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AECOM1013 Centre RoadSuite 222Wilmington DE, 19805aecom.com302-468-5880 tel302-999-9831 faxProject name:BR 1-424A on Old Corbit RoadTo:Jason HastingsState Bridge Engineer800 S. Bay RoadDover, DE 19901Project ref:T200507102From:Joseph HofsteeDate:CC:March 27, 2018Neil ShemoMemoAECOM developed a Benefit Cost Analysis (BCA) for the replacement of Bridge 1-424A on OldCorbit Road. In order to complete this, AECOM used the Federal Emergency Management AgencyBCA Toolkit 5.3.0. The Federal Office of Management and Budget (OMB) require federally fundedprojects to demonstrate cost effectiveness for the use of public funds. As such, FEMA developed theBCA Toolkit to meet this requirement set forth by OMB. The Damage-Frequency (DFA) MitigationProject Long Form wizard was used to generate a Benefit Cost Ratio (BCR) for analysis. The DFAmodule is the only module that can be used for non-building projects such as roads, bridges, andutilities. Based on the information that is allowed to be entered into the BCA, a BCR of 0.10 wasobtained. A BCR of 1.0 or greater is required for a project to be eligible for funding. This memo willexplain what data and information was used in developing the BCA and some of the restrictionsassociated with the BCA Toolkit.BR 1-424A and a large portion of Old Corbit Road, as determined by Federal EmergencyManagement Agency (FEMA), is located within floodplain zone AE not within the LiMWA (Limit ofModerate Wave Action Line), as can be seen in Firmette 100003C030K (attached). ZONE AE is anarea where a detail study was completed and the base floodplain is provided. Areas outside theLiMWA have wave heights of less than 1.5 feet. Old Corbit Road has a Base Flood Elevation of 8 feet.Old Corbit Road has the following Stillwater elevations: 6.25 feet for the 10 year, 7.25 feet for the 50year, and 7.69 feet for the 100 year. The previous mentioned Stillwater elevations are from acompleted Flood Insurance Study (FIS) Report conducted along the Appoquinimink River.Old Corbit Road lies east of Odessa and provides a direct connection between Old Sate Roadand Silver Run Road. Old Corbit Road is a local road with an average daily traffic (ADT) of 340vehicles. The ADT was calculated in 2015 through the use of automated traffic recorder counts alongthe roadway. There are 16 homes located directly on Old Corbit Road and an additional 10 homeslocated in a small neighborhood along Old Corbit Road. The overtopping of the roadway results in anadditional 0.78 miles of travel for vehicles to detour around the closure from the intersection of OldState Road and Old Corbit Road to the intersection of Silver Run Road and Old Corbit Road. Theadditional distance associated with the closure results in an additional 45 seconds of travel.The existing roadway elevation is 2.60 feet above sea level in the area of the bridge. Currentlythe roadway overtops twice daily in the area of the bridge as a result of the two high tides. Theaverage water elevation event is 3.17 feet above sea level due to the tidal influence. The proposed1/4
MemoBR 1-424A on Old Corbit Roadbridge would be reconstructed to a proposed elevation of 6.18 feet. Where the proposed bridgeapproaches would tie in will result in the lowest elevation along Old Corbit Road being 4.25 feetreducing the occurrences of the roadway overtopping.In order to complete the BCA, we need to determine what would warrant a closure of theroadway and the number of closures that would occur. Studies have found 6 inches of water can resultin a driver losing control of a car and 2 feet of water can result in a vehicle being swept away. As aresult, for our purposes it was assumed the road would need to be closed if the road was overtoppedby 6 inches or more of water. AECOM has examined the National Oceanic and AtmosphericAdministration (NOAA) data for Reedy Point from January 1, 2008 to December 31, 2017, which is theclosest gauge to the project site and shares the same base flood plain elevation of 8 feet. From thatdata the average number of hours per year that the water elevation exceeded 3.1 feet and 4.75 feetwere determined. The elevation of 3.1 feet was used for determining the number of existing closures;this number was obtained by adding 6 inches to the roadways current lowest elevation of 2.6 feet.The elevation of 4.75 feet was used for determining the number of post mitigation closures; thisnumber was obtained by adding 6 inches to the roadways post mitigation lowest elevation of 4.25 feet.For that ten year period the water elevation exceeded 3.1 feet 4441 hours per year on average. Forthat ten year period the water elevation exceeded 4.75 feet 2435 hours per year on average.On March 27, 2017, we met with the Odessa Fire Company to discuss the potential closure ofOld Corbit Road. During discussions with emergency responders, they cited having to respond on siteseveral times a year for vehicles that become partially submerged in the area of Bridge 1-424A.The BCA was developed to compare the future benefits of the mitigation work compared to thecost associated with the mitigation work. For this case the mitigation work is the reconstruction of theBridge 1-424A to raise the bridge to reduce the occurrences of the bridge overtopping during tidalevents. As stated previously, the DFA Project Mitigation Long Form was used. The first step is toidentify the structure and the mitigation type, the structure was Bridge 1-424A and the mitigation typeselected was Elevation.The next component entered is the project useful life (PUL). The PUL as defined by FEMA isthe estimated amount of time (in years) that the mitigation action will be effective; how long it will laston the landscape. The PUL data field is used to calculate annualized benefits. For BR 1-424A the PULis 50 years. PUL in this case is limited by FEMA acceptable limits for useful life of a bridge. The FEMAPUL table defines this as 35-50 years for bridges with the standard value being 50 years. As a result ofthe Delaware Department of Transportation defining useful life of a bridge at 100 years for a newbridge structure in the DelDOT Bridge Manual, 50 years is allowed to be used. No backup data will berequired to be submitted as part of the BCA formal submission as a result of using the standard value.For the cost of the portions of the BCA, a Mitigation Project Cost of 3,750,000 was usedwhich constitutes the bridge replacement cost and engineering design cost. A Base Year of Cost of2018 was used; the base year of costs for this mitigation project is the year that the cost estimate wasdeveloped. An annual maintenance cost of 10,000 was used. A discounted rate is applied to thefuture 50 years of maintenance cost. A discount rate of 7% was used; this is the Federal Office ofManagement and Budget (OMB) mandated discounted rate that must be used for all BCAs. Thediscounted rate determines the time-value of money. A discount rate is used to calculate a value today(the Net Present Value) of future benefits so that they can be compared to the costs of a mitigationproject. This resulted in a present worth of 138,007 of the annual maintenance cost. The final projectmitigation cost for the project is 3,888,007.The next component of the BCA is determining the benefits of the projects. This is where theBCA is very limited in what can be entered for a roadway/bridge project; there are only three benefitsavailable: additional trip miles, lost productivity, and mental stress. Mental stress and lost productivityAECOM2/4
MemoBR 1-424A on Old Corbit Roadcannot be applied for this project. To measure the benefits of reducing additional trip miles, theadditional trip miles before mitigation need to be compared to the additional trip miles after mitigationwhich was used to measure the project effectiveness. The project effectiveness is how well the projectwill reduce future damages. Only structure acquisition and demolition and structure acquisition andrelocation projects can assume that a project is completely effective.The per diem cost of additional trips was determined by entering the following data: Estimate Number of One-Way Trips per day – 340 Additional Time per One-Way Trips – 1 min Number of additional miles per trip – 0.8 miles Federal Rate mileage rate - 0.54/mile (this is prepopulated)The economic loss per day of loss of function is 336/day.The historic damages before mitigation was determined by converting the 4441 hours per yearthat the road is impassable to equivalent day per years which is 185 days. The historic damages aftermitigation was determined by converting the 2435 hours per year that the road is impassable toequivalent day per years which is 101 days. This results in an annual damage before mitigation of 62,229 and an annual damage after mitigation of 33,974. When converted to present value it resultsin a before benefit of 858,807 and after benefit of 468,867. This results in the project having a netpresent mitigation value of 389,940 ( 858,807 - 468,867). Net Present Value of Future Benefits isthe amount of annual benefits that will occur for the life of the project, represented in a present orcurrent dollar value. This brings the values of future benefits in line with the current value of the projectcost. Future benefits are discounted by using a discount rate.The Benefit-Cost Ration is the Mitigation Benefits divided by the mitigation cost in this scenariothe value ended up being 0.10 ( 389,940/ 3,888,007). As a result, the project would not qualify for aFEMA grant using the standard BCA model.FEMA will allow for the use of alternative Benefit Cost Analysis however this requires FEMAapproving the model prior to submitting a grant application. With that in mind, we examined theadditional cost that the Odessa Fire Company would experience as a result of the closure. The firstitem we looked at was the additional mileage cost associated with traveling around Bridge 1-424Awhen it is impassable. For days closed and distance traveled we used the same information that wasused for additional vehicle miles traveled. Based on another module in the BCA toolkit, that is used fordetermining the BCA for improvements to a fire house, these results in a net mitigation benefit of 33,011. The other item we looked at was the cost associated with the Odessa Fire Companyresponding to a vehicle stuck in the water. If we were to assume 6 vehicles stuck in the water a yearwith the cost of responding assumed to be 3,000 per incidents, the before mitigation cost per yearwould be 12,000. Assuming that 3 vehicles would still need to be rescued in the post mitigationscenario this will result in a cost of 6,000 per year. As a result, the net benefit is 3,000 per year.Even when including the cost benefit associated with the Odessa Fire Company, the BCA does notmeet the requirements.The final additional item that could be included is historical damages to the cars. This wouldrequire obtaining the insurance claims for the vehicles that were damaged. This was beyond thescope of the study and likely there would not be enough records available to significantly alter theprevious outcomes, it is not recommended to pursue obtaining the insurance claims.Attachments:AECOM3/4
MemoBR 1-424A on Old Corbit Road-BCA report for Bridge 1-424A-NOAA values for Reedy Point-FEMA Firmettes-PUL with FEMA Standards-Travel Times around BR 1-424AAECOM4/4
MemoBR 1-424A on Old Corbit RoadBCA Report for BR 1-424A on Old Corbit RoadAECOM
27 Mar 2018Project: BR 1-424A on N24 Old Corbit RoadTotal Benefits: 389,940Project Number:T200507102Disaster #:State: DelawarePg 1 of 5Total Costs: 3,888,007Program:BCR:FMA0.10Agency: AECOMPoint of Contact: Joe HofsteeAnalyst: Joseph HofsteeProject Summary:Project Number:Program:Analyst:Point of Contact:Address:T200507102Disaster #:FMAAgency:Joseph HofsteeJoe HofsteeDiscount Rate:Phone Number:AECOM0.070302-468-58801013 Centre Road, Wilmington, Delaware, 19805Email:Comments:Structure Summary For:BR 1-424A, Middletown, Delaware, 19709, New CastleStructure Type: OtherHistoric Building: NoBenefits: 389,940Costs: 3,888,007MitigationElevationContact: Joseph HofsteeHazardDamage-Frequency AssessmentBCR: 0.10BCRBenefitsCosts0.10 389,940 3,888,007Fire House, Delaware, , New CastleStructure Type: BuildingBenefits: 0Version: 5.3.0Historic Building: NoCosts: 0Contact:BCR: 0.00
27 Mar 2018Project: BR 1-424A on N24 Old Corbit RoadTotal Benefits: 389,940Project Number:T200507102Disaster #:State: DelawareTotal Costs: 3,888,007Program:BCR:FMAPoint of Contact: Joe HofsteeStructure and Mitigation Details For:Pg 2 of 50.10Agency: AECOMAnalyst: Joseph HofsteeBR 1-424A, Middletown, Delaware, 19709, New CastleBenefits: 389,940Costs: 3,888,007BCR: .10Hazard: Damage-Frequency Assessment - FloodMitigation Option: ElevationLatitude:Longitude:Mitigation InformationBasis of Damages: Historical DamagesNumber of Estimated Damage Events: 4328Number of Events with Know RecurrenceIntervals: 4328Version: 5.3.0Project Useful Life: 50
27 Mar 2018Project: BR 1-424A on N24 Old Corbit RoadTotal Benefits: 389,940Project Number:T200507102Disaster #:State: DelawarePg 3 of 5Total Costs: 3,888,007Program:BCR:FMAPoint of Contact: Joe Hofstee0.10Agency: AECOMAnalyst: Joseph HofsteeRoads And BridgesFacility Description:Estimated Number of One-WayTraffic Trips Per Day: 340Old Corbit Road/BR 1-424AAdditional Time per One-Way Trip: 0:1Number of Additional Miles: 0.8Federal Rate: 0.540Economic Loss Per Day ofLoss of Function: 336Historic Damages Before and After MitigationAnalysis Year: 2018Analysis Duration: 54Utilities ( /day):Year Built: 1965User Input Analysis Duration: 10Buildings ( /day):Roads/Bridges ( /day): 336.37Damages Before MitigationDamages After MitigationDamage Year:RI: 1.00Are Damages In Current Dollars? YesRI: 1.00Are Damages In Current Dollars? YesBuildings (Days):Utilities (Days):Roads (Days): 185.0Buildings (Days):Utilities (Days):Roads (Days): 101.0Total 62,229Total Inflated 62,229Volunteers CostNumber of Volunteers Required:Cost of Volunteers Time ( /Hour/Person):Per-Person Cost of Lodging for a Volunteer:Number of Hours Volunteered/Person:Number of Days Lodging/Volunteer:Cost of Volunteers:Version: 5.3.0Total 33,974
27 Mar 2018Project: BR 1-424A on N24 Old Corbit RoadTotal Benefits: 389,940Project Number:T200507102Disaster #:State: DelawarePg 4 of 5Total Costs: 3,888,007Program:BCR:FMA0.10Agency: AECOMPoint of Contact: Joe HofsteeAnalyst: Joseph HofsteeSocial BenefitsMental Stress and AnxietyLost ProductivityNumber of Person:0Number of Worker:0Treatment Costs per person: 2,443.00Productivity Loss per person: 8,736.00Total Mental Stress and Anxiety Cost: 0.00Total Lost Productivity Cost: 0.00BCR Calculation ResultsExpected Annual Damages BeforeMitigationExpected Annual Damages AfterMitigationExpected Avoided Damages AfterMitigation (Benefits)Annual: 62,229Annual: 33,974Annual: 28,255Present Value: 858,807Present Value: 468,867Present Value: 389,940Mitigation Benefits: 389,940Mitigation Costs: 3,888,007Benefits Minus Costs:( 3,498,067)Benefit-Cost Ratio:0.10Cost EstimateProject Useful Life (years):50Construction Type:Mitigation Project Cost: 3,750,000Detailed Scope of Work:YesAnnual Project Maintenance Cost: 10,000Detailed Estimate for Entire Project:YesFinal Mitigation Project Cost: 3,888,007Years of Maintenance:50Cost Basis Year:Present Worth of Annual Maintenance Costs: 138,007Construction Start Year:Estimate Reflects Current Prices:YesConstruction End Year:Project Escalation:Version: 5.3.0
27 Mar 2018Project: BR 1-424A on N24 Old Corbit RoadTotal Benefits: 389,940Project Number:T200507102Disaster #:State: DelawarePg 5 of 5Total Costs: 3,888,007Program:BCR:FMAPoint of Contact: Joe HofsteeAgency: AECOMAnalyst: Joseph tachmentsFacility DescriptionWas calculated in 2015 usingautomated traffic recorder counts.Mitigation Project CostBased on previous cost estimatecompleted by DelDOT an increased forinflation.Number of Additional MilesTravel times were conducted in 2015 by Travel Time.pdfthe Delaware Department ofTransportation.Project useful lifePUL is based on the standard FEMAuseful life for bridges.Roads/BridgesWithout the project the roadway overtops as result of tidal events as resultthe road is impassable.Version: 5.3.00.10RE Old Corbitt Road.msgPUL with FEMA standards.pdf
MemoBR 1-424A on Old Corbit RoadNOAA Data Values for Reedy PointAECOM
NOAA Data from Reedy Point, Delaware200820092010201120122013201420152016201710 year averageAverage water elevation Hours exceeding 3.1 feet Days exceeding 3.1 feet Hours exceeding 4.75 feetDays exceeding 4.75 666667
MemoBR 1-424A on Old Corbit RoadFEMA FirmettesAECOM
MemoBR 1-424A on Old Corbit RoadPUL with FEMA StandardsAECOM
MemoBR 1-424A on Old Corbit RoadTravel Times around BR 1-424A ClosureAECOM
Dover, DE 19901 CC: Neil Shemo AECOM 1013 Centre Road Suite 222 Wilmington DE, 19805 aecom.com 302-468-5880 tel 302-999-9831 fax Project name: BR 1-424A on Old Corbit Road . the Delaware Department of Transportation defining useful life of a bridge at 100 years for a new bridge structure in the DelDOT Bridge Manual, 50 years is allowed to be .
