Cal-B/C was developed for the California Department of Transportation (Caltrans) as a tool for benefit-cost analysis of highway and transit projects. It is an Excel (spreadsheet) application structured to analyze several types of transportation improvement projects in a corridor where there already exists a highway facility or a transit service (the base case). Benefits are calculated for existing and (optionally) for induced traffic, as well as for any traffic diverted from a parallel highway or transit service. Peak and off-peak benefits are estimated separately. Highway impacts are provided for HOV and non-HOV passenger vehicles and trucks. Highway time savings are based on a speed-congestion relationship adapted from the 1997 Highway Capacity Manual, which assumes a highway lane capacity of 2000 vph. (An HOV lane's capacity is 1600 vph.) Minimal input data are required because the spreadsheet is populated with many default values suited to California urban and rural applications. All defaults and intermediate calculations may be overridden as desired by the user.

Project Types Evaluated: Highway projects may include general improvements, HOV and passing lanes, interchange improvements, and constructing a bypass highway. Transit projects may include new or improved bus services, with or without an exclusive bus lane, light-rail, and passenger heavy-rail projects. A proposed highway or transit project may be evaluated independently or in the presence of the competing mode, in which case benefits to diverted traffic are estimated.

Scope of Application: As appropriate, each analysis is based on annual transit person-trips and the representative annual average daily traffic for a highway facility. Values are input for the base case and the proposed improvement alternative. Inputs are factored to peak and off-peak volumes and (for highways) truck volumes. HOV lane volumes, if included, are entered separately. As needed, free-flow speeds, before after transit trip times, transit vehicle-miles and before-after accident data are entered, along with fixed costs and annual costs, on a year-by-year basis.

Benefit Categories Considered:

• User benefits (time savings)
• Reduced vehicle operating costs (for highway users)
• Accident reduction benefits (both highway and transit)
• Reduced emissions (CO, NOx, PM10, VOC) (optional output)

Cost Categories Considered:

• Total life cycle investment and annual operating and rehabilitation costs

The 20-year economic lifetime to be analyzed begins after a startup period for project implementation, which may last up to seven years. Thus, costs and benefits are discounted through a total time period ranging from 20 to 27 years.

Economic Performance Measures Provided for the Proposed Project:

• Net present worth
• Benefit-cost ratio
• Internal rate of return
• Payback period

Other Quantitative Impacts Considered:

• Undiscounted total costs and benefits by impact category

Example

The User's Guide (Booz-Allen & Hamilton Inc., 1999a) describes a Cal-B/C application to evaluate the improvement of an existing passenger rail line that runs 50 miles adjacent to an existing 6-lane highway in a Southern California urban area. The construction period for the improvement is three years, followed by an operational economic lifetime of 20 years.

The AADT on the existing highway is 130,000, and the forecast AADT for 23 years in the future (3 years construction plus 20 years operational life) is 267,800. The rail line improvement is not expected to cause an increase in highway traffic, so the with-project AADT is the same as without. The diversion of highway traffic to the rail line is NOT reflected in the with-project future AADT but rather is accounted for in the transit demand inputs. Default values are used for percent trucks and vehicle occupancies.

Data are entered describing the past three years of actual collision experience on the highway, where there were 2 fatalities, 35 injury and 50 property damage only (PDO) collisions recorded. The statewide average accident rate for the existing facility type is entered (0.80 accidents per million vehicle-miles) along with the expected percentages of fatal and injury accidents (2% and 32%, respectively). The expected accident rate, once the rail line is implemented, is also entered (0.56 per million vehicle miles) along with the percentages of fatalities and injury accidents (1% and 33%), which reflect the reduced highway congestion after the rail service improvement. Both sets of expected accident rates are factored to be consistent with the actual collision experience before being used to estimate the benefits from collision reduction.

Annual person-trips by transit (rail) are entered for the without-project case: 310,000 for year 1 (the year after construction is completed) and 460,000 for year 20. Transit person-trips for years 1 and 20 for the with-project case are also entered (400,000 and 600,000, respectively). It is assumed that 60% of the transit demand occurs during five peak hours of the typical day. It is also assumed that 65% of the new transit riders for the with-project case are diverted from the parallel highway, so that quantity of traffic is automatically subtracted from the previously entered with-project future highway AADT estimates. Annual transit vehicle-miles for with-project and without-project are entered as 532,000 and 740,000 vehicle-miles, respectively, assuming no growth in service during the project lifetime. The average train length is specified as 4 vehicles per train for the with-project case and 3 vehicles per train for without-project. Rail line improvements are expected to decrease the average trip time from 50 to 45 minutes per rail trip. Finally, rail-crossing improvements that are involved are expected to reduce the number of rail accidents by 5%.

Default values are accepted for all other demand and operational inputs. The pertinent cost data are the following:

Cost Data for Passenger Rail Example

When highway AADT's are entered, the program automatically estimates the peak and non-peak traffic volumes and speeds for the 1st and 20th year after construction, for the with-project and without-project cases. In this example, data from a regional travel model were available and used to replace the Cal-B/C volume estimates with what are thought to be the more accurate values. In the optional input area, the peak period highway passenger vehicle and truck volumes were overridden by with-project and without-project, peak and off-peak volume estimates for passenger vehicles and trucks, for both year 1 and year 20 following construction.

As data are entered, Cal-B/C automatically summarizes the economic impacts in the "Results" page of the spreadsheet. The option to include benefits due to induced travel was selected. Based on the given data, the summary of economic impacts calculated at a 6% discount rate is:

Summary of Impacts for Passenger Rail Example:

Note, in this example, that the option to estimate air quality emission benefits was not selected.

Cal-B/C can be used to evaluate a project that improves highway travel or transit travel, or a project where benefits accrue to both modes, such as a highway widening which also improves express bus running times. For proper evaluation, the user must identify in the project setup area all of the purposes that the project is intended to serve. In the case of projects including transit improvements, the user may specify the percent of new riders who previously were highway users, so that the benefits can be properly estimated for diverted traffic. Time benefits to newly generated (induced) traffic are optionally calculated according to consumer surplus principles, assigning them half the time saving benefits realized by prior users. If the option to calculate induced traffic benefits is not chosen, induced travel benefits are ignored.

Very little input data are needed if the user is willing to accept the built-in default values. The data that must be entered to perform an analysis are the following:

• The type of project and its location—urban southern or northern CA, or rural (determines some default parameters)
• Length of the construction/implementation period (number of years)
• Up to three types of initial costs, for each year in the construction/implementation period
• Up to four categories of post-opening costs, for each of 20 years of assumed project life

If the proposed project involves a highway improvement, the following are also required:

• Number of highway lanes (existing and proposed)
• Free-flow highway speed
• Length of the highway section
• Current Annual Average Daily Traffic (AADT)
• Expected AADT in the 20th year after the project would open (with & without the project)
• Current (3-year) counts of fatal, injury, and property damage only (PDO) collisions
• Expected accident rates for the type of facility in question (with & without the project)
• Expected percentages of fatal and injury collisions (with & without the project)

If the proposed project involves a transit improvement, the following are also required:

• Annual person-trips in the 1st year after the project would open (with & without project)
• Annual person-trips in the 20th year after the project would open (with & without project)
• Annual vehicle-miles in the 1st year after the project would open (with & without project)
• Annual vehicle-miles in the 20th year after the project would open (with & without project)
• Average transit trip time in the peak and off-peak under existing conditions
  

Several more data are required for certain project types:

• Number of HOV lanes (if HOV lanes are involved)
• HOV vehicle occupancy rule, 2+ or 3+ (if HOV lanes are involved)
• Hourly HOV traffic during the peak period (HOV traffic is not differentiated in off-peak)
• Whether an exclusive bus right-of-way exists (if a bus improvement project)
• Average number of vehicles per train (if a rail improvement project)
• Percent reduction in expected transit accidents (if a transit safety project)
• Truck speed (if a passing lane project)
• ADT data, number of lanes, and free flow speed information for the bypass or intersecting route (if a bypass or intersection improvement project)

The user will often specify several other data items, which have default values:

• Total length of the peak periods (defaults to 5 total hours per day)
• Expected AADT in the 1st year after the project would open (with & without the project)
• Percent trucks - with & without the project (defaults to 9%)
• Average vehicle occupancies (peak HOV and peak & off-peak for non-HOV, with & without the project)
• Average transit trip time in the peak and off-peak under with-project conditions
• Percent transit trips made during the peak period (defaults to 7.8% per hour of peak)
• Percent new transit trips diverted from the parallel highway (defaults to 0%)

Beyond these limited input requirements, the user can override other default and calculated values. This can be done if detailed volume and speed estimates over time are available from regional planning models or simulation models. If accurate outside speed and trip time estimates are available, it is a good idea to input such data, because the internal speed-congestion relationship used to estimate highway time savings is crude. The model estimates highway speed as:

Speed = FreeFlowSpeed/(1+0.15(v/c)10)

Where "v" is the average hourly volume for the period (peak or off-peak) and "c" is capacity, which is assumed to be 2000 vph per lane for regular highways and 1600 vph per lane for HOV facilities.

Typical daily peak and off-peak volumes are determined by factoring the annual average daily traffic based on the default assumption that each peak hour contains 7.8% of daily traffic. Alternatively, peak and off-peak volumes, as well as speeds, for HOV's, non-HOV's, and trucks may be entered directly if available from other sources. At a minimum, the default percentage of traffic in the peak period may be overridden if better local values are available.

Modestly detailed year-by-year cost data must be provided, in several fixed and annual cost categories. Although cost data are not explicitly categorized by mode, enough categories exist (three fixed and four annual cost categories) that the user can keep mode-specific accounts separate if desired.

Cal-B/C is accompanied by a technical supplement document (Booz-Allen & Hamilton, Inc. 1999b) that provides a detailed and thoughtful discussion of all of the elements entering into a project benefit-cost analysis. The technical supplement also provides detailed comparisons of the Cal-B/C methodology and assumptions relative to many of the other available public sector benefit-cost analysis tools, some of which are also described on this web site.

Sources