Q: During the detailed survey of a hill road alignment, which operation should be carried out first to establish reliable control for subsequent measurements?

Introduction / Context: Detailed surveys for hill roads require robust horizontal and vertical control because steep terrain amplifies errors in gradients, cross-slopes, and earthwork estimates. Establishing benchmarks is foundational for all subsequent operations in the survey workflow. Given Data / Assumptions: Project: hill road detailed survey after preliminary alignment. Need: stable vertical control (reduced levels) and reference points. Equipment: precise levels/total stations for transfer of elevations. Concept / Approach: Bench Marks (BMs) provide permanent elevation references. With known BMs, surveyors can correctly set grades, profile the centerline, and layout cross-sections. Without them, longitudinal levels and curve setting would be unreliable, risking design inaccuracies and construction disputes. Step-by-Step Solution: Establish and verify Bench Marks tied to a datum.Run control leveling to transfer RLs along the proposed corridor.Proceed to take longitudinal/cross sections, then refine horizontal/vertical curves.Carry out hydrological/soil surveys and stake out after control is secure. Verification / Alternative check: Standard survey practice places control establishment (BMs and traverse) at the start so that all subsequent measurements are consistent and repeatable. Why Other Options Are Wrong: Hydrology/soils: rely on correct levels/locations from control. Alignment adjustments and staking: require accurate control first. Profiles/sections: cannot be trusted without BMs. Common Pitfalls: Using temporary, unstable marks in steep terrain. Skipping BM verification after landslides or heavy rainfall. Final Answer: Fixation of Bench Marks

Q: What is the standard side length of warning (cautionary) traffic sign boards used on roads?

Introduction / Context: Warning (cautionary) traffic signs are typically equilateral triangles mounted point-up to alert drivers about upcoming hazards. Their dimensions are standardized to ensure legibility and uniformity across networks, with smaller sizes used on lower-category roads and constrained sites. Given Data / Assumptions: Category: warning signs (triangular). Question seeks the standard side length used commonly in practice for compact sites and ordinary roads. Concept / Approach: While larger triangular signs (for higher-speed roads) are also in use, many standard MCQ references cite a commonly adopted triangular side of about 50 cm for local/low-speed applications, providing sufficient conspicuity without excessive panel size. The dimension relates to minimum legibility at typical approach speeds and balances fabrication/installation constraints. Step-by-Step Solution: Identify sign type: equilateral triangle (warning).Select standard compact side length used on regular roads.Adopt 50 cm side length as the answer aligned with common practice references. Verification / Alternative check: Field practice often employs larger sizes on highways (for higher speeds), but for many ordinary roads, 50 cm is a widely quoted figure in exam-oriented compilations. Why Other Options Are Wrong: 30–45 cm: too small for consistent legibility. Common Pitfalls: Confusing regulatory (circular) and informatory (rectangular) signs with warning (triangular) sizes. Ignoring speed environment when selecting sign size. Final Answer: 50 cm

Q: In traffic forecasting for highways, the increase in traffic volume attributable to a general rise in the number of transport vehicles (independent of specific new projects) is termed what?

Introduction / Context: Accurate traffic forecasting separates different components of future traffic so that design is neither overly conservative nor unsafe. Standard categories distinguish background growth from project-induced changes. Given Data / Assumptions: Observed increase due to overall motorization and economic growth. No specific single development (like a new industrial estate) directly causing the rise. Concept / Approach: Normal traffic growth is the background increase tied to population, income, and vehicle ownership trends. Development traffic arises from a specific planned development in the influence area. Generated traffic is additional travel induced by improved facility/service level (e.g., new road reducing travel time). The question clearly points to background growth from more vehicles overall, hence “normal traffic growth.” Step-by-Step Solution: Identify growth driver: general rise in vehicle numbers.Map to category: normal (background) growth.Exclude other categories: not tied to a discrete development; not induced by the project itself. Verification / Alternative check: Highway planning texts and IRC guidance treat background growth separately so that generated/development traffic can be estimated and added explicitly when relevant. Why Other Options Are Wrong: Development traffic: tied to specific land-use projects. Generated traffic growth: a consequence of improved facility or reduced impedance. Current traffic: a snapshot, not a growth category. Common Pitfalls: Double counting growth by adding both normal and generated components without careful delineation. Using short-term seasonal spikes as trend indicators. Final Answer: Normal traffic growth

Q: What is the minimum lateral clearance specified for road markers from the edge of a kerb so that the markers do not obstruct vehicles and remain visible?

Introduction / Context: Road markers (such as delineators or boundary markers) placed along kerbed edges must maintain a safe lateral offset to avoid being struck by passing vehicles and to remain within drivers’ sight envelopes. Standards prescribe minimum clearances that balance safety, visibility, and practical placement in constrained rights-of-way. Given Data / Assumptions: Markers are along a kerbed roadway edge. Lateral clearance is measured horizontally from the kerb edge to the marker. Urban context with typical lane widths and shy-line considerations. Concept / Approach: A minimum offset prevents mirror and body strikes and accommodates shy distances near vertical objects. A commonly cited minimum offset for such markers is about 50 cm from the kerb face, adequate for most light vehicles while remaining readable and within maintenance reach. Step-by-Step Solution: Identify the kerb face as reference.Apply standard minimum offset: ≥ 0.50 m.Locate and anchor markers accordingly, ensuring uniformity. Verification / Alternative check: Practical urban roadway sections frequently adopt 0.5 m as a workable minimum; larger offsets may be used on high-speed roads for additional shy distance. Why Other Options Are Wrong: 40–45 cm: insufficient shy distance; higher risk of strikes. 55–60 cm: acceptable but not the minimum; consumes more verge width. Common Pitfalls: Measuring from the carriageway edge line rather than from the kerb face. Ignoring local constraints like drains and utility covers which may require local adjustments. Final Answer: 50 cm

Q: Border Roads Organisation (BRO) for construction and maintenance of roads in hilly and border regions of India was established in which year?

Introduction / Context: The Border Roads Organisation (BRO) is pivotal to strategic connectivity, especially across Himalayan terrain and other border states. Knowing its formation year helps contextualize the timeline of India’s post-independence infrastructure expansion and the institutional framework behind high-altitude road building. Given Data / Assumptions: Question asks the establishment year of BRO. Focus is on the formal inception date of the organisation. Concept / Approach: The BRO was formed to plan, execute, and maintain road networks in border areas to ensure logistics, defense mobility, and socioeconomic development. Its creation predates several major geopolitical events and enabled systematic, centrally coordinated works in difficult terrains. Step-by-Step Solution: Recall institutional history of BRO: inception around the beginning of the 1960s. Differentiate between organisational formation and later flagship projects initiated in the early 1960s. Select the established year: 1960. Verification / Alternative check: Historical summaries consistently cite 1960 as the founding year, followed by rapid scaling of projects across Himalayan corridors and the North-East during the early 1960s. Why Other Options Are Wrong: 1947/1954/1958: Pre-date the decision to create a dedicated border roads agency. 1962: Reflects a period of intensified activity, but not the initial establishment date. Common Pitfalls: Confusing the organisation’s formation year with the commencement year of specific projects. Final Answer: 1960.

Q: Compound horizontal curve design: the minimum desirable ratio of the radii of the two constituent circular arcs (R1/R2) is generally kept at or above which value to ensure a smooth transition?

Introduction / Context: Compound curves—two or more circular arcs of different radii joined tangentially—are used when geometric constraints prevent a single-radius curve. To preserve driver comfort and avoid abrupt changes in curvature, the radii should not differ too much; a commonly adopted minimum ratio helps maintain a gentle curvature progression. Given Data / Assumptions: Two adjacent circular arcs with radii R1 and R2. Requirement: minimum ratio R1/R2 for desirable operation and aesthetics. Concept / Approach: A very small inner radius paired with a much larger outer radius causes sudden curvature change at the junction, which impairs comfort and may challenge superelevation transitions. A rule of thumb is to maintain R1/R2 ≥ 1.5 so that curvature increases or decreases moderately across the junction, allowing consistent steering and superelevation/runoff within limited lengths. Step-by-Step Solution: Define curvature change between adjacent arcs. Apply the recommended practice: R1/R2 not less than about 1.5. Choose 1.5 as the minimum ratio from the options provided. Verification / Alternative check: Design guides often permit a range but discourage ratios below 1.5 because they create a near “kink” in curvature even if tangency is satisfied, undermining comfort and drainage transitions. Why Other Options Are Wrong: 1.25: Too small; curvature change remains abrupt. 1.75 or 2.0+: Acceptable but more restrictive than the common minimum; not “minimum”. Common Pitfalls: Using compound arcs without adequate transition lengths or superelevation runoff, especially on high-speed facilities. Final Answer: 1.5.

Q: Vehicle braking on roads: the operational efficiency of brakes depends most directly on which set of real-world conditions?

Introduction / Context: Stopping distance and control during braking depend on more than brake hardware. The tyre–road interface dictates the usable friction; thus, road surface condition, tyre condition, and the presence of moisture/contaminants critically influence braking efficiency and safety outcomes on highways and urban roads. Given Data / Assumptions: Vehicles operate on variable pavement textures and gradients. Tyre condition varies across fleets and seasons. Weather and spills add moisture or contaminants. Concept / Approach: Maximum deceleration without wheel lock or loss of control occurs when tyre–road friction is high and stable. Macrotexture and microtexture provide drainage and micro-interlock; worn or underinflated tyres reduce effective friction, while water, mud, oil, or loose aggregates form films or marbles that degrade grip. Therefore, braking efficiency is a system property of brake mechanics and contact conditions together. Step-by-Step Solution: Assess road surface: polished or flooded surfaces reduce friction. Assess tyres: adequate tread depth and correct pressures improve drainage and contact patch performance. Account for moisture/contaminants: increase stopping distances and risk of hydroplaning. Conclude that all listed factors materially affect braking efficiency. Verification / Alternative check: Empirical stopping-distance charts vary coefficients of friction by surface (dry/wet asphalt, concrete) and tyre condition, consistently demonstrating their combined influence on achievable deceleration without ABS intervention. Why Other Options Are Wrong: Single-factor choices understate the multi-variable nature of braking performance. “None” contradicts well-documented roadway safety research. Common Pitfalls: Over-relying on ABS/ESC while neglecting tyre maintenance and roadway drainage design. Final Answer: All the above.

Question 1

According to I.R.C. recommendations, a traffic volume study for rural roads should be conducted for 7 consecutive days during which seasonal period to capture representative conditions?

Accepted Answer

Introduction / Context: Traffic volume studies underpin planning, capacity assessment, and pavement design for rural roads. The Indian Roads Congress (I.R.C.) emphasizes that counts be taken during representative periods so seasonal fluctuations—especially those driven by agricultural activity—are reflected in design traffic estimates. Given Data / Assumptions: Facility type: rural roads with agricultural influence. Duration: 7 days of continuous counting. Objective: capture realistic traffic, accounting for seasonal variations. Concept / Approach: Rural traffic can vary significantly between harvest peaks and lean (off-harvest) periods. Conducting 7-day studies in both characteristic seasons yields a more robust estimate of AADT (annual average daily traffic) by bracketing the likely range and allowing seasonal factors to be derived for design traffic forecasts. Step-by-Step Solution: Plan two 7-day counts: one in harvesting and one in lean season.Compute average daily traffic for each and apply expansion factors.Combine with seasonal adjustment to estimate AADT and design traffic (e.g., commercial vehicle growth). Verification / Alternative check: Design manuals and typical state PWD practices mirror the I.R.C. guidance by discouraging counts only during unusual or festival periods; dual-season counting reduces bias from crop-cycle-induced peaks/lulls. Why Other Options Are Wrong: Harvesting season only: overestimates average flow. Lean season only: underestimates average flow. None of these: incorrect; I.R.C. recommends considering seasonal variation explicitly. Common Pitfalls: Conducting counts during holidays/fairs, which distort typical patterns. Using a single short count without seasonal adjustment factors. Final Answer: Both harvesting and lean season

Question 2

For hill roads, what is the maximum super-elevation (rate of transverse tilt) that should not be exceeded to ensure safety and vehicle stability?

Accepted Answer

Introduction / Context: Super-elevation is the transverse inclination provided on horizontal curves to counteract the centrifugal force on vehicles. On hill roads, geometric constraints and low-speed regimes allow a higher limiting super-elevation than in plains, but it must still be capped for safety and comfort, especially in wet or icy conditions. Given Data / Assumptions: Facility: hill roads with horizontal curves. Objective: determine the codal upper limit of super-elevation. Vehicles travel at moderate speeds; friction and drainage considerations apply. Concept / Approach: IRC recommendations permit a higher limit for hill roads compared to plain terrain to accommodate sharper curves, typically up to 10%. This value balances vehicle stability, skid resistance, and construction practicality on mountainous alignments. Step-by-Step Solution: Select hill-road context.Apply the IRC limiting value for e_max on hill roads.Adopt e_max = 10% for design checks and detailing. Verification / Alternative check: Empirical practice across Indian hill highways adopts 10% as the ceiling, whereas plains frequently limit e to about 7% due to higher design speeds and comfort constraints. Why Other Options Are Wrong: 5%, 7%, 8%: lower than allowed in hills; may be uneconomical on tight curves. 15%: too steep for comfort and safety in most conditions. Common Pitfalls: Providing excessive e on stretches prone to snow/ice, which can cause downslope skidding. Ignoring transition lengths for super-elevation runoff. Final Answer: 10%

Question 3

On a highway with ruling gradient 3%, what gradient should be provided on a horizontal curve of radius 300 m after applying grade compensation?

Accepted Answer

Introduction / Context: Grade compensation reduces the algebraic gradient on horizontal curves to offset the additional tractive resistance that vehicles experience while negotiating curvature. Without compensation, the effective effort demanded on a curve would be higher than on a tangent with the same gradient, penalizing heavy vehicles. Given Data / Assumptions: Ruling gradient on tangent, G_ruling = 3.00%. Curve radius, R = 300 m. Use the standard compensation formula for curves (subject to a cap). Concept / Approach: IRC practice uses grade compensation (%) ≈ 75 / R for R in metres, limited to a maximum (often 0.8%). For R = 300 m, compensation = 75 / 300 = 0.25%. The compensated gradient on the curve = ruling gradient − compensation. Step-by-Step Solution: Compute compensation: C = 75 / 300 = 0.25%.Apply to ruling gradient: G_curve = 3.00% − 0.25% = 2.75%.Check cap: 0.25% < 0.8%, so no capping required. Verification / Alternative check: As R increases, compensation decreases towards zero; at small R (sharp curves), compensation approaches the cap, aligning with practical experience. Why Other Options Are Wrong: 2.00%, 2.25%, 2.50%: over-compensate for R = 300 m. 3.00%: ignores compensation and would demand unnecessary tractive effort on the curve. Common Pitfalls: Using the compensation formula with R in km instead of metres. Forgetting to enforce the maximum cap when R is very small. Final Answer: 2.75%

Question 4

During the detailed survey of a hill road alignment, which operation should be carried out first to establish reliable control for subsequent measurements?

Accepted Answer

Introduction / Context: Detailed surveys for hill roads require robust horizontal and vertical control because steep terrain amplifies errors in gradients, cross-slopes, and earthwork estimates. Establishing benchmarks is foundational for all subsequent operations in the survey workflow. Given Data / Assumptions: Project: hill road detailed survey after preliminary alignment. Need: stable vertical control (reduced levels) and reference points. Equipment: precise levels/total stations for transfer of elevations. Concept / Approach: Bench Marks (BMs) provide permanent elevation references. With known BMs, surveyors can correctly set grades, profile the centerline, and layout cross-sections. Without them, longitudinal levels and curve setting would be unreliable, risking design inaccuracies and construction disputes. Step-by-Step Solution: Establish and verify Bench Marks tied to a datum.Run control leveling to transfer RLs along the proposed corridor.Proceed to take longitudinal/cross sections, then refine horizontal/vertical curves.Carry out hydrological/soil surveys and stake out after control is secure. Verification / Alternative check: Standard survey practice places control establishment (BMs and traverse) at the start so that all subsequent measurements are consistent and repeatable. Why Other Options Are Wrong: Hydrology/soils: rely on correct levels/locations from control. Alignment adjustments and staking: require accurate control first. Profiles/sections: cannot be trusted without BMs. Common Pitfalls: Using temporary, unstable marks in steep terrain. Skipping BM verification after landslides or heavy rainfall. Final Answer: Fixation of Bench Marks

Question 5

What is the standard side length of warning (cautionary) traffic sign boards used on roads?

Accepted Answer

Introduction / Context: Warning (cautionary) traffic signs are typically equilateral triangles mounted point-up to alert drivers about upcoming hazards. Their dimensions are standardized to ensure legibility and uniformity across networks, with smaller sizes used on lower-category roads and constrained sites. Given Data / Assumptions: Category: warning signs (triangular). Question seeks the standard side length used commonly in practice for compact sites and ordinary roads. Concept / Approach: While larger triangular signs (for higher-speed roads) are also in use, many standard MCQ references cite a commonly adopted triangular side of about 50 cm for local/low-speed applications, providing sufficient conspicuity without excessive panel size. The dimension relates to minimum legibility at typical approach speeds and balances fabrication/installation constraints. Step-by-Step Solution: Identify sign type: equilateral triangle (warning).Select standard compact side length used on regular roads.Adopt 50 cm side length as the answer aligned with common practice references. Verification / Alternative check: Field practice often employs larger sizes on highways (for higher speeds), but for many ordinary roads, 50 cm is a widely quoted figure in exam-oriented compilations. Why Other Options Are Wrong: 30–45 cm: too small for consistent legibility. Common Pitfalls: Confusing regulatory (circular) and informatory (rectangular) signs with warning (triangular) sizes. Ignoring speed environment when selecting sign size. Final Answer: 50 cm

Question 6

Given basic capacity per lane C (veh/h), speed V (km/h), and S (m) as the sum of stopping distance and average vehicle length, the capacity formula discussed applies to which type of road facility?

Accepted Answer

Introduction / Context: Macroscopic capacity relations express lane capacity as a function of speed and effective spacing. One such form uses V in km/h and S (m) representing the effective space headway (stopping distance plus vehicle length). This construct aligns with uninterrupted flow on multilane one-way facilities where uniform speed–spacing assumptions are more tenable. Given Data / Assumptions: C = basic capacity per lane (vehicles/hour). V = space-mean speed (km/h). S = stopping distance + average vehicle length (m). Uninterrupted, one-way flow; driver behavior approximated by uniform spacing. Concept / Approach: Conceptually, capacity per lane ≈ (speed / spacing) after unit conversions. For one-way two-lane (per direction) roads, flows in the same direction allow consistent spacing assumptions and minimal opposing flow interference, matching the formula’s basis. Mixed two-way two-lane facilities have additional constraints (overtaking, opposing streams) that this simple relation does not capture well. Step-by-Step Solution: Interpret C ∝ V / S after converting km/h and metres to consistent units.Recognize uniform same-direction flow assumptions.Conclude applicability: two lanes moving in one direction (one-way). Verification / Alternative check: Highway capacity literature typically derives C = 1000 * V / S (after unit handling), which is best-suited to same-direction multilane contexts rather than bidirectional two-lane roads where passing maneuvers govern. Why Other Options Are Wrong: District roads: a classification, not a flow pattern; capacity varies widely. Two-lane roads (two-way): opposing streams and passing restrictions violate the simple spacing premise. None of these: incorrect because a matching facility exists (two lanes, one-way). Common Pitfalls: Using time headway without corresponding speed conversion, leading to unit errors. Applying one-way capacity relations to constrained two-way undivided roads. Final Answer: Two-lane roads in one direction (one-way)

Question 7

In traffic forecasting for highways, the increase in traffic volume attributable to a general rise in the number of transport vehicles (independent of specific new projects) is termed what?

Accepted Answer

Introduction / Context: Accurate traffic forecasting separates different components of future traffic so that design is neither overly conservative nor unsafe. Standard categories distinguish background growth from project-induced changes. Given Data / Assumptions: Observed increase due to overall motorization and economic growth. No specific single development (like a new industrial estate) directly causing the rise. Concept / Approach: Normal traffic growth is the background increase tied to population, income, and vehicle ownership trends. Development traffic arises from a specific planned development in the influence area. Generated traffic is additional travel induced by improved facility/service level (e.g., new road reducing travel time). The question clearly points to background growth from more vehicles overall, hence “normal traffic growth.” Step-by-Step Solution: Identify growth driver: general rise in vehicle numbers.Map to category: normal (background) growth.Exclude other categories: not tied to a discrete development; not induced by the project itself. Verification / Alternative check: Highway planning texts and IRC guidance treat background growth separately so that generated/development traffic can be estimated and added explicitly when relevant. Why Other Options Are Wrong: Development traffic: tied to specific land-use projects. Generated traffic growth: a consequence of improved facility or reduced impedance. Current traffic: a snapshot, not a growth category. Common Pitfalls: Double counting growth by adding both normal and generated components without careful delineation. Using short-term seasonal spikes as trend indicators. Final Answer: Normal traffic growth

Question 8

What is the minimum lateral clearance specified for road markers from the edge of a kerb so that the markers do not obstruct vehicles and remain visible?

Accepted Answer

Introduction / Context: Road markers (such as delineators or boundary markers) placed along kerbed edges must maintain a safe lateral offset to avoid being struck by passing vehicles and to remain within drivers’ sight envelopes. Standards prescribe minimum clearances that balance safety, visibility, and practical placement in constrained rights-of-way. Given Data / Assumptions: Markers are along a kerbed roadway edge. Lateral clearance is measured horizontally from the kerb edge to the marker. Urban context with typical lane widths and shy-line considerations. Concept / Approach: A minimum offset prevents mirror and body strikes and accommodates shy distances near vertical objects. A commonly cited minimum offset for such markers is about 50 cm from the kerb face, adequate for most light vehicles while remaining readable and within maintenance reach. Step-by-Step Solution: Identify the kerb face as reference.Apply standard minimum offset: ≥ 0.50 m.Locate and anchor markers accordingly, ensuring uniformity. Verification / Alternative check: Practical urban roadway sections frequently adopt 0.5 m as a workable minimum; larger offsets may be used on high-speed roads for additional shy distance. Why Other Options Are Wrong: 40–45 cm: insufficient shy distance; higher risk of strikes. 55–60 cm: acceptable but not the minimum; consumes more verge width. Common Pitfalls: Measuring from the carriageway edge line rather than from the kerb face. Ignoring local constraints like drains and utility covers which may require local adjustments. Final Answer: 50 cm

Question 9

In highway traffic engineering for at-grade roundabouts (rotaries), the weaving length of a roadway is defined as the distance between which two features of the channelized layout?

Accepted Answer

Introduction / Context: Weaving length is a fundamental concept in the design and capacity analysis of modern roundabouts and traditional traffic rotaries in highway engineering. It represents the roadway segment over which vehicles entering and exiting the circulatory carriageway cross paths (weave), and it governs safe operation, speed, and throughput under heterogeneous traffic compositions often found in Indian conditions. Given Data / Assumptions: Facility: at-grade rotary/roundabout with channelised approaches. Weaving occurs between successive entry and exit points. Channelising (splitter) islands guide entering and exiting streams. Concept / Approach: By definition used in design manuals, the weaving length is the distance measured along the circulatory roadway between the ends of two adjacent channelising (splitter) islands. This is the section where streams merge, cross, and diverge. Adequate weaving length allows drivers to change lanes and complete manoeuvres at comfortable deceleration/acceleration rates, thereby limiting conflict and maintaining capacity. Step-by-Step Solution: Identify where entering traffic merges with circulating traffic: immediately downstream of the entry splitter island. Identify where exiting traffic diverges toward the next exit: immediately upstream of the exit splitter island. Define weaving segment as the portion between these two splitter islands. Select the option describing this exact distance. Verification / Alternative check: Capacity relations for weaving sections use parameters such as weaving length (L_w), weaving width, proportion of weaving traffic, and entry widths. Shorter L_w increases lane-change conflicts and reduces capacity, confirming the necessity of measuring between splitter islands where weaving actually happens. Why Other Options Are Wrong: Half circumference/diameter: Geometric descriptors of the central island, not the conflict segment. Total width of adjoining radial roads: A cross-sectional dimension, not a longitudinal distance along the circulatory carriageway. Inscribed circle to outer kerb: Radial/offset measure, unrelated to weaving definition. Common Pitfalls: Measuring along the central island edge instead of along the vehicle path between splitter islands. Ignoring that weaving begins after the entry nose and ends before the exit nose. Final Answer: Between the channelising (splitter) islands.

Question 10

Roadside safety appurtenances: which of the following statements about safety fences and guard stones on embankments and curves is correct under typical Indian practice?

Accepted Answer

Introduction / Context: Roadside safety features reduce run-off-road crash severity, especially on elevated embankments and horizontal curves. The selection between guard stones, safety fences (guardrails), and barriers depends on embankment height, curve radius, and available recovery area. Recognizing threshold values helps designers pick the minimum treatment to protect errant vehicles. Given Data / Assumptions: Embankment heights: < 1.6 m, 1.6–3 m, 3–6 m, > 6 m. Curves with radius less than 750 m are sharper and riskier. Spacing of guard stones around 2.5 m is a traditional provision. Concept / Approach: Where drop-offs are significant, containment is preferred over delineation. At moderate heights (1.6–3 m), guard stones provide physical and visual guidance. For higher embankments and sharper curves, safety fences (e.g., W-beam guardrails) are recommended, particularly on the outside of curves where the risk of departure is greatest. At very high embankments (> 6 m), bilateral protection may be justified where both sides present hazards. Step-by-Step Solution: Match embankment height bands with customary treatments. Associate sharper curves (R < 750 m) with installing safety fences on the outside edge. Recognize that very high embankments require stronger or bilateral containment. Conclude all listed prescriptions are consistent; choose “All the above”. Verification / Alternative check: These thresholds align with common Indian practice for two-lane rural highways and hill roads, where visibility constraints and slope hazards warrant progressive protection measures based on risk. Why Other Options Are Wrong: Picking any single provision ignores other equally valid criteria that also apply. “None of these” is incorrect since each statement reflects accepted practice. Common Pitfalls: Using delineators alone on high embankments where containment is needed. Forgetting that the outside of a curve is the departure side requiring priority protection. Final Answer: All the above.

Question 11

On hill roads with constrained alignment and short transition lengths, which type of transition curve is most commonly provided to connect straights and circular curves?

Accepted Answer

Introduction / Context: Transition curves provide a gradual change of curvature between tangents and circular arcs, allowing a smooth, comfortable path with controlled lateral acceleration and steering rate. In hill roads, site constraints often limit available length, influencing the practical choice of transition geometry and setting-out methods. Given Data / Assumptions: Hill roads: steep cross slopes, tight right-of-way, frequent curves. Need for easy field setting-out and acceptable vehicle dynamics at moderate speeds. Comparison among common transition types. Concept / Approach: The spiral (clothoid) has theoretically ideal linear curvature with length, but the cubic parabola also closely approximates a linear rate of change of curvature over moderate lengths and is easy to set out using simple offset methods—an advantage on rugged terrain. Traditional Indian hill-road practice frequently adopts the cubic parabola because it balances comfort with practical surveying and construction needs when transition length is short. Step-by-Step Solution: Identify needs: smooth curvature change and ease of field layout. Compare options: spiral vs. cubic parabola; both acceptable, but cubic parabola is simpler to peg in the field on hills. Exclude lemniscate (better for very large deflection with double curvature) and pure circular (no transition). Select cubic parabola as the type generally provided on hill roads. Verification / Alternative check: Setting-out tables and classical hill-road manuals show cubic parabola offsets from the tangent or long chord, confirming its traditional popularity when resources and visibility are constrained. Why Other Options Are Wrong: Circular: lacks transition and causes abrupt lateral acceleration. Lemniscate: specialized double-curvature application; uncommon for typical hill-road curves. Spiral: widely used on plains and high-speed roads; field simplicity often favors cubic parabola in hills. Common Pitfalls: Ignoring superelevation and sight distance needs when selecting transition length and type. Final Answer: Cubic parabola transition.

Question 12

Border Roads Organisation (BRO) for construction and maintenance of roads in hilly and border regions of India was established in which year?

Accepted Answer

Introduction / Context: The Border Roads Organisation (BRO) is pivotal to strategic connectivity, especially across Himalayan terrain and other border states. Knowing its formation year helps contextualize the timeline of India’s post-independence infrastructure expansion and the institutional framework behind high-altitude road building. Given Data / Assumptions: Question asks the establishment year of BRO. Focus is on the formal inception date of the organisation. Concept / Approach: The BRO was formed to plan, execute, and maintain road networks in border areas to ensure logistics, defense mobility, and socioeconomic development. Its creation predates several major geopolitical events and enabled systematic, centrally coordinated works in difficult terrains. Step-by-Step Solution: Recall institutional history of BRO: inception around the beginning of the 1960s. Differentiate between organisational formation and later flagship projects initiated in the early 1960s. Select the established year: 1960. Verification / Alternative check: Historical summaries consistently cite 1960 as the founding year, followed by rapid scaling of projects across Himalayan corridors and the North-East during the early 1960s. Why Other Options Are Wrong: 1947/1954/1958: Pre-date the decision to create a dedicated border roads agency. 1962: Reflects a period of intensified activity, but not the initial establishment date. Common Pitfalls: Confusing the organisation’s formation year with the commencement year of specific projects. Final Answer: 1960.

Question 13

Compound horizontal curve design: the minimum desirable ratio of the radii of the two constituent circular arcs (R1/R2) is generally kept at or above which value to ensure a smooth transition?

Accepted Answer

Introduction / Context: Compound curves—two or more circular arcs of different radii joined tangentially—are used when geometric constraints prevent a single-radius curve. To preserve driver comfort and avoid abrupt changes in curvature, the radii should not differ too much; a commonly adopted minimum ratio helps maintain a gentle curvature progression. Given Data / Assumptions: Two adjacent circular arcs with radii R1 and R2. Requirement: minimum ratio R1/R2 for desirable operation and aesthetics. Concept / Approach: A very small inner radius paired with a much larger outer radius causes sudden curvature change at the junction, which impairs comfort and may challenge superelevation transitions. A rule of thumb is to maintain R1/R2 ≥ 1.5 so that curvature increases or decreases moderately across the junction, allowing consistent steering and superelevation/runoff within limited lengths. Step-by-Step Solution: Define curvature change between adjacent arcs. Apply the recommended practice: R1/R2 not less than about 1.5. Choose 1.5 as the minimum ratio from the options provided. Verification / Alternative check: Design guides often permit a range but discourage ratios below 1.5 because they create a near “kink” in curvature even if tangency is satisfied, undermining comfort and drainage transitions. Why Other Options Are Wrong: 1.25: Too small; curvature change remains abrupt. 1.75 or 2.0+: Acceptable but more restrictive than the common minimum; not “minimum”. Common Pitfalls: Using compound arcs without adequate transition lengths or superelevation runoff, especially on high-speed facilities. Final Answer: 1.5.

Question 14

Vehicle braking on roads: the operational efficiency of brakes depends most directly on which set of real-world conditions?

Accepted Answer

Introduction / Context: Stopping distance and control during braking depend on more than brake hardware. The tyre–road interface dictates the usable friction; thus, road surface condition, tyre condition, and the presence of moisture/contaminants critically influence braking efficiency and safety outcomes on highways and urban roads. Given Data / Assumptions: Vehicles operate on variable pavement textures and gradients. Tyre condition varies across fleets and seasons. Weather and spills add moisture or contaminants. Concept / Approach: Maximum deceleration without wheel lock or loss of control occurs when tyre–road friction is high and stable. Macrotexture and microtexture provide drainage and micro-interlock; worn or underinflated tyres reduce effective friction, while water, mud, oil, or loose aggregates form films or marbles that degrade grip. Therefore, braking efficiency is a system property of brake mechanics and contact conditions together. Step-by-Step Solution: Assess road surface: polished or flooded surfaces reduce friction. Assess tyres: adequate tread depth and correct pressures improve drainage and contact patch performance. Account for moisture/contaminants: increase stopping distances and risk of hydroplaning. Conclude that all listed factors materially affect braking efficiency. Verification / Alternative check: Empirical stopping-distance charts vary coefficients of friction by surface (dry/wet asphalt, concrete) and tyre condition, consistently demonstrating their combined influence on achievable deceleration without ABS intervention. Why Other Options Are Wrong: Single-factor choices understate the multi-variable nature of braking performance. “None” contradicts well-documented roadway safety research. Common Pitfalls: Over-relying on ABS/ESC while neglecting tyre maintenance and roadway drainage design. Final Answer: All the above.

Question 15

Aerodynamic drag on vehicles: if A is the projected frontal area (m^2), V is vehicle speed (km/h), and C is a lumped constant, which proportionality correctly expresses wind resistance R for highway speeds?

Accepted Answer

Introduction / Context: At typical highway speeds, aerodynamic drag is a major component of tractive resistance for road vehicles. Drag depends on fluid density, a shape-dependent drag coefficient, frontal area, and the square of speed. For practical calculations, these factors are often grouped into a single constant for given ambient conditions and vehicle type. Given Data / Assumptions: R: wind (aerodynamic) resistance force. A: projected frontal area in m^2. V: speed in km/h (constant C absorbs unit conversions). C: lumped constant incorporating 0.5 * rho * C_d and unit factors. Concept / Approach: The fundamental relation is R = 0.5 * rho * C_d * A * v^2 (with v in m/s). When speed is expressed in km/h, a constant C converts units and embeds air density and C_d for the selected conditions, leading to R = C * A * V^2. The quadratic dependence on V explains why fuel economy deteriorates rapidly with speed. Step-by-Step Solution: Start with the standard drag equation in SI units. Convert the speed variable to km/h: absorb factors into a single constant C. Recognize the remaining functional dependence: proportional to A and V^2. Select R = C * A * V^2. Verification / Alternative check: Road-load coastdown tests fit tractive effort versus speed as F = a + bV + cV^2; the V^2 term corresponds to aerodynamic drag, reinforcing the quadratic relation across conventional speed ranges. Why Other Options Are Wrong: Linear (C A V) understates drag growth; cubic (C A V^3) overstates force (power scales with V^3, not force). C^2 A V or (C V)/A: dimensionally inconsistent with force for fixed definitions. Common Pitfalls: Confusing the cubic dependence of power (P = R * v ∝ V^3) with the quadratic dependence of drag force. Final Answer: R = C * A * V^2.

Question 16

According to IRC terrain classification based on cross slope, a country with cross slope between 10% and 25% is categorized as which type of terrain?

Accepted Answer

Introduction / Context: Terrain classification influences design speed, ruling gradient, curvature, sight distance, and earthwork quantities in highway alignment design. The Indian Roads Congress (IRC) classifies terrain primarily by the natural cross slope of the ground, enabling designers to adopt appropriate geometric standards and cost expectations. Given Data / Assumptions: Cross slope band considered: 10% to 25%. IRC-based categorization sought (plain, rolling, mountainous, steep). Concept / Approach: IRC adopts cross-slope ranges roughly as: Plain (0–10%), Rolling (10–25%), Mountainous (25–60%), and Steep (> 60%). These ranges reflect increasing construction difficulty and tighter geometric compromises as cross slope rises. Rolling terrain allows moderate speeds with reasonable earthwork, while mountainous and steep terrain require restrictive standards and more structures (retaining walls, hairpin bends). Step-by-Step Solution: Match the given cross-slope band 10–25% to the IRC table. Find the corresponding category: Rolling. Select “Rolling” as the correct answer. Verification / Alternative check: Project feasibility reports routinely adopt rolling standards for this slope band, reflected in chosen design speeds and curvature limits on state and national highways crossing undulating plateaus and foothills. Why Other Options Are Wrong: Plain: 0–10% only. Mountainous: 25–60%—steeper than the stated band. Steep: > 60%—very rugged terrain. Common Pitfalls: Mistaking local short gradients for average terrain classification—use cross slope, not isolated road gradients. Final Answer: Rolling.

Question 17

Widening at transitions: when a single-lane carriageway transitions to a two-lane carriageway, the width change is introduced through a taper approximately equal to which of the following?

Accepted Answer

Introduction / Context: Transitions from single-lane to two-lane carriageways must be smooth to minimize abrupt steering and speed changes. The taper ratio (longitudinal length to lateral widening) guides field implementation, ensures driver comfort, and maintains safety, especially on undivided rural roads where overtaking and speed variance are common. Given Data / Assumptions: Transition from one-lane to two-lane carriageway. Need a practical range of taper values rather than a single rigid number. Concept / Approach: Recommended tapers reflect expected operating speeds and sight conditions. Too short a taper causes sudden lateral shifts; too long a taper consumes unnecessary length without added benefit. A range of about 1:15 to 1:20 (length:offset) is commonly adopted for rural highway transitions, providing a manageable compromise across traffic mixes and speeds. Step-by-Step Solution: Define total widening required (from single-lane to two-lane standard). Multiply the lateral widening by the chosen taper ratio to get taper length. Adopt the range 1 in 15 to 1 in 20 to accommodate local speed and site constraints. Verification / Alternative check: Field practice and geometric design references consistently specify this taper range, with finer adjustments made for posted speed, sight distance, and presence of intersections or access points near the transition zone. Why Other Options Are Wrong: 1 in 10: Too abrupt for typical speeds; can surprise drivers. 1 in 15 or 1 in 20 alone: Acceptable individually but the recommended answer is a range, not a single fixed ratio. 1 in 25: Overly long for general practice, unless dictated by special constraints. Common Pitfalls: Starting the taper too close to a crest curve or intersection, reducing driver expectancy and sight distance. Final Answer: 1 in 15 to 1 in 20.

Question 18

Flexible pavement design philosophy: which statement best describes the basis on which flexible pavements are designed in highway engineering?

Accepted Answer

Introduction / Context: Flexible pavements are multilayered systems that distribute wheel loads to the subgrade. Because materials (bituminous mixes, granular bases, subgrade soils) are nonlinear, stress-dependent, and climate-sensitive, design cannot rely on pure theory alone. Instead, modern practice blends mechanics with calibration to performance data. Given Data / Assumptions: Design must handle traffic repetitions, seasonal moisture/temperature, and material variability. Mechanistic models estimate critical responses (strains, stresses, deflections). Empirical transfer functions link responses to observed distresses (rutting, fatigue, roughness). Concept / Approach: Mechanistic–empirical (M–E) design uses layered elastic or viscoelastic models to compute tensile strain at the bottom of bituminous layers and compressive strain on top of the subgrade, then applies empirically derived damage relationships to determine layer thicknesses meeting a specified reliability over design traffic (e.g., cumulative standard axles). Historical methods like CBR are empirical but are often interpreted within a mechanistic framework for rational checks. Step-by-Step Solution: Model load responses using mechanistic tools (e.g., layered analysis). Compute critical strains and compare to allowable limits via empirical transfer functions. Iterate layer thicknesses until performance criteria (rutting, fatigue) are satisfied. Verification / Alternative check: Calibration sections and long-term pavement performance databases confirm that predictions align when empirical models are tuned to local climate/materials, validating the blended approach over purely theoretical or purely empirical methods alone. Why Other Options Are Wrong: Pure theory: Ignores material nonlinearity and site-specific performance. Pure empirical: Lacks generality beyond the original calibration domain. Exact plasticity: Impractical for routine layered systems and typical inputs. Common Pitfalls: Using uncalibrated empirical models for climates or materials very different from the source database. Final Answer: A compromise of pure theory and pure empirical formula (mechanistic–empirical approach).

Question 19

In highway engineering history, who first proposed a basic empirical formula for determining pavement thickness in design practice?

Accepted Answer

Introduction / Context: Pavement design evolved from early empirical rules toward modern analytical–mechanistic methods. Before layered elastic theory and fatigue-based limit states became common, engineers relied on basic empirical formulas that related anticipated wheel loads to an appropriate slab or surface thickness for safe performance. This question checks historical attribution for the earliest widely cited basic pavement thickness formula in practice-focused literature. Given Data / Assumptions: The question seeks the pioneer associated with the first basic pavement thickness rule-of-thumb. Context is early 20th-century road construction when empirical relationships guided slab and surface thicknesses. No numerical computation is required—only correct attribution. Concept / Approach: Identify the historical contributor commonly credited in traditional exam texts for introducing a basic thickness relationship that predated more refined approaches (e.g., Westergaard's theory for rigid pavements and later flexible pavement design charts). Among the provided names, Kelly is typically cited as the earliest proposer of a simple thickness formula in many standard MCQ compilations and survey references used in competitive exams. Step-by-Step Solution: Review early empirical contributors listed in classic highway texts.Match the name most consistently referenced as the first to suggest a basic thickness rule.Select Kelly as the historically recognized proposer for the earliest empirical thickness relation. Verification / Alternative check: Later contributors such as Goldbeck are associated with specific rigid pavement thickness expressions, while Spangler is more linked to soil–structure and pipe deflection work; hence, Kelly aligns best with the earliest general thickness rule attribution in exam-oriented literature. Why Other Options Are Wrong: Goldbeck: known for a later rigid-pavement thickness expression, not the earliest general formula. Spangler: more prominent in soil mechanics and flexible pipe behavior, not the first pavement thickness rule. Picket: not the standard attribution for the first basic thickness formula in common references. Common Pitfalls: Confusing 'first' proposer with more widely used later formulas (e.g., Goldbeck). Assuming modern mechanistic–empirical methods replace historic attributions for exam questions—they often still test the historical naming. Final Answer: Kelly

Question 20

In geometric design of highways, identify the incorrect statement about super-elevation e and its functional dependence on key variables.

Accepted Answer

Introduction / Context: Super-elevation is the transverse slope provided on horizontal curves to counteract centrifugal effects and improve vehicle stability. For design speed V and curve radius R, the basic relationship e + f = V^2 / (g * R) (in consistent units) shows how e depends on speed, gravity, and curvature. This question asks which statement about e is incorrect. Given Data / Assumptions: e is provided as a ratio or percentage of cross slope. V is the design speed, R is the radius of the horizontal curve, g is acceleration due to gravity. Pavement width does not enter the fundamental e–V–R–g relation. Concept / Approach: The fundamental dependence is e ∝ V^2 and e ∝ 1/R, with gravity g in the denominator. Width of pavement affects lane configuration and runoff length but does not directly appear in the governing relation for required e for a given V and R. Step-by-Step Solution: Recognize from e + f = V^2/(gR) that e increases with V and decreases with R and g.Note that pavement width W does not appear in the formula; thus, any claim of direct proportionality to W is incorrect.Conclude that the incorrect statement is the one tying e directly to pavement width. Verification / Alternative check: Design standards specify super-elevation independently of pavement width; width influences other features like shoulder cross-fall and runoff length but not the basic e calculation. Why Other Options Are Wrong: e increases with speed: qualitatively true because e ∝ V^2. e is inversely proportional to g: correct since g appears in the denominator. e is inversely proportional to R: correct; tighter curves (smaller R) need larger e. Common Pitfalls: Equating construction practicalities (wider pavements ease runoff) with the core e formula. Confusing design speed V with operating speed distribution. Final Answer: Super-elevation is directly proportional to the width of the pavement.

Highway Engineering Questions