SPECIAL TRANSPORTATION
STRUCTURES
(Notes for Guidance )
Transportation Systems
Radu ANDREI, PhD, P.E.,
Professor of Civil Engineering
Technical University “Gh. Asachi” IASI
Lecture
Two
Transportation Systems
Developing a transportation system
Modes of transportation & organizations
Problems
Additional Readings
Developing a transportation
system(1)
Definition of a transportation system
• The transportation system in a developed nation is an
aggregation of vehicles, guideways,terminal facilities and
control systems that move freight and passengers.
• The transportation system involves a network of modes that
have evolved over many years. The transportation systems
that have evolved have produced a variety of modes that
complement each other . Thus intercity travel involves auto
and air modes; intercity freight travel involves pipeline, water,
rail and trucking; urban passenger travel involves auto or
public transit
Developing a Transportation
System(2)
Main components
of a transportation mode
•
The main components of any of these various modes of
transportation are : the fixed plant( the infrastructure
network)/the rolling stock( the park of specific vehicles)/ the
management scheme (these systems are permanently planned,
designed, built, operated and maintained by specific organizations
and agencies). New techniques are being applied for operating and
maintaining these systems , safely and economically.
•
The system consists of vehicles , guideways, terminl facilities, and
control systems, all these operating according established
procedures and schedules in the air, on land, and on water. The
system also requires harmonious interaction with the user, the
operator and the environment.
Developing a Transportation
System (3)
Advantages and complementarity of various transportation
modes
•
.Each mode of transport has inherent advantages of cost, travel
time, convenience and flexibility that makes it “ right for the job”
under the certain set of circumstances.
• The automobile is considered a reliable,comfortable and
flexible form of personal transportation for many people.
• Air transportation , supplemented by the auto for local travel
will be selected when distances are great and time travel is
at a premium
• Trucks have the advantage of mobility and flexibility and the
ability to provide door-to-door services
Developing a Transportation
System (4)
Advantages and complementarity of various transportation
modes
•
Waterways can ship heavy commodities at low costs, but at low
speeds and only between on a river or a canal.
•
Railroads can hole an imense variety of commodities at low cost
between any two points but usually require truck transportation to
deliver the goods to a freight terminal or to their final destination.
•
Rail shipments , usually are made once or twice a week in big lots,
whereas truck shipments are made in smaller amounts and on a
daily basis , depending on demand. Even the lower rail freight rates
do not compete with track flexibility, a trend to combining the
capabilities of both modes is now arisen toward intermodalism.
Developing a Transportation
System (5)
Interaction of supply and demand of transport
•
The transportation system that exist at any point in time is the result
of the interaction of two main factors :
•
(a) the demand of transport which depends from the state of the
economy.
•
(b) the extent and quality of the system expressed in its capacity
to supply transportation facilities and services.
•
Thus in periods of periodical unemployment or rising of fuel costs,
the demand for transportation tends to decrease. However if if a
new and significantly cheaper transportation mode is introduced,
the demand for the new mode will increase , decreasing demands
for the existing old modes.
Developing a Transportation
System (6)
Interaction of supply and demand of transport(continuing)
•
If for particular situation of a transport facility( for example the study of
supply and demand for a tooled bridge), we consider two curves, one of
describing the demand for transportation at a particular point in time and
the other describing how available transportation service or supply is
affected by the volume of traffic that uses the system, we can use these
curves to determine the volume of traffic which can be expected to use the
respective transport facility .
•
This point will be found where the demand curve intersects the the supply
curve , because any other value, different from this point will create un
undesired schift in demand, either upward or downward, until the echilibrium
point is reached. If the volume incresed beyond the equilibrium point, cost
would go up and demand will drop. Likewise, if the volume dropped below
the equilibrium point, cost would go down and demand will increase. Thus in
both instances we are approaching the equilibrium
Developing a Transportation
System (6)
Interaction of supply and demand of transport(continuing)
•
At any point, the nation’s transportation system is in a state of
equilibrium as expressed by the traffic carried for each mode and
the levels of service provided, expressed in terms of time, cost,
frequency and comfort.
•
This equilibrium is the result of the f permanent evolution and
interaction of the following factors :
•
market forces such as state of economy, competition, costs and
prices for services ,
•
government actions ( regulation, subsidy, promotion)
•
and transport technology ( speed, capacity,range, reliability)
Modes of Transportation (1)
General considerations
•
Conceived as a complex network of modes and facilities that furnishes
shippers and travelers with a wide range of choices in terms of service
provided, the transportation system of a country or of the region or of a city
has to be highly developed.
•
Each mode of transportation has to offer a unique set of service
characteristics in terms of travel time, frequency, comfort , reliability,
convenience and safety. To describe the relative values of these attributes
the term level of service is currently used.
•
In order to make the tradeoffs and to select the appropriate mode of
transport thye , the traveler or the shipper must compare the level of service
offered with the cost.
Modes of Transportation (2)
Freight and passenger traffic
•
The principal modes of intercity freight transportation are highways, railways
water and pipeline . Traffic carried by each of these modes have varied
considerably in the last fifty years .
•
The four principal carriers for freight movement (rail, truck,pipeline and
water ) account for between 15 to 40 percent of the total, the air freight,
which is an important carrier for high-value goods is insignificant,
representing usually less the half percent from the total.
•
The distribution of passenger transportation is much different from that of
freight, one mode such as that of the automobile accounts between 65 to 80
percent of all domestic intercity passenger -kilometers traveled. The
remaining modes - air, bus and rail share a market representing 20 to 35
percent.
Modes of Transportation (3)
Public transportation
• Public transportation is a generic term used to describe any
and all of the familly of transit services available to urban and
rural residents.
• The public transportation system must provide high -capacity,
energy -efficient movement in densely traveled corridors.
Also it must provide efficent options in medium or lowdensity areas for the auto owners who do not wish to drive
and an essential service to those without access to an
automobile - school children,senior citizens, and others who
may be economically or physically disadvantaged.
Modes of Transportation (4)
Public transportation key-factors
•
According a study , undertaken in 1990 ,by the American
Association of State Highway and Transportation Officials (AASHTO)
in US, in consolidating the role of the public transportation the
following six key factors has been identified:
•
funding alternatives with the aim of obtaining funds from a wide
range of public and private sources;
•
management alternatives aimed to provide an acceptable level
of service at a resonable cost;
•
development of public -private sector seen as an innovative
approach to develop a healthier transport industry;
Modes of Transportation (5)
Public transportation key-factors ( continuing)
•
political cooperation and support seen s essential if public transportation
is to carry out its mission in an effective manner, the commitment of a
governor or of maire to public transportation being a vital element for
success
•
technological advances in bus, rail, and ferry modes , consisting in
advances in vehicle design, developmet and implementation of electric cars
and other ecological vehicles, are expected
Modes of Transportation (6)
Public transportation key-factors ( continuing)
•
insustry involvment in public transportation is expected to be
implemented through the cooperation of several national
organiazations , which collectivelly can help influence key areeas of
concern , including funding, cost-effectiveness and productivity,
pubic-private cooperation, coordination, community relations and
urban planning and development. These organiazations may include
The Ministry of transport and public works, The Transportors Union,
The National Aministration, of Roads,etc,
•
In USA such organiazations include the American Public Transit
association (APTA) the Amerivan Association of State ighway and
Transportation officials -AASHTO, the Federal Transit Administration
(FTA) and the Federal Highway Administration (FHWA)
Modes of Transportation (7)
Highway transportation
Problems (1)
• To illustrate the importance of transportation in our
life, make a comparison of how your typical day
might be changed with or without one mode of
transportation. Consider your personal
transportation as well as goods and services that
you relay on.
• Review the classified section of the telephone
directory of your city and identify the main
transportation agency and organizations located in
your town.
Problems (2)
•
A bridge have been constructed over the river Siret. The total cost excluding
tools to travel across the bridge is expressed as C= 10+ 0.5V, where Vis the
the number of vehicles per hour and C is the cost /vehicle in cents. The
demand for for travel across the bridge is V= 3000-10C
•
Notes:
•
1.The amount of traffic will depend on cost
•
2.The cost to cross the bridge will depend on the bridge toll and the travel
time for cars and trucks. If only a few vehicles cross, little time is lost
waiting at the tollbooth or in congested traffic. However as more and more
trucks are using the bridge the time required to cross will increase, waiting
lines will be formed along the tollbooth and also may appear traffic
congestion on the other end.
Problems (3)
•
In the conditions described for the bridge in the previous slide perform the
following:
– determine the volume of traffic across the bridge (483veh/day)
– if a tool of 25 cents is added what will be the volume of traffic
across the bridge ? (511 veh./day)
– an additional tollbooth is added, thus changing the travel time
across the bridge, and the new cost function becomes:
C=10+0.3V. Determine the volume of traffic which will cross the
bridge in these new conditions ( 725 veh/day)
– determine the tool to yield the highest revenue for demand and
and supply function for initial condition (…)
Problems (2)
• Keep a diary of all trips you make for a period of one week,
recording the the purpose of each trip, how you traveled, the
approximate distance traveled , and the trip time. From this
estimate the proportion of your monthly budget is spent for
transportation and try to extrapolate these data to the tripmaking characteristics for all students of your group
• Most departments or agencies for transportation incorporate
at least five major transportation engineering subspecialties
within their organizations. List and indicate at least three
tasks falling under each subspecialty.
Problems (3)
•
In the hypothesis that a country has a population of 23
million people and a average ownership of 0,5 cars per
person, each driven an average of 10,000 Km per year, at
100Km per 7 liter of gasoline. Officials estimate that an
additional EUR 75 million per year in revenue will be
necessary to improve the highway system and they
proposed an increase in the gasoline tax, to meet this
need. Determine the required in cents per liter.
• List at least three major detrimental effects that are directly
related to the construction and use of our highway
transportation system. Do the same exercise for our rail
transportation system.
Problems (4)
•
For the city of Iasi, describe briefly the actual transportation
system, including its transportation modes. Try to formulate
your own opinion about how this transportation system
meet the needs and expectations of the citizens of Iasi.
Which improvements or corrections are necessary to by
applied ?
• Estimate the number of motor vehicles in the city of Iasi, and
the total number of km driven each year. What is the total
revenue raised for each 1cent/ liter tax? Assume that the
average vehicle achieves 36 Km per 3.785 liter of gasoline.
Additional Readings
• Andrei R. Land Transportation Engineering, Technical
Publishers, Chisinau, 2002
• Garber j.N., Hoel A.,L, Traffic and Highway Engineering,
revised second edition, PWS Publishing,1999
• American Highways
• www.trb.org/trb newsletter
• www.andnet.ro