Roadway Measurement System Evaluation (2011)

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C H A P T E R 4 Conclusions and RecommendationsThe original goals of the S03 research were to prequalify com- mercial data collection vendors for bidding on the Safety Proj- ect S04B, Mobile Data Collection; to evaluate the precision and accuracy of the mobile roadway and pavement inventory data collection services as they relate to selected roadway safety data elements collected at highway speeds; and to produce a recommended list of roadway data elements and associated specifications to be collected under S04B. The following sec- tions highlight the conclusions and recommendations related to each of these goals. Prequalification of Vendors for SHRP 2 Safety Project S04B The evaluation of the final data sets eliminated three of the 10 commercial vendors—Teams 06, 08, and 10—from fur- ther consideration because of lack of coverage or data format issues. Of the remaining seven teams, none provided all of the requested data elements. Some vendors focused on provid- ing only a few data elements and performed very well, while others focused on providing more data elements but appar- ently sacrificed accuracy and precision in doing so. Because the results of the rodeo were inconclusive, SHRP 2 decided to prequalify all of the participants. Team 10 decided not to con- tinue in the pursuit of Project S04B. Before commencing data collection under the S04B con- tract, it is recommended that the ground rules for the data col- lection effort be described very clearly. As part of this effort, a SHRP 2 Safety Data Collection Manual should be developed to define each data element, how it is to be measured and reported, including the units to use, and any other necessary information. The manual should include photographs, diagrams, formulas, and any other items necessary to ensure SHRP 2 receives the required data. This will likely be an iterative process between the S04B contractor and the developer of the manual during the first few months of the contract.19As part of the quality assurance for the S04B project, it is recommended that SHRP 2 establish validation sites in each region. These sites would typically be 0.2-mi or 0.3-mi long and be laid out to verify the following: DMI, GPS, image interval and quality, cross-slope, grade, and the contractor data take- off process from the images collected. The S04B data collection contractor would survey the site before starting work in that region and periodically throughout the regional data collection effort. The data collected would be processed and provided to the S04A contractor, who would compare the data to reference data and previous historical data from the S04B contractor to verify that its systems are maintaining the appropriate level of calibration. Precision and Accuracy The S03 study resulted in the evaluation of the precision and accuracy of mobile roadway and pavement inventory data col- lection services as they relate to selected roadway safety data elements collected at highway speeds. The results of the rodeo, along with the discussion in the Assessment of State of the Practice in Chapter 3, provide a background related to the expected precision and accuracy of mobile data collection units for the S04A and S04B projects. Recommended Roadway Data Elements A reduced set of data elements for collection during the S04B project was developed by considering the following four items: • Data elements reported by the teams; • Rodeo target accuracies for each data element; • Desired data element accuracies to research the causes of rural, run-off-road, single vehicle accidents, as presented in SHRP 2’s forthcoming S01E report (1); and

20• Best accuracy achieved by the teams during the rodeo for each data element reported. Items reported by none of the participants were removed. The remaining data elements were reviewed to determine the accuracies to be sought during the S04B data collection effort. This resulted in the 88 data elements listed in Table 3.1. If the purpose of the S04B project is to answer questions relating only to rural, run-off-road accidents, then the list of data elements to be collected under this project can be further reduced. This reduced list of 53 data elements is shown in Table 4.1.(continued on next page) Table 4.1. Data Elements for Rural, Run-off-Road Accidents in SHRP 2 Safety Project S04B Rodeo CTRE Best Target Desired Achieved Recommended Feature Data Element Definition Accuracy Accuracy Accuracy Accuracy Assets Barrier Systems Pavement Markings Roadside Obstacles Rumble Strips Signs Street Lighting Driveways Barrier type Location Barrier beginning location Barrier ending location Barrier offset— beginning Barrier offset— ending Barrier height Post type End treatment type— beginning End treatment type—end Location of marking—begin Location of marking—end Marking type Cable, W beam, tri beam, box beam, concrete barrier, other Roadside or median GPS coordinates of the begin- ning of entire barrier system GPS coordinates of the end of entire barrier system From edge of lane to face of barrier (in.) From edge of lane to face of barrier (in.) From ground surface to top of barrier (in.) Strong post (metal [6-in I beam]), weak post (metal [C-channel, box post, 3-in I beam]), wooden post, n/a, other Impact Attenuator, buried end, terminal end, fist, bridge connection, none, other Impact Attenuator, buried end, terminal end, fist, bridge connection, none, other GPS coordinates of start of pavement marking GPS coordinates of end of pavement marking Centerline; lane lines (skips); edge/fog line 100% 100% ±3 ft ±3 ft ±0.25 ft ±0.25 ft ±1 in. 100% 100% 100% ±3 ft ±3 ft 100% 100% 100% ±3 ft ±3 ft ±0.25 ft ±0.25 ft ±1 in. 100% 100% 100% ±3 ft ±3 ft 100% 64% 73% ±3 ft ±3 ft −4.03 ft −2.96 ft 1.23 in. 42% 18% 15% ±3 ft ±3 ft 99% 100% 100% sub-1 m sub-1 m ±3 in. ±3 in. ±1 in. 100% 100% 100% sub-1 m sub-1 m 100%Cost Implications of Recommended Data Set Prior to the rodeo, the research team asked the participants to fill out a questionnaire regarding the approximate costs asso- ciated with three scenarios of data collection. The three scenar- ios presented are summarized in the following sections. Regional Data Collection Scenario 1 • Survey location with a 200-mi radius. • Approximately 4,000 survey miles within survey location.

21(continued on next page) Table 4.1. Data Elements for Rural, Run-off-Road Accidents in SHRP 2 Safety Project S04B (continued) Marking offset Centerline marking type Special pavement marking location Special pavement marking description Raised pavement markers present Location of raised pavement markers Type of roadside obstacles Offset of roadside obstacle Location of road- side obstacle Rumble strip lateral location Location of rumble strip—begin Location of rumble strip—end Rumble Strip Offset Support type Support location Lanes Offset of each type of line (center, lane and edge) from right edge of pavement. Measured to the nearest edge of marking from the right edge of pavement. Broken yellow, broken/solid yellow, double yellow, etc. GPS coordinates of edge of marking nearest to the data collection vehicle. RXR, SCHOOL, arrows, stop bar, etc. Yes/No Centerline; lane lines; edge/fog line; center and edge lines; center, lane and edge lines Tree, Shrub, Building, Mailbox, Pole, Fence, Stone, etc. From edge of lane to nearest point on obstacle GPS coordinates of each obstacle Centerline or shoulder GPS coordinates of start of rumble strips GPS coordinates of end of rumble strips From edge of lane to point on rumble strip nearest to the lane Post, pole, sign structure, bridge, other GPS coordinates of the location where the nearest post/pole of the support enters the ground. For an overhead sign, the post/pole on the right side of the road will be used. If the overhead sign is mounted on a bridge, the location where the right-hand side of the sign is mounted. ±1 in 100% ±3 ft 100% 100% 100% 100% ±0.25 ft ±3 ft 100% ±3 ft ±3 ft ±1 in. 100% ±3 ft ±1 in 100% ±3 ft 100% 100% 100% 100% ±0.25 ft ±3 ft 100% ±3 ft ±3 ft ±1 in. 100% sub-2m 1.49 in 100% ±3 ft 24% 74% 73% 39% 7.72 ft ±3 ft 100% ±3 ft ±3 ft 0.08 in. 74% ±3 ft ±1 in 100% sub-1 m 100% 100% 100% 100% ±3 in sub-1 m 100% sub-1 m sub-1 m ±1 in. 100% sub-2m Pavement Markings (continued) Rodeo CTRE Best Target Desired Achieved Recommended Feature Data Element Definition Accuracy Accuracy Accuracy Accuracy Assets

22(continued on next page) Rodeo CTRE Best Target Desired Achieved Recommended Feature Data Element Definition Accuracy Accuracy Accuracy Accuracy Assets Table 4.1. Data Elements for Rural, Run-off-Road Accidents in SHRP 2 Safety Project S04B (continued) Roadway Inventory Multi-sign Sign type(s) Location of street lighting Median Yes/no Record the MUTCD code for each sign. If not a standard sign record sign legend. GPS coordinates of light pole 100% 100% ±3 ft 100% 100% ±3 ft 78% 36% ±3 ft 100% 100% sub-1 m Driveway location Driveway type Number of lanes Lane widths Location of measurement Lane add point Lane drop point Special lane function type Median type Location of measurement Median width Shoulder type Shoulder paved width Shoulder Grade Cross Slope Curvature GPS coordinates of near side of driveway Residential, farm, retail/ commercial, industrial Number of full-width lanes at a location Report lane width to the nearest whole foot. GPS coordinates of reported data. Reported when the number of lanes changes, or lane width changes more than 1 foot, but not in transition areas. GPS coordinates of start of a full lane width. GPS coordinates of end of a full lane width. Two-way left turn lane, HOV lane, bicycle lane, reversible lane, bus bay, etc. Soil, paved (striped), paved (barrier), raised curb, none, other GPS coordinates or Reference post of reported data. Reported when the type changes, or the width changes more than 1 foot, but not in transition areas. Paved, unpaved, composite (part paved, part unpaved), and curb Width of paved portion of shoul- der. Reported from edge line to edge of paved surface to the nearest foot. ±3 ft 100% 100% ±6 in. ±3 ft ±3 ft ±3 ft 100% 100% ±3 ft ±0.5 ft 100% ±0.5 ft ±3 ft 100% 100% ±0.328 ft (0.1 m) ±3 ft ±3 ft ±3 ft 100% 100% ±3 ft ±0.5 ft (0.15 m) n/a ±0.5 ft (0.15 m) ±3 ft 70% 33% −0.02 ft ±3 ft n/a n/a 11% 80% ±3 ft −0.13 ft 100% −0.03 ft sub-1 m 100% 100% ±0.328 ft (0.1 m) sub-1 m sub-1 m sub-1 m 100% 100% sub-1 m ±0.5 ft (0.15 m) 100% ±0.5 ft (0.15 m) Signs (continued)

23Geometric Features Grade in direction of travel Location of measurement Location of measurement Roadway cross slope Horizontal curve PC (point of curvature) Horizontal curve length Horizontal curve radius Direction (“+” uphill in direction of travel, or “—” downhill in direction of travel) and per- cent of slope GPS coordinates of reported data. GPS coordinates of reported data. Cross-slope of lane being driven. Direction (“+” slopes towards side of road or “—” slopes towards center of road) and percent of slope. GPS coordinates where curve begins ±0.5% ±3 ft ±3 ft ±0.01% ±3 ft ±2 ft ±25 ft ±0.5% ±3 ft ±3 ft ±0.10% ±3 ft ±25 ft (7.62 m) ±25 ft (7.62 m) −0.164% n/a n/a −0.2045% −154.97 ft −17.5 ft 128.48 ft ±0.5% sub-1 m sub-1 m ±0.2% sub-1 m ±25 ft (7.62 m) ±25 ft (7.62 m) Table 4.1. Data Elements for Rural, Run-off-Road Accidents in SHRP 2 Safety Project S04B (continued) Shoulder total width Location of measurement Total width of shoulder (compos- ite only), including paved and unpaved parts. Measured to the first obstacle, or the break in slope. GPS coordinates of reported data. Reported when the shoulder type changes, or the width changes more than 1 foot, but not in transition areas. ±0.5 ft ±3 ft ±0.5 ft (0.15 m) ±3 ft −0.29 ft ±3 ft ±0.5 ft (0.15 m) sub-1 m Shoulder (continued) Rodeo CTRE Best Target Desired Achieved Recommended Feature Data Element Definition Accuracy Accuracy Accuracy Accuracy Roadway Inventory• Mixed road types from interstates to locals. • Discontinuous survey segments. • Survey segments of 5–10 mi each. • Data to be processed and provided to SHRP 2:  Research grade data for all 113 rodeo data elements;  Geographic information system (GIS) map of surveyed roadways; and  Georeferenced video images, with camera configuration files for future data analysis. Regional Data Collection Scenario 2 • Survey location with a 200-mi radius. • Approximately 4,000 survey miles within survey location.• Mixed road types from interstates to locals. • Discontinuous survey segments. • Survey segments of 5–10 mi each. • Data to be processed and provided to SHRP 2:  Research-grade data for selected groups of rodeo data ele- ments (53 data elements), as follows: ▪ Assets (barrier systems, pavement markings, signs, and street lighting) ▪ Geometrics (all) ▪ Intersections (configuration and traffic control) ▪ Pavement condition (pavement profile and texture) ▪ Roadway inventory (railroad crossing and ramps)  GIS map of surveyed roadways; and

24 Georeferenced video images, with camera configuration files for future data analysis. Regional Data Collection Scenario 3 • Survey location with a 200-mi radius. • Approximately 4,000 survey miles within survey location. • Mixed road types from interstates to locals. • Discontinuous survey segments. • Survey segments of 5–10 mi each. • Data to be processed and provided to SHRP 2:  Research-grade data for selected groups of rodeo data elements (9 data elements), as follows: ▪ Geometrics (all) ▪ Pavement condition (pavement profile and texture)  GIS map of surveyed roadways; and  Georeferenced video images, with camera configuration files for future data analysis. Responses were received from seven out of 10 partici- pants. Table 4.2 summarizes the responses received from all participants. Teams 03, 04, 05, 08, and 10 did not seem to understand that Scenario 1 required the most intensive data processing, as evidenced by their costs going up for Scenar- ios 2 and 3, even though data processing for the latter two was less. Considering the responses received from the participants, the reduced data elements list for S04B, and the research team’sScenario 1 Scenario 2 Scenario 3 Estimated Estimated Estimated “Ball Park” “Normal” “Ball Park” “Normal” “Ball Park” “Normal” Costs Turnaround Costs Turnaround Costs Turnaround Team ($/mile) Time (days) ($/mile) Time (days) ($/mile) Time (days) Team 01a 330 100 280 90 230 60 Team 02 no response no response no response Team 03 100 15 300 200 130 30 Team 04b 30 30 100 90 50 45 Team 05 55 60 90 60 60 75 Team 06 80 30 70 30 50 20 Team 07 no response no response no response Team 08 1,000 60 1,500 90 1,200 80 Team 09 no response no response no response Team 10c 40 60 120 180 no response aDoes not include pavement profile & texture. bDoes not include geometrics or pavement profile & texture data. cResponse came from one part of the team. Table 4.2. Data Collection Cost Summary Based on Questionnaireexperience with research-grade, nationwide data collection efforts, SHRP 2 can expect the effort for this work to be in the range of $350–$1,000 per survey mile. This could go even higher, depending on the region and the density of the assets to be collected. Cost implications for mobile data collection are dependent on several items and can vary greatly from firm to firm. Some of the items that affect the cost of mobile data collection include the following: • Size of the network to be surveyed—number of miles or sections; • Geographic coverage of the network to be surveyed—local, regional, national; • Environment in which the network is located—rural, sub- urban, urban, or heavy urban; • Road types to be surveyed—e.g., interstate, rural primary, urban local; • Time frame within which work is to be performed; • Number of data elements to be recorded; • Grade of data being collected—network, project, or research; and • Data analysis methodology(ies). For example, performing network-level, statewide collection of pavement profile (IRI), rutting, and digital images on 1,000 lane miles of mixed rural and urban interstate highways would cost in the order of $35–$40 per mile.

25Summary Overall, the rodeo was considered a success. Analysis of the data provided by rodeo participants revealed some issues to be addressed before the commencement of the S04B data collec- tion. The two most critical of these issues are the following: • Develop a SHRP 2 Safety Data Collection Manual that defines each data element, how it should be measured and reported, including the units to use, and other necessary information. The manual should include photographs, dia- grams, formulas, and any other items necessary to ensure SHRP 2 receives the desired data in the appropriate format. This will likely be an iterative process between the S04B contractor and the S04A contractor during the first few months of the contract. • As part of the quality assurance for the S04B project, it is rec- ommended that short validation sites be established in each region. These sites would be about 0.2 or 0.3 mi long and be laid out to verify the following: DMI, GPS, image interval and quality, cross-slope, grade, and the contractor data take- off process from the images collected. Two reduced lists of data elements have been produced con- sidering the data elements reported by the rodeo participants and the desired data element accuracies from both the rodeo and CTRE’s white paper on rural run-off-road accidents. • Table 3.1 contains a list of 88 data elements that can be used to help researchers answer a wide range of highway safety questions for both urban and rural environments; and • Table 4.1 contains a list of 53 data elements that can be used to help researchers answer highway research questions relat-ing to issues in rural environments, most notably rural, run- off-road accidents. The cost implications for research-grade mobile data col- lection depend on the following general items: • Cost of the field data collection; • Data analysis methods employed; • Quality control measures needed to reach the desired data accuracies; and • Project time frame. The cost for collecting research-grade highway safety data cannot be obtained from previous contracts inasmuch as there have not been any previous large-scale highway safety research projects before, and in particular not any completed nationwide. On the basis of the responses of some of the participants to the data collection scenarios questionnaire and the experience of ARA with nationwide research-grade data collection during the SHRP Long-Term Pavement Performance program, SHRP 2 can expect the cost for the S04B project to range between $350 and $1,000 a survey mile. Considering that the study areas include North Carolina, Pennsylvania, Florida, and Washing- ton, the costs will probably be toward the high end of this range. Reference 1. Hallmark, S., Y.-Y. Hsu, L. Boyle, A. Carriquiry, Y. Tian, and A. Mudgal. SHRP 2 Report S2-S01E-RW-1: Evaluation of Data Needs, Crash Surrogates, and Analysis Methods to Address Lane Departure Research Questions Using Naturalistic Driving Study Data. Trans- portation Research Board of the National Academies, Washington, D.C., forthcoming.