Category: Culverts

Categories
Culverts Road Construction

Culvert Location Guide

Culvert location guide can be discussed as follows as it located in various geographical conditions and climate variation.   

(a) In general, the flow line of a culvert should conform as nearly as practicable to the gradient and direction in the stream bed or channel.

(b) The stream should have a direst any an entrance and exit on the culvert. Abrupt adjustments to direct can cause turbulence and the probability of scouring in some aspects of the stream and silting in other.

(c) Generally the stream should pass underneath the road in the first opportunity.

The ideal grade line for a culvert is one that produces neither silting nor excessive velocities and sour. Normally the grade type of the culvert should coincide while using stream bed, however, in most circumstances it may be desirable to deviate from it e.g.:-

• Where sedimentation is anticipated that occurs the culvert invert may be set several inches higher compared to the stream bed, but on a single slope.

• Where headroom is limited, setting a culvert below stream bed grade is likely to result in sedimentation and reduced waterway area. This should be avoided either by using a low, wide culvert say for example a box culvert or a pipe arch, or by raising the street grade.

• In steeply slopping areas, as on hillsides, it’s not always necessary to put the culvert on the same steep grade. The culvert can be put on the ‘critical’ slope and then a spillway provided in the outlet in order to avoid scouring. This prevents the culvert shorter and under shallower cover.

• At times a shorter length of culvert can be used and/or a better foundation obtained by shifting the culvert to one side of the natural channel. When this is done, care should be arrive at construct the inlet and outlet channels to supply for a smooth flow from the water, particularly around the downstream side in order to minimize or prevent erosion.

Not only above, as culvert location guide but also varied conditions apply with different kind of project around the world.

Categories
Culverts Road Construction

Preliminary Planning of Culvert Construction

The  preliminary planning of culvert construction  would be to study the drainage plans and specifications, and inspect your website to determine the resources required and plan the works.

There are a variety of matters which must be considered inside preliminary planning with the work. These are generally:-

(1) The construction safety regulations that might connect with the task, e.g. requirements for shoring trenches, etc.

(2) Location of public utility services which may be affected by the work and the agreed procedure to be adopted for the notification of utility authority. The utility authority ought to be asked to find and mark in the grass the positioning with their facility which can be affected by construction. Too great a credence mustn’t be added to the records of the utility authority. These records in many cases are inaccurate or incomplete. In which a service requires re-adjustment, early advice ought to be fond of the service authority as this work often cannot be given priority on the authority’ normal work.

(3) Subsurface conditions. Where significant amounts of excavation are involved, the site (and site investigation reports where available), should be examined to gain a standard knowledge of the subsurface condition.

(4) provision for traffic side tracks, etc.

(5) Planning and scheduling in the works in terms of the earthworks operations. No less than a number of the drainage work will likely be around the “critical path” and unless it’s commenced and completed promptly, the entire project may be delayed.

(6) The need to determined the center line and invert levels of the pipe on the ground well ahead with the start at work. Normally this setting out is performed with the supervisor after which it checked with the supervising engineer as it is often the engineer’s responsibility to ensure culverts are correctly located knowing that invert levels are such that effective drainage is achieved. ( In most cases, large complicated drainage structures and critical skew angles has to be set out by the engineer.) Should the supervisor consider that the pipe location requires changing, he or she must refer his proposal for the engineer before any tasks are undertaken. In some cases such proposals may involve design changes requiring Divisional Office approval. In such instances it takes time to obtain the necessary approvals. And this highlights the need for all drainage sites being examined very early in the task to be sure that construction delays are avoided.

These steps are following as general guide lines to preliminary planning of culvert construction and it might be changed according special job site culvert construction.

Categories
Culverts Road Construction

Road Drainage System


The road drainage system, as put on roads, covers removing water through the roadway, prevention of water from reaching the road and the controlled movement of water along and under the road.

The water involved may attain the roadway caused by:-

• Rain falling onto the roadway
• Surface run-off from adjacent catchment areas
• Underground water movement
• Moisture rising from your water table under the roadway.

The presence of water is undoubtedly the most common cause of road failures. Water saturating a sub grade or pavement may cause pavement failures; water running along the fringe of the pavement can cause scouring and water running down the batter of an embankment or cutting may cause serious erosion. Also the saturation of soil next to the batter is a type of cause of slips.

Consequently the soundness of a roadway depends largely upon an effective and adequate  road drainage system . It is therefore necessary that a proper system be provided back then of construction and effective maintenance of the system be carried out during the life of the road. The significance of drainage cannot be over-emphasized.

The type of drains and drainage structures can be broadly listed under four classifications:-

(1) Culverts (pipes, box culverts, etc.)
(2) Surface drainage
(3) Flood ways
(4) Sub-surface drainage

The job plans, specifications and special provisions indicate the type and extent of road drainage system and stipulate the minimum standards of materials and construction.

Categories
Culverts Road Construction

Culvert Construction

1.0 Introduction
Culvert Construction Procedure

2.0 Abbreviation
SE       – Site Engineer
TO       – Technical Officer
PPE       – Personal Protective Equipment
QAE       – Quality Assurance Engineer
ME       – Materials Engineer
TS       – Technical Specification

3.0 Resources

Man Power Equipment/ Tools Materials
SE 1 No. Back Hoe Loader (if necessary) 15 mm thick Plywood Sheets
TO 1 No Excavator 50 x 50mm and 50 x 25mm timber Reefers
Surveyor    
Survey helpers Concrete Mixer Grade 15 & 25 Concrete
Supervisor Dump Truck Reinforcement Steel [Y10mm,Y12mm,Y16mm, Y25mm, 6mm]
Skilled & Unskilled laborers Rammer Compactor Binding wire
  Leveling Instrument Polythene film
  Water Pump Mould Oil
  2 Nos. Poker vibrators( 1 is standby) Gunny Bags
  Wheel Barrows Backfill Material
  Mortar Pans Water
  Timber Planks/ Steel Plates Cover Blocks
  Hand Tools 6”×4” Rubble
  Hydraulic Breaker (if necessary) PVC Pipe(Type 600)
    Geo textile
    Metal for stone packing
    Cement
    Fine Aggregates
    Coarse Aggregates

4.0 Quality Control Procedure

4.1 Material sampling and testing.
The materials Engineer would take the samples from required materials such as concrete and soil according to the specified frequency and locations.
Concrete: in concrete, one set of cubes would be made per 10 cu.m of concrete. At least one sample would be taken on each day that a particular grade is used. Crushing strength of the concrete cubes would be tested for the samples at ages of 7 and 28 days. Each sample would be identified by identification No and it is displayed on the test cubes and a same identification No would be included in the sample register. The identification tag includes, the date of cast, age of test and date of test to be performed.

4.2  Inspection Check list 
To ensure that the all activities being performed with the expected quality, an inspection check list would be filled by the person in charge for the reconstruction of Culvert in case of Pre-construction, during construction and post construction. The inspection check list shall include the specific requirements, safety and environmental measures. Inspection checklist for culvert construction

4.3 Dimension Control
All specified lengths, widths and heights would be properly maintained during culvert construction and all these dimensions would be checked with the inspection check list. In case of identifying the undesirable changes in specified dimensions and even   beyond the specified tolerances, the particular work would be reworked before the subsequent work.

5.0 Methodology of Work
Methodology flow chart  and the work would be carried out for only half of the culvert first and second part would follow the finish of the first part.

5.1 Removal of Existing Structures
Existing structures would be removed with prior approval of the Engineer and as per the Technical Specification.

5.2 Excavation
1. This work consists of the necessary excavation for foundation of culverts, head walls, wing walls and other structures.
2. Necessary diverting of streams, construction and subsequent removal of necessary
coffer dams,sheet pile driving, shoring, dewatering, pumping and removal of any obstructions for placing the foundation, backfilling, clearing the site of debris and the disposal of excess excavated materials would be also included in this work schedule.
3. Prior to commencement of excavation, the limit of excavation would be set out as shown in the drawings and directed by the Engineer.
4. All excess soil and other material from the excavation including logs, boulders etc would be removed from the site and disposed to the locations approved by the Engineer.

5.3 Structural & Masonry Work

1. Prior to commencement structural and masonry work, the excavated areas would be compacted to the required level given by the Engineer if necessary.
2. Concrete trial mixing, sampling and testing would be carried out as mentioned in  Technical Specification and accordance with the BS 1881 standard and subsequently all the test results would be submitted to the Engineer for approval.
3. Subsequently form work of base and re-bar would be carried out according to the construction drawings and the base would be made with a grade as instructed by the Engineer and concrete would be thoroughly compacted by vibration.
4. Concrete would be placed in such a manner as to avoid segregation by means of chutes and the displacement of reinforcing bars and would be spread in horizontal layers where practicable.
5. All concrete surfaces would be kept wet for 7 days after placing concrete.
6. Abutment and wing wall would be constructed by using random rubble or concrete up to the level of capping beam with providing weep holes as per the details given by the Engineer.
7. All the exposed surfaces of RRM would be plastered with cement mortar.
8. As done in the base all the procedures would be carried out for constructing the capping beam as per the construction drawings.
9. Having completed all the necessary work in placing reinforcing bars and form work, the deck would be concreted with a grade as instructed by the Engineer.
10. The surface of the deck would be kept wet for at least 7 days after placing concrete.
11. No temporary loads would be placed on the deck. Deck slab would be opened to traffic after the Engineer’s direction and not sooner than 28 days after the placing of the concrete has been completed.

1 No. Water Tanker