Bridge Classification, Planning, and Geometry

Introduction

A bridge is a structure that carries a road, railway, pedestrian route, utility, or watercourse over an obstacle while transferring loads safely to the ground. For a civil draftsman, bridge work begins before detailed reinforcement or fabrication drawings. The first task is to understand the site, select a suitable structural system, establish the bridge geometry, and communicate the arrangement accurately through plans, elevations, sections, and schedules.

Bridge classification is not merely descriptive. It affects span arrangement, foundation requirements, construction method, material use, clearance, maintenance, and cost. A short crossing over a drainage channel may be served by a slab bridge or box culvert, whereas a deep valley or navigable river may require a truss, arch, cable-stayed, or suspension system.

This chapter develops the practical foundations needed to distinguish major bridge types and prepare a preliminary bridge layout. Detailed structural design must be undertaken by a qualified bridge engineer using the governing national code, hydrological data, geotechnical investigations, traffic requirements, and approved loading standards.

Learning Objectives

After studying this chapter, the learner should be able to:

1. Classify bridges according to structural form, material, use, and span arrangement.
2. Explain the load-transfer behaviour of beam, slab, truss, arch, cable-stayed, suspension, and culvert systems.
3. Select a preliminary bridge type for a stated site condition.
4. Establish bridge alignment, carriageway, span, abutment, pier, clearance, freeboard, and waterway requirements.
5. Prepare and check plan, elevation, and cross-sectional bridge drawings.
6. Identify common drafting errors and coordinate geometry with hydraulic, geotechnical, and construction information.

1. Important Bridge Terminology

The deck is the portion supporting traffic and distributing loads to the main structural members. The carriageway is the paved or usable width provided for vehicular traffic. A footway or sidewalk accommodates pedestrians. Parapets, railings, or crash barriers protect users at the edges.

The superstructure includes the deck, beams, trusses, arches, cables, bearings, and associated members above the supports. The substructure consists mainly of abutments, piers, foundations, wing walls, and retaining elements. An abutment supports the end of a bridge and retains the approach embankment. An intermediate support is a pier.

The span is the distance between adjacent supports. Depending on the context, span may mean the centre-to-centre distance between bearings or the clear distance between faces of supports; the drawing must state the adopted convention. The overall bridge length is the total longitudinal length, while the clear waterway is the unobstructed width available for water flow.

The soffit is the underside of a deck or slab. Deck level normally refers to the finished road or walkway level. Bed level is the channel-bed elevation. High flood level (HFL) is the specified flood-water elevation, generally based on hydrological analysis and the adopted return period. Freeboard is the vertical distance between the design flood level and the underside of the bridge or another controlling structural element.

A bridge may be described as single-span or multi-span, simply supported, continuous, or integral. It may also be classified as straight, skew, or curved according to its alignment.

2. Classification of Bridges

2.1 Classification by structural action

A bridge’s structural form indicates how the principal forces are carried.

#### Beam and girder bridges

A beam bridge transfers deck loads to longitudinal beams, which carry bending and shear to bearings and supports. Reinforced-concrete beams, prestressed girders, steel plate girders, rolled steel sections, and composite steel–concrete girders are common forms. Beam bridges are comparatively simple to draw, construct, inspect, and extend into multi-span arrangements.

For a simply supported ideal beam carrying a uniformly distributed load, the maximum bending moment occurs near midspan and the maximum vertical shear occurs near a support. These relationships are useful for conceptual understanding, but final design must include permanent loads, traffic actions, impact or dynamic effects where required, braking, wind, temperature, seismic actions, and combinations specified by code.

#### Slab bridges

A slab bridge uses a reinforced or prestressed concrete slab as the principal spanning element. It is economical for relatively short spans because it has few components and a shallow structural depth. A slab may act mainly in one direction when supported on two opposite sides, or in two directions when supported along four sides and proportioned accordingly. The draftsman must show slab thickness, edge beams if present, deck crossfall, reinforcement cover, drainage outlets, and the relationship between the slab and abutments.

#### Truss bridges

A truss is a triangulated framework in which members are ideally connected at joints and carry primarily axial forces. Top and bottom chords resist overall compression and tension, while web members transfer shear through axial action. Actual connections, member self-weight, eccentricity, bending stiffness, and secondary stresses mean that real trusses are not perfectly pin-jointed.

Trusses can achieve longer spans than ordinary beams without an excessive increase in material depth. Their depth, panel length, bracing, inspection access, and vertical clearance must be coordinated. A truss above the deck is called a through or pony arrangement depending on the extent of overhead framing; a deck truss carries the deck near the top chord.

#### Arch bridges

An arch carries much of its principal action as compression along its curved form. The horizontal component of arch thrust must be resisted by foundations, abutments, or tie members. Arches are appropriate where strong rock or competent foundations are available and where an architectural or landscape response is desired. The rise-to-span relationship, springing level, spandrel arrangement, construction sequence, and waterway clearance are important in drawings.

A tied arch uses a tie member to resist the horizontal thrust, reducing the demand on the foundations. A true masonry or concrete arch, however, depends strongly on the support conditions and the compression behaviour of the arch ring.

#### Cable-stayed bridges

In a cable-stayed bridge, the deck is supported directly by inclined stays connected to one or more towers. The stays provide vertical support and transfer forces to the towers and deck. Cable-stayed bridges are commonly used for medium to long spans, particularly where a prominent tower is acceptable. Drawings should identify tower legs, stay anchorage zones, cable spacing, deck level, construction stages where relevant, and navigation or road clearances.

#### Suspension bridges

A suspension bridge carries the deck from vertical hangers attached to main cables draped between towers and anchored at the ends. The main cables carry high tension, while the anchorages resist the cable forces. Suspension bridges are efficient for very long main spans but require substantial anchorages, aerodynamic consideration, movement accommodation, and careful construction planning.

#### Culverts

A culvert is a structure that allows water to pass beneath a road, railway, or embankment. Common forms include pipe culverts, slab culverts, box culverts, and multiple-cell box culverts. A culvert is normally considered when the waterway is relatively small and the road embankment can pass over a buried structure. Important elements include inlet and outlet transitions, headwalls, wing walls, aprons, scour protection, debris passage, maintenance access, and hydraulic capacity.

A culvert should not be selected solely because its initial cost is low. Blockage, sedimentation, inadequate inlet control, erosion, difficult maintenance, and insufficient flood opening may create serious risks.

2.2 Classification by material and use

Bridges may be constructed from reinforced concrete, prestressed concrete, structural steel, masonry, timber, aluminium, or combinations of materials. Material selection depends on span, durability, local skills, availability, construction equipment, exposure, fire requirements, and life-cycle cost.

By use, bridges may be highway, railway, pedestrian, cycle, aqueduct, service, or combined-use structures. A temporary bridge may be modular or rapidly assembled, while a permanent bridge is designed for the specified service life and environmental exposure.

2.3 Classification by continuity and alignment

A simply supported bridge has supports that permit idealized rotation and, depending on bearing type, longitudinal movement. A continuous bridge extends over two or more spans, producing a continuous deck or girder system. An integral bridge connects the deck and substructure more rigidly and may reduce bearing and joint maintenance, but it requires careful consideration of thermal movement, soil interaction, and construction tolerances.

A bridge is square when its supports are approximately perpendicular to the longitudinal centreline. A skew bridge crosses the obstacle at an angle, so the support line is not perpendicular to the bridge centreline. Skew can reduce the required road length or suit an existing channel, but it complicates load distribution, detailing, bearings, drainage, and construction. A bridge on horizontal curvature requires special attention to sight distance, superelevation, deck geometry, and barrier alignment.

3. Selecting a Bridge System

Bridge selection is a multidisciplinary decision. A practical preliminary sequence is:

1. Identify the obstacle, crossing function, design life, and required level of service.
2. Survey the terrain, existing road, channel, utilities, property boundaries, and environmental constraints.
3. Establish hydrology and hydraulics, including catchment behaviour, design discharge, flood levels, debris, scour, and permissible afflux.
4. Investigate soil and rock conditions, groundwater, seismicity, and foundation depth.
5. Compare structural systems by span capability, construction method, material availability, maintenance, appearance, and cost.
6. Develop alternative layouts and eliminate those that fail clearance, hydraulic, geometric, or constructability requirements.
7. Obtain review by the responsible bridge engineer and approving authority.

The shortest structure is not always the best. A pier placed in a river may reduce girder span but increase obstruction, scour risk, debris accumulation, and foundation cost. Conversely, a long clear span may require deeper girders, heavier erection equipment, and expensive foundations at the abutments.

4. Bridge Geometry and Layout

4.1 Reference lines and coordinate control

A bridge drawing should have a clear horizontal and vertical reference system. Establish the road centreline, bridge centreline, support lines, channel centreline, chainages, benchmark elevation, and north arrow. The plan should distinguish existing ground, proposed works, property limits, utilities, water edges, flow direction, and construction limits.

The bridge centreline may coincide with the road centreline, but this must not be assumed. A skew crossing is defined by the angle between the bridge alignment and the support or obstacle line. The chosen angle should be labelled consistently; different offices may define skew using either the acute angle between lines or its complement.

4.2 Span arrangement

A preliminary layout identifies the number of spans and support locations. For a single span, the principal longitudinal dimension may be represented conceptually as:

where L_total is the overall distance between the outside faces or defined ends of the bridge, L_clear is the clear opening between supports, and a is the adopted end allowance on each side. This is a geometric relationship only; the exact definition of bridge length must follow the project standard.

For a multi-span bridge, the total structural length is the sum of the individual span dimensions plus any specified joint or support offsets. The drawing must state whether dimensions are measured between bearing centre-lines, support centre-lines, or face-to-face.

Span selection must satisfy hydraulic opening, navigation or road clearance, foundation feasibility, girder transport, erection, expansion joints, and maintenance requirements. Piers should be kept out of the active main channel where possible, especially where debris and scour are significant.

4.3 Carriageway and cross-section

The cross-section should show the full functional width, not only the pavement. A typical bridge cross-section may include:

• carriageway lanes;
• shoulders or marginal strips;
• footways or cycleways;
• parapets and crash barriers;
• kerbs, drainage channels, and scuppers;
• deck slab, beams, diaphragms, and wearing course;
• utilities and inspection access;
• crossfall or superelevation.

The required carriageway width is controlled by the road classification, design speed, traffic lanes, shoulders, pedestrian provisions, and the relevant highway standard. A draftsman must not select a width from appearance or from the existing pavement alone; the approved geometric design must govern.

4.4 Vertical profile and clearance

The bridge elevation must coordinate road grade, deck thickness, water level, navigation requirements, and approach embankments. Vertical clearance is the unobstructed height available beneath or above the bridge for a road, railway, vessel, or other required passage. The controlling clearance is usually measured from the relevant finished surface or design water level to the lowest permitted structural or nonstructural obstruction.

For a water crossing, a preliminary freeboard relationship may be written as:

where F is freeboard in metres, z_soffit is the elevation of the controlling soffit or underside point, and z_design is the adopted design flood-water elevation. Positive freeboard means the soffit is above the design level. The required value is not universal; it depends on the governing hydraulic standard, debris risk, backwater effects, and the importance of the crossing.

For road or rail underpasses, clearance is generally expressed as:

where C is clear height, z_obstruction is the lowest allowable obstruction elevation, and z_surface is the finished road or rail surface elevation. The formula is a vertical geometric definition, not a substitute for the minimum clearance specified by the authority.

4.5 Waterway and hydraulic opening

The waterway layout must be based on a hydrological and hydraulic assessment. The designer considers design discharge, flood frequency, upstream and downstream levels, channel roughness, contraction, expansion, sediment, debris, scour, and allowable afflux. The draftsman’s role is to represent the approved hydraulic envelope accurately and to ensure that piers, wing walls, aprons, and protection works are shown in relation to the channel.

A simple area–velocity relationship is often used in hydraulic analysis:

where Q is discharge in cubic metres per second, A is flow area in square metres, and V is mean flow velocity in metres per second. This relationship is dimensionally consistent, but it does not by itself determine a bridge opening. Velocity varies over a section, and resistance, contraction, backwater, and changing water surface must be analysed using appropriate hydraulic methods.

The clear waterway is not necessarily equal to the channel width measured on an ordinary day. It should reflect the approved design condition and the required passage of flood flow. Hydraulic openings should also allow access for inspection and maintenance where practical.

4.6 Freeboard and flood considerations

Freeboard protects the bridge from contact with floodwater, floating debris, wave action, and uncertainty in estimated flood levels. The adopted flood level should be clearly identified in the elevation drawing. The drawing should show ordinary water level if useful, design flood level, channel bed, soffit, pier nose, scour level, and any required debris or navigation clearance.

Freeboard must be checked at the controlling location. A sloping or superelevated deck can produce different soffit elevations across the width. In skew bridges, the effective hydraulic opening and local clearance may vary along the crossing.

4.7 Bearings, joints, and movement

Bearings transfer reactions while permitting the rotations and movements required by the structural system. Expansion joints accommodate deck movement at designated locations. Their locations influence drainage, riding quality, inspection, and maintenance. A preliminary drawing should show bearing lines and joint locations even when detailed bearing design is not yet complete.

Thermal movement is often estimated conceptually from:

where ∆L is change in length, α is the coefficient of thermal expansion in reciprocal degrees Celsius, L is the original length, and ∆T is the temperature change in degrees Celsius. This linear expression assumes uniform temperature change and unconstrained expansion. Actual bridge movement may also include creep, shrinkage, bearing deformation, settlement, seismic effects, and temperature gradients.

5. Drafting Bridge Plans, Elevations, and Sections

A coordinated bridge drawing set commonly contains a general arrangement drawing, plan, longitudinal elevation, transverse cross-section, setting-out details, foundation information, drainage details, and schedules. The general arrangement drawing should allow a reviewer to understand the entire bridge without consulting reinforcement drawings.

The plan should show alignment, chainages, support lines, span dimensions, carriageway, footways, parapets, wing walls, channel edges, flow direction, utilities, and north arrow. The elevation should show ground profile, deck profile, supports, foundations, water levels, bed levels, freeboard, clearances, and vertical dimensions. The cross-section should show deck build-up, crossfall, lane arrangement, barriers, utilities, beams, slab, and drainage.

Dimensions should be complete but not duplicated inconsistently. Use a consistent hierarchy: principal setting-out dimensions, structural dimensions, clearances, and detail dimensions. Levels should use a stated datum. Lines should distinguish existing, proposed, hidden, centre, dimension, and cutting-plane information.

A good drawing communicates design intent, not merely geometry. Notes should identify units, design standards, material assumptions where approved, construction joints, levels, tolerances, and the requirement to verify dimensions on site. Revisions must be controlled so that superseded drawings cannot be mistaken for current information.

Figure: Schematic bridge geometry showing elevation, clear span, freeboard, waterway, and a typical transverse deck section.

6. Worked Preliminary Layout Example

Consider an illustrative single-span road bridge over a small stream. The approved preliminary data are:

• clear hydraulic opening: 18.0 m;
• bearing-centre span: 19.0 m;
• carriageway: two lanes, total width 7.0 m;
• footway: 1.5 m on each side;
• design flood level: elevation 102.40 m;
• underside of deck at the controlling point: elevation 103.65 m;
• channel bed at the section: elevation 99.90 m.

The available freeboard is:

The vertical distance from the design flood level to the channel bed is:

Thus the hydraulic depth at the adopted design level is 2.50 m, subject to the hydraulic model and actual cross-section. The total functional deck width, excluding any additional outside maintenance strips, is:

The drawing should show the 18.0 m clear opening separately from the 19.0 m bearing-centre span. It should not label both dimensions simply as “span.” The example does not prove that the bridge is hydraulically adequate or structurally safe; it demonstrates how approved data are transferred into a coordinated preliminary layout.

7. Applied Case: Replacement of a Flood-Prone Crossing

Background

This illustrative case concerns a two-lane rural road crossing a seasonal stream. The existing pipe culvert frequently blocks with branches and sediment. Floodwater overtops the road, interrupts agricultural access, and erodes the downstream embankment.

Problem

The replacement must maintain two-way traffic, pass the adopted design flood, reduce blockage risk, permit safe inspection, and avoid unnecessary disturbance to the stream. The site contains weak alluvial soil near the channel and competent material at greater depth.

Analysis

A larger pipe culvert could increase capacity, but several pipes would create multiple inlets, blockage points, and difficult maintenance. A box culvert would provide a wider opening but would still be buried beneath the road and could require substantial excavation. A single-span slab or girder bridge would provide an open waterway and allow the channel to remain visible and accessible.

The preliminary alternatives are compared as follows:

Approach and solution

The preferred preliminary solution is a single-span reinforced-concrete or prestressed-girder bridge with abutments outside the active channel. The layout retains the existing road alignment where feasible, provides the approved carriageway and pedestrian width, and places the soffit above the design flood level with the required freeboard. Wing walls guide the approach embankments, while erosion protection is provided at the outlets and abutment toes as determined by the hydraulic and geotechnical designs.

The drawings must show the temporary diversion or staged construction arrangement, because maintaining traffic and protecting the stream during construction are essential. The foundation design must address scour, settlement, and lateral stability. The final choice between slab, beam, or girder construction depends on the verified span, available lifting equipment, concrete supply, construction access, and life-cycle evaluation.

Outcome and learning points

The open-span arrangement reduces the number of obstructions in the waterway and improves inspection. However, it may have higher initial substructure and superstructure costs than a small culvert. The case demonstrates that bridge selection must consider resilience, maintenance, hydraulics, construction, and whole-life performance rather than only the smallest initial quantity of material.

8. Common Errors, Limitations, and Professional Responsibilities

Common bridge drafting errors include confusing clear span with bearing span, omitting skew angles, using inconsistent datums, failing to show flood levels, drawing inadequate parapet offsets, overlooking drainage outlets, and allowing the approach road to conflict with wing walls. Other errors arise when the plan, elevation, and cross-section are prepared independently and do not share the same chainages and levels.

Preliminary geometry is not final design. A drawing can be geometrically neat but technically unsafe if it is based on poor survey data, an incorrect flood level, an unverified soil profile, or an obsolete standard. Hydraulic results must be coordinated with structural and geotechnical decisions. Temporary works, construction access, environmental permits, utility protection, and traffic management also require professional review.

Bridge documentation is a safety-critical record. The draftsman must use controlled revisions, preserve traceability, report discrepancies rather than conceal them, and never alter an approved dimension without authorization. Computer-aided design and building-information modelling can improve coordination, clash detection, quantity extraction, and revision control, but software does not validate engineering assumptions automatically. AI-assisted drafting may help identify missing labels or compare drawing versions, but outputs require human checking, data protection, and approval by competent professionals.

9. Contemporary Practice and Best Practices

Modern bridge planning increasingly considers resilience to floods, earthquakes, scour, corrosion, heat, and changing traffic demand. Whole-life carbon, durability, ease of inspection, replaceable components, and adaptation to future widening may influence the selected system. Digital terrain models, total-station and GNSS surveys, laser scanning, unmanned aerial imagery, and coordinated three-dimensional models improve site understanding when used with appropriate quality control.

Best practice for a diploma-level drafting workflow is to:

1. use verified survey control and a stated datum;
2. establish the road and bridge centreline before dimensioning;
3. show clear, bearing, and overall dimensions distinctly;
4. coordinate plan, elevation, and section through common chainages;
5. identify design flood level, freeboard, channel bed, and scour information;
6. verify carriageway, footway, barrier, drainage, and utility zones;
7. check skew, superelevation, and clearance at the controlling location;
8. use layer standards, readable annotation, and controlled revisions;
9. obtain independent checking before issue for construction; and
10. retain the approved design basis with the drawing set.

Chapter Summary

Bridge classification links structural behaviour to practical application. Beam and slab bridges rely mainly on bending; trusses use triangulated axial members; arches develop compression and foundation thrust; cable-stayed and suspension bridges use tension systems; and culverts pass water beneath an embankment through buried structures. Classification may also be based on material, use, continuity, and alignment.

Preliminary bridge planning requires coordinated consideration of span, support location, carriageway, footways, alignment, skew, vertical clearance, freeboard, waterway, flood level, foundations, construction, and maintenance. Clear distinction between clear span, bearing span, and overall length prevents serious layout errors. The bridge drawings must communicate these relationships consistently in plan, elevation, and cross-section.

Hydraulic and geometric equations such as Q = A V, F = z_soffit − z_design, and ∆L = α L ∆T are useful for preliminary understanding when their assumptions and units are respected. They do not replace code-based structural, hydraulic, or geotechnical design. Professional bridge drafting is therefore both a graphical and an engineering-coordination activity.

Key Terms

Bridge: A structure carrying a route or service over an obstacle.

Superstructure: Structural components above the supports.

Substructure: Abutments, piers, foundations, and related supporting works.

Deck: The portion of a bridge that supports and distributes traffic loads.

Carriageway: The paved or usable width provided for vehicular movement.

Span: The defined distance between supports or bearings.

Clear span: The unobstructed opening between support faces.

Abutment: An end support that also retains the approach embankment.

Pier: An intermediate support between bridge ends.

Soffit: The underside of a deck, slab, or beam.

Freeboard: Vertical distance between a design flood level and a controlling soffit.

Waterway: The opening or area available for passage of water.

Skew: The angular relationship between bridge alignment and support or obstacle line.

Beam bridge: A bridge whose principal members resist bending and shear.

Truss: A triangulated framework whose members act primarily axially.

Arch: A curved compression-dominant structural form.

Cable-stayed bridge: A bridge in which inclined stays directly support the deck from towers.

Suspension bridge: A bridge in which hangers suspend the deck from main cables.

Culvert: A buried structure conveying water beneath a road or embankment.

Bearing: A component transferring load while permitting specified rotation or movement.

Review Questions

Short Answer Questions

1. What is the difference between a bridge superstructure and substructure?
2. Define clear span and explain why it should be distinguished from bearing span.
3. State two structural characteristics of a truss bridge.
4. What is freeboard in a bridge-waterway layout?
5. List four items that should appear on a bridge longitudinal elevation.

Long Answer Questions

1. Compare beam, slab, truss, arch, cable-stayed, suspension, and culvert systems in terms of structural action and typical application.
2. Explain the procedure for selecting a preliminary bridge type at a river or stream crossing.
3. Discuss how alignment, skew, carriageway, footways, barriers, and drainage influence a bridge cross-section.
4. Explain the importance of hydrology, waterway, freeboard, debris, and scour in bridge planning.
5. Describe the information that should be included in a coordinated bridge plan, elevation, and transverse section.

Analytical / Application Questions

1. A proposed bridge has a soffit elevation of 105.20 m and an adopted design flood elevation of 103.85 m. Calculate the freeboard and explain what additional information is needed before accepting the arrangement.
2. A rural stream crossing experiences frequent blockage of a multi-pipe culvert. Compare a box culvert and a single-span bridge, considering hydraulics, maintenance, foundations, construction, and environmental effects.
3. Prepare a preliminary checklist for a skew two-lane bridge, including geometric, hydraulic, structural-coordination, drafting, and construction considerations.

Multiple Choice Questions with Answers

Question 1

Which bridge type primarily uses triangulated members carrying axial tension and compression?

A. Slab bridge

B. Truss bridge

C. Arch bridge

D. Suspension bridge

Correct Answer: B. Truss bridge

Question 2

What is the principal purpose of an abutment?

A. To support the middle of a multi-span deck only

B. To retain the approach embankment and support a bridge end

C. To carry traffic directly across the carriageway

D. To measure the design flood level

Correct Answer: B. To retain the approach embankment and support a bridge end

Question 3

A bridge soffit is at elevation 103.65 m and the design flood level is 102.40 m. What is the freeboard?

A. 0.75 m

B. 1.15 m

C. 1.25 m

D. 2.50 m

Correct Answer: C. 1.25 m

Question 4

Which system transfers substantial horizontal thrust to its supports unless a tie is provided?

A. Arch bridge

B. Beam bridge

C. Slab bridge

D. Cable-stayed bridge

Correct Answer: A. Arch bridge

Question 5

Which item is most directly associated with a culvert?

A. Main cable anchorage

B. Tower saddle

C. Buried waterway beneath an embankment

D. Truss panel point

Correct Answer: C. Buried waterway beneath an embankment

Question 6

If a flow section has area 12 m² and mean velocity 2.5 m/s, what discharge follows from Q = A V?

A. 4.8 m³/s

B. 14.5 m³/s

C. 30 m³/s

D. 48 m³/s

Correct Answer: C. 30 m³/s

Question 7

Which drawing view most directly shows carriageway width, footways, barriers, crossfall, and deck build-up?

A. Transverse cross-section

B. Site location map only

C. Longitudinal elevation only

D. Revision schedule

Correct Answer: A. Transverse cross-section

Question 8

Why can placing a pier in an active river channel be undesirable?

A. It always eliminates the need for foundations

B. It can increase obstruction, debris accumulation, and scour risk

C. It prevents any load from reaching the superstructure

D. It guarantees a shorter construction period

Correct Answer: B. It can increase obstruction, debris accumulation, and scour risk

Question 9

Which statement best describes a cable-stayed bridge?

A. The deck is directly supported by inclined stays connected to towers

B. The deck is carried only by buried pipes

C. The deck is supported by a masonry barrel with no tension elements

D. The deck is suspended from hangers attached to a main cable between anchorages only

Correct Answer: A. The deck is directly supported by inclined stays connected to towers

Question 10

For the thermal relation ∆L = α L ∆T, what does α represent?

A. Discharge

B. Coefficient of thermal expansion

C. Clear span

D. Mean flow velocity

Correct Answer: B. Coefficient of thermal expansion