GATE Questions & Answers of Traffic Engineering Civil Engineering

The speed-density relationship for a road section is shown in the figure.

The shape of the flow-density relationship is

A well-designed signalized intersection is one in which the

A priority intersection has a single-lane one-way traffic road crossing an undivided twolane two-way traffic road. The traffic stream speed on the single-lane road is 20 kmph and the speed on the two-lane road is 50 kmph. The perception-reaction time is 2.5 s, coefficient of longitudinal friction is 0.38 and acceleration due to gravity is 9.81 m/s2. A clear sight triangle has to be ensured at this intersection. The minimum lengths of the sides of the sight triangle along the two-lane road and the single-lane road, respectively will be

Given the following data: design life n = 15 years, lane distribution factor D = 0.75, annual rate of growth of commercial vehicles r = 6%, vehicle damage factor F = 4 and initial traffic in the year of completion of construction = 3000 Commercial Vehicles Per Day (CVPD). As per IRC:37-2012, the design traffic in terms of cumulative number of standard axles (in million standard axles, up to two decimal places) is ______

Peak Hour Factor (PHF) is used to represent the proportion of peak sub-hourly traffic flow within the peak hour. If 15-minute sub-hours are considered, the theoretically possible range of PHF will be

vehicales arriving at an intersection from one of the approach roads follow the poisson distribution. The mean rate of arrival is 900 vehicales per hour. If a gap is defined as the time difference between two successive vehicale arrivals (with vehicales assumed to be points), the probability (up to four decimal places) that the gap is greater than 8 seconds is _______________

The queue length (in number of vehicles) versus time (in seconds) plot for an approach to a signalized intersection with the cycle length of 96 seconds is shown in the figure (not drawn to scale).

At time $ t=0 $, the light has just turned red. The effective green time is 36 seconds, during which vehicels discharge at the saturations flow rate, $ s $ (in vph). Vehicles arrive at a uniform rate, $ v $ (in vph), throghout the cycle. Which one of the following statement is TRUE?

The saftey within a roundabout and the efficency of a roundabout can be increased, respectively, by

Two cars $ P $ and $ Q $ are moving in a racing track continuously for two hours. Assume that no other vehicles are using the track during this time. The expressions relating the distance travelled d (in km) and time t (in hour) for both the vehicles are given as

$ \begin{array}{l}P:\;d=60\;t\\Q:\;d=60\;t^2\end{array} $

Within the first one hour, the maximum space headway would be

In a one-lane one-way homogeneous traffic stream, the observed average headway is 3.0 s. The flow (expressed in vehicles/hr) in this traffic stream is________

While traveling along and against the traffic stream, a moving observer measured the relative flows as 50 vehicles/hr and 200 vehicles/hr, respectively. The average speeds of the moving observer while traveling along and against the stream are 20 km/hr and 30 km/hr, respectively. The density of the traffic stream (expressed in vehicles/km) is _________

If the total number of commercial vehicles per day ranges from 3000 to 6000, the minimum percentage of commercial traffic to be surveyed for axle load is

The critical flow ratios for a three-phase signal are found to be 0.30, 0.25, and 0.25. The total time lost in the cycle is 10 s. Pedestrian crossings at this junction are not significant. The respective Green times (expressed in seconds and rounded off to the nearest integer) for the three phases are

Which of the following statements CANNOT be used to describe free flow speed (uf) of a traffic stream ?

The acceleration –time relationship for a vehicle subjected to non-uniform acceleration is,

$ \frac{dv}{dt}=(\alpha-\beta v_0)e^{-\beta t} $

shere, v is the speed in m/s, t is the time in s, α and β are parameters, and v0 is the initial speed in m/s. If the accelerating behavior of a vehicle, whose driver intends to overtake a slow moving vehicle ahead, is descried as,


Considering α = 2 m/s2, β = 0.05 s-1 and $ 1.3\;m/s^2\frac{dv}{dt} $ at $ t=3s $, the distance (in m) travelled by the vehicle in 35 s is _______.

The following statements are made related to the lengths of turning lanes at signalized intersections:

(i) 1.5 times the average number of vehicles (by vehicle type) that would store in turning lane per cycle during the peak hour
(ii) 2 times the average number of vehicles (by vehicle type) that would store in turning lane per cycle during the peak hour
(iii) Average number of vehicles (by vehicle type) that would store in the adjacent through lane per cycle during the peak hour
(iv) Average number of vehicles (by vehicle type) that would store in all lanes per cycle during the peak hour

As per the IRC recommendations, the correct choice for design length of storage lanes is

The relation between speed u (in km/h) and density k (number of vehicles/km) for a traffic stream on a road is u = 70 - 0.7k. The capacity on this road is __________ vph (vehicles/hour).

The minimum value of 15 minute peak hour factor on a section of a road is

The speed-density (u−k) relationship on a single lane road with unidirectional flow is , u=70-0.k where u is in km/hr and k is in veh/km. The capacity of the road (in veh/hr) is ___________

An isolated three-phase traffic signal is designed by Webster's method. The critical flow ratios for three phases are 0.20, 0.30, and 0.25 respectively, and lost time per phase is 4 seconds. The optimum cycle length (in seconds) is ___________

The average spacing between vehicles in a traffic stream is 50 m, then the density (in veh/km) of the stream is ________________

An observer counts 240 veh/h at a specific highway location. Assume that the vehicle arrival at the location is Poisson distributed, the probability of having one vehicle arriving over a 30-second time interval is ____________

A student riding a bicycle on a 5 km one-way street takes 40 minutes to reach home. The student stopped for 15 minutes during this ride. 60 vehicles overtook the student (assume the number of vehicles overtaken by the student is zero) during the ride and 45 vehicles while the student stopped. The speed of vehicle stream on that road (in km/hr) is

On a section of a highway the speed-density relationship is linear and is given by v=80-23k where v is in km/h and k is in veh/km. The capacity (in veh/h) of this section of the highway would be

A pre-timed four phase signal has critical lane flow rate for the first three phases as 200, 187 and 210 veh/hr with saturation flow rate of 1800 veh/hr/lane for all phases. The lost time is given as 4 seconds for each phase. If the cycle length is 60 seconds, the effective green time (in seconds) of the fourth phase is ______________

It was observed that 150 vehicles crossed a particular location of a highway ina duration of 30 minutes. Assuming that vehicle arrival follows a negative exponential distribution, find out the number of time headways greater than 5 seconds in the above observation? __________

Two major roads with two lanes each are crossing in an urban area to form an un-controlled intersection. The number of conflict points when both roads are one-way is “X” and when both roads are two-way is “Y”. The ratio of X to Y is

A two-lane urban road with one-way traffic has a maximum capacity of 1800 vehicles/hour. Under the jam condition, the average length occupied by the vehicles is 5.0 m. The speed versus density relationship is linear. For a traffic volume of 1000 vehicles/hour, the density (in vehicles/km) is

the probability that k number of vehicles arrive (i.e. cross a predefined line) in time t is given as λtke-λt/k!  Where λ is the average vehicle arrival rate. What is the probability that the time headway is greater than or equal to time t1?

A vehicle negotiates a transition curve with uniform speed v. if the radius of the horizontal curve and the allowable jerk are R and J respectively, the minimum length of the transition curve is

If the jam density is given as kj and the free flow speed is given as μf, the maximum flow for a linear traffic speed-density model is given by which of the following options?

The cumulative arrival and departure curve of one cycle of an approach lane of a signalized intersection is shown in the adjoining figure. The cycle time is 50s and the effective red time is 30s and the effective green time is 20s. what is the average delay?

As per IRC: 67-2001, a traffic sign indicating the Speed Limit on a road should be of

On a specific highway, the speed-density relationship follows the Greenberg’s model v=vflnkj/k, where vf and kf are the free flow speed and jam density respectively. When the highway is operating at capacity, the density obtained as per this model is

A three-phase traffic signal at an intersection is designed for flows shown in the figure below. There are six groups of flows identified by the numbers 1 through 6. Among these 1, 3, 4 and 6 are through flows and, 2 and 5 are right turning. Which phasing scheme is not feasible?


Combination choice Phase I Phase II Phase III
P 1, 4 2, 5 3, 6
Q 1, 2 4, 5 3, 6
R 2, 5 1, 3 4, 6
S 1, 4 2, 6 3, 5

The capacities of “One-way 1.5m wide sidewalk (persons per hour)” and “One-way 2-lane urban road (PCU per hour, with no frontage access, no standing vehicles and very little cross traffic)” are respectively

The shape of the STOP sign according to IRC: 67-2001 is

A roundabout is provided with an average entry width of 8.4 m, width of weaving section as 14 m, and length of the weaving section between channelizing islands as 35 m. The crossing traffic and total traffic on the weaving section are 1000 and 2000 PCU per hour respectively. The nearest rounded capacity of the roundabout (in PCU per hour is)

Design parameters for a signalized intersection are shown in the figure below. The green time calculated for major and minor roads are 34 and 18s respectively.

The critical lane volume on the major road changes to 440 vehicles per hour per lane and the critical lane volume on the minor road remains unchanged. The green time will

A linear relationship is observed between speed and density on a certain section of a highway. The free flow speed is observed to be 80 km per hour and the jam density is estimated as 100 vehicles per km length. Based on the above relationship, the maximum flow expected on this section and the speed at the maximum flow will respectively be

If a two-lane national highway and a two-lane state highway intersect at right angles, the number of potential conflict points at the intersecton, assuming that both the roads are two-way is

In signal design as per Indian Roads Congress specifications, if the sum of the ratios of normal flows to saturation flow of two directional traffic flow is 0.50 and the total lost time per cycle is 10 seconds, the optimum cycle length in seconds is

If the standard deviation of the spot speed of vehicles in a highway is 8.8 kmph and the mean speed of the vehicles is 33 kmph, the coefficient of variation in speed is