PROM: A considered approach

A new way of routing pipelines is proving increasingly popular with the water companies. Craig Roberts and Paul Hart of Black & Veatch explain the company's Pipeline Routing Optimisation Method

Water companies face many difficulties when routing pipelines through the complex British landscape, having to consider environmental, geotechnical and human considerations between the start and end locations. A new geographical information system (GIS) based approach to pipeline routing is finding favour with water companies.

Pipeline Routing Optimisation Method (PROM) assists in optimising route selection and saves time and money during the process.

As a part of a water resources and forecast supply demands study for Anglian Water Services (AWS), Black & Veatch undertook a strategic review of environmental and geotechnical considerations, and pipeline engineering requirements, for about 500km of proposed large-diameter bulk supply water transmission pipelines. PROM was created to make better-informed decisions about the various corridor routing options available to AWS.

The tool automatically provides pipeline routing options given environmental, geo-technical and operational considerations. Its use has now widened within AWS, and it is being used on various pipeline infrastructure projects.

The tool has brought benefits such as reduced costs associated with the route planning process, more efficient routes minimising capex and opex, and automatic profiles and schedules for pipeline management and cost estimation. PROM tools have also been developed for Bristol Water and South East Water.

PROM is a fusion of tools, data, established GIS techniques and a series of outputs that together create a pipeline-routing package.

Data sets
At the core of PROM are the data sets. For each PROM routing, more than 70 data sets are collected, standardised and imported into a spatial database. This includes all the available environmental- and geotechnical-based data sets as well as infrastructure data such as road networks, existing water networks and even property footprints.

This data is the intelligence behind PROM. The tool brings together the influence and constrains all of the information in the various data sets places upon a potential pipeline route.

It typically recommends to clients that the data captured should cover the entire area in which they operate, to enable routes to be run anywhere within their region. A large proportion of data sets are in the public domain and are freely available from government departments.

To date, a number of data sets have been derived from Ordnance Survey's MasterMap product. Depending on the data availability, a combination of some or all of the OSMM Topographic, Integrated Transport Network, Address Point and Cartographic Text layers have been used to produce data sets as diverse as pond footprints and road corridors with road classifications attached.

All the data is stored with metadata (information about the data). The metadata includes, among other things, the data's origin, description, creation date and replacement date. The structured nature of PROM has the benefit that all the routing options considered are fully auditable and repeatable. B&V says the database in itself is proving to be a powerful tool for PROM clients. It is being utilised for a variety of GIS analysis spin-offs including above-ground site selection work and PR09 cost assessments.

Once all the data sets for a route have been compiled, environmental and geotechnical experts from Black & Veatch meet the client to determine how influential each data set and its subcategories are to the routing of a pipeline. This process involves the analysis of each data set, drawing out significant categories and applying a common weighting scheme to capture and store the experts' knowledge.

For example, they may associate a heavy weight to an area specified as an environmental designation, which tells PROM the area should be avoided if possible. These weights or scores combined create a weighting profile.

The final step in the production of the potential pipeline routes database is to aggregate all the data sets based on the weighting profile into a single database, which enables the generation of optimal routes. B&V calls this the "least-score database". It now holds the knowledge to support the generation of routes which will typically exhibit reduced capex and opex costs.

A route is generated by entering the source and destination locations. The method determines the least accumulative score to traverse across a study area from the specified source to the destination using the least-score database.

Multiple destinations can be evaluated at the same time to determine the optimal routing to all destinations, or just the best single option. PROM can also determine the optimal route to take when connecting to a destination specified as a line, such as an existing pipeline.

Areas can also be specified as a routing destination. Where these routes traditionally take months, PROM can generate multiple routing options in less than a day.

This efficiency in the route-planning process is estimated to be saving between £20,000 and £40,000 on a typical pipeline project. In addition to PROM-generated routes, manually plotted routes can be dropped in to the tool and evaluated for comparison purposes. This is proving to be valuable in other areas where clients want to evaluate routes partly designed or already in the ground.

Arguably the most powerful feature of the PROM are the outputs it generates. These consist of:
  • A route validation package - all data sets (licence allowing) that went into defining a route, plus the generated routes are packaged and distributed on a DVD with licence-free GIS reader software for evaluation by project teams
  • GIS ArcGIS SHP and Google KML data files of the route are created for the client to evaluate using either their own GIS software or Google Earth
  • A hydraulic profile of each route option is exported into whichever format the client needs
  • A score is generated allowing one option to be evaluated relative to another
  • Schedules are generated. These automatically report every aspect of the route from urban/rural lengths to the number and length of river and roads crossed, including the name and classification of the road
The amount and variety of data generated allows routes to be evaluated quickly and effectively. Unsuitable routes can be dismissed and efforts focused on suitable options.

Digital distribution of all the necessary data sets also allows more informed, auditable decisions to be made, as well as reducing the time and environmental impact of printing large-scale paper maps for project teams to review.

Anglian Water was the first company to use PROM. The method was used on a strategic review of environmental and geotechnical considerations, and pipeline engineering requirements for about 500km of proposed large-diameter bulk supply water transmission pipelines.

Initially the project started with ten routes crossing the region. But, when engineers began to understand the benefits of the PROM, and the ease with which routes could be generated, a further two routes were run, and variations of pipeline connection locations tested. For each route, at least four options were generated and considered.

In total, more than 70 different routes were generated and analysed. Mark Chandler, @One Alliance efficiency manager, said of the work: "PROM has saved an estimated £40,000 during the water resources project."

Anglian has since used PROM on several infrastructure planning projects. Guy Gregory, the enabling programme manager for the @One Alliance, says: "Every pipeline over 1km should be run through PROM early in its lifecycle."

Gregory lists one of the key benefits of PROM as placing the initial route, quite often one of the hardest tasks. Traditional methods involved multiple experts and up to three months' work to locate a first route.

Only once this route is placed can the assessments begin. Using PROM this initial route is placed in less than a day.

Gregory says: "PROM adds benefit as it enables us to quickly identify a number of route corridors that can be investigated before a final route is chosen. It is key to establishing a number of potential corridors as consideration of alternatives are key for the preparation of an Environmental Impact Assessment if one is required."

Never static
A key benefit of PROM is its flexibility and reusability. Data within PROM is never static: weightings can be easily adjusted, new data sets easily added, local knowledge or field study findings easily dropped in to provide localised exclusion areas.

Different weighting profiles can be created to provide a different emphasis to the influential of the constraints.

The entire process can be tailored to generate routes to meet clients' priorities at business, programme or project level. For example, in an early scheme run for Anglian Water, opex costs were a driving factor in determining a route.

The topographic model was weighted accordingly and routes were encouraged to stay low avoiding higher ground and elevation change. PROM is finding favour with AWS, South East Water and Bristol Water.

It is proving to be a "versatile, flexible and adaptable tool that is finding applications in differing areas of the utilities business". B&V is currently enhancing the method to provide initial high-level costing estimates and are considering the inclusion of a carbon-footprinting module.

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