEXIBLE VEHICLE DRIVING PASSING PASSING DRIVING ESAL CLASS LANE LANE LANE LANE TOTAL PERCENTAGE FACTOR C1 0 0 0 0 0 0.0% 0.0004 C2 238 127 122 245 732 1.0% 0.0006 C3 237 95 103 236 672 0.9% 0.0024 C4 503 103 96 487 1,189 1.6% 1.04 C5 3,496 505 474 3,765 8,239 11.0% 0.24 C6 2,385 470 491 2,626 5,972 8.0% 0.54 C7 330 203 133 507 1,172 1.6% 1.45 C8 2,079 196 262 2,039 4,576 6.1% 0.58 C9 20,486 6,736 2,955 17,260 47,437 63.5% 0.92 C10 1,007 524 366 1,102 2,999 4.0% 1.11 C11 529 118 123 510 1,280 1.7% 1.24 C12 160 44 17 168 389 0.5% 1.23 C13 45 4 2 33 84 0.1% 1.35 TOTAL = 31,493 9,126 5,144 28,979 74,742 100.0% ESALS/LANE = 42.1% 12.2% 6.9% 38.8% ESALS/DIRECTION = 54.3% 45.7%
TABLE 5 - FRONT AXLE WEIGHT BY CLASS AND LANE WIM #40 - SOUTH ST. PAUL April 2010 VEHICLE LANE 1 FRONT AXLE LANE 2 FRONT AXLE LANE 3 FRONT AXLE LANE 4 FRONT AXLE MONTH CLASS (Kips) ± 9% (Kips) ± 9% (Kips) ± 9% (Kips) ± 9% February C2 2.28 -- 2.16 -- 2.15 -- 2.25 -- March 2.24-1.75% 2.16 0.00% 2.15 0.00% 2.22-1.33% April 2.30 0.88% 2.13-1.39% 2.12-1.40% 2.18-3.11% February C3 3.18 -- 3.16 -- 3.11 -- 3.11 -- March 3.15-0.94% 3.16 0.00% 3.10-0.32% 3.08-0.96% April 3.24 1.89% 3.12-1.27% 3.05-1.93% 3.06-1.61% February C9 10.49 -- 10.42 -- 10.41 -- 10.41 -- March 10.46-0.29% 10.43 0.10% 10.33-0.77% 10.36-0.48% April 10.43-0.57% 10.49 0.67% 10.2-2.02% 10.42 0.10% TABLE 6 - GROSS VEHICLE WEIGHT BY CLASS AND LANE WIM #40 - SOUTH ST. PAUL April 2010 VEHICLE LANE 1 GVW LANE 2 GVW LANE 3 GVW LANE 4 GVW MONTH CLASS (Kips) ± 5% (Kips) ± 5% (Kips) ± 5% (Kips) ± 5% February C2 3.95 -- 3.71 -- 3.73 -- 3.90 -- March 3.86-2.28% 3.70-0.27% 3.72-0.27% 3.83-1.79% April 3.91-1.01% 3.66-1.35% 3.77 1.07% 3.77-3.33% February C3 6.13 -- 5.91 -- 5.91 -- 6.02 -- March 6.01-1.96% 5.86-0.85% 5.85-1.02% 5.93-1.50% April 6.08-0.82% 5.86-0.85% 5.95 0.68% 5.95-1.16%
35,000 30,000 Figure 1 Average Volume and Average Overweight Volume vs. Day of the Week NB Vehicles SB Vehicles NB Overweight Vehicles SB Overweight Vehicles 450 400 350 Average e Number of Vehicles 25,000 20,000 15,000 10,000 300 250 200 150 100 Average Num mber of Overweight Vehicles 5,000 50 0 Sunday Monday Tuesday Wednesday Thursday Friday Saturday Day of the Week 0
160,000 140,000 120,000 100,000 80,000 12,000 10,000 8,000 Heavy Commercial Vehicles 60,000 40,000 20,000 0 Figure 2 Total Vehicles, Passenger Vehicles, and Heavy Commercial Vehicles vs. Hour of the Day Total Vehicles Passenger Vehicles Heavy Commercial Vehicles 6,000 4,000 2,000 0 Total and Passenger Vehicles 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 10 11 11 12 12 13 13 14 14 15 15 16 16 17 17 18 18 19 19 20 20 21 21 22 22 23 23 24 Hour of the Day
1,000 900 800 700 600 500 400 300 200 100 0 Figure 3 Overweight Vehicles by Class vs. Hour of the Day C4 C5 C6 C7 C8 C9 C10 C11 C12 C13 Overweight Vehicles 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 10 11 11 12 12 13 13 14 14 15 15 16 16 17 17 18 18 19 19 20 20 21 21 22 22 23 23 24 Hour of the Day
1,400 1,200 1,000 800 600 400 200 0 Figure 4 Overweight Vehicles by Direction vs. Hour of the Day Total Overweight Vehicles NB SB Overweight Vehicles 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 10 11 11 12 12 13 13 14 14 15 15 16 16 17 17 18 18 19 19 20 20 21 21 22 22 23 23 24 Hour of the Day
3,000 2,500 Figure 5 Class 9's and 10's by Direction vs. Gross Vehicle Weight NB Class 9 SB Class 9 NB Class 10 SB Class 10 2,000 Vehicles 1,500 1,000 500 0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 Weight (Kips)
50% 45% 40% Figure 6 Speed vs. Vehicle Type and Direction of Travel NB Passenger Vehicles SB Passenger Vehicles NB Heavy Commercial Vehicles SB Heavy Commercial Vehicles 35% 30% Percentage 25% 20% 15% 10% 5% 0% 0 40 40 45 45 50 50 55 55 60 60 65 65 70 70 75 75 80 80 85 85 100 100+ Speed (mph)
45% 40% 35% 30% 25% 20% 15% 10% 5% 0% Figure 7 Speed vs. Day of the Week Sunday Monday Tuesday Wednesday Thursday Friday Saturday Percentage 0 40 40 45 45 50 50 55 55 60 60 65 65 70 70 75 75 80 80 85 85 100 100+ Speed (mph)
Figure 8 Speed vs. Hour of the Day 50% 0 1 45% 1 2 2 3 40% 3 4 4 5 5 6 35% 6 7 7 8 30% 8 9 Percentage 25% 9 10 10 11 11 12 20% 12 13 13 14 15% 14 15 15 16 10% 16 17 17 18 5% 18 19 19 20 0% 0 40 40 45 45 50 50 55 55 60 60 65 65 70 Speed (mph) 70 75 75 80 80 85 85 100 100 + 20 21 21 22 22 23 23 24
1,800,000 1,600,000 Figure 9 Total Gross Vehicle Weight by Class and Lane NB Driving Lane NB Passing Lane SB Driving Lane SB Passing Lane 1,400,000 1,200,000 tal Gross Weight (Kips) Tot 1,000,000 800,000 600,000 400,000 200,000 0 C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 C13 Vehicle Class
Figure 10 Total Gross Vehicle Weight by Class C10 1.8% C11 0.6% C12 0.2% C13 0.0% C1 0.0% C9 25.4% C2 44.4% C8 2.5% C7 0.5% C6 3.3% C5 5.2% C4 0.5% C3 15.6%
25,000 Figure 11 Total ESALs by Class and Lane NB Driving Lane NB Passing Lane SB Driving Lane SB Passing Lane 20,000 15,000 ESALs 10,000000 5,000 0 C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 C13 Vehicle Class
C10 4.0% Figure 12 ESALs by Class C11 1.7% C12 0.5% C13 0.1% C1 0.0% C2 1.0% C3 0.9% C4 1.6% C5 11.0% C6 8.0% C9 63.5% C7 1.6% C8 6.1%
1,200 Figure 13 Monthly Class 9 GVW Histogram Lane 1 (NB Driving) Unloaded Peak 28 32 Kips Feb 10 Mar 10 Apr 10 1,000 800 Frequency 600 400 200 0 20 30 40 50 60 70 80 90 100 GVW (Kips)
600 Figure 14 Monthly Class 9 GVW Histogram Lane 2 (NB Passing) Unloaded Peak 28 32 Kips Feb 10 Mar 10 Apr 10 500 400 Frequency 300 200 100 0 20 30 40 50 60 70 80 90 100 GVW (Kips)
450 400 Figure 15 Monthly Class 9 GVW Histogram Lane 3 (SB Passing) Unloaded Peak 28 32 Kips Feb 10 Mar 10 Apr 10 350 300 Frequency 250 200 150 100 50 0 20 30 40 50 60 70 80 90 100 GVW (kips)
1,200 Figure 16 Monthly Class 9 GVW Histogram Lane 4 (SB Driving) Unloaded Peak 28 32 Kips Feb 10 Mar 10 Apr 10 1,000 800 Frequency 600 400 200 0 20 30 40 50 60 70 80 90 100 GVW (Kips)
40 35 30 100 95 90 85 80 Loaded (Kips) 25 20 Figure 17 Unloaded and Loaded Peaks by Lane vs. Date Lane 1 Unloaded Peak Lane 2 Unloaded Peak Lane 3 Unloaded Peak Lane 4 Unloaded Peak Lane 1 Loaded Peak lane 2 Loaded Peak Lane 3 Loaded Peak Lane 4 Loaded Peak 75 70 65 60 55 50 Unloaded (Kips) 1/22/10 1/29/10 5/7/10 2/5/10 2/12/10 2/19/10 2/26/10 3/5/10 3/12/10 3/19/10 3/26/10 4/2/10 4/9/10 4/16/10 4/23/10 4/30/10