Pipe Renewal Planner provides the user with a tool to calculate a weighted score for each pipe based on whatever aspects the user chooses. Scoring pipes is highly system specific depending on the issues in that system and the availability of data. Pipe Renewal Planner can include any aspect that can be entered for a pipe or calculated for the pipe.

Scores that can be calculated for a pipe include:

Scores that can be based on properties include standard HAMMER CONNECT properties such as:

Or Use Data Extensions such as:

Each of the properties used above (e.g. capacity, material, and cover) is referred to as an aspect. The first set of aspects are calculated in special routines and are referred to as "Predefined Aspects" since there are HAMMER CONNECT analyses that are used to determine the scores. See the Help for each of those individual aspects.

The overall process for determining the "Pipe Score", which is the final result of this analysis, is:

Each of these steps is described in more detail below.

Pipe Renewal Planner - methods used

The result of the Pipe Renewal Planner analysis is a pipe score for each pipe. This is calculated for the j-th pipe using

Score (j) = w_iR_ij

Where w_i is the weight for the i-th aspect and R_ij is the score for the j-th pipe for the i-th aspect.

The intent is that the individual scores (R values) are on a scale of 0 to 100 (100 being the worst). The w's should add up to 1 so that the overall score will also be on a 0 to 100 scale.

The scores for the individual aspects are determined on a continuous or a stepwise scale as appropriate for that type of aspect.

Aspects such as pipe break and criticality use the continuous function while user defined properties such as year installed and material use the stepwise function. The horizontal axis is described by some raw values such as pipe break rate in breaks/year/mile or maximum velocity (ft/sec) in pipe during fires or year installed.

Pipe Break: For the pipe break aspect, the user should run the Pipe Break Analysis to calculate the projected break rate for each pipe. The individual pipe break score is calculated as:

Where break_j = break rate in j-th pipe, and breakmax = maximum break rate in all pipes.

Criticality: The criticality score is based on the shortfall in meeting demand as calculated by the HAMMER CONNECT criticality analysis. Criticality may be based on taking an individual pipe element out of service or more accurately in taking a distribution segment out of the system (see criticality help for more discussion on this as well as details of calculating criticality below). The score for criticality is:

Where criticality is the shortfall due to an outage of the j-th pipe and criticalitymax is the greatest shortfall from any pipe.

Capacity (fire flow): Assigning fire flow scores to a pipe is somewhat more difficult in that fire flows are node, not pipe, properties. The goal is to identify which pipes serve as bottlenecks in the system. These are pipes which have high velocity or head loss gradient when a downstream node fails the meet needed fire flow. The determination of a shortcoming in capacity is defined as the maximum difference between the target velocity and actual velocity for the worst fire flow event for each pipe. The user defines a velocity that would make a pipe a candidate for being a bottleneck (say 5 ft/s).

For each pipe, the raw score is defined as:

r_j=max[v-v_t]

Where v = velocity, ft/s, v_t = target velocity, ft/s

The target value used is taken as the velocity specified in the "Use Pipe Velocity Greater Than" field of the auxiliary output section of the fire flow alternative.

The scaled score for pipe j would be:

Where rmax is the amount the velocity exceeds the target at the pipe with the highest velocity.

The calculations are similar for hydraulic gradient except that there is no target value (i.e. zero).

It may be necessary to eliminate small pipes (e.g. 2 in. pipes) from this calculation since they are not expected to carry fire flow. It may also be necessary to eliminate nodes from the fire flow analysis in areas where fire flows are not to be provided. Selecting the target velocity also involves some judgment in that too low of a value will point out some pipes that normally have a high velocity as being bottlenecks and too high of a will mean that virtually no pipes will have a non-zero value for R_ij.

It is usually preferable to base capacity score on headloss gradient as it is sensitive to pipe roughness while velocity is not. Using hydraulic gradient produces a higher score for rougher pipes which is desirable.

Discrete aspect: In the case of aspects whose score is based on some pipe property, the user selects some function and manually enters the function using a table such as shown below:

Using the Pipe Renewal Planner

Before using Pipe Renewal Planner, the user needs to identify which aspects will be used in scoring pipes and which properties are going to be used as a basis for calculating the aspect scores.

(It may be necessary to define new properties in User Data Extensions and import values for properties from external data sources using ModelBuilder or copy/paste features. In order to import values, it is essential that there exist a common key field shared by the HAMMER CONNECT model and the external data source.)

Calculation of raw scores for aspects such as capacity (fire flow) and criticality (shortfall) can be time consuming such that it may be advisable to have already run these analyses before starting the Pipe Renewal Planner and noting which scenario was used. However, if any properties are changed that may affect scores, it may be necessary to rerun the scenario from within Pipe Renewal Planner.

The user can start Pipe Renewal Planner by selecting Analysis > Pipe Renewal Planner or picking the Pipe Renewal Planner button. This opens the welcome dialog if no analyses have already been run.

Select the New button on top of the left pane to create a new analysis. It opens with the following default values:

The user can rename the analysis by selecting the third button over the left pane.

The user should select the Representative Scenario which need not necessarily be the current scenario. This scenario will be used as the source of property values and the location to save results except for those places where another scenario is explicitly called out.

General Tab: In the General tab in the right pane the user can create new aspects or delete aspects using the buttons on top of the dialog.

The Use button determines which aspects are to be included in the pipe score calculation as indicated by the check.

Under the Aspect column, the user can define new aspects. The default Aspects - Pipe Break, Criticality and Capacity (Fire Flow) -- are automatically included in the list although they can be deleted. To create a new Aspect, click inside a blank cell in the Aspect column and select the ellipse (...) button. This will open the dialog below where the scoring for the new aspect can be defined by first selecting the New button, then naming the Aspect.

The user then picks which field is to be used as the basis for this Aspect, initializes the values and sets the scores. If the property is a numerical value, then the value in the Value column is the upper limit of the range (above) while if the property is text, the list of possible text values is displayed (below).

The Selection Set column determines whether the Pipe Renewal Planner will be run for the entire network (default) or some previously defined selection set of pipes.

The Weight column is the place where the user defines the weights assigned to each aspect. Ideally, the weights should add up to 1 but the user may use some other weighting system.

The Compute Scenario box when checked means that HAMMER CONNECT will recalculate the indicated scenario when it calculates the Pipe Score. If unchecked, the Pipe Renewal Planner will use the most recent results from that scenario.

The Scenario column indicates which scenario is to be used to calculate the raw score for that Aspect. It is important that the user pick the correct type of scenario. For example, if the Aspect is criticality, the scenario selected should be one containing the results of a criticality run.

Predefined Aspects Tab: The Predefined Aspects Options tab gives the user additional control over the handling of the three predefined aspects - Pipe breaks, Criticality and Capacity. In each of those sub-tabs, the user can decide whether to calculate the score on a continuous scale (default) or set up some stepwise function to convert the raw score into a scaled score to the overall pipe score. The user indicates this by selecting:

Use continuous scale

Or

Use Stepwise scale

If the user selects the continuous scale, then no additional information is necessary. If the user selects the stepwise scale, then he must define the scale as done for other aspects.

The criticality and capacity score provide the user with additional capability to specify some additional options.

In calculating the criticality score, the shortfall may be calculated based on distribution segments rather than pipe elements. (Segments are the minimum portion of the system that can be isolated by valving. See help topic on segments.) There is not a one-to-one association between segments and pipes. A pipe may be made up of several segments depending on valving. The user has the ability to control how the segment shortfall is transformed into pipe shortfall. In the figure below, there are two segments than overlap pipe 102-a short one and a long one.

The user has three ways to handle multiple segments:

For the example above, suppose pipe 102 is 200 ft long and 195 ft are in Segment B (criticality = 10) while the remaining 5 ft are in segment A (criticality = 60). The corresponding scores would be:

, depending on the user's choice.

The capacity score as described in the "Pipe Renewal Planner - methods used" topic, is based on the maximum extent that the velocity exceeds the target velocity in a fire flow analysis. Because some pipes are small and not intended for fire flow, those pipes can be excluded from the analysis using the minimum diameter value (default = 2 in). Pipes that small or smaller will not have a capacity score calculated for them.

The velocity used in the calculate is the velocity that will occur when the residual pressure meets the required residual. For pipes with large capacity, this value will be much greater than the needed fire flow. If the user wants the velocity to simply meet the needed fire flow, then the "Fire Flow (Upper Limit)" parameter in the fire flow alternative should be set to a value just slightly above the needed fire flow.

Results Tab

To run the pipe scoring calculation, the user would pick the green compute button on the top of the left pane. To simply validate that the calculation is runable, pick the small drop down arrow next to the compute button and pick Validate.

Once the run is complete, a summary results table is displayed with the following columns: