BC Gas Cleans Up Its Data for GIS

When GIS arrived on the scene some 20 years ago, it was regarded as little more than a broad-brush planning tool with limited sources and applications. Its ability to look at information with a locational component, of course, made it ideal for demographic background research. For example, by using customer counts by ZIP codes or census tracts, and aggregate incomes for those census areas from tax return data, companies could determine income levels, population or spending habits by community. The far more precise locational information that AM/FM provided made it possible to identify specific details such as consumption by billing period for individual customers in a defined area, the number of valves in an area per length of pipe, or the number of leaks per year by age of pipe.

The BC Gas data conversion team of Ted Norcott (background) and Peter Crowder (foreground) loads missing address data onto a MicroStation plate map file prior to conversion to Smallworld.
Click here to enlarge image

With so much common ground, perhaps it was inevitable that AM/FM and GIS would eventually merge. When this occurred a few years ago, the availability of more customer and facility data allowed more complex questions to be tackled, such as: Where do we locate service facilities to minimize costs? Which areas are high-demand in particular seasons? Which areas are growing and will have increased demand? If we have a cold winter, will we be able to deliver enough gas to these high-demand areas with existing lines?

These and an ever-growing list of questions are being dealt with using GIS in combination with facilities information. Because of its ability to interface with a range of other enterprise applications, GIS has become a key element in the overall IT strategy. In particular, global positioning system (GPS) technology has had a major impact on the delivery of services and the management of personnel and equipment. With the help of GPS, network operators are able to monitor vehicle location and movement on a GIS screen, which also shows the network infrastructure. At the same time, communications advances and mobile computing via laptops and palmtops have brought about many changes in the way things are done. But to take full advantage of these developments, major map database upgrades may need to be implemented.

One utility currently undergoing this process on a large scale is BC Gas, based in Vancouver, British Columbia. Since 1981, Mains Information Systems (MAINS) has been the company’s primary AM system, supplying a graphical record in MicroStation dgn format of outside plant distribution facilities. The data is stored in map form, typically with a municipal landbase of block lines, lot lines and street names as a backdrop, and gas facilities (mains pipes, valves and other fittings) as an overlay. MAINS, which is a computer-assisted design/drafting (CADD) system, provides plotting and screen viewing capabilities, but it lacks the attribute database to support data analysis and reporting functionality for FM, which is now considered essential for operating a modern utility company. Consequently, the decision was made in late 1998 to proceed with a far-reaching project to convert all the MAINS data collected since 1981 to the Smallworld GIS system. The aim is to provide FM and GIS capability throughout the company, encompassing its nearly 6,000 miles of transmission and distribution gas lines.

Coastal Upgrade Project

Paper plot from one of the original MicroStation files before Quality Assurance/Quality Control work. The plot shows broken lot lines and has no address data. These anomalies must be corrected prior to conversion.
Click here to enlarge image

To support these advances, the Coastal Upgrade Project has been commissioned to clean up the existing MicroStation plate map files prior to conversion to the new GIS system. This vital preparatory stage involves editing the map data contents to remove anomalies and ensure structural consistency.

The passage of time, changes in personnel, changes in the gas industry, and changes to MicroStation all have encouraged variations in the data files. These variations must be removed or accounted for, otherwise huge problems can arise at the conversion stage. Data placed on the wrong level of the MicroStation file, or incorrectly coded in some other way, can fail to appear on the map. This could result in hazards such as a contractor snagging a gas line or fiber optic cable that isn’t indicated on the engineering plot. Ambiguous data can even be permanently lost at the migration stage from one database system to another, as the machine may ignore it altogether.

“The cost and value of the data collected since 1981 is staggering,” said Ted Norcott, BC Gas’ GIS specialist. “It’s not a resource that we can afford to jeopardize. In all, a total of 669 mapsheets have to be rigorously checked for compliance to the current BC Gas mapping standards before they can be converted to the new system.”

The process of checking this much data is potentially arduous and inexact. To improve speed and accuracy in the Coastal Upgrade Project data preparation, Ted Norcott and his drafting team are using quality assurance/quality control (QA/QC) software with the capability to diagnose and flag map errors and institute corrections.

The main QA/QC software package at the heart of the preparation stage is GDM RESYMBOL. RESYMBOL uses a rule file, produced from the project standards, to scan and check each data file. It then creates an unspecified elements (.uns) file that contains copies of all the symbology features that do not match the rules. The operator is driven to the individual anomalies, and the proper solutions usually can be enacted simply by hitting the “Process Fixes” button.

MRF Clean is another software tool being used to process the maps. This software is run after symbology problems have been fixed. It nodes (breaks) all line intersections to ensure there are no crossing lines, and flags segments and dangling endpoints.

A key factor is that both software packages have the ability to process multiple files. This has proved to be an effective time-saving measure, as operators can start a batch of files at day’s end when the computers generally are not in use. In the morning, the data can be taken straight off the server and distributed immediately to the people doing the checking.

Inherent Pitfalls

As with any complex undertaking, there are pitfalls to this type of database upgrade. Many of these arise from the way a distribution network is represented in map form. BC Gas uses a number of different pressures in various parts of its system. Each pressure system has several sizes and types of pipe, as well as valves and other fittings, some operated manually, some with mechanical controls. Each element is considered a “feature,” which must be distinctly represented on the map file. Altogether more than 1,400 features are involved. In the current system, they can be identified by graphical characteristics. Each is assigned a particular level, color, weight and symbol, so an experienced user can look at the file and know precisely what each feature represents.

One of the project’s unusual aspects is that the existing database uses a symbol font rather than cells to place fittings on the gas mains in graphical form. Certain characters of this font are allowed on certain levels of the MicroStation file, depending on the type of gas main in question. The same fitting may be allowed on many different levels, as all the gas mains require them.

Checking all these features for compliance would be an enormous undertaking without the kind of spec checking software that is being used. “Some of the problems we’ve encountered have been quite unique,” said Norcott. “As the work has progressed, we’ve had to go to GDM Software with some special requests. Their RESYMBOL package was working well, but they also came up with customized enhancements based on our experience.”

Map features that are allowed by the rule file but that are not correctly located can create further complications. “A few elements may make it through the RESYMBOL check because they have the correct symbology but have been placed on a gas main not related to that particular fitting,” said Peter Crowder of McElhanny Consulting Services, a major subcontractor on the current database upgrade program. “These undetected errors are flagged as dangles by MRF Clean. The operator then fixes the error and runs the file through a third program called GDM QuikChek to ensure that the proper fix was applied.” A feature of the QuikChek program, called Best Guess, provides the likeliest interpretation of each error. In one design file, there can be as many as 1,500 occurrences of the same error. All can be corrected as a batch by clicking “Select” on the Best Guess dialogue box, without the operator having to know what was wrong with the element in the first place.

GDM QuikChek software runs against a BC Gas MAINS file. The Best Guess feature provides the likeliest solution to the 1,517 occurrences of the same error.
Click here to enlarge image

According to Crowder, probably the most challenging aspect of the data preparation stage has been the creation of the rule files that the QA/QC software relies on. “Elements were constantly being picked up by RESYMBOL that were not in the rules,” he said. “We would have to forward them to the conversion team to see if they were really allowed. The database includes files which are worked on by two different sections of BC Gas’ drafting department and the specifications are not always common to both.”

Fortunately, BC Gas was able to create the rule file from their existing Excel spreadsheet, which specified all the criteria of color, weight, line and level that made up the mapping standard.

Organization of the job is also challenging, as the files need to be taken out of production or frozen while they’re being cleaned, which means no other work can be done on them until they’re put back into the system. The fact that so many departments are involved with the files on a daily basis makes taking them out of production a major logistical concern.

It’s a painstaking process, but a necessary one for a company wishing to retain its position as one of North America’s largest gas utilities. When the Coastal Upgrade Project is completed and basic GIS implementation is in place in the fourth quarter of 2000, the benefits are expected to be considerable. From an operator’s point of view, the most visible change will be the seamlessness of the system itself. Instead of 669 individual files, there will be a single network map. To isolate specific data, the operator will no longer have to work from separate sheets, but will be able to zoom in until the relevant data fills the screen. This will eliminate the problem of features not lining up from page to page.

A further factor is that an object-oriented system such as this allows users to work on alternate engineering designs without locking a part of the database for a long time. Some system improvements can take months to design, and this is often difficult to manage in traditional check-in/check-out environments.

And there are other advantages, as Russ Bonny, BC Gas’ AM/FM implementation manager explains: “The technology is well-suited to a company with widespread offices that are connected via a WAN. This will give us corporate-wide access to spatial and attribute data about our gas distribution network and the customers it serves. We can now implement new business processes that are consistent across multiple departments. This, in the long run, will provide better operational efficiency and flexibility. We have, or will have, interfaces to major applications such as work management, network analysis and document management. And we have the potential to link the system to other operations, like transmission, in the future.”

Michael O’Toole is a freelance writer with a background in journalism and corporate communications. He was based for a number of years in the United Kingdom, where he produced training materials and corporate video scripts for companies such as British Gas, National Power and BP Oil. He now works in Calgary, Canada.


Previous articlePOWERGRID_INTERNATIONAL Volume 5 Issue 1
Next articleELP Volume 78 Issue 2

No posts to display