# Appendix B Glossary of Terms

The following is a glossary of the terms used in the STEAM software.

Accident Costs -- The costs that result from an accident which may
include fatalities, injuries and property damage. Accident costs are
composed of internal and external components indicating whether costs
are borne by highway users or borne by society as a whole.

Capital Costs - This is the full cost of the capital improvement, which
includes any engineering studies, right-of-way acquisition and all
construction expenditures. For multiyear projects, capital costs include
all expenditures made from start to completion. This variable is in
dollars.

Centroid File -- Contains information on the zones specified for the
travel time analysis. Each zone is identified with the corresponding
node location. Only one centroid file is necessary and is used in both
the base and improvement cases. All market sectors require this file.

Cost per Gallon of Fuel -- The average cost per gallon of fuel paid by
transportation users. Gallon equivalents are used for transit modes that
do not use liquid fuel such as electric commuter trains (Units are in
dollars per gallon).

Emission Costs Per Ton -- The damage caused by a ton of emissions for a
given pollutant. The default values of emission costs per ton include
mortality, morbidity, agricultural damage, and loss of visibility. The
pollutants included in the analysis are Hydrocarbons (HC), Carbon
Monoxide (CO), Nitrogen Dioxide (NOx), and Particulate Matter (PM10).
(Units are dollars per ton).

Emission Rates -- The amount of emissions produced in grams by a vehicle
traveling one mile. The pollutants included in the analysis are
Hydrocarbons (HC), Carbon Monoxide (CO), Nitrogen Dioxide (NOx), and
Particulate Matter (PM10). (Units are grams per mile).

Expansion Factor. The expansion factor is used to expand the trip tables
to an annual value. A market sector that represents daily work trips may
have an expansion factor of 250 to represent all work days for a given
year.

External Accident Costs -- External costs are viewed as not perceived by
users and/or incidents upon other elements of society and are treated
the same way as emissions, noise, and global warming costs in the
benefit-cost analysis (Units are dollars per accident).

Fuel Consumption Rates -- These are the average fuel efficiency rates
expressed in gallons per mile for various types of vehicles (Units are
gallons or gallon equivalent per mile).

Fuel Costs -- The dollar value of a gallon of fuel or gallon equivalent
for vehicles that do not use liquid fuel such as commuter railroads
(Units are dollars per gallon or gallon equivalent).

Internal Accident Costs -- Internal costs are viewed as incident upon
and perceived by highway users and are treated in the same way as travel
time, operating, and out-of-pocket costs to highway users in the
benefit-cost analysis (Units are dollars per accident).

In-Vehicle Travel Time File -- One of the three "Other Changes Files"
which contains times for in-vehicle travel that are not accounted for in
the network analysis. The units are minutes of travel on a zone-to-zone
basis. A base and improvement case file is necessary for market sectors
that choose to input other in-vehicle travel time changes.

In-Vehicle Value of Time -- The dollar value placed on an additional
hour spent in a vehicle in traveling from origin to destination (units
are dollars per hour).

Market Sector -- Market sector is the term used in STEAM that allows the
software user the ability to divide demand into any combination of
transportation modes, trip purposes, and time periods.

Market Sector Name. The market sector name is used simply to keep track
of individual market sectors and can be up to 28 characters.

Market Sector Output File -- This file contains a summary of the output
of the market sector which is combined with other market sectors to
produce a summary analysis. Each market sector requires a unique market
sector output file name.

Midpoint of Construction. This is the year that falls in the mid point
of the construction period. For single year construction projects the
midpoint of construction would be the same as the year of opening.

Mode of Transportation. This input option allows the user to select one
of eight mode choices that include: auto, truck, carpool, local bus,
express bus, light rail, heavy rail, and other. Modes that are not
currently defined such as bicycle or walking can be put in the "other"
categetory.

Network Input File -- Contains the road network information that is used
in the network analysis module to calculate the minimum travel times and
distances for each zone-to-zone pair. Base and improvement case network
files are required for market sectors for which perform a network
analysis is performed.

Network Output File -- This file is the location that the STEAM model
stores the minimum travel times and distances for a given network. This
information is used later in the benefit-cost estimation. Base and
improvement case network output file are necessary for market sectors
for which a network analysis is performed.

Non-Fuel Highway User Costs -- The costs incurred by highway users that
are not included in fuel costs. They may include items such as vehicle
operating costs (tires, oil, etc.) (Units are dollars per mile).

Out-of-Pocket Cost File -- One of the three "Other Changes Files", which
contain out-of-pocket user costs that are incurred during a trip. These
costs may be items such as tolls or parking charges. The units are cents
per trip on a zone-to-zone basis. Base and improvement case files are
necessary for market sectors for which the user chooses to input other
out-of-pocket cost changes.

Out-of-Vehicle Travel Time File -- One of the three "Other Changes
Files", which contain times for out-of-vehicle or walk and wait travel
that are not accounted for in the network analysis. The units are
minutes of travel on a zone-to-zone basis. Base and improvement case
files are necessary for market sectors for which the user chooses to
input other out-of-vehicle travel time changes.

Peak Vehicles. The average change in transit peak vehicles that occurs
as a result of the highway or transit improvement.

Speed Relationship. Allows the user to select from four speed
relationships as a function of AWDT/C (average weekday daily
traffic/capacity). The four speed relationship choices are Daily, Peak,
Off-peak, and BPR Type Models.

Trip Table File -- This file contains the market sector trip table that
is used to estimate benefits and costs in the analysis. The trip table
includes all person (or truck vehicle) trips on a zone-to-zone basis for
that market sector during the specified period. Base and improvement
case trip table files are required for all market sectors.

Transit Vehicle Hours. The total annual change in transit vehicle hours
that occurs as a result of the highway or transit improvement.

Transit Vehicle Miles. The total annual change in transit vehicle miles
that occurs as a result of the highway or transit improvement.

Useful Life. Useful life is the estimated number of years that a
proposed facility can be used without requiring major reconstruction of
the facility.

Value of Time - The dollar value placed on an additional hour spent in
traveling from origin to destination (units are dollars per hour).

Vehicle Occupancy. The vehicle occupancy is the average number of people
per vehicle and is used to estimate the number of vehicle trips for a
given market sector based on the market sector person trip tables.
Separate occupancies can be provided for the Base Case and the
Improvement Case.

Walk-and-Wait Value of Time -- The dollar value placed on an additional
hour spent either walking or waiting for a transit vehicle when
traveling from origin to destination (units are dollars per hour).

Year of Opening. This is the year that the improvement project is
planned to be completed and opened for use.