CHAPTER 5: DISTRESS-DATA COLLECTION—AUTOMATED METHOD
5.5 DATA COLLECTION
5.5.1 Establishing Speed Range
The cell phone IRI data were collected on North Trigger Road, Edwards, in Peoria County. The data were collected by (1) a cell phone mounted in the sedan car, (2) cell phone mounted in the truck, and (3) profilometer attached to the truck. The speed for both the sedan car and the truck varied from 25 to 55 mph. Roadroid recommended 25 mph as the lowest speed to collect data, and a maximum of 100 mph speed was recommended. However, driving at 100 mph on seal-coated roads would not be safe; and for this reason, the maximum driving speed was set close to the posted speed.
5.5.1.1 N Trigger Road, Edwards, Peoria County
The IRI values obtained from a sedan car with Roadroid, a truck with RoadBump, and a truck hosting profilometer are shown in Figure 37. According to the graph, as expected, the profilometer data varied with an increase in speed. However, IRI values increased when the cell phone was mounted in the sedan car and the truck; and the IRI values increased with an increase in vehicle speed. The increase of IRI was greater in the truck, as compared to the sedan car. The average IRI measured by the profilometer was 137.4 inch/mile; and the average IRI measured by the cell phone with Roadroid app mounted in the car was 167.9 inch/mile, which is 22.2% higher than the profilometer
measurement. In contrast, the average IRI measured by the cell phone with Roadroid app mounted in the truck was 251.9 inch/mile, which is 83.3% higher than the profilometer measurement. The
RoadBump app average IRI was the highest of all four average IRI values, 389 inch/mile.
Figure 36. Variations in IRI values at different driving speeds using profilometer and cell phone apps, N Trigger Road, Peoria County.
5.5.1.2 N Odom Road, Benton, Franklin County
During the N Odom Road site visit, the IRI data were collected using the Roadroid app by (1) a cell phone mounted in the sedan car and (2) a cell phone mounted in the truck. The speed limit for both the sedan car and truck varied from 25 mph to 35 mph. This speed limit was chosen from our
experience with the Peoria County data (i.e., Figure 37) collection, which indicated that higher speed gave higher IRI values. The vehicle was driven both ways (i.e., eastbound and westbound) at a given speed, and the IRI values were averaged for both directions. Figure 38 shows the average IRI data measured by the cell phone Roadroid app in the sedan car and in the truck. According to the results, the average IRI values measured by the cell phone app were 113.8 inch/mile in the car and 211.2 inch/mile in the truck, approximately 85.6% higher than in the car.
Figure 37. Variations of IRI values at different driving speeds using profilometer and the cell phone app Roadroid, North Odom Road, Franklin County.
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0 10 20 30 40 50 60
IRI (inch/mile)
Speed (mph)
Car (Roadroid) Truck (Roadroid) Profilometer Car (RoadBump)
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0 10 20 30 40 50 60
IRI (inch/mile)
Speed (mph)
Car (Roadroid) Truck (Roadroid)
5.5.1.3 Mt. Zion Road, Benton, Franklin County
The same process was followed as in the case of N Odom Road, but the readings from placing the cell phone in the truck were problematic due to some technical problems in the cell phone; it was
running out of battery power. According to this site visit, the road was newly surfaced; however, the site had a severe condition of loose aggregates exposed on the pavement surface.
The speed limit followed was the same as for North Odom Road. Figure 39 shows the IRI data measured by cell phone in the sedan car. Comparing N Odom and Mt. Zion roads, the average IRI value measured on Mt. Zion Road is higher (i.e., 231.3 inch/mile) than the North Odom Road IRI value (i.e., 113.8 inch/mile). A higher IRI value indicates rougher pavement, and a lower IRI value indicates smoother pavement. The newly surfaced Mt. Zion Road indicated rougher pavement. The loose aggregates on the pavement surface could influence the IRI data recorded by the cell phone. Note that the IRI values calculated for the Mt. Zion Road and the N Odom Road were more consistent when compared to the N Trigger Road data in Peoria County. Lower speeds gave more consistent IRI readings for the seal-coated roads.
Figure 38. Variations of IRI values at different driving speeds using the cell phone app Roadroid, Mt. Zion Road, Franklin County.
5.5.1.4 1200 N Road, Monticello, Piatt County
During the 1200 N Road site visit, the data were collected by a cell phone mounted in the sedan car to record the IRI values at speeds set for 25 to 35 mph in both directions. Figure 40 shows the IRI data measured by the cell phone in the sedan car. According to Roadroid app performance trends, if the speed is increased, the Roadroid app typically gives lower roughness values. However, the IRI values measured were 171.1 inch/mile and 215.4 inch/mile at speeds of 25 mph and 35 mph, respectively.
This difference is a 25.9% increase at 35 mph over the IRI value at 25 mph.
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Figure 39. Variations of IRI values at different driving speeds using the cell phone app Roadroid, 1200 N Road, Piatt County.
5.5.1.5 N 730 E Road, Springfield, Sangamon County
For the N 730 E Road site visit, the data were collected by (1) a cell phone mounted in the sedan car, (2) a cell phone mounted in the truck, and (3) a profilometer attached in the truck. Figure 41 shows the IRI data measured by cell phone in the car, cell phone in the truck, and profilometer in the truck.
Profilometer-based IRI values decrease with an increase in speed; and the result is the same for the IRI values measured by the cell phone in the car—IRI values decrease with increasing speed.
However, the IRI value increased for the cell phone in the truck, especially at 40 mph. The increase in the IRI value is greater in the truck, as compared to the sedan car. The average IRI measured by the profilometer is 293 inch/mile; and the average IRI measured by the cell phone mounted in the car is 226 inch/mile, 22.9% lower than the profilometer measurement. In contrast, the average IRI
measured by the cell phone mounted in the truck is 239.7 inch/mile, 18.2% lower than the profilometer measurement.
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0 10 20 30 40 50 60
IRI (inch/mile)
Speed (mph) Car (Roadroid)
Figure 40. Variations of IRI values at different driving speeds using the cell phone app Roadroid, N 730 E Road, Sangamon County.
From Figure 41, it can be seen that more consistent IRI readings could be achieved by mounting the cell phone in the car driven at about 25 to 40 mph. However, the IRI data obtained from the truck indicated higher values, as compared to those from the car.