HLR Section 3.1
HL Route Network
| CONTENTS
3.1 | Define a Heavy Load Network - Overview
| 3.1.1 Creating Links
| 3.1.2 Creating Routes
| 3.1.3 Analysis of Selected/All Structures
3.2 | Create & Edit Links (Detailed Description)
3.3 | Create, Edit & Print Routes (Detailed Description)
| Other Links: | Main Index | Links | Routes | Vehicle Data |
3.1 Defining a Heavy Load Network
| A heavy load network must be described in terms of a series of links, or road sections, interconnected by nodes. It is not a requirement that nodes be located at existing intersections or road junctions or that road sections run between these junctions. Although nodes can be located at any point along the road or highway, they are normally situated at points where other heavy load routes intersect the route currently being defined. An example is shown in the figure below. Nodes must be numbered using a label consisting of a maximum of three alpha-numeric characters. No restriction is placed on the case of the alphabetic characters nor the order of the characters (e.g. 69, A69, 69a are all valid node numbers). Symbols (such as * ^ # / @ and so on) are not permitted.
| 3.1.1 Creating Links Links are created by specifying the node number at each end of the link and (optionally) a list of identification numbers for each structure lying on the link. A full descriptive title, as well as a short abbreviated name, for the link must also be provided. Links may be "empty" and contain no structure data (this can be added later as information comes to hand) .Refer to Section 3.2 for a full description of the link creation process. It is recommended that links should always be created first, before entering data relating to structures lying on those links. The reason is that one of the structure data attributes refers to the node number associated with the notional forward direction of the link (the Start node number). If the link containing this number has not yet been created HLR will warn you that the node does not exist (although it will allow you to save the structure data).
| 3.1.2 Creating Routes Heavy load routes may be created in one of two ways - either by specifying the individual links making up the route; or by specifying whole or part sections of routes that have previously been defined and saved to the HL route database. Routes saved to the database are often referred to as "standard" routes. Although it is not essential to create standard routes they are useful because they allow an often-travelled path to be quickly and easily selected. Section 3.3 describes the route-creation process in greater detail. Building the Network HLR has been designed in a manner which allows the heavy load route network to be built up over time. The network can, in fact, initially consist of a single link with a single structure on that link. It can then be expanded as additional structure data subsequently becomes available. Similarly, links need not initially have any structures assigned to them. This facility allows the framework for a heavy load network to be initially designed in terms of its component links and nodes and structure data added later as and when it comes to hand. Route Direction The notional "forward" direction of the route is assumed to be defined by the sequence of node numbers entered during the route creation stage. The first node in the first selected link constitutes the "start" node for the route. This convention allows vehicles to be moved along the route in the "reverse" direction if so desired. When a reverse analysis is performed, link node numbers and the order in which structures are analysed along the route are automatically inverted. Note that this reversal also applies to the span sequence of continuous bridges i.e. the HL vehicle is moved over the continuous structure in the correct sense. (Refer to Section 5.1.2 - Node Associated with Span 1). When creating different standard routes that each contain the same link number, (i.e. the link is common to all routes), it is important that the positive sense of each route runs in the positive sense of the link. Furthermore, all structures in that link must have the same associated Start node number, even if they lie on separate carriageways. Refer to Section 5.1.2 (Node Associated with Span 1) for a detailed explanation of this attribute. Displaying, Saving & Printing Routes When defined, (or newly created), routes are schematically displayed on the Route form as a vertical line diagram. Node numbers, abbreviated link names and structure numbers are all shown. Discontinuities are represented by "dummy" links. Refer to Section 3.3 for a full description of saving and printing route data.
| 3.1.3 Analysis of Selected/All Structures An option has also been provided in HLR for analysing either a list of structures arbitrarily selected from the database or all structures in the database. This caters for situations where only a spot check is required of a few key bridges on the proposed route or all bridges need to be checked for a proposed new standard heavy load vehicle (such as a new crane). Refer to Section 3.3.4 for details.