Traffic Engineering MCQ Quiz in मराठी - Objective Question with Answer for Traffic Engineering - मोफत PDF डाउनलोड करा

Concept:

Free Mean Speed:

From the speed-density diagram, it can be defined as the maximum speed at which the number of vehicles in a unit length is zero i.e. density is zero.

Density:: It can be defined as the number of vehicles per unit length. The unit of measurement is vehicles/km.

Jam Density: From the speed-density relation and flow-density curve, it can also be seen that it is the maximum density at which there is no flow on the road.

Traffic Flow: The number of vehicles passing through a particular point in a certain time interval is defined as traffic flow. Also, the number of vehicles counted in one hour is called traffic flow (q).

The relation between k, u, and q is given below-

\({\bf{q}} = {\bf{k}} \times {\bf{u}}\;{\bf{veh}}/{\bf{hour}}\)

From the curves above, As long as the relation between density and speed is linear, it can be seen that maximum flow (or flow capacity) occurs at kj/2 and uf/2.

\({{\bf{q}}_{{\bf{max}}}} = \left( {\frac{{{{\bf{k}}_{\bf{j}}}}}{2}} \right)\left( {\frac{{{{\bf{u}}_{\bf{f}}}}}{2}} \right)\;{\bf{veh}}/{\bf{hour}}\)

Calculation:​

Given 

_Uf = Free-flow speed = 80 kmph

K_j = Jam density

K_j = \(\frac{{1000}}{{S}}= \frac{{1000}}{{6.9}} \)

\({{\bf{q}}_{{\bf{max}}}} = \left( {\frac{{{{\bf{k}}_{\bf{j}}}}}{2}} \right)\left( {\frac{{{{\bf{u}}_{\bf{f}}}}}{2}} \right)\;{\bf{veh}}/{\bf{hour}}\)

Concept:

As per Webster's method, the optimum cycle is given by,

\(C_o=\frac{{1.5L + 5}}{{1 - Y}}\)

Where, C_o = Optimum signal cycle

L = 2n + R 

n = Number of phases, R = All red time

Y = Critical flow ratio

Y = y1 + y2 (the value of Y should be less than 1)

Here, y1 = q1/s1 and y2 = q2/s2

Calculation:

Given,

n = 2, Y = 0.6, R = 10 second

L = 2n + R = 2 × 2 + 10 = 14 Second

So, as per Webster's method

\(C_o=\frac{{1.5L + 5}}{{1 - Y}}\)

C_o = \(\frac{(1.5 × 14 + 5)}{(1-0.6)}\)

C_o =  65 Second

Explanation:

Traffic sign:

In older days road locomotives carried a red flag by day and a red lantern by night. Safety is the prime motive of every traffic.

Kinds of road signs,

• Mandatory
• Cautionary and
• Informatory

Mandatory sign: 

Violation of mandatory signs can lead to penalties. Example: Stop, Give way, limits, prohibited, no parking, and compulsory sign.

The diameter of a mandatory sign disc must be 60 cm.

Overtaking Prohibited

Cautionary signs: 

Cautionary/ warning signs are, especially for safety. Do's and don'ts for pedestrians, cyclists, bus passengers, and motorists.

Information signs:

Information signs are especially beneficial to the passengers and two-wheelers.

Explanation:

For the intersection of two-lane two-way roads from both sides:

Major conflicting points = 16, Minor conflicting points = 8 and thus total conflicting points (X) = 24

For the intersection of two-lane one-way rod and two-lane one-way road:

Major conflicting points = 4 Minor conflicting points = 2 and thus total conflicting points (Y) = 6

So, X/Y = 24/6 = 4

Additional Information

For the intersection of a two-lane one-way rod from both sides:

Major conflicting points = 7 Minor conflicting points = 4 and thus total conflicting points = 11

Important Points:

Explanation:

There are four general types of co-ordination of signals for road network:

Simultaneous system: In this system all the signals along a given road always show the same indication (green, red etc.) at the same time. As the division of cycle is also the same at all intersections, this system does not work satisfactorily.

Alternate system: In this system, alternate signals or group of signals show opposite indications in a route at the same time. This system is also operated by a single controller but by reversing the red and green indicator connections at successive systems. This system is generally considered to be more satisfactory than simultaneous system.

Simple progressive system: In this system, the signal phases controlling “Go” indications along this road is scheduled to work at the predetermined time schedule.

Concept:

Normal traffic growth

It is the increase in traffic volume due to the cumulative annual increases in the numbers and usage of motor vehicles.

Normal Traffic Growth = Current Traffic (Existing Traffic) ×TPF 

and

TPF(Traffic Projection Factor)

\(𝑇𝑃𝐹 = (1 + 𝑟)^{x+n}\)

Where: r = Annual rate of traffic increase (0 – 10%), n = design life in years (20 – 50 years),  x = construction period in years (2 – 4 years) 

Induced Traffic

It consists of traffic that did not exist previously in any form and which results from the construction of the new facility, and of the traffic composed of extra journeys by existing vehicles as a result of the increased convenience and reduced travel time via the new road.

Converted traffic

It is that which results from changes in mode of travel; for instance, the building of a motorway may make a route so attractive that traffic that previously made the same trip by bus or rail may now do so by car.

Development Traffic

It is the future traffic volume component that is due to developments on land adjacent to a new road over and above that which would have taken place had the new road not been built.

Explanation:

Classification of traffic signs:

1) Mandatory/Regulatory sign:

• The regulatory or mandatory signs are used to inform the road Users of certain laws and regulations to provide safety and free flow to traffic.
• Shape: Circular

​Note:

Exception: Stop and Give way sign

The stop sign is octagonal in shape and the Give Way sign has the shape of an inverted triangle.

2) Warning sign:

• These signs are used to warn the road users at sufficient distance in advance about the impending road condition.
• Warning signs are also known as cautionary signs.
• Shape: Triangle

3) Informatory sign:

• Informatory signs are provided to guide the road user about the routes, destination, and to provide information that makes travel easier, safe, and pleasant.
• Shape: Rectangle

Explanation:

The theoretical maximum capacity for a single lane is given by,

C = (1000V)/S

Where,

C is capacity is vehicle/hr

V = speed in km/hr

S = minimum clear distance between two vehicles and it is given as:

S = 0.2V + 6 (if V is in kmph)

(or)

S = 0.7v + 6 (if v is in m/s)

Calculation:

Given: V = 40 km/hr

S = 0.2 × 40 + 6 = 14 m

The capacity for a single lane is:

C  = 1000 × 40/14

C = 2857 Veh/hr

C≈ 2860 Veh/hr

Explanation

Road capacity in general refers to the maximum traffic flow obtainable on a given roadway using all available lanes; usually expressed in vehicles per hour or vehicles per day.

This depends upon several factors

• Traffic conditions
• Road geometry characteristics
• Environmental factors

Calculation:

Capacity = \(\frac{1000V}{S}\)

S = SSD+L ,SSD = Stopping side distance , L = Length of the vehicle

V=Design speed 

Here V = 80 Kmph L= 6 m .f= 0.35

Now SSD = v × t+ \(\frac{v^2}{2× g× f}\)

Here v = design speed in m/s = \(\frac{80}{3.6}\) = 22.22 m/s 

So SSD = 22.22 × 2 + \(\frac{22.22^2}{2\times 9.81\times0.35}\) = 116.33 m 

Put in the formula of capacity C= \(\frac {1000\times80}{116.338+6}\) = 653

According to IRC,