trans sys chap28
TRANSCRIPT
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Introduction to Transportation
Systems
1
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PART III:TRAVELER
TRANSPORTATION
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Chapter 28:Urban Public Transportation
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Urban Public Transportation Introduction
LOS Services History Costs Temporal Peaking and its Implications
Characteristics of the Industry A Model of Investment and Maintenance Service Design ITS Fares and Financial Viability Conclusion
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LOS Variables for Urban
TravelersLet us review our level-of-service variables
for travelers.)Travel time)Reliability)
Cost)Waiting time)Comfort)
Safety)Security
are all examples of level-of-service
variables that are relevant to any travelertransportation mode.5
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How Public Transportation
Measures Up Comfort in a crowded rush-hour subway
car is not high One has to wait for service depending on
the service frequency of the mode one is
considering Travel time may be greater or less than
that of an automobile, depending on the
circumstances How about self-image?
CLASS DISCUSSION6
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Some Other LOS VariablesSecurityAvailability of serviceSafetyAccessibility to service
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Types of Urban PublicTransportation Service
Conventional BusPara-TransitDemand-Responsive ServiceRail SystemsSubways
Commuter RailIntermodal Services
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Life-Cycle CostsCosts
M1
M3
M2 M4
CapitalCosts
0 1 2 3 4 time[M i is maintenance cost in year i]
9Figure 28.2
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DCF = Cc+ Mnn=1 (1 + i)nwhere Cc is the capital cost and iis an interest rate or discount rate
that reflects the time-value ofmoney as well as a risk factor.
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Maintenance Costs
= f( Quality of initial construction, current state ofinfrastructure, wear-and-tear caused by traffic)
Maintenance
InfrastructureWear-and-Tear
Maintenance
Figure 28.3
Wear-and-Tear
Quality ofInfrastructure
Time11
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Benefits of Maintenance as
a Function of InfrastructureQuality
Benefitof $1 ofMainte-nance
Quality ofInfrastructure
Poorly WellMaintained Maintained
12Figure 28.4
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The Impact of Delaying
Maintenance
Value ofInfrastructure
Benefit of
Benefit ofMaintenance of $M
Wear-and-Tear
Maintenance of $M
Time
Figure 28.5 13
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Wear-and-Tear as a Function
of Infrastructure Quality
Wear-
and-TearCausedby Unit ofTraffic
InfrastructurePoorlyMaintained
WellMaintained Quality
Infrastructure Infrastructure
14Figure 28.6
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LOS as a Function of Quality
of Infrastructure
LOS
Quality of
Infrastructure15
Figure 28.7
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The Vicious Cycle
The quality of our infrastructuredeteriorates, level-of-servicedeteriorates, and considering theequilibrium framework, traffic
volumes will deteriorate.So revenue goes down and there
are even fewer dollars to spend to
improve our infrastructure bycounterbalancing the effects ofwear-and-tear throughmaintenance.
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The Vehicle CycleThe basic equation for sizing a fleet is as follows:
NVEH = VC
HEADWAY
where NVEH is number of vehicles in the fleet;VC is the vehicle cycle on this route -- the time ittakes the vehicle to traverse the entire route; and
HEADWAY is the scheduled time betweenconsecutive vehicles.
Alternatively,
NVEH = FREQUENCY VC
where FREQUENCYis the number of vehicles
per unit of time passing a point on the route.17
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Vehicle Cycle1 hour
1 hourSuppose we want a service frequency of four
vehicles per hour.
How many vehicles do we need? How would you reduce the number ofvehicles needed?
CLASS DISCUSSIONFigure 28.8 18
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Control Strategies for Rail
SystemHolding TrainsStation-Skipping
Short-TurningA A A
1 2
A A AFigures 28.10, 28.11 19
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ITS -- Public Transportation
Applications The ITS concept, described in Chapter
24, can be applied to publictransportation. These applications,known collectively as Advanced Public
Transportation Systems (APTS), includesuch technologies as automatic vehiclelocation and automatic passengercounters, which can provide the basis formore efficient fleet managementsystems, both in fixed rail and bussystems.
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Traveler Information through
ITSIntermodal Transfers
There are operating strategies that wouldallow transit systems to operate moreeffectively. These strategies areinformation-driven and ITS technologiescan be a boon to the transit industry both inimproving operations and service and in
providing timely information to travelers.The latter in and of itself could be animportant market initiative for the public
transportation industry.21
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Fares, Ridership and
FinanceFares
ServicesOffered (Ridership)Volume
FinancialSituation
Subsidy
RevenuesCosts
22Figure 28.12
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Linear Demand FunctionV [Volume]
V0
FMAX F [Fare]
(Fopt = Fmax/2)
Figure 28.13 23
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Parabolic Demand FunctionV [Volume]
V0
parabola
FMAX F [Fare]
(Fopt = Fmax/3)
Figure 28.14 24
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Inelastic Demand FunctionV [Volume]
V0
F [Fare]
The horizontal line would reflect little or no changein demand (inelastic demand) as a function of farefor some range of fares. So why not simply raise fares and hence revenue? Equity Air Quality Congestion on highways
Figure 28.15 25