Cover Image

Not for Sale



View/Hide Left Panel
Click for next page ( 51


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 50
50 Guidebook for Conducting Local Hazardous Materials Commodity Flow Studies Table 5-2. Traffic and hazmat placard survey methods. Survey Method Description What It Provides What It Requires Assumptions about hazmat transported on Information about overall truck observed trucks (e.g., that hazmat transport A count of the total number of Total Truck Surveys traffic levels during sampled time conforms to national averages); assumptions observed trucks periods about types and configurations of trucks used to transport hazmat Assumptions about hazmat transported on Information about truck traffic Truck Type and A count of observed trucks by observed trucks by type and configuration levels, by type and configuration, Configuration Surveys truck type and configuration (e.g., that hazmat transport conforms with during sampled time periods national averages) Information about the number and Assumptions about truck traffic patterns and UN/NA Placard ID ID and count of observed types of hazmat placards present the types and configurations of trucks used Surveys hazmat placards during sampled time periods to transport hazmat A count of the total number of Information about overall truck Assumptions about types and configurations Total Truck Combined observed trucks and ID and traffic levels and the number and of trucks used to transport hazmat; data with UN/NA Placard count of observed hazmat types of hazmat placards present collectors who can record truck count ID Surveys placards during sampled time periods information and placard information Information about truck traffic Data collectors who can record truck type Truck Type and A count of observed trucks by levels by type and configuration and configuration and placard information; Configuration truck type and configuration and the number and types of may require more training of volunteers on Combined with UN/NA and ID and count of observed hazmat placards present during data collection process and monitoring of Placard ID Surveys hazmat placards sampled time periods collected data to ensure consistency Observation of trucks and/or Information for more than one Experienced data collectors; more training of Directional and placards on multiple road roadway lane collected at a single volunteers on data collection process, and Intersection Surveys directions or at intersections at location; may reduce number of monitoring of collected data to ensure the same time data collectors needed consistency Coordination with local, state, or federal Review of information found Highly specific information about license and weigh stations or patrol units; Manifest Surveys on shipping papers and hazmat shipment content for both potentially, a very intensive data collection interviews of truck drivers placarded and unplacarded loads process for high-traffic roadways Together, information about traffic levels and hazmat content will be used to develop an understanding about when, where, and how much hazmat is being transported in a jurisdiction, as discussed in Chapter 6. Appendix D.3, Let HMCFS Objectives Guide Precision, contains further information about matching HMCFS objectives with data precision requirements. Table 5-2 pro- vides a summary of various traffic and hazmat content survey methods that can be used to obtain different levels of data precision and identify the commodity flows--quantities and characteri- zation of transported hazmat. 5.3 Collect Field Data The project team members and other project participants collect field data after sampling and precision levels have been determined, the survey method has been selected, survey locations have been identified, and data collectors have been trained. As discussed in the previous section, collection of most new HMCFS data will be through manual surveys of commercial truck traf- fic. Focusing the surveys on certain sizes of commercial vehicles--for example, DOT Class 3 trucks and above (over 10,000 lbs. gross vehicle weight)--helps the project team focus data col- lection on vehicles most likely to be transporting hazmat. Appendix J.1 contains sample images of truck types and configurations, as well as placard con- figurations. It can be used as a "cheat sheet" for data collectors. The truck types and configuration examples are grouped in eight different categories ("A" for standard gas and liquid tanks through

OCR for page 50
Collect and Validate New Data 51 "H" for other trucks). The truck type and configuration categories are the same as the VIUS cat- egories identified in Appendix H. These groupings are useful because they differentiate between truck types and configurations that are more and less likely to be carrying hazmat. The placard identification examples are taken from the 2008 ERG (5). The cheat sheet only provides truck and placard examples, and is not exhaustive of all truck types and placards. See Appendix H and the 2008 ERG for more information about the truck and placard types included in each category. Several different truck or hazmat placard surveys are described in this section, ranging from simple truck counts to complex truck type and configuration and placard ID counts at intersec- tions. The selection of a particular survey method will depend on the following: Level of information needed to support HMCFS objectives; Local conditions (e.g., visibility); Traffic levels; Available data collection resources (e.g., number of data collectors); Ability of data collectors; and Assumptions that the project team is willing to make about truck or hazmat traffic patterns. Traffic survey information may be recorded using a variety of mechanisms, but a simple clipboard with tabulation sheets should work effectively for most applications. The tabulation sheets should include the following information: Location and direction of roadway, Date and day of week, Time period (start and end), Data collector name(s), Weather conditions, Page numbers (if multiple pages used for same location/date/time period), A location for notes or comments about data collection, and Vehicle count information. Accurate documentation is key to data usability. Complete and accurate documentation may be highly variable when multiple data collectors participate in the project. The project team should be sure that each data collection record is properly completed and documented, especially for location and direction, date and day of week, and time period fields. This information also can be used to help track volunteer effort expended (remember that travel time and mileage to and from data collection locations can be additional when used for in-kind match). Data collection sheets are provided in Appendix J for each survey type, which are discussed in the following sections. Application of survey data for identifying hazmat flows is summarized in Table 5-2, and use of survey data for estimating hazmat flows is described in Appendix K. The project team should review these sections before selecting a commercial vehicle survey method for the HMCFS. 5.3.1 Commercial Vehicle Surveys 5.3.1.1 Total Truck Surveys Surveys of the total number of commercial vehicles (trucks) are usually very easy for data col- lectors to conduct: they simply count the number of commercial vehicles that are observed at individual locations during a specified timeframe, and make a "tally mark" (in sets of five) on a data sheet for each count. A blank total truck count sheet and a completed example sheet are provided in Appendix J.2. The sheet provides for seven different truck count periods. If additional space is needed for each time period, simply continue on the next line or next page, making sure to note that the time periods are the same. Remember that using these data will require assump- tions about the types and percentage of vehicles carrying hazardous materials--for example, that

OCR for page 50
52 Guidebook for Conducting Local Hazardous Materials Commodity Flow Studies national-level percentages of hazmat transport by truck apply to the location. Use of these data for estimating commodity flows is discussed in Appendix K.4. 5.3.1.2 Truck Type and Configuration Surveys Other information about types of commercial vehicles can be collected in addition to total vehicle counts. Most DOT vehicle classification counts by automated systems use FHWA's des- ignation of vehicle class by tonnage and number of axles per vehicle. This type of information is not very useful for hazmat classifications. Rather, trucks can be classified according to cargo body types and configurations as discussed above. These counts will allow national averages for haz- mat transportation, by hazmat class and division, to be applied for each truck type and config- uration, rather than a national average for all trucks regardless of type and configuration. This also may serve as a basis for identifying future changes in truck traffic patterns in the jurisdic- tion, and may provide information useful for other local planning applications (i.e., transporta- tion planning)--for example, some truck types are more frequently heavier or overloaded than others, which affects roadway infrastructure maintenance cycles. Appendix H shows how the 2002 VIUS data were evaluated for truck cargo body types and configurations relative to hazmat transportation. A blank sample truck type and configuration count sheet corresponding to the VIUS categories and a completed example sheet are provided in Appendix J.3. A different sheet should be used for each count period. Remember that using these data will require assumptions about the percentage of vehicles that are carrying hazardous materials, for example, that national-level percentages of hazmat transport by truck type and configuration apply to the location. Use of these data for estimating commodity flows is dis- cussed in Appendix K.5. 5.3.2 UN/NA Placard ID Surveys A count of hazmat placards provides better information about the types of hazmat transported in an area than simply counting trucks and assuming that a certain percentage of them carries hazardous materials. The goals of a placard count are as follows: To identify whether a vehicle is placarded or has a UN/NA placard ID; To identify the class/division of the transported material(s), which is indicated by color and pattern of placard (see Appendix A); and To identify information--words or numbers--written on the placard (see Appendix B). Addi- tional markings may be present on the vehicle/vessel, for example, an orange UN number on ISO tanks and some tank trailers, or "Marine Pollutant." Some vehicles do not have a hazmat class/division or 4-digit placard ID, but use a "Dangerous" placard for when they are transport- ing combinations of hazardous materials above threshold quantities. The data collection procedure for UN/NA placard ID counts is similar to the procedure for truck counts, except that instead of counting trucks, the placard information is recorded. Because placarded trucks only make up around 4 to 5 percent of commercial trucks, on average, this may result in relatively low placard counts for many locations and time intervals. A blank placard count sheet and a completed example sheet are provided in Appendix J.4. Multiple placards on the same truck should be circled to differentiate between all placards observed and the number of placarded trucks observed. The sample sheet provides for seven different truck count periods. Remember that this type of data count will not provide information about the types and con- figurations of trucks carrying the hazardous materials or traffic levels, so it has limited applicabil- ity for some HMCFS objectives (for example, maximum scenario definitions). It is also important

OCR for page 50
Collect and Validate New Data 53 Things to Keep in Mind for Conducting Placard Surveys Placard surveys require observation of placarded vehicles as they pass by data col- lection locations. Good visibility of the observed traffic lanes is required, and an experienced data collector who is using binoculars is beneficial. Although this counting technique results in direct information about the hazmat transportation patterns in an area, it is more specific and difficult to conduct than truck type counts for the following reasons: Placards are less than 1 square foot in size, and placard numbers are 3.5 inches tall. Although vehicles are required to display placards on front, side, and back of the transported unit, the placement of the placards is not the same for each vehicle. High speeds and congested traffic can make it difficult for even experienced observers to identify every placard, especially when placards are obscured by other vehicles. to remember that vehicles carrying less-than-placard-threshold levels can still be carrying haz- ardous materials, so a count of placarded vehicles will not yield a complete picture of hazmat transport. Use of placard count data combined with truck count data for estimating commodity flows is discussed in Appendix K.6. Use of placard ID data for estimating commodity flows is dis- cussed in Appendix K.7. 5.3.3 Combined Commercial Vehicle and UN/NA Placard ID Surveys 5.3.3.1 Total Truck and UN/NA Placard ID Surveys A more intensive data collection technique is to combine truck counts with UN/NA placard ID counts. Observations of placards and trucks are recorded for the same locations and times. This allows for both identification of the percentage of placarded trucks for the time period, and identification of the hazmat placards. A blank sample truck and placard ID count sheet and a completed example sheet are provided in Appendix J.5. Multiple placards on the same truck should be circled to differentiate between all placards observed and the number of placarded trucks observed. The sample sheet provides for four different truck/placard count periods. Remember that this type of data count will not provide information about the types and con- figurations of trucks carrying the hazardous materials or traffic levels, so it has limited applicabil- ity for some HMCFS objectives (for example, maximum scenario definitions). It is also important to remember that vehicles carrying less-than-placard-threshold levels can still be carrying haz- ardous materials, so a count of placarded vehicles will not yield a complete picture of hazmat transport. Use of these data for estimating commodity flows is discussed in Appendix K.8. 5.3.3.2 Truck Type and Configuration and UN/NA Placard ID Surveys A combined count of truck type and configuration and hazmat placard IDs increases the com- plexity of the data count. These counts can be used to identify overall truck traffic levels, propor- tions of truck traffic by type and configuration and the percentages of placarded trucks for each category, and identification of the hazmat placards. This information also can be used for rough estimates of relative quantities (small, medium, or large amounts) of transported hazardous materials--for example, depending on their configurations, a straight tank truck may have a capacity of around 3,000 gallons while a tractor-trailer tank truck may have a capacity of around

OCR for page 50
54 Guidebook for Conducting Local Hazardous Materials Commodity Flow Studies 9,000 gallons. Also keep in mind that many tank trailers with placards on them are empty and either cleaned or--more likely--contain residual product. A blank truck type and configuration and placard ID count sheet and a completed example sheet are provided in Appendix J.6. Multiple placards on the same truck should be circled to differenti- ate between all placards observed and the number of placarded trucks observed. Separate count sheets should be used for each period. The spacing provided in rows for different truck type/ configurations should accommodate either the number of tally marks for trucks or identification of hazmat placards for most roadways for a 30-minute count. Multiple sheets may be used if needed during the same time period, noting the multiple page numbers for the same time period. Use of these data for estimating commodity flows is discussed in Appendix K.9. As with other counts of placard ID information, it is important to remember that vehicles carrying less-than- placard-threshold levels still can be carrying hazardous materials, so a count of placarded vehi- cles will not yield a complete picture of hazmat transport. Although collection of combined truck and placard data is manageable for a single data collector for roads with low traffic volumes, it can be particularly challenging for high-traffic-volume locations. For these locations, it is almost essential to have data collectors working in pairs. 5.3.4 Directional and Intersection Surveys The truck and placard ID traffic survey examples provided in Sections 5.3.2 and 5.3.3 assume that data are collected for only one direction of a single roadway per time period. Another level of complexity is for recording traffic data for both roadway directions, and/or at a three-way or four-way roadway intersection. For example, rather than having eight data collection locations for a four-way intersection (one for each direction of each roadway segment), the information can be collected at a single location. Potentially, this can reduce the number of data collectors needed, but it also can be a very intensive effort for busy roadways or intersections, and is best accomplished using experienced data collectors. A blank sample data sheet is provided in Appendix J.7 that can be used for collecting truck type and configuration (corresponding to the VIUS categories) and placard ID information for both directions of a roadway, or at an intersection. Each data sheet provides for recording information for up to 25 trucks. For each truck, the truck type, configuration, placard ID, and directional infor- mation (as applicable) are recorded by circling the corresponding categories. Each truck type cate- gory is listed for groups "A" through "H" as shown on the example sheet provided in Appendix J.1. Truck configurations are shown for straight trucks (ST), tractor-trailers or straight trucks with a trailer (TT), and tractor with multi-trailer (MT) configurations. Placard categories are provided for the nine hazmat classes along with a tenth category for other placards, e.g., "Dangerous," "Marine Pollutant," etc., and there is space for recording more specific placard information such as numbers or words. "Un" is used to identify "unknown" or "uncertain" information for all categories. The sheet also allows for identification of directional movements for both directions of a road- way or for turning movements at intersections. If recording both directions of a single roadway (and not at an intersection), the data collector can indicate the direction of travel for each truck (e.g., "NB" for northbound trucks, or "SB" for southbound trucks). This can be done using either the "Approaching On" or "Departing On" columns--although both columns are marked in the example sheet, using both columns is not absolutely necessary for single-direction truck traffic surveys since the directions are the same for an individual truck. (That is, in single-direction sur- veys, all northbound trucks continue northbound. In this case it would be possible to use only one column to indicate direction.) If recording data at intersections, the data collector indicates the direction that the truck was travelling when it approached the intersection and the direction a truck was travelling after it