Comprehensive Transportation Plan - March 2019

Step 4 : Sum the values for Steps 1-3 and multiply by 0.30 (30%). This is the NCDOT approved Miscellaneous Factor, added to reflect potential additional cost categories (e.g. historical preservation, archaeology, etc.) that may impact the project. This subtotal is the contract cost. Step 5 : Multiply Step 4 by 15% on Federal funded projects and 10% on State funded projects. These values represent the engineering and contingency costs. Step 6 : Apply the Terrain Adjustment Factor by multiplying the factor by the sum of Step 4 and Step 5. Morrisville falls within the Piedmont region, which has a Terrain Adjustment Factor of 1.15. This factor is added to account for additional project costs typically associated with topography, and differs for North Carolina’s mountain and coastal regions. This is the construction cost. Step 7 : Apply NCDOT’s Right-of-Way “Rule of Thumb” calculation to include right-of-way costs equivalent to 40-50% of the project cost. This range was vetted through discussions with roadway design engineers with recent experience in the Town of Morrisville. Step 8 : Sum the results of Step 6 and Step 7 to obtain an overall project cost. This is the value shown on the project sheets in Appendix B . Crash History To ensure that project recommendations best serve areas with existing safety concerns, crash data from June 2013 to May 2016 was analyzed relative to crash severity and frequency. Crash frequency includes a raw count of crashes along roadway project segments. The crash severity metric (EPDO Score) was calculated using NCDOT’s methodology ( Equation C-1 ) that converts each crash to a “property damage only” equivalency. This is called the equivalent property damage only (EPDO) index, and gives greater weight to more severe crashes. Table C-2 below shows the coefficients used by NCDOT to weight crashes by severity.

Equation C-1: EPDO Index Calculation ܧ ܲ ܦ ܱ = 76.8( ܭ ൅ ܣ ) + 8.4( ܤ ൅ ܥ ) + 1( ܲ ܦ ܱ ) Table C-2: EPDO Coefficients SEVERITY DESCRIPTION

WEIGHT

K A B C

fatality

76.8 76.8 8.4 8.4

incapacitating injury

evident non-incapacitating injury

injury not evident, but complaint of pain or lapse in consciousness

PDO

property damage only

1

Cross Section Each project sheet has a cross section that is reflective of the specific roadway elements proposed as a part of that project. These specific cross sections were developed to be consistent with recommendations shown in Chapters 3 and 4 , and by relying on past plans and coordination with NCDOT. The generalized cross sections shown in Appendix B were used as a reference point during this exercise.

C-2 | PAGE