| setting_key | setting_value | comment |
|---|---|---|
| aadi_min | 1 | Minimum age at distress initiation |
| aadi_max | 20 | Maximum age at distress initiation |
| t100_min | 10 | Minimum time to 100 pct |
| t100_max | 150 | Maximum time to 100 pct |
| iv_min | 0.5 | Minimum initial distress value when it initiates (percent) |
| iv_max | 5 | Maximum initial distress value when it initiates (percent) |
| iv_expected | 1 | Expected percentage distress at initiation |
| historic_reset_cs | 0,0 | 2,0 | 10,2 | 30,10 | 100,40 | PLM for resetting last survey values if survey was before resurfacing. X = last distress, Y = initial value assigned |
| historic_reset_ac | 0,0 | 2,0 | 10,1 | 30,5 | 100,30 | PLM for resetting last survey values if survey was before resurfacing. X = last distress, Y = initial value assigned |
| reset_resurf_thresh1 | 5 | Value of pre-treatment value below which zero penalty factor applies to estimated AADT and T100 if a SURFACING is placed over existing distress |
| reset_resurf_thresh2 | 20 | Value of pre-treatment value above which 100% penalty factor applies to estimated AADT and T100 if a SURFACING is placed over existing distress |
| reset_holding_thresh1 | 10 | Value of pre-treatment value below which zero penalty factor applies to estimated AADT and T100 if a HOLDING ACTION is placed over existing distress |
| reset_holding_thresh2 | 30 | Value of pre-treatment value above which 100% penalty factor applies to estimated AADT and T100 if a HOLDING ACTION is placed over existing distress |
S-Curve Parameters
Overview
Parameters held in under the s_curve_default and s_curve_potholes lookup sets define the limits for the key parameters involved in the Distress increment model, which follows an S-Curve similar to the format used in the HDMIII models.
In the Cassandra S-Curve model, there are three key parameters that control the shape of the distress progression curve. These parameters are shown in bold red in the figure below, and are:
Initial Value : this is the percentage distress that will be assigned when the distress is first initialised.
AADI : Age at Distress Initiation (AADI) - this is the surface age at the time when the distress initiates.
T100 : Timne for the distress to reach 100% of element area. This parameter controls the rate at which distress will increase. It is mainly a theoretical parameter to control slope of increase.
Parameters held in under the s_curve_default and s_curve_potholes lookup sets define:
the minimum and maximum thresholds for each of the above three parameters. These limits ensure that distress progression is stable and realistic, even when edge cases are encountered that might have lead to unrealistic values being assigned to Initial Value, AADI or T100.
the expected Initial Value assigned when distress first initialises (at age = AADI)
Function shapes related to resetting of the S-curve for an element and distress depending on the treatment type.
Lookup Set Key
The keys to identify parameters related to the S-Curves for distress progression can be found in the s_curve_default and s_curve_potholes lookup sets (case-sensitive).
Change Level
Parameters held under the s_curve_default and s_curve_potholes lookup sets generally do NOT need to be modified for each network.
Lookup Parameters
Parameters contained in this lookup set are detailed below. Note that parameter keys are case-sensitive.
Default for All Distresses
Generally, it is not necessary to specify a separate set of parameters for each distress. For most distresses (excluding Potholes - see below), the minimum and maximum ranges we want to allow for Initial Value, AADI and T100 are similar. Thus, we use a ‘default set’ for most distresses and a separate set for Potholes.
Users that want to create a more discriminating model can split the lookups into separate sets for each distress type (e.g. Flushing, Alligator Cracking etc.). This will, however, require that the modeller also updates the underlying C# model to use the new lookup factors instead of the default values shown below.
As the table below shows, some lookup values specific minimum and maximum values for AADI, T100 and Initial Value while other values relate to Resets under treatment. For more information on how the parameters are used to reset the S-curve after treatment see this page.
Important
Values shown under the column ‘setting_value’ are defaults/example values. You should take responsibility to understand and modify these values for each project based on your specific network configuration.
Values for Potholes
Potholes generally involve quite small percentages of the element area. Even in a severe case, the area covered by potholes is likely to be below 2% of the total surface area if one assumes each pothole has a diameter of 300mm.
Since pothole distress area is nearly an order of magnitude below other distresses, a different set of constraints are applied for potholes. Specifically, the expected Initial Value is only 0.1% compared to 1% for other distresses.
The table below shows the S-Curve factors assigned to potholes:
| setting_key | setting_value | comment |
|---|---|---|
| aadi_min | 1 | Minimum age at distress initiation |
| aadi_max | 20 | Maximum age at distress initiation |
| t100_min | 10 | Minimum time to 100 pct |
| t100_max | 150 | Maximum time to 100 pct |
| iv_min | 0.1 | Minimum initial distress value when it initiates (percent) |
| iv_max | 0.3 | Maximum initial distress value when it initiates (percent) |
| iv_expected | 0.1 | Expected percentage distress at initiation |
| historic_reset_cs | 0,0 | 0.5,0 |2,1 | 5,1.5 | 100,2 | PLM for resetting last survey values if survey was before resurfacing. X = last distress, Y = initial value assigned |
| historic_reset_ac | 0,0 | 0.5,0 |2,1 | 5,1.5 | 100,2 | PLM for resetting last survey values if survey was before resurfacing. X = last distress, Y = initial value assigned |
| reset_resurf_thresh1 | 0.5 | Value of pre-treatment value below which zero penalty factor applies to estimated AADT and T100 if a SURFACING is placed over existing distress |
| reset_resurf_thresh2 | 2 | Value of pre-treatment value above which 100% penalty factor applies to estimated AADT and T100 if a SURFACING is placed over existing distress |
| reset_holding_thresh1 | 0.8 | Value of pre-treatment value below which zero penalty factor applies to estimated AADT and T100 if a HOLDING ACTION is placed over existing distress |
| reset_holding_thresh2 | 3 | Value of pre-treatment value above which 100% penalty factor applies to estimated AADT and T100 if a HOLDING ACTION is placed over existing distress |