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66 CLASSIFICATION OF SOFTWARE FUNCTIONALITIES Transportation Modeling Categories analytical or deterministic. Analytical and deterministic tools are usually based on the procedures found in the Highway Capacity Manual. The resulting factorsâcapacity, density, level of service (LOS), delay, queueâfrom these tools are based on empirical equations derived from fi eld data and small-scale experiments. This type of tool is able to analyze small-scale effects but is not practical for large-scale, network applications. DynusT. This dynamic traffi c assignment simulation model was released under a GNU General Public License as a precondition for award of SHRP 2 Project C10B, Partner- ship to Develop an Integrated, Advanced Travel Demand Model with Fine-Grained, Time-Sensitive Networks: Sacramento-Area Application. (A GNU General Public License is a free software license. DTALite and DynusT were released under this license for use in SHRP 2 Projects C05 and C10B) A dynamic traffi c assignment model is a computerized analysis package that tracks the movements of individual vehicles in a model street network and quantifi es the performance of the network by summing the results of individual vehicle movements. DynusT is being enhanced and mated with SACSIM, which is an activity-based tr affi c model released in an open-source format by the Sacramento Area Council of Governments. This model will be enhanced and mated with DynusT in the SHRP 2 C10B project. DynusT is also the platform for the WISE Operation Module. GUI. Graphical user interface. 7 ACRONYMS AND GLOSSARY
67 WISE SOFTWARE USERS GUIDE simulation, macroscopic. Macroscopic simulation models use the fundamental traffic qualities of speed, volume, and density on a sectional basis (i.e., network links). This means that tracking individual cars in a macroscopic model is impossible. They require less detailed network link data to operate than do microscopic models, but they do not offer as much detail. simulation, mesoscopic. Mesoscopic simulation models provide middle ground be- tween the macro- and microscopic approaches. Mesoscopic models typically are able to track individual vehicles, but they also rely on speed, volume, and density relation- ships to determine the movement of these vehicles. simulation, microscopic. Microscopic simulation models are capable of tracking in- dividual vehicles on a second-by-second basis to capture the ways that these vehicles interact with each other. This means that these models employ car-following and lane- changing algorithms to determine individual vehicle behaviors. tool suite. A tool suite is a computer software package that combines two or three of the simulation types described above. In this way, a user is able to easily model a net- work with different fidelities when necessary. Examples include VISSIM with VISUM and TransCAD with TransModeler. traffic signal optimization. Traffic signal optimization software packages are tools used to develop signal-timing plans at both isolated locations and synchronized cor- ridors or grids. These tools also require basic information such as traffic counts for intersections. travel demand model. Travel demand models are mathematical models that are used to determine the travel patterns based on demand. Originally, these types of models were developed to determine the impact of infrastructure improvements. They forecast specific outputs, such as mode choice, destination choice, and route choice. GEOGRAPHIC SCALE The geographic scale of a work zone becomes important when attempting to model potential traffic impacts. A variety of software packages exists across a broad spec- trum for modeling different sizes of networks. Software on the lower end of the spec- trum, such as Highway Capacity Software (HCS), describes traffic with simple in/out patterns and is a good match for isolated work zones. Other types of software that are capable of modeling entire regional road systems would be a good fit for network (grid) and regional work zones where detours may need to be analyzed. The geographic scale of a work zone is a consideration of both the size and impact of any potential road work. The types of work zone geographic scales fall into four main categories: isolated, corridor (pipe), network (grid), and regional.
68 WISE SOFTWARE USERS GUIDE corridor (pipe). A corridor work zone (or pipe work zone) is any road work that oc- curs along a major highway segment. An example of this type of work zone would be an interstate widening or repaving project. This type of work zone is slightly larger in size and has the potential to cause more traffic disruption on the regional level. isolated. An isolated work zone can be thought of as a single point within a much larger network. Examples of isolated work zones can include rural lane closures or re- designed intersections. This type of work zone is small in size and should have minimal impact on traffic over the regional network. network (grid). A network work zone (or grid work zone) is any project that involves construction on connected, interdependent roads with multiple access points. This type of construction may also require one or more viable alternate routes. Examples include interstate reconstruction, full roadway closures, and work zones in urban cen- ters. This type of work zone is large in size and will disrupt traffic patterns on a large scale. However, the impact is usually restricted to an urban area. regional. A regional work zone is similar to a network work zone in that it involves construction taking place on connected and interdependent routes and may require de- tours. The difference between the two is the size of the traffic impacts. Regional work zones will cause regional-level traffic impacts. This could possibly mean disrupting several urban areas or several towns in a region. FUNCTIONALITY Software tools are used to make decisions regarding planning, operations, construc- tion management, and logistics. Based on each fieldâs purpose, the functionality ranges from costâbenefit analysis to traffic impacts and delay to efficient material transport and management. construction management. Construction management involves the overall planning, coordination, determination of resource requirements, and implementation of the project. Determination of time-of-day for construction, project design and optimal construction scheduling, and traffic impact analysis are considered as part of the anal- ysis for estimating the impact of management strategies. logistics. Logistics involves determining efficient practices to transport materials and optimal scheduling to reduce operational and storage costs. The work zone logistics would involve, for example, the duration of the closure of lanes and determining con- struction techniques and how the workers will put up the cones. operations. Operations involve analysis of current management and safety of traffic and other users. Operations typically involve planning and maintaining signs, signals, pavement markings, and lighting. The management of ITS and safety initiatives to
69 WISE SOFTWARE USERS GUIDE improve driver behavior are considered. Determination of traffic measurements such as delay, speed, occupancy, levels of service, queue lengths, and others are used to evaluate the behavior and functionality of traffic operations and management. planning. Planning involves making long-term decisions and goals. The involvement of all users of the system is normally considered as part of the process as improvement strategies are evaluated to improve the overall functionality of the system. Forecasting future demand growth, employment, and land use are normally considered, as well as estimating impacts of proposed future improvements. USERS AND PROPRIETARY ISSUES Users such as engineers and transportation planners are intended to incorporate soft- ware packages that were evaluated for various functionalities identified in the previous section. engineers. Use by engineers typically involves studying traffic impacts from an opera- tional aspect as well as the planning process of project-specific construction and opera- tional management strategies. Project design and coordination are topics considered with the engineers interested in actual implementation of such strategies. planners. Use by planners typically involves the advanced long-term planning of strate- gies for a road network depicting various projects to improve systemwide functional- ity. Demand forecasting, employment, and land use strategies are topics of interest for such planners, as well as system effects and air quality issues based on traffic and population growth. proprietary. Proprietary software is defined as software that is licensed under exclusive legal right of the developer and/or owner. The user is given the right to use the software under license agreements and is restricted from tampering with and modifying such software. Other software may be termed as open source or freeware, meaning the use and licensing are more liberal in the use of, the study of, and changes and improvements of software made by users. Freeware focuses more on the free use of software, and open source is focused on the community use and development of software to benefit the overall software community. DATA INPUTS cost of various strategies. Different construction strategies have different implications on life-cycle costs. Use of fast construction material and techniques can result in reduc- tion in the period of time work zones are implemented but may require higher regular maintenance costs during the life cycle of the project. These costs and benefits need to be evaluated at a life-cycle level.
70 WISE SOFTWARE USERS GUIDE pavement. As identified in the interviews in Phase 1, for most departments of trans- portation (DOTs) and metropolitan planning organizations (MPOs), pavement man- agement systems play a critical role in determining projects and project sequencing. Therefore, it is critical to determine the software tools that need pavement inputs and how they are used. production rate for various strategies. Several construction strategies identified during the interviews have different production rates depending on the materials being used, the construction technique, weather, and night versus day. Such factors have a signifi- cant effect on the duration of the work zone. traffic. Traffic data include volume counts, speeds, travel time, and density and are used to calibrate and validate simulation models. MEASURES OF EFFECTIVENESS agency cost. For the WISE Software Program, agency cost is the project-related cost to con- struct each of the renewal projects listed in the analysis. The construction cost includes all expenditures necessary for the design, construction, and maintenance of traffic costs incurred during construction. Agency cost does not include the delay cost incurred by the driving public. If a project is delayed, the agency cost includes the increase in the project cost due to postponing the construction of the project. environmental impact. The environmental impact is directly related to the amount of emissions vehicles make during their trips. This measure is especially relevant when a large amount of congestion is present. road user cost. This figurative cost is ascribed to all road users who face delay and con- gestion It represents the negative impact of such road conditions and the road userâs preference to avoid such costs. safety surrogate. Any data set that can act as a surrogate to safety. For example, speed variance, number of lane changes, and conflicting points. traffic conditions. Traffic conditions represent a broad data set used by traffic engi- neers and planners to assess the traffic conditions (such as speed, delays, accelerations, lane changing) on any particular roadway. queue length and delay. Queue lengths and delays are used as a measure of effective- ness to evaluate the type and level of impact a work zone will have. RESOURCE REQUIREMENTS animation or presentation. When applied to software, the term often means its ability to make animations or presentations. This is very important for traffic simulation, not only to present results but also to locate trouble spots in the network.
71 WISE SOFTWARE USERS GUIDE availability of source code or algorithm. Open-source software is any computer pro- gram that allows fellow developers to see the actual code that makes up the software. This visibility makes it easier for developers in similar areas to calibrate. Open-source software is usually free or donation-based. computational speed. The computational speed of software is a measure of the amount of time it takes to execute all of the required steps from start to finish. Most steps can be performed in a matter of minutes, but steps in more complicated systems can take several hours. cost. The cost of software is the price that the developer and/or publisher asks the user to pay for the product. This is the opposite of nonproprietary software, which is avail- able for free or by donation. effort in application. The amount of effort required to transfer an existing network or data set into a newer system. Excel based. Excel-based software uses Microsoft Excel as a âwindowâ into which the software is entered. This means that the software is merely an extension of Excel rather than a unique software package. level of effort for training. A measure of a software packageâs ease of use. Easy soft- ware can be understood after only a few demonstrations, but more complicated soft- ware may require several days of training. As a general rule, open-source software is usually more complex and less user-friendly than commercially developed software. memory. The amount of memory a given program will take up is a measure of the size (in bytes) of the program and its files. transferability of data to other packages. The ability of data to be exchanged across multiple packages is important in order to coordinate output between packages. This is usually facilitated by either file conversion or reliance on a universal file format. DYNAMIC DEMAND CHANGES departure time choice. Departure time choice is usually a facet of the mode choice a trav- eler must make. For instance, a traveler using a passenger car may depart at any time, while a traveler using bus transit must wait until the next bus arrives in order to depart. destination change. A destination change occurs when a traveler diverts to a destina- tion other than the one originally intended when the trip began. induced or foregone demand. Induced demand (latent demand) is a phenomenon that occurs when traffic volumes increase when facility LOS and/or capacities increase. Foregone demand is the opposite effect, when facilities with low LOS and/or capacities experience lower volumes because of travelersâ hesitancy to use such facilities.
72 WISE SOFTWARE USERS GUIDE mode shift. Any shift in mode that a traveler makes in order to complete a trip. This action could be part of an overall trip plan or could result from dissatisfaction with the current mode. route diversion, en route. A diversion that occurs when travelers decide to alter their route during the trip. This diversion might be because of any of a number of factors, including Intelligent Transportation System (ITS) signs warning of impending conges- tion, radio announcements, word-of-mouth, or approaching traffic congestion per- ceived first-hand. route diversion, pretrip. A type of diversion that occurs when a traveler decides to alter his or her route before the trip begins.
