Chapter 5 6 Flashcards
1
Q
Surfaces
A
provide support forvehicles traveling on transportation facilities
2
Q
Guideways
A
in addition toproviding support, also provide lateral guidance
3
Q
- Surface Courses\n* Base Course\n* Subbase\n* Geotextiles
A
COMPONENTS
4
Q
Surface courses
A
usually consist ofasphalt or Portland cement concrete
5
Q
Base courses
A
consist of aggregatessuch as gravel and crushed rock
6
Q
Subbases
A
may consist of eitherunstabilized compacted aggregate or stabilized materials
7
Q
geotextiles
A
used to add strength,control moisture, and prevent the movement of fine materials into drainagelayers
8
Q
Asphalt
A
The pavement isconsidered to be flexible
9
Q
plasticdeformation
A
The failuremechanism of asphalt
10
Q
Concrete
A
The pavement isconsidered to be rigid
11
Q
Fatigue
A
The failuremechanism of concrete
12
Q
Traffic loads \n\nEffects of environmental conditions \n\nEvaluation of the load–bearing capacity of the subgrade material \n\nAvailability of materials
A
DesignConsideration
13
Q
Computerized optimization program \n\nMechanistic methods based on stress–strain calculations \n\nEmpirical methods
A
DesignMethods
14
Q
Pumping
A
a failure mechanismwhere fine materials in a saturated base form a slurry with the water in thebase. As wheel loads pass over the pavement, some of this slurry is forced outthrough cracks in the surface of the pavement
15
Q
AASHTO RIGID PAVEMENT DESIGNMETHOD
A
the most common design method for Portlandcement pavement for highways; it relates soilconditions, traffic characteristics and pavement design characteristics to a performance index value expected at theend of the pavement’s design life
16
Q
PORTLAND CEMENT ASSOCIATIONMETHOD
A
it is an iterative method, inwhich it is assumed that the pavement fails in fatigue after a certain number of significant deflections
17
Q
- Alligator Cracking\n* Block Cracking\n* Transverse Cracking\n* Longitudinal Cracking\n* Raveling\n* Drip Track Raveling\n* Bleeding or Flushing
A
Pavement Failure
18
Q
v ALLIGATORCRACKING
A
a series of interconnected or interlaced crackscaused by fatigue failure of the asphalt concrete surface under repeatedtraffic loading.
19
Q
v BLOCKCRACKING
A
cracks forming largeinterconnected polygons, usually with sharp corners or angles. These cracks aregenerally caused by hardening and shrinkage of the asphalt and/or reflectioncracking from underlying layers such as cement–treated base
20
Q
v TRANSVERSECRACKING
A
cracks approximately at rightangles to the pavement centerline. These may be caused by shrinkage ordifferential thermal stress of the asphalt concrete or may be by reflectivecracks.
21
Q
v LONGITUDINALCRACKING
A
cracks approximately parallelto the pavement centerline. These are caused by poorly constructed constructionjoints and shrinkage of the asphalt concrete surface: they may also bereflective cracks
22
Q
v RAVELING
A
wearing away of the pavementsurface caused by the dislodging of aggregate particles and binder. This isusually a result of insufficient asphalt binder in the mix or stripping ofasphalt from particles of aggregate.
23
Q
v DRIPTRACK RAVELING
A
progressive disintegration ofthe surface between the wheel paths caused by dripping of gasoline or oil fromvehicles
24
Q
v BLEEDINGOR FLUSHING
A
the exuding of bitumen onto thepavement surface, causing a reduction in skid resistance. ;generallycaused by excessive amounts of asphalt in the mix and/or low air voids content.It occurs in asphalt fills the voids in the mix during hot weather and thenexudes out onto the surface of the pavement.
25
ü Bituminous seal coat \n\nü Asphalt concrete overlays \n\nü Recycling of asphalt concrete pavement
Maintenance andrehabilitation for asphalt concrete pavement
26
v FAULTING \n\nv SETTLEMENT \n\nv BLOWUPS \n\nv JOINTOR CRACK SPALLING \n\nv SURFACEATTRITION OR SURFACE ABRASSION \n\nv SURFACEPOLISH
Types of pavement distress affecting Portland cement concrete pavements
27
v FAULTING
elevation differences betweenadjacent slabs at transverse joints. usually the result of pumping,and is a major source of Portland concrete pavement failure.
28
v SETTLEMENT
local sagging in the pavementcaused by differential settlement, consolidation, or movement of the underlyingearth mass.
29
v BLOWUPS
localized upward buckling andshattering of the slabs at transverse joints or cracks. It can occur whentransverse joints are filled with incompressible solid materials. They areespecially common where pavement is sanded in winter to counteract icy conditionsand in areas subject to large temperature changes.
30
v JOINTOR CRACK SPALLING
the breakdown ordisintegrations of slab edges at joints or cracks, usually resulting in theloss of sound concrete and the progressive widening of the joint or crack.
31
v SURFACEATTRITION OR SURFACE ABRASSION
abnormal surface wear, usuallyresulting from poor–quality surface mortar or coarse aggregate.
32
v SURFACEPOLISH
lossof the original surface texture due to traffic action
33
ü Installation of edge drains \n\nü Grinding of the slabs \n\nü Replacement of badly cracked or deteriorated slab \n\nü Asphalt concrete overlays \n\nü Grooving to reduce hydroplaning \n\nUseof special thin concrete surface treatment
Maintenance andrehabilitation actions for Portland cement concrete pavements
34
* Subgrade\n* Ballast\n* Ties\n* Rails\n* Spikes\n* Jointbar\n* Gage Bars\n* Rail Anchors
TRACK STRUCTURES
35
v AREMA
technical and specification writing arm of theAssociation of American Railroad; its standards are used throughout North America,including Canada and Mexico
36
v Rail Section
A description ofthe weight and profile of the rail. The rail section is usually stamped on theweb of rail. The first two or three numbers tell the weight per 3’ (one yard)section of rail.
37
5/8” beneath the top surface of the rail
Distance between two running rails
38
56–1/2” or 4’ 8–1/2”.
Standard Gage
39
GageSide
The area betweenthe two running rails.
40
v Field Side(of the Track)
The area on the“out sides” of each of the running rails
41
v Ballast
crushedaggregate (frequently stone) that is used within a track.
42
v Compromise Bars
aspecial type of Splice Bar that connects one piece of rail that is of one railsection to another piece of rail of a different rail section.
43
v Cross Tie
astandard railroad tie. Cross ties are either 6” x 8” or 7” x 9”. Length variesfrom 8 to 8–1/2’.
44
v Joint BarsCast
steel bars that connect one piece of rail to the next. Joint bars are punchedwith holes to match the end drilling on a rail.
45
v Rail
Thesteel beams on which the railcar wheels travel. eitherbolted together at the joints using joint bars or it is continuously welded. A full length of bolted * is usually 33’ or 39’.
46
v Relay
“Used”track material.
47
v Spike
The“nail” that holds a rail to a tie.
48
v Sub ballast
crushedaggregate (frequently stone) that is installed before track constructionbegins. ;provides a foundation and drainage for the track structure.
49
v Switch Tie
atie that is longer than the standard 8– 1/2’ cross tie and is used through aturnout from the switch points and continuing beyond the frog. They aregenerally 7” x 9” and vary in length from 9’ to 17’.
50
v Tie Plate
thesteel plate that is installed between the tie and the rail and is pre–punchedfor track spikes. ;prevent the rail from cutting into the tieand will distribute the load that is on the rail across a larger area of thetie.
51
single shouldered
have one ridgeagainst which the rail is spiked
52
double shouldered
they have two ridges into which the base of the rail must fit and be spiked against.
53
v Tie Plug
Asoft wood filler that is used to fill the hole where a track spike is removedbefore the tie is respiked.
54
v Track Ballast
crushedaggregate (frequently stone) that is used under and between the ties of a track.
55
v Track Bolt
Abolt with a button head and oval neck and a threaded nut designed to fastentogether rails and splice bars and other rail joint fastenings
56
* Bumping Post\n* Derail\n* Wheel Stops
Track Accessories
57
v Bumping Post
atriangular steel structure at the end of a track that prevents a railcar frommoving beyond the end of the track by making contact with the railcar coupler.
58
v Derail
adevice installed on a track to intentionally derail a car for safety purposes.(e.g. to prevent a car on an industry side track from rolling out onto themainline.)
59
v Wheel Stops
smallerdevices that are attached on a track to prevent a railcar from moving beyondthe wheel stops by making contact with the railcar wheels..
60
v Compromise Joint
thepoint where two rails that are different rail sections connect with CompromiseBars.
61
v Crossing Diamond
steelcasting that allows two tracks to intersect and cross each other.
62
v Flangeways
thegap between the running rail and anything installed along the gage side of arail.
63
v Surfacing
newtrack and turnouts are constructed directly on the subgrade and then buried instone. After this, they are raised out of the stone to the final elevation bytamping stone under the ties. The excess stone is contoured or removed and therails are aligned to remove any kinks.
64
Ties
–areused to maintain gage and to transmit wheel loads from the rails to theballast.
65
Center–BoundTrack–
A condition where repeated loads will further compact the ballast under theends of the ties, leaving them supported only at their centers.
66
· StoneBlocks \n\n· HardWood \n\n· Concrete \n\n· Steel \n\n· HybridPlastics
Composition of Ties
67
Creosote
– acomponent used to treat hardwood ties that makes last for at least 30 – 40years before needing replaced.
68
· Length– 8 to 9 feet
Length of Tie
69
· Width– 7 inches
Width of Tie
70
· Height– 8 to 9 inches
Height of Tie
71
· Distancebetween face of ties – 10 inches
Distance between ties
72
Rails
– Apermanent track composed of a line of parallel metal rails fixed to sleepers,for transport of passengers and goods in the trains.
73
Distancebetween two rails –1.435 meters (standard)
Distance between rails
74
Commonlength of rails – 39feet (standard)
Common length of rails
75
RailWeights in common use – 42kg/m to 75 kg/m
Rail weights
76
* Track Resurfacing\n* Tamper
Track Maintenance
77
TrackResurfacing –
acombination into a single operation of restoration of horizontal and verticalalignment, replacement of worn or defective ties or rails, and cleaning orrestoration of ballast.
78
Tamper–
amachine used in track maintenance.
79
Noise
is unwanted sound judged to beunpleasant, loud or disruptive to hearing.
80
includes control of noise at the source, location and designof facilities, construction of noise barriers, insulation of receptors andnoise mitigation for airports
Mitigationof noise impacts
81
decibel (dB)
is used to measure sound level
82
A–weighted soundlevel scale
the scale most often encountered in analysis of transportation–relatednoise. This scale correlates well with human response, and is available as abuilt in feature on most sound meters
83
Reduce noise at the source\nLocation and orientation of runways to route arrivals and departures\nInsulation Receptors\nOperational restrictions\nInstallation of noise barrier
Airport Noise Mitigation
84
1. Reduce noise at the source –
focused onjet engine design. it include the primary jet andmachinery noise. The introduction of fan jet engines resulted in majorreduction in primary jet noise since the fan exhaust. Machinery noise has beenreduced by acoustical lining of theinlet and ducts. As as result engine noise has been reduced by about 15 Dbsince the introduction of commercial jet aircraft.
85
2. Location and orientation of runways toroute arrivals and departures
– this is assessed by constructing maps forecastingnoise level contours around the proposed runways and approach paths.
86
3. Insulationreceptors –
for residential areas FAR requires that were day–nightaverage noise level (Ldn) exceeds 65 dBA, it should beinstalled to reduce interior noise levels to 45 dBA or less. It include insulation of roof and walls, blocking the air paths such ascracks around doors, installation of storm doors and storm windows andinstallation of acoustical doors and windows.
87
4. Operationalrestrictions
– include modifications to flight paths and flight profiles,especially on takeoff, and curfews or others on late nightoperation.
88
5. Installationof noise barriers \n
– Noise barriers have been used to shieldreceptors from noise from ground operations including takeoff runs.
89
*Use of Mufflers\n* Use of Quiet Pavement\n* Use of Noise Dampers on wheels and use of rail facing\n* Installation of noise barriers
Measures tocontrol highway and railway noise:
90
Noise barriers
commonly consist of earth berms or walls constructed of wood, metal orconcrete. In addition transparent and translucent plastic have been used. Bermsand walls are sometimes combined.
91
Fresnel diffraction/Barrier Attenuation
Primary noise attenuation mechanism
92
N is equal to two multiplied to the quotient of eight and lambda
Fresnel Number
93
Clean water act\nEndangered species act
Federal laws related to mitigation of habitat encroachment
94
· tidalmud flats· saltwatermarshes · freshwatermarshes · swampsbogs
Wetlands include habitats such as
95
* Particulates\n* Metals such as lead, copper and zinc\n* Hydrocarbon, nutrients and bacteria
Runofffrom paved areas often contains a variety of contaminants:
96
1. Spilled Fuel2. Pavement Wear3. AtmosphericDust4. Wear of Tireand Vehicle Parts5. Fecal Matter
Theultimate sources of these contaminants include:
97
WaterQuality
governed by EPA (Environmental ProtectionAgency) regulations issued under the Clean Water Act. Section 405 of the CleanWater Act of 1987 contains language directly related to stormwater management
98
Flood Control Policy
is generally a matter of local concern, and is usually governedby local ordinances. In addition, transportation agencies may be subject tolitigation if damage results from intensified discharges or upstream floodingdue to backwater.
99
Water Quantity
for flood control the recurrence interval for the design storm is normally 10 years or more.
100
Water Quality
are designed to detain the “first flush” of the storm, whichcontains most of the contaminants
101
* Detention basins\n* Infiltration trenches\n* Porous pavements\n* Vegetative Filter Strips\n* Grassed swales\n* Wetlands
Facilitiescommonly used for stormwater management include the following:
102
1. Settling2. Chemical Decay3. BiologicalUptake4. Adsorption5. VariousPhysical, chemical, and biological processes
Methods inRemoving Pollutants
103
1. Concerns aboutimpact on groundwater.2. Whereinfiltration is used.3. Concerns aboutthe impact on wetlands.
Constraints on StormwaterManagement Systems include:
104
Hazardous wastes and contaminated soils
often present in the right–of–way of transportationfacilities
105
Transportation agencies
are often responsible for remediation of these hazards, eventhough they may result from the actions of previous landowners.
106
* Petroleum\n* Asbestos\n* Lead
Types of Hazardous waste
107
1. Service Station2. Various industrial uses
The main sources of hazardouswaste and soil contamination are:
108
Service stations,
for instances, are usually located alongside major highway;whenever existing highway are widened, it is likely to be necessary to acquireservice station sites.
109
Soilcontamination
is when hazardous substances are mixed into thenatural soil then the soil becomes contaminated making the soil not usable foranything and it can harm many things
110
1. Agriculturalwaste2. Humanwaste3. Industrialwaste4. Mercury5. Lead6. Pesticidesand Herbicides7. PetroleumhydrocarbonRoadsalts
SOil Contaminants
111
1. Landfilling2. Containment3. Treatment
REMEDIATION OPTIONS BY SPECIALIZEDENGINEERING FIRMS:
112
Landfill
– carefully designed structure built into or on top of the groundin which trash is isolated from the surrounding environment (groundwater, air,rain). This isolation is accomplished with a bottom liner and daily covering ofsoil.
113
CONTAINMENT
This involves sealing off hazardous waste orcontaminated soil by means of capping, grout curtains, slurry walls, or sheetpiles, or encapsulation in concrete vaults or bridge abutments
114
Incineration
A waste treatment technology, which includes thecombustion of waste for recovering enery; coupled with high temperature waste treatmentsare recognized as thermal treatments
115
Solidification/Stabilization
is a treatmenttechnology for contaminated soils, either for cleanup/remediation alone or aspart of a brownfield redevelopment.
116
Aeration/Land Farming
soils are spread and volatile petroleum productsare allowed to evaporate; in land farming, it is combined with aprocess of fertilization and cultivation in which microbes break down thepetroleum.
117
Traffic congestion
exists wherever demand exceed the capacity
118
Trends in accident rates
trends
119
Organizational
Agencies involved in transportation safety
120
Equality of access
Provide adequate access to the transportation system for all types of people
121
Poor, elderly and physically handicapped
3 groups seen underserved\n
122
technical\nlegal\npolitical elements
process of developing a transportation system
123
AASHTO, ASTM, Civil Aviation board
Design Standard
124
bid documents, plans, specifications, estimates
design documents
125
includes the designof geometric cross sections, horizontal lignment, vertical alignment, intersections and various design details
Geometric design for transportation facilities
126
Vertical alignment
documented by a profile
127
Profile
agraph which has elevation as its vertical axis and distance, measured stations along the centerline or other reference line of the facility as its horizontal axis
128
Horizontal alignment
horizontal tangents, circular curves an dpossibly transition curves without transition curves
129
Superelevation
Used to counteract the centripetal acceleration produced as a vehicle rounds a curve
130
Earthwork quantities
usually expressed as volumes, in metric units.
131
Mass diagram
Calculation of optimum haul strategies and earthwork costs is done by meads of using this diagram
132
mass diagram
a graph of cumulative volume of earthwork versus distance in stations from the beginning of the job, in which cut is considered to be positive and fill negative.
