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MicroBENCOST

MicroBENCOST was developed in the early 1990's through the National Cooperative Highway Research Program as a comprehensive and convenient framework for doing highway user benefit-cost analysis on personal computers. Like many early transportation models, it is a DOS application that also functions in the Windows environment.

MicroBENCOST is designed to analyze different types of highway improvement projects in a corridor. Benefits are calculated for existing and induced traffic, as well as for diverted traffic in the presence of a competing parallel route or when a bypass project is evaluated. The program allocates traffic between the highway being evaluated and the parallel routes, if present, using an equilibrium procedure that equalizes marginal user costs on competing routes for hour-by-hour traffic volumes. Eight different traffic allocation options exist, depending on the traffic year and the nature of the marginal user costs considered.

Vehicle delays and operating costs may be estimated for up to nine passenger vehicle types and up to nine truck types. Default values exist for four passenger vehicle types (small car, medium/large car, pickup/van, and bus) and seven truck types. Defaults include their percentages of the fleet, values of time, weights, and unit operating costs. The percent of HOV-lane users is specified if HOV facilities are present. User timesavings vary with the class of highway and the type of improvement being considered. The program incorporates:

  • Speed vs. volume-capacity-ratio relationships for rural highways based on the 1985 Highway Capacity Manual,
  • Interchange and intersection delay relationships derived from off-line TRANSYT-7F simulations,
  • Railroad grade crossing delays based on simple deterministic queuing concepts,
  • Incident and work zone delays also based on simple queuing concepts.

Values of time are factored to reflect discomforts due to stopping, congestion, and rough pavement. Although the program provides many default values, the amount of input needed to set up a run can be substantial.

Project Types Evaluated: MicroBENCOST evaluates seven types of highway projects: (1) capacity enhancement, (2) bypass construction, (3) intersection or interchange improvement, (4) pavement rehabilitation, (5) bridge improvement, (6) highway safety improvement, and (7) railroad grade crossing improvement. Highways may contain several different types of HOV facility configurations. Only highway projects are considered.

Scope of Application: The analysis is based on estimated Annual Average Daily Traffic (AADT) for through traffic on the highway of concern with and without the proposed improvement, as well as AADT's without the project on a competing parallel highway, if one is present. Each highway is divided into as many as 20 segments for input of basic geometric data as well as segment-specific traffic increments and cross-street data. Two short-cut traffic forecasting methods are provided to estimate annual traffic through all the years of the analysis period.

Benefit Categories Considered:

  • User travel times
  • Vehicle operating costs
  • Accidents

User benefits for induced traffic are counted as half the amounts that accrue to trips previously on the facility, consistent with consumer surplus theory.

Cost Categories Considered:

  • Total initial cost
  • Salvage (residual) value at the end of the evaluation period
  • Rehabilitation and maintenance costs during the analysis period

MicroBENCOST treats salvage values and changes in facility rehabilitation and maintenance costs as both costs and benefits (see the B/C ratio definitions, below). The program estimates residual values for infrastructure components at the end of the evaluation period. This reduces the portions of infrastructure costs compared against the benefits.

The program lets the user specify the year when each construction cost component is incurred, and when future year benefits begin to flow. The analysis period, including the time needed for construction prior to the start of benefits, may last up to 40 years.

Economic Performance Measures Provided for the Proposed Project:

  • Net present worth
  • "Gross" B/C ratio (User Benefits/Construction+Maint. Cost-Salvage Value)
  • "Net" B/C ratio (User Benefits+Salvage Value+Maint. Cost Saving/Construction Cost)
  • Internal rate of return

Other Quantitative Impacts Considered:

  • Change in emissions of carbon monoxide (kg.) - not $-quantified
  • Change in fuel consumption (gals.)

MicroBENCOST is distributed by the Texas Transportation Institute, where it was developed, and by McTrans (http://mctrans.ce.ufl.edu/). The software and documentation are available for less than $100.

Example

The MicroBENCOST User's Manual (McFarland et al, 1999a) describes the evaluation of a proposed $135 million freeway that bypasses an urban area, drawing traffic from an existing major arterial through town. The existing arterial carries 25,000 vehicles per day in 1991 and is forecast to carry 40,000 vehicles per day in 20 years, if the bypass is not built. There also exists a minor arterial that bypasses town parallel to the proposed new freeway. The alternate route carries 20,000 vehicles per day in 1991, forecast to grow 2.38% annually if the bypass freeway is not built (the same without-improvement growth rate as the existing arterial through town). All alignments have zero grades and curvatures. The freeway construction period is two years, followed by an operational economic lifetime of 20 years. To simplify matters, delays due to work zones and traffic incidents are ignored in the analysis.

The following data are specified to define the problem.

Project Characteristics
Project Type Bypass
Current Year 1993
Alternate Route? Yes
Area Type Urban
Construction Cost $135,000,000


Route Characteristics
Characteristic Existing Route Alternate Route Proposed Route
Name Texas Ave. 2-Lane West Bypass New East Bypass
Class Other Principal Arterial Minor Arterial Other Freeway
Number of Segments 2 1 2
Traffic Data Input Base & Growth Rate Base & Growth Rate Base & Growth Rate
Hourly Traffic Distrib. Hours of Day Hours of Day Hours of Day
HOV Facility No No No
Base Year 1991 1991  
Base Year Thru Traffic 25,000 20,000  
Annual Growth Rate 2.38% 2.38%  
Seg. 1: Name Existing Seg. A Alternate Route Proposed Seg. A
Seg. 1: Access Control None None Full
Seg. 1: Length 5.2 10.8 7.6
Seg. 1: Inters. Type Signals Signals Simple Diamond
Seg. 1: # of Inters. 2 3 1
Seg. 1: # Lanes Inb. 2 1 2
Seg. 1: # Lanes Outb. 2 1 2
Seg. 1: Data by Direction No No No
Seg. 1: Median Width 8 0 12
Seg. 1: Design Cat. Suburban Suburban  
Seg. 1: Functional Cl. Principal Minor  
Seg. 1: Inters. Spacing 2.6 (default) 3.6 (default)  
Seg. 1: % Grade 0 0 0
Seg. 1: Deg. Curvature 0 0 0
Seg. 1: Add'l. Local AADT 0 0 0
Seg. 1: Minor Route AADT 5000 2000 5000
Seg. 1: Minor Access Ctrl. None None None
Seg. 1: Minor Lane Inb. 1 1 1
Seg. 1: Minor Lanes Outb. 1 1 1
Seg. 1: Minor Design Cat. Suburban Suburban Suburban
Seg. 1: Minor Func. Cl. Minor Minor Minor
Seg. 1: Minor Median Width 0 0 0
Seg. 1: Minor Dist. to Next Int. 1.5 0.4 0.7
Seg. 1: # Work Zones 0 0 0
Seg. 1: # Incident Cat. 0 0 0
Seg. 2: Name Existing Seg. B   Proposed Seg. B
Seg. 2: Access Control None   Full
Seg. 2: Length 5.5   7.8
Seg. 2: Inters. Type Signals   Simple Diamond
Seg. 2: # of Inters. 5   3
Seg. 2: # Lanes Inb. 2   2
Seg. 2: # Lanes Outb. 2   2
Seg. 2: Data by Direction No   No
Seg. 2: Median Width 8   12
Seg. 2: Design Cat. Intermediate    
Seg. 2: Functional Cl. Principal    
Seg. 2: Inters. Spacing 1.1    
Seg. 2: % Grade 0   0
Seg. 2: Deg. Curvature 0   0
Seg. 2: Local Base AADT 0   0
Seg. 2: Minor Rt. AADT 10000   10000
Seg. 2: Minor Access Ctrl. None   None
Seg. 2: Minor Lane Inb. 2   2
Seg. 2: Minor Lanes Outb. 2   2
Seg. 2: Minor Design Cat. Intermediate   Suburban
Seg. 2: Minor Func. Cl. Minor   Minor
Seg. 2: Minor Median Width 0   8
Seg. 2: Minor Dist. to Next Int. 0.25   0.5
Seg. 2: # Work Zones 0   0
Seg. 2: # Incident Cat. 0   0

Default values are used for the percentage of trucks, vehicle fleet characteristics, highway capacities, accident rates, and the vehicle delay and cost parameters.

Note that no traffic is given for the proposed bypass freeway, which reflects the convention that, for bypass projects, induced traffic is zero. The only benefits considered are due to traffic diversion from the existing routes to the new bypass.

Future traffic is allocated among the three competing routes using "with-improvement volumes and user delay costs at the end of the analysis period," one of eight allocation methods available. Future annual traffic estimates can be modified, if desired.

The following annual estimates are tabulated for each route segment of each route, with and without the proposed bypass:

  • Average Speed
  • Annual Average Daily Traffic (AADT)
  • Minor Route (cross-street) AADT
  • Fuel Consumption (gals.)
  • Carbon Monoxide (kg.)
  • Total Value of User Travel Time
  • Total Vehicle Operating Cost
  • Total Accident Cost

Changes due to the bypass in total annual delay costs, vehicle operating costs, and accident costs are also tabulated.

The following "bottom line" summary of the evaluation is generated:

Summary of the Evaluation
Total Discounted User Benefits (Mill.$) $135.969
Discounted Construction Cost (Mill.$) $128.571
Discounted Salvage Value (Mill.$) $42.308
Discounted Increase in Maint. and Rehab. (Mill.$) $10.870
Fuel Consumption Savings (Mill. Gal.) -27.668
Carbon Monoxide Emission Reduction (Mill. Kg.) 6.520
Net Present Value (Mill.$) $38.835
Gross Benefit-Cost Ratio 1.400
Net Benefit-Cost Ratio 1.302
Internal Rate of Return (Percent) 7.170%

The bypass project is shown to be economically favorable. Note that some components of the infrastructure are regarded as having substantial residual values at the end of the 20-year horizon, which reduces the net construction cost by about 25% after the salvage value is discounted through 20 years at the default discount rate of 5%.

The above example illustrates the minimum amount of information that must be provided in order to evaluate a typical project that includes an alternate route. While it may appear like a great deal of information, the actual data input process is completed quickly, due to the user-friendly data input screens and extensive use of suggested default values.

In addition to the inputs shown above, the following default values are likely to be modified in most typical applications:

  • Discount rate (default = 5%)
  • Breakdown of total construction cost into components
  • Infrastructure component service lives
  • Unit costs of fatal, injury, and property damage accidents
  • Percent trucks
  • Breakdowns of the passenger vehicle and truck fleets into specific vehicle types

The components of infrastructure construction cost are:

  • Preliminary Engineering
  • Right-of-Way
  • Major Structures
  • Grading and Drainage
  • Sub-base and base
  • Surface

Three additional user-defined components may also be included.

MicroBENCOST divides the total project construction cost into components based on default percentages, depending on project type and area type (urban or rural). Typical service lives for the components are compared to the evaluation period and used to estimate the corresponding residual values remaining at the end of the period.

MicroBENCOST incorporates a huge library of default values to allocate traffic and to perform the different steps of cost and benefit estimation. All values are accessible and may be changed by the user. A companion program is provided to update this library on a permanent basis. Since the library of default values was assembled in the early 1990's by the NCHRP project, and some values are obtained from data sources created previously, the user should be careful to adjust for the possibility that some default values, such as unit costs of accidents, values of time, and unit vehicle costs, could be out of date.

The User's Manual details the library of default data used by the program. (McFarland et al, 1993a) All of these data may be accessed and modified. Some of the key data tables are:

  • "Discomfort" factors used to increase values of time when congestion is present
  • "Discomfort" costs and speed reduction factors due to poor pavement condition
  • Passenger and truck fleet composition and occupancies, by functional class and area type
  • Passenger fleet composition and occupancies for HOV users, by HOV facility type
  • Value of time, and unit costs for fuel, oil, tires, depreciation, and vehicle maintenance by vehicle type and area type (1990 $)
  • Gross vehicle weights for different truck types, by area type
  • % of AADT and directional split in each hour of the day, by functional class and area type
  • % of AADT and number of hours of the year in each volume level category, by functional class and area type
  • The distribution of train traffic over the hours of the day, by area type, which is used to estimate highway user delays for railroad grade crossing projects
  • Default lane and shoulder widths, by functional class and area type
  • Design free flow speeds by highway type or arterial class
  • Speed limits by functional class and area type
  • Lane capacities for freeways, multilane, and 2-lane rural highways by highway type, number of lanes, lane width, shoulder width, and design speed
  • Relationships of speed versus volume-capacity ratio for freeways and multilane highways, by highway type and design speed
  • Relationships of speed versus volume-capacity ratio for 2-lane rural highways, by grade and percent no-passing
  • Average arterial running speeds by arterial class, free flow speed, and average segment length
  • Percent traffic with interrupted flow for major and minor routes, by intersection and interchange type
  • Percent vehicles stopping and average delay by intersection and interchange type and hourly volume with interrupted flow
  • Adjustment factors for progression by type of signal, type of arrival, and hourly volume with interrupted flow
  • Ramp volume as percent of ADT, ramp speed as % of free flow speed, and incremental travel distance, by interchange type and flow condition
  • Percentage of traffic diverting around inadequate bridges, by vehicle type (for bridge improvement projects)
  • Pavement condition (PSI) and routine maintenance cost, by functional class and area type
  • Fatal, injury, and property-damage-only (PDO) accident rates by area type, facility type, number of lanes, and AADT
  • Cost per fatal, injury, and PDO accident by area type and facility type (1990 $)
  • Percent of VMT traveled and % VMT under cold-start conditions traveled for different ambient temperatures and altitudes, by area type (for emission calculations)
  • Lane capacity adjustments for open lanes in the presence of work zones or incidents

Individual accident rates and unit costs of accidents are given for highway segments, intersection or interchanges, railroad crossings, and bridges.

User benefits are estimated separately for different hours of the day or of the year in order to accommodate different levels of demand, and then are aggregated. The user can choose to base user benefit calculations either on the expected traffic distribution for the 24 hours of the typical day, or on the expected traffic distribution over all hours of the year.

Although the user can access and change default data for the unit costs associated with vehicle operation (such as $/gal of fuel consumed) as well as certain parameters which influence CO emissions, the equations for estimating emissions and for estimating the physical quantities associated with vehicle operating costs (such as gallons of fuel consumption) are built into the model and cannot be changed. This might present a problem for estimating these future impacts if vehicle technologies change significantly. The built-in emission model is a regression fit to 1987 data generated by MOBILE 4, which predicts grams/mile of CO based on average speed, ambient temperature, altitude, year, and percent of cold-starts. The model is said to capture the effects of changing vehicle technologies expected through 2005. The built-in equations for estimating vehicle operating cost quantities (fuel, oil, tires, depreciation, and maintenance) for the different default vehicle types are functions of grade, speed, curvature, and speed changes. These vehicle operating cost equations were calibrated on field data obtained from a 1982 study. (Zaniewski et al) These equations are described in detail in the 1993 NCHRP report. (McFarland et al, 1993b)

Sources

McFarland, W. F., J. Memmott, M. Chui, M. Richter, and A. Castano-Pardo. MicroBENCOST User's Manual (Draft). Texas Transportation Institute, Texas A&M University. College Station, TX. Prepared for NCHRP Project 7-12. October 31, 1993a.

McFarland, W. F., J. Memmott, and M. Chui. Microcomputer Evaluation of Highway User Benefits - Final Report for NCHRP 7-12 (Draft). Texas Transportation Institute, Texas A&M University. College Station, TX. October 31, 1993b.

Zaniewski, J.P. et al. Vehicle Operating Costs, Fuel Consumption, and Pavement Type and Condition Factors. Final Report. Texas Research and Development Foundation. Austin TX. June 1982.