APPENDIX K GLOSSARY
| Centroid | A point within a traffic zone that represents the assumed focal point of the land use activity. For modeling purposes, a centroid is a point in the zone from which traffic generated by the zone can be connected to the surrounding roadway system. |
| Geometrics | In traffic studies, the features of roadway design, roadway alignment, grade, cross-section, access control, intersections, and interchanges. |
| Intersection Capacity Utilization method | In traffic studies, a method for analyzing intersection operating conditions by calculating a volume-to-capacity (V/C) ratio for each governing "critical" movement during a traffic signal phase. The V/C ratio for each phase is summed with the others at the intersection to produce an overall V/C ratio for the intersection as a whole. The V/C ratio represents the percentage of intersection capacity utilized. For example, a V/C ratio of .85 indicates that 85 percent of the capacity is being used. |
| Level of Service (LOS) | In traffic studies, the different operating conditions that occur in a lane or roadway when accommodating various traffic volumes. A qualitative measure of the effect of traffic flow factors such as special travel time, interruptions, freedom to maneuver, driver comfort, convenience, and (indirectly) safety and operating cost. In this study, levels of service are described by a letter rating system of A through F, with LOS A indicating stable traffic flow with little or no delays and LOS F indicating excessive delays and jammed traffic conditions. |
| Machine count | A traffic count made using an automatic counting machine that tallies vehicles as they pass over a pressurized hose laid across a vehicle path. |
| Mode choice | A choice of means of travel (e.g., car, public transit, walking, cycling). |
| Network building | In traffic studies, redrawing the roadway system in a format that can be understood by the model program. The extent of the network developed to accurately study an area must take into account traffic expected to be generated locally and from the surrounding region. A network looks like a simplified and stylized version of a roadway map, with a series of straight lines (links) used instead of curves. Links are coded with data such as their distance, speed of travel, roadway capacity, and number of travel lanes. |
| Path building | The development of travel paths for traffic. The model determines the minimum impedance path from a selected origin to its destination. This would depend on the variables related to the various possible routes, such as distance and travel time or speed. |
| Reserve capacity | The unused capacity of a vehicle travel lane. The number of additional vehicles that could make a particular turning movement before that movement reaches capacity. |
| Special nuclear material | Plutonium, uranium enriched in the isotope U-233 or in the isotope U-235, and any other material which, pursuant to the provisions of Section 51 of the Atomic Energy Act of 1954, as amended, has been determined to be special nuclear material, but does not include source material, or any other material enriched by any of the foregoing. |
| Standard of significance | The limit of acceptable performance of the traffic network. Exceeding this limit would constitute a significant adverse effect in terms of traffic conditions. |
| Trip assignment | The allocation of vehicle trip ends to available routes between locations in a traffic study area. |
| Trip distribution | The allocation of vehicle trips onto the surrounding roadway network from a specified location. |
| Trip generation | The number of vehicle trip ends associated (produced) by a particular land use of a traffic study site. |
| Trip matrix adjustment | This process factors the person trips generated to vehicle trips. The vehicle occupancy factor is typically 1.5. |
| Trip matrix balancing | This process converts a production-attraction matrix to an origin-destination trip table. |
| Type A pTrip matrix balancingackaging | "A packaging designed to retain the integrity of containment and shielding . . . under normal conditions of transport as demonstrated by" a water spray test, a free-drop test, a compression test, and a penetration test (40 C.F.R. parts 173.403(gg), 173.465). |
| Uranium hydride | A bed of the porous form of the material used to transport and store tritium. |
| V/C ratio | Volume-to-capacity ratio. |
| Vehicle trip ends | A single or one-directional vehicle movement with either the origin or destination inside a traffic study site. |
| Waste Isolation Pilot Plant (WIPP) | A facility in southeastern New Mexico being developed as the disposal site for transuranic and transuranic mixed waste, not yet approved for operation. |
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