istanbul technical university department of geomatics...

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ISTANBUL TECHNICAL UNIVERSITY DEPARTMENT OF GEOMATICS ENGINEERING

Prof. Dr. Ergin TARI translated by Res. Assist. Serpil ATEŞ

TRANSPORTATION and

TRANSPORTATION STRUCTURES –

GENERAL DEFINITIONS

Transportation, Transportation Structure: Transportation is explained as

the phenomena of replacement of living creatures (human and animal) and

goods (solid, liquid, gas) and energy with respect to human demand and

benefit. Man-made engineering structures serve for transportation are called

transportation structures [Müller, 1984, p.8]. According to this definition, all

highway, rail, water and air transportation systems; liquid and gas pipelines, cable

systems such as electricity, telegraph, telephone and internet are in the concept of

transportation structures. There are many different features that must be taken into

account at design, construction and management phases aforementioned

engineering structures. It is impossible to consider all of these features in the

context of this course. Therefore, highways and railways will be considered,

however, it is possible to use given information about geometric design and layout

for other transportation structures.

2 Engineering Surveying-Prof. Dr. Ergin TARI

TRANSPORTATION and


GENERAL DEFINITIONS Classification of Highways: All of the roads can not be built at

same standards. They are classified according to certain parameters.

These classifications are taken into account at determination of

design criterion (standards).

Classification parameters are;

1. habitation (urbanization) status

2. traffic volume

3. topography of the terrain


TRANSPORTATION and


GENERAL DEFINITIONS 1- Urbanization status:

Highways are divided into two groups according to urbanization status; urban roads and non-urban roads [KGM; 2005, s.8,9], [Müller; 1988, s.68,70].

2- Traffic volume:

Quality and quantity of the vehicles have an important role in determination of road standards. Annual average daily traffic or maximum hourly traffic are taken into account at design of the highways and amount of the future 15-20 years’ traffic is estimated [Umar; Yayla; 1997, p.83-91].

3-Topography of terrain: Topography of terrain is divided into three groups; plane, rough and mountainous. This classification is important at selecting design speed. A highway can be constructed through these 3 types of terrain. But the class (classification) should not be changed frequently.

A highway should also not be constructed from plane terrain to the mountainous terrain or in the opposite direction by neglecting the rough terrain.


TRANSPORTATION and


GENERAL DEFINITIONS Classification of Railway: There are 4 types of railways according to

topographic characteristic of the terrain; flat terrain railway, hilly terrain

railway, mountainous terrain railway and mountain railway [Evren;2002, s.14].

According to urbanization and transportation distance; intercity railway,

suburban railway and urban railway can be a classification (tram, high speed

tram, subway) [Evren; 2002, s.14].

There are different railway classifications; according to types of trains that use

the railway; complex line (common route for passenger and freight train),

passenger line; according to number of the tracks single and double track;

according to power source that provide motion; steam-operated, diesel,

electrical; according to track width; normal line (aperture between rail axes

is 1500 mm), wide and narrow line.


TRANSPORTATION and


GENERAL DEFINITIONS

Design Speed (Vp): is a base speed for design criterion (geometric

standards) determination. Design speed for highways is defined in different

forms at various sources;

[Umar; Yayla; 1997, s.81]: maximum safe speed without influence of

other vehicles at normal weather conditions.

[Kiper; 1988, s.11]: maximum safe speed at normal traffic flow and in

normal weather conditions (including rainy weather).

[Pietzsch; 1979, s.28]: maximum safe speed of %85 of the vehicles

in case of normal traffic flow at clean and wet road without the lose

of flow.


TRANSPORTATION and


GENERAL DEFINITIONS Design speeds according to road classes in Turkey [KGM; 2005,

p.7-9]

Road and Link Road (2x2)

Terrain class: Plain Rough Mountainous

Vp(km/h) : 120 100 80

Urban road


Terrain Class Highway Urban Road

Multi Lane Two Lane Multi Lane Two Lane

Plain 100 60 90 60 80 60 70 50

Rough 80 60 80 60 70 50 60 30

Mountainous 80 60 60 50 60 40 60 30

TRANSPORTATION and TRANSPORTATION

STRUCTURES – GENERAL DEFINITIONS

Non-urban road


Land Class Multilane

Road (2x2)

Two lane road

1.class 2.class 3.class 4.class

Plane PV ( km / s ) 100 90 100 80 80 70 70 60 50 40

Rough PV ( km / s ) 90 80 80 70 70 60 60 50 40 30

Highland PV ( km / s ) 80 60 70 60 60 40 50 30 30 20



Design speed is the maximum speed that can be safely applied at

railways and also called track speed limit. This speed is used to

determine geometric standards for railways. In addition, applicable

maximum speed is defined considering locomotive traction, cooper

load and operating conditions. This speed is used to plan the

operation [Evren; 2002, s.90-91].




Road Geometry: highway or railway is a narrow engineering structure that has very large length compared to the width and forms a space surface. The vertical (longitudinal) geometry of this surface is defined with route and the horizontal geometry is defined with typical cross sections and super-elevation.

Route (Alignment): is a line belonging to road geometry that can be exactly defined along the road.

Route Definition for Highway: For divided roads; is axis of the central (island) reserve, for two-lane roads; if roadside shoulders has same width is platform axis, if roadside shoulders has different width-pavement axis is selected as a route axis [Müller; 1988, s.86]. In the climbing lane and road expansion regions, only the main platform is taken into account.

Route Definition for Railway: for single track railway is route axis, for double track railway; pavement axis is the route axis for the railway.




Figure 3.1: Intersection Points and Deviation Angle of

Horizontal (Vertical) Route Geometry


curve

curve

curve

S i-1

(U ) i-1

S i

(U ) i

S i+1

(U ) i+1

(g ) i+1

D i+1

(g ) i

D i

(g ) i-1

D i-1



Route Geometry: longitudinal geometry of the road is determined with the design of route geometry. Despite it is a space curve, route geometry is not determined with closed function such as f(x, y, z)=0. Horizontal and vertical route geometry are designed separately [Müller, 1984, s.9].

Horizontal Alignment: is designed with using line segment, arc and transition curves in respect to guidelines and design criterion. Superelevation and superelevation runoff are also designed in route geometry. The base map of the route geometry is a large-scale (1/1000;1/2000) topographic map. Digital Terrain Model (DTM) is used as a basis on computer aided design.

Horizontal Intersection Point: is the breakpoint of two consecutive line segments of the horizontal route geometry (Figure: 3.1). Despite lack of compliance with this definition, starting and end points of the route are also considered as a intersection point. While they are not a route point, intersection points play very important role in the calculations.




Figure 3.2: Defining Point Chainage (Stationing) on Horizontal

Route Geometry


P

T

S

'

'

'

0

T

T

T

T

T

S

S

1

2

3

3

3

2

2

1

1



Horizontal Deviation Angle: is an angle (∆i) between line segments

at intersection points of horizontal route geometry (Figure 3.1). This

angles are the main quantities of the horizontal geometry

computations.

Distance from the origin-Km (Chainage-stationing): The

horizontal distance measured through horizontal geometry from the

selected beginning point to any point of the route. For example, at

Figure 3.2; stationing of P is S0T1 line + T1T'1 curve + T'1T2 line +

T2P curve. Distance from the origin is written in this form;

kmp = kilometer + meter, fractions of meter (14+038,673)




Main Point, Detail Point: Connection points from one geometric

element to another on vertical and horizontal alignment of the road

called main points (beginning and end points of circular arc,

transition curves, superelevation runoff (ramp)...etc.). Stationing of

this points which are shown with different letters, computed with

calculation except some special cases.

Although it is shown as a continious line at graphical design, layout

of the route cannot be done in the same way. The route must be

transferred to the ground point by point. The frequency provided by

main points is extremely poor. So the detail (intermediate) points

stationing with the formula below are also applicated to the terrain.

kmPi = k∆l ; k = 1,2,3,...,n (with ∆l as 20, 25, 50 meters) (3.1)




During application projects, point densification may

be required in some parts of route with taken

Δl=(5,10)m. In addition to those points, existing

transportation structures, watershed lines and intersect

points are also called detail point. Stationing of this

points is calculated by measuring horizontal distance

to a closest point with known stationing.




Direction of Horizontal Curvature: Direction of the curves on the horizontal route geometry becomes important at computations. Direction of the curvature is defined with location of the curvature center according to direction of the chainage increase. Curves are named as right curve (curve to right) or left curve (curve to left) according to this direction.

Superelevation: Although transition curves can reduce the effect of radial force on a vehicle this can also be further reduced or even eliminated by raising one side (the one away from curve center) of the road relative to the other. The difference in height between the two sides of the road is known as the superelevation. In some sources, horizontal inclination of the road platform caused by the height differences mentioned above, called superelevation [Umar, Yayla; 1997, s.136-137].



STRUCTURES – GENERAL DEFINITIONS Vertical Alignment: is established with adding curves and line segments end to end considering guidelines and design criterion. Vertical route geometry is designed on the profile base.

Profile: is the intersection of physical earth and vertical surfaces along the horizontal alignment of the road. Design of the horizontal route geometry and computations should be finished in order to create profile.

Vertical Intersection Point: is the breakpoint of two consecutive line segments of the vertical route geometry (Figure 3.1). Despite lack of compliance with this definition, starting and end points of the route are also considered as intersection points. Vertical intersection points are represented with U. Horizontal projection of any vertical intersection point coincides with any route horizontal geometry point. Therefore, vertical intersection points has stationing.

Vertical Deviation Angle: is an angle between extension of consecutive line segments(Figure 3.1). This angles are the main quantities (magnitudes) of the vertical geometry computations.




Figure 3.3: Grade line, Ground line, Grade Elevation

and Ground Elevation of Profile


H=0

Embankment

(Fill)

Excavation

(Cut)

P

H

H ölç

P

pro

P

Existing Terrain

Project Line



Direction of Vertical Curvature: curvature direction of curve arcs on vertical route geometry is very important. According to location of curve center, there are 2 different types of vertical curves. If the center of the curve directed to the ground it is called closed curve or crest vertical curve; if the center directed to the sky it is called open curve or sag vertical curve [Umar; Yayla; 1997, s.168].

Center Line Point: Each of the horizontal alignment main and detail points that has calculated layout elements and marked on the ground are called center line [Umar; Yayla; 1997, s.113]. Stationing of the center line point is also the name of the point.

Cross Section: Sections that are perpendicular to the horizontal route geometry. Stationing of the center line must be written on the cross sections.




Ground Elevation: is the elevation of center line points (for profile) and

characteristic points of natural terrain (for cross section). Ground elevation

shows natural topographic characteristics of the terrain (Figure 3.3)

Ground Line: is obtained by combining sequential points of known ground

elevation with line segments (Figure 3.3 and 3.4). Ground line shows natural

characteristic of terrain graphically along profile and cross section route.


Grade (Project) Elevation: is the design elevation of the vertical route

geometry points on the profile base. It is determined with computation (Figure

3.3).

Grade (Project) Line: is the graphical visualization of vertical route geometry

designed on profile (Figure 3.3). Grade and ground elevation of any P point is

obtained from vertical route geometry (Figure 3.3). With known grade and

ground elevation, typical cross section is transferred to cross sections of P.

Thus, grade line is obtained on cross sections (Figure 3.4). Grade elevation of

the cross section points is determined with computation.

Typical Cross Section: is a section that represents horizontal and vertical

geometry of transportation structure which is perpendicular to horizontal route

geometry without superelevation [Evren; 2002, s.129], [Müller, 1984, s.206].




While obtaining grade line (project line) of cross section, superelevation

application must be taken into account on horizontal alignment. Generally,

one type cross section is not enough along the transportation structures.

Special cross section types are used at; subways, climbing line sections of the

highways, high level excavation and fills require retaining wall, bridges and

culverts…etc.

Typical cross section represents; inclination of embankment slope and

excavation slope, size of bottom, interception and side ditch, divided roads,

number of lanes, width of shoulders, pavement and central (island) reserve,

number of railway lines, line width and distance between line axis…etc.

Typical cross section is one of the main elements of transportation structure

standards determination and must be considered with design speed.






Figure 3.4: Grade line, Ground line and other Definitions of Cross-

Section


H=0 Bottom

Ditch

Side Ditch

Project Line

Interception

Ditch

Existing

Terrain

H ölç

P H

pro

P

Fill(Embankment)

Ce

nte

r li

ne

3+245,67

Earthwork: Closed areas created by grade line and ground line of profiles and

cross-sections show the requied eathwork. Filling-excavation must be done in

the areas where grade (project) heights are smaller-bigger than ground heights.

Complex Cross-section: Cross-section that has both filling area and

excavation (cut) area.

Girder Cross-section: Cross-section that has only cut area.

Cut and Fill Slope: Inclined surface created between the road and the territory

at the end of the erthwork.

Side ditch: Ditch that provides the drainage of rain water fall to the cut slope

and the road surface.




Interception Ditch: created ditch when needed at junction point of

escarpment and territory (Figure 3.4).

Bottom Ditch: applied at junction point of fill slope and territory. The aim of

the bottom ditch is to prevent the collapse the bottom of fill slope due to

rainwater (Figure 3.4).

Relocation, Variant: certain part of the horizontal geometry need to be

changed at the end of the route horizontal geometry design and route vertical

geometry design in parallel with this route horizontal geometry. Relocation is

the horizontal geometry changes within the cross-sections. Variant is the

horizontal geometry changes out of the cross-sections. Profiles and cross-

sections must be updated at variant, but they are not updated at relocation.




27 Engineering Surveying-Prof. Dr. Ergin TARI translated by Res. Assist. Serpil ATEŞ

istanbul technical university department of geomatics...

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