User-Friendly Traffic Incident Management (TIM) Program Benefit-Cost Estimation Tool

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Figure 16. Screenshot. User interface of Safety Service Patrol Benefit-Cost subtool for data input on roadway geometry, safety service patrol program information, traffic information, and incident information.

This screenshot shows the Segment Information screen. In the upper-left corner, the words SSP-BC Tool appear. Under that, a box of horizontal bars appears, indicating that the user will click on that icon to reveal the sidebar. In the upper-right corner, the words Save Project Data, Start New Project, and Upload Project Data appear. Below the word Data, a question mark inside a blue circle appears.

A Left Panel, Central Panel, and Right Panel are shown, each outlined in red. The Left Panel is the Segment screen. Below the word “Segment” is a drop-down box with Segment 1 shown in it. Beneath that drop-down box is a text field with “First segment” displayed. Beneath that is a drop-down box with Modesto, CA displayed. Beneath that is a highlighted box called Roadway Geometry. A green checkmark inside a white circle appears to the right of Roadway Geometry. Beneath that, “Segment Length in Miles” appears, with the number “10” displayed in a text entry box to the right. A lowercase white “i” appears in a black circle to the right of the text field box. Beneath that, “Number of Ramps” appears, with the number 0 displayed in a text entry box to the right. A lowercase white “i” appears in a black circle to the right of the text field box. Beneath that, “General Terrain” appears, with “Flat” displayed in a drop-down box to the right. A lowercase white “i” appears in a black circle to the right of the text field box. Beneath that, “Horizontal Curvature” appears, with “Straight” displayed in a drop-down box to the right. A lowercase white “i” appears in a black circle to the right of the text field box. A Calculate Ratio button and a Reset Information button appear at the bottom of the screen.

The Central Panel includes the title SSP Program Information. Beneath the title, “Operation Time” appears. A lowercase white “i” appears in a black circle to the right of “Operation Time”. Beneath “Operation Time” four checkboxes appear, each with the following text: AM Peak (which is checked), PM Peak, Weekday Off Peak, Weekend. Beneath the four checkboxes, “Incident Duration” appears. “Choose how to enter savings” appears beneath that, and a lowercase white “i” appears in a black circle to the right. An Average Duration button and a By Lane Blockage buttons appear beneath “Choose how to enter savings”. Beneath the buttons, “Enter Average Duration Savings (Minutes)” and the number “10” appears in a text entry box. Also in the Central Panel is a Traffic Information section. A green checkmark in a white circle appears to the right of the Traffic Information Title. Beneath the Traffic Information title, “Posted Mainlane Speed Limit (MPH) appears. To the right, the number 70 appears in a text entry box. Beneath that, the words “Time”, “Traffic Volume (VEH/H/Lane)”, and “Truck Percentage (0-100)” appears. Beneath “Time”, “AM PEAK” appears. Beneath “Traffic Volume (VEH/H/Lane)”, the number 2000 appears. Beneath “Truck Percentage (0-100)”, the number 12 appears. Another section, “Weather Information (ensure selections add up to 100%)” appears.

The Right Panel shows the Incident Information screen. Beneath the Incident Information title, "AM Peak" displays. Under "AM Peak", "Incident Blockage Severity", "Average Incident Duration (Minutes)", and "Number of Managed Incidents" appear on a line. Beneath the line, "Shoulder Blockage" displays. The number "15" appears in the text field beneath "Average Incident Duration (Minutes)" and "250" appears in the text field beneath "Number of Managed Incidents". Beneath that line, "One Lane Blockage" appears and the number "27" appears in the text field beneath "Average Incident Duration (Minutes)". The number "100" in the text field beneath "Number of Managed Incidents". Beneath another line, "percentage of Estimated Secondary Incidents (enter as 0-100) appears. The number "4" appears in the text field.

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Figure 17. Screenshot. Project output/calculate ratio screen.

The Project Output/Calculate Ration screen shows the title Test_Case_2. Beneath and to the left of the title, “Segments” appears. Beneath that, a “Select All” button and a “Select None” button appear. The Select None button is grayed out. Beneath the Select All button, two checkboxes appear. Both checkboxes are checked. The first checkbox displays “Test2_seg1” and the second checkbox displays “Test2_seg2”. To the right of both checkboxes and text, a pencil icon and a trash can icon appear. A Produce Report button displays beneath and to the center of that content. To the right of that content is a Savings box. The Savings box displays the following content: the text, “Study period duration: 12 months”. Beneath that is text that reads “Delay Savings (Hours)” and to the right of that is a text box with “87.01” displayed. There is a checkmark inside a square to the far right. Beneath that line is text that reads “Fuel (Gallons)” and to the right of that is a text box with negative “17602.79” displayed. There is a checkmark inside a square to the far right. Beneath that line is text that reads “Secondary Accidents” and to the right of that is a text box with “2.35” displayed. There is a checkmark inside a square to the far right. Beneath that line is text that reads “Hydrocarbon (HC, MT)” and to the right of that is a text box with negative “1.09” displayed. Beneath that line is text that reads “Carbon Monoxide (CO, MT)” and to the right of that is a text box with negative “8.13” displayed. There is a checkmark inside a square to the far right. Beneath that line is text that reads “Nitrogen Oxide (NOx, MT)” and to the right of that is a text box with negative “0.54” displayed. There is a checkmark inside a square to the far right. Beneath that line is text that reads “Carbon Dioxide (CO2, MT)” and to the right of that is a text box with negative “175.45” displayed. There is a checkmark inside a square to the far right. Beneath that line is text that reads “Sulfur Oxide (Sox, MT)” and to the right of that is a text box with negative “2.82” displayed. There is a checkmark inside a square to the far right. Beneath that list is text that reads “Benefit-Cost Ratio of Chosen Factors”. Beneath that line of text is a text box with the numbers “8.45”.

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Figure 19. Chart. Fit diagnostics for total travel delay of light-duty vehicles.

Figure shows the fit diagnostics for total travel delay of light-duty vehicles. The figure includes several charts:

• Residual predicted value
• Rstudent predicted value
• Rstudent leverage
• Residual quantile
• Observed predicted value
• Cook’s D Observation
• Percent residual
• Proportion Less Fit Mean and Proportion Less Residual
• Supporting information:
  • 1319 observations
  • 7 parameters
  • 1312 error DF
  • 7.87e6 MSE
  • 0.614 R-square
  • 0.6122 Adj R-square

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Figure 24. Chart. Scatterplots of residuals against explanatory variables.

Figure shows the residual by regressors for the total delay of cars in hours. The figure plots residual on the vertical axis for six charts:

1. NofLaneIndex1
2. Duration in hours
3. Free flow speed in kilometers per hour
4. COMPTP(*10k)
5. Volume in thousands
6. Gradient(*10k)

The residuals suggest data fitting functions such as log-normal distributions. Incident duration has a random scatter plot suggesting a quadratic relationship between incident duration and travel delay of cars. Also, variance is not constant and there is fanning. Residuals of volume show cosine or bimodal distribution. Form Residuals associated with the free flow speed, truck composition, and gradient are also randomly scattered around zero. So the linear assumption seems reasonable.

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