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Collect and Validate New Data 45 helpful for developing a general understanding of transport patterns within a jurisdiction or those originating and terminating in a jurisdiction. Extensive interviews are needed to develop an empir- ical understanding of hazmat transport over a network. Interview information also is important for guiding data collection, including verification of data collection locations and times. 5.1.1 Interviews with Hazmat Shippers, Receivers, and Carriers For entities that are known to store hazmat (Tier II or locally required reports may be a source of this information), or entities Communicating with facilities and carriers is that are located along or known to ship/receive/carry hazmat over one way of obtaining commodity flow infor- transport corridors that are of key interest, suggested interview mation. Cambria County LEPC in Pennsylvania discussion points include the following: talks with local industry plant managers to What hazardous materials are shipped/received/carried? verify the types of hazmat shipments identi- What is the origin, destination, or both, of the hazardous mate- fied through vehicle and placard counts. They rials? use information provided by railroads to ver- When are the hazardous materials shipped/received/carried by ify railcar and placard counts. time of day, day of week, season of year, etc., and what is the fre- quency of shipment? How are the hazardous materials shipped/received/carried (modes)? Over what transport routes are the hazardous materials carried? How much (number of shipments, volumes, etc.) hazardous material is shipped/received/ carried? 5.1.2 Interviews with Emergency Responders and Managers, and Other Key Informants Emergency responders deal with hazards on a daily basis and are a valuable source of real-life information. Ultimately, they are among the primary beneficiaries of the HMCFS, but they may be skeptical about the value of the effort if they are not familiar with the concept. Including emer- gency responders on the interview team can go a long way toward enhancing the quality of infor- mation provided and understood by interviewers. Keep in mind that local jurisdictional and "turf" issues may also affect the type and amount of information that can be obtained in inter- views. Buy-in and approval from senior agency officials may help encourage staff participation. Suggested interview discussion points for emergency management and response personnel, or other key informants, include the following: With which areas of the jurisdiction are you experienced? What have you observed regarding locations, times, methods, frequency, and content of haz- mat transport? Are there corridors or network segments that seem to be a higher priority for understanding hazmat transport? If so, do you have suggestions for data collection locations and times? Are there particular locations that are a higher risk for truck incidents and accidents than others? Do you know of other individuals who should be contacted about hazmat transport in the jurisdiction? 5.2 Considerations for Field Data Collection The bulk of the effort for the project team and project participants for most HMCFS projects will be the collection of new data about hazmat transport by roadways. This is because obtaining locally specific information about hazmat transport by roadway usually requires some form of

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46 Guidebook for Conducting Local Hazardous Materials Commodity Flow Studies traffic survey through human observation. Existing data sources provide information at state or national levels, and although many large metropolitan areas and states have implemented moni- toring systems on key transportation routes, typically, the systems are not very useful for describ- ing hazmat-specific transportation information. Also, vehicle-mounted sensor systems (e.g., RFID tags) for public monitoring of truck traffic and hazmat cargos are not on the immediate horizon. This does not mean that truck traffic information that was collected using automated systems is not useful for an HMCFS. Truck traffic volume data can be used to identify locations where hazmat data collection may be focused or be used to validate manual count information. Infor- mation about daily and seasonal variations in truck traffic patterns also can be identified from data collected by automated traffic counter systems, and weigh-in-motion (WIM) data can be used to estimate proportions of empty versus loaded trucks. General and truck traffic levels can be used to identify locations and times where the driving population may be at greater risk for hazmat incidents, or where roadway congestion will present response challenges. These data are typically maintained by state transportation agencies. However, trends for overall truck traffic may not directly apply to hazmat truck traffic, especially where seasonal variations in hazmat production, processing, or consumption apply. Considerations for Selecting Traffic Survey Locations The safety of data collection personnel and the driving public is paramount. Consider Incident Command System principles in planning to collect new data, as applicable. Data collection personnel require a clear view of the roadway section(s) for which they are to collect information. Visibility requirements for placard counts may be more restrictive given placard sizes. Intersections allow data collectors to identify the turning movements of vehicles, including the road that the vehicle is turning from and the road onto which the vehicle is turning. Parking lots of fueling stations, shopping centers, abandoned buildings, high- way maintenance, and material storage lots, roadway turnouts, or drives in the public right of way can make good data collection locations. License and weight stations (when open) also can be good data collection locations. Nighttime counts require sufficient lighting to allow identification, vehicle type, placards, or other factors. Lighting also should provide sufficient driver visibility to assure safety of data collectors and the driving public. Dry grass, weeds, or other debris under running (or hot) vehicles can ignite fires. Selecting locations that do not impede or endanger the driving public or incon- venience property owners is essential. Permission for collection of data on pri- vate property should be obtained when necessary. Objections are rare when property owners understand the purpose and nature of the data collection, provided that business and personal activities are not impeded. Coordination with local emergency management and law enforcement is important to provide pubic legitimacy, promote participation, and enhance use of the results. Passers-by may report traffic observers as engaging in suspicious activities, especially around industrial facilities or military installations. A letter about the data collection effort from the LEPC or other local agency may be useful to help answer questions from law enforcement or security personnel who are following up on such reports.

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Collect and Validate New Data 47 Traffic surveys for an HMCFS involve collecting vehicle, placard, or shipping manifest infor- mation, or combinations of these tasks. The traffic observations are recorded and analyzed to describe hazmat flows, as discussed in Chapter 6. It is important that traffic surveyors be able to collect data safely, efficiently, and effectively. 5.2.1 Determining Count Intervals Many LEPCs and other local entities use volunteers for HMCFS data collection. Time and schedule availability may be limited for volunteers, and data collection may be conducted dur- ing times of extreme temperatures--very cold or very hot--requiring data collection to be per- formed from the inside of vehicles. Attention and accuracy of data collection are limited to a few hours at a time per individual, maximum. Thus, there needs to be a balance between traffic count intervals that are optimal and those that are practical. Following are some recommendations for determining count intervals. Using count intervals in even fractions of an hour simplifies the extrapolation of counting seg- ments into 1-hour periods; 1-hour counts are preferred, and 30-minute or 15-minute counts are secondary options. Conducting at least 30-minute or 1-hour counts reduces the effects of traffic variation while providing sufficient timeframes for recording traffic counts. Longer count durations are possible, but they should be recorded in separate 30-minute or 1-hour segments. Starting count intervals on the half-hour or hour can ease data analysis for differences in traf- fic patterns by time of day. 5.2.2 Training Data Collectors Maintaining consistency and accuracy of collected data directly affects the validity of HMCFS conclusions. This can be particularly challenging when using volunteers who have a variety of edu- cational training and occupational backgrounds. Key members of the project team should prac- tice and be familiar with all types of data collection methods that will be used for the project--for example, vehicle counts, placard counts, interviews--before providing training to other project participants. Not only will this help identify data collection pitfalls, needs, and procedures, but it also can help validate that the data collection locations, information, and sampling/precision requirements are appropriate to meeting the project's objectives. After the key members of the project team understand the data collection process and requirements, they can provide training to other team members. Training can include the following, as applicable: Safety procedures, notifications, and scheduling/coordination of data collection; Methods for identifying vehicles; Methods for identifying placards; Procedures for recording data; Recommended locations for data collection; Recommended interview questions; and Other information relevant to the HMCFS project. Training can be performed through presentations at general meetings, specific training meetings, individually, or in small groups. It also will be helpful to include "real-time" data collection exer- cises at the end of training sessions to provide trainees with an opportunity to work through the "nuts and bolts" of vehicle or placard observations and data recording procedures. It is important to remember that conducting traffic surveys can seem intimidating at first for many volunteers, but the process soon becomes much easier for data collectors as they gain experience. This can be facil- itated by having data collectors work in pairs, especially in the initial stages of a data collection effort.

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48 Guidebook for Conducting Local Hazardous Materials Commodity Flow Studies 5.2.3 Scheduling Data Collection (Sampling) Keeping in mind the physical and practical limitations of traffic data collection, the goal for sur- veying trucks or other vehicles is to collect information that is sufficient to identify the following: General traffic patterns and Differences in traffic patterns for different days and times, as required by objectives. The sampling framework used for data collection should be driven by the HMCFS objectives (discussed in Section 2.2), the type The LEPC in Polk County, Texas, used a and level of traffic that is observed, and the need to identify differ- focused data collection effort on two major ences in traffic patterns for different times of the day, different days highway corridors for their commodity flow of the week, from week to week, or month or season of the year. study. Overall project direction was handled Obviously, a greater amount of good quality, well sampled data by the county's emergency management increases the potential reliability of hazmat and traffic flow descrip- office. Data collection on one corridor was tions. However, more data requires more time for collecting, pro- scheduled and coordinated by a volunteer fire cessing, analyzing, and validating. chief. Data collection on another corridor was As with any study that involves sampling, there is a trade-off scheduled and coordinated by a pipeline com- between data collection feasibility, efficiency, and the ideal. In pany employee. Volunteers from three local many cases, the goal of an HMCFS may be to develop a general volunteer fire departments, a local amateur understanding of the characteristics of hazmat flow patterns. This radio club, a county commissioner, and a city often can be accomplished using low-level sampling frameworks mayor all participated. Truck and placard and limited data. As the critical nature of HMCFS objectives counts for each corridor were collected over a increases, high-level sampling frameworks and more data may be 1-month period, and all days of the week and required. Table 5-1 provides a summary of traffic sampling times of day were covered. framework examples, as well as the advantages and disadvantages of each. Appendix D.2, Let HMCFS Objectives Guide Sampling, Table 5-1. Sampling frameworks, examples, advantages, and disadvantages. Sampling Sampling Examples Advantages Disadvantages Framework Easiest for data collectors; minimum Difficult to reliably identify traffic Convenience As available for data collectors scheduling management patterns at any one location or timeframe Easy to conduct over time for data Cannot be used to reliably characterize collectors; moderate scheduling One location per major roadway, at traffic on different segments of same management; moderate degree of Representative different times of day on any given road or other roads, determine seasonal information about traffic patterns for weekday, during any season traffic patterns, or transport patterns roadway; lowto-moderate level of data throughout a network collection resources required Multiple locations per major High degree of scheduling management; High degree of information about traffic roadway, at different times of day, may require high level of time Cluster patterns throughout a transportation on multiple days of week, during commitment from data collectors or network multiple seasons other data collection resources Dependent on traffic characteristics Requires statistical calculations to Very high degree of information about on given network segment; less data determine sampling requirements; Stratified or traffic patterns throughout a are required for low traffic volumes, extremely high degree of scheduling Proportional transportation network; focuses effort and more data for high traffic management; may require high level of on high-priority segments volumes data collection resources Requires statistical calculations to At random times of day, days of Very high degree of information about determine sampling requirements; Random week, seasons of year, for a specific traffic patterns on sampled network extremely high degree of schedule network segment segment management; requires high level of data collection resources All traffic data for all times of day, Nearly impossible to attain with current days of week, and seasons of year, Complete information about traffic Census systems; requires an extreme degree of for specific network segment or patterns at sample locations data reduction entire network

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Collect and Validate New Data 49 For More Information About Sampling Local entities that are concerned about sampling requirements are encouraged to Review Appendix C.2 and Appendix H. If you still have questions, seek the advice of a transportation planner, consultant, university faculty member, or other individual with training in statistical sampling and traffic analysis. Review other sources of information about traffic data collection and sampling, including Traffic Monitoring Guide (TMG), U.S.DOT, Federal Highway Administration, Office of Highway Policy Administration, 2001. Available online at http://www.fhwa.dot.gov/ohim/tmguide/. Oriented to traffic data collection by state DOTs, it includes discussions about sampling considerations and truck data collection using FHWA's vehicle classification system. Introduction to Traffic Engineering: A Manual for Data Collection and Analy- sis, Thomas R. Currin, Thomson Learning, 2001. An easy-to-use overview of different data collection techniques for various traffic studies, including data collection at intersections. Traffic Engineering Handbook, 6th Edition, edited by Walter H. Kraft, Institute of Transportation Engineers, 2009. The primary reference for transportation engineering professionals. It includes chapters on traffic characteristics, sam- pling, and analysis. suggests guidelines for matching HMCFS objectives with sampling frameworks. Appendix E contains additional information about data collection using the different sampling frameworks. 5.2.4 Determining Precision of Traffic and Hazmat Data The precision of traffic and hazmat characterization data also determine what can be identi- fied about hazmat flows in a community. Traffic information may include the following: Number of vehicles observed (e.g., trucks), discussed in Section 5.3.1.1; Types and configurations of vehicles observed (e.g., van versus flatbed trucks, straight trucks versus tractor-trailer trucks, etc.), discussed in Section 5.3.1.2; Types of hazmat placards observed, discussed in Section 5.3.2; Combinations of vehicle and hazmat placard observations, discussed in Section 5.3.3; Vehicle and/or hazmat placard observations on both roadway directions or at intersections at the same time, discussed in Section 5.3.4; or Number of containers or packages in a shipment--this can be considerably difficult for most truck traffic surveys to determine, except for shipping manifest surveys, discussed in Section 5.3.5. Hazmat characterization information may include the following: Whether a vehicle is carrying hazmat over placarding threshold levels (e.g., whether a truck does/does not have a placard); Hazmat class or division (e.g., as indicated by type of placard); UN/NA placard ID number (e.g., as indicated on a placard or on the side of a tank); or Specific material/chemical information, which can be considerably difficult for most truck traffic surveys to determine, except for shipping manifest surveys.