60 solved GATE CE questions on Transportation Engineering, drawn from 5 exam years and grouped by year. Every question shows the official answer and a step-by-step solution.
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Revision companion
State the design speed, vehicle type, and traffic parameters before selecting a formula. These selected foundations connect highway geometric design, traffic flow theory, and pavement design. The original exercises use idealized supplied data for learning; they are not instructions for designing roads or intersections.
Our study notes and original examples support the PYQs below; they are not official exam questions or a replacement for the current syllabus.
A simple circular curve is defined by its radius R. Superelevation (e) and side friction (f) balance the centripetal acceleration: e + f = v²/(gR), where v is in m/s and g = 9.81 m/s². The degree of curve D is related to R by R = 1718.87/D (for a 30 m arc definition in metric units).
Check yourself: Have you converted the design speed to m/s before substituting into the equilibrium equation?
Stopping sight distance (SSD) accounts for perception-reaction distance and braking distance. On a level road, SSD = vt + v²/(2gf), where v is speed in m/s, t is perception-reaction time, and f is the longitudinal friction coefficient. Overtaking sight distance is substantially longer and depends on the maneuver model assumed.
Check yourself: Is the gradient zero, or does the grade correction factor apply?
The fundamental relationship is q = k × v, where q is flow (vehicles/hr), k is density (vehicles/km), and v is space-mean speed (km/hr). At maximum flow (capacity), density is between zero and jam density. Space-mean speed is the harmonic mean of spot speeds, not the arithmetic mean.
Check yourself: Are you using space-mean speed or time-mean speed in the flow equation?
Webster's optimum cycle length minimizes total delay for a given set of phase flows. The effective green time accounts for start-up lost time and end clearance. The degree of saturation is the ratio of actual flow to saturation flow for each phase; values above 1.0 indicate oversaturation and growing queues.
Check yourself: Have you subtracted total lost time from the cycle length to get total effective green?
Flexible pavements distribute load through granular layers; rigid pavements use slab action. The California Bearing Ratio (CBR) characterizes subgrade strength. Equivalent single-axle loads (ESALs) convert mixed traffic to a standard 80 kN single axle. Higher axle loads increase ESALs non-linearly (approximately by the fourth power).
Check yourself: Is the load conversion using the correct power law for the pavement type?
Original teaching example · not a PYQ
Original mini-example: a horizontal curve has a radius of 250 m. The design speed is 72 km/h and the coefficient of lateral friction is f = 0.15. Assume g = 9.81 m/s² and a level road. Find the required superelevation rate e.
Required superelevation e ≈ 0.013 (about 1.3%).
Three vehicles pass a point with spot speeds of 40, 50, and 60 km/h. What is the space-mean speed?
Space-mean speed ≈ 48.6 km/h.
Space-mean speed = n / Σ(1/vᵢ) = 3 / (1/40 + 1/50 + 1/60) = 3 / (0.025 + 0.02 + 0.01667) = 3 / 0.06167 ≈ 48.6 km/h. The arithmetic (time-mean) speed is 50 km/h, which is higher as expected.
Supplemental reading, not an official GATE reading list or an endorsement of these notes.
Free video lectures covering highway alignment, geometric design, traffic engineering, and pavement design aligned with the GATE CE transportation syllabus.
This page shows 60 recent questions from the released archive, newest first. For older questions and complete papers, browse all GATE CE papers. Questions can carry more than one subject tag; counts are not marks weightage.
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