Review observations on MNB drawings

To

The Concessionaire

Subject: Submission of Design reports and Construction Drawings for Proposed Minor Bridge at Ch 56+844-reg

Ref No: Your Letter submission

Dear Sir,

With reference to your submissions, reviews have been done as per Clause 12.3 of CA and please find our Sr Bridge Design Engineer comments.

1. The Concessionaire should mention in the covering letter the specific clause of the CA under which submissions are made to IE.
2. The Concessionaire has mentioned – “working drawings are submitted for review and approval”. The Concessionaire should clarify the term “working drawing” with reference to the Quality Assurance Manual (QAM) prepared and submitted to IE for review. There is no stipulation in the CA for the Engineer to approve drawings.
3. The IE has reviewed the drawings as required under Clause 12.3 of CA. The Concessionaire should provide documentation to demonstrate they have complied to Item 2.3 of Table 3.1 to IRC SP 47. This has been communicated to Concessionaire through IE letter no. xx.
4. The total width of the structure is proposed as 11.5 m. As this bridge is on a new alignment the width of the structure should be as per Sch. D-Annex. 1-Para 2-Clause 7.3, i.e., the width of each carriageway should be as for 3-lane structure. The width proposed by the Concessionaire is not in accordance with provisions of CA.
5. Further review of drawings could not be taken up in view of the deficiency pointed out above. The Concessionaire must validate the proposed width with reference to the CA, manuals, IRC codes and clarify how the proposed width has been fixed.

This is for your information and compliance.

Thanking you,

To

The Concessionaire

Subject: Review and Comments of the Senior Bridge Design Engineer on MNB Drawings-Reg

Dear Sir,

With reference to the review of the final drawings for the minor bridges in the project highway, our senior . bridge design engineer has reviewed the following drawings and consecutively made his observations:

A. Review observations on MNB drawings of new construction on straight portions. (At km Chainages 10.000 and 15.000).

1. Hydraulic details like HFL and design discharge should be included.

2. Calculations for design of dowel bar should be included. Also, the method for fixing dowel bars should be included in the notes.

3. The centre line of the existing and proposed structure is not correctly shown. Review and correct

4. Wearing course over the slab should be shown.

5. Details shown in Section Z-Z should be reviewed and corrected.

6. A buried-type expansion joint is proposed at pier locations. A note should be added about the provision of this expansion joint over the widened and existing portions.

B. Review observations on MNB drawings of new construction on the curve portion. (At km Chainages 16.000, 17.000, 19.000).

1. These three bridges are falling in transition/ccurve alignment. The drawings should be suitably corrected to reflect horizontal curvature.

2. Concessionaire informed me that the methodology for extension of the substructure is being reviewed and the drawings will be revised.

3. The bottom profile of the top slab (existing) is not correctly shown. Review and correct.

4. The filter media thickness behind the abutment is shown as 300 mm. The thickness is to be revised to 600 mm.

C. Review observations on MNB drawings of having different types of girders. (At km Chainages 20.000 and 25.000).

1. In the type drawing for retaining walls, the minimum founding depth below GL should be revised to 1200/1500 mm as appropriate.

2. Pocket for provision of expansion joint to be shown.

3. The end span length (c/c of bearings) is 17600 mm, and for the two inner spans it is 16250 mm. In all connected drawings, the dimensions of the two types of girders should be clearly differentiated. Further other corresponding dimensions for the two girders should be shown. Cut off length of bottom reinforcement of girders to be indicated for one type of bar.

4. At certain locations, the depth of the top slab of the superstructure is shown as VARIES. This should be corrected to 220 mm.

5. Design loads of neoprene bearings should be indicated in the drawing.

D. Review observations on MNB drawings of Central Widening (at km Chainages 30.000 and 35.000).

1. Dimensions of the existing structure should be clearly marked.

2. SEC-EE, DD, and shear key remarks have to cooperate.

3. The expansion joint is proposed as 10 mm. This should be modified to 20mm.

4. Note on confirmatory boring to be deleted and details of borings carried out to be included.

5. A drawing showing miscellaneous details should be submitted for review.

6. Comer reinforcement for skew slabs should be provided.

7. Note on design loading standard should be included.

E. Review observations on MNB drawings of Eccentric Widening (at km Chainages 40.000 and 50.000).

1. A note about dismantling is shown in the front view of piers and abutment. The note pertains to slab dismantling, but the arrow marks point towards the substructure. Please correct.

2. Soffit details of the existing slab are to be checked and modified.

3. Camber on one side is shown as 1.859% as against 2.5% required. Review and correct.

1. Details C & D are shown; these are not marked on the main part of

2. Founding levels shown should be corrected to indicate design levels.

3. A widening is to be done on one side; the slab widening reinforcement is shown on both. Bridge at Ch. 129+418.

4. There is some discrepancy between OGL and proposed founding levels. Review and resubmit.

5. Founding level of P2 is to be shown.

6. a  This is proposed for central widening. There is some difference between the proposed and existing centre lines. Please verify and correct the detailing of the slab as required. 16. Bridge at Ch. 154+490.

7. Existing length of superstructure should be indicated in drawing.

Conclusion on Review Observations on MNB Drawings

So, you are being instructed to comply with his instructions and submit the final drawings for our certifications as early as possible.

Thanking you.

To

The Concessionaire

Subject: Comments of the Senior Bridge Design Engineer for Minor Bridges-Reg

Dear Sir,

With reference to the review of the final drawings for the minor bridges in the project highway, our senior bridge design engineer has reviewed the following drawings and consecutively made his observations:

A: MNB at Ch: 30+000

• Detail of existing bridge showing the components like superstructure, substructure, and foundation; their dimensions and material used like masonry, PCC, and RCC.

• Bore hole data to be furnished in GAD.

• Locations of drainage spouts to be marked in GAD.

• Arrangement for drainage (in median and edge) to be shown (super elevation case).

• Abutment (top dimension of shaft) to be shown in GAD and also pier dimension.

• In GAD, protection is not provided on both sides, U/s and D/s, to protect it from scouring. Please clarify.

• Slope of stone pitching on earthen slope should be shown, and also corresponding dimensions of cantilever return should be checked.

• In GAD, boulders are provided below filter media for earthen slope protection. The same is to be provided on top of filter media.

• The vertical clearance should be checked with reference to the minimum FRL and design discharge.

• Median is proposed with crash barriers (on both sides) on the existing slab. Please show the details of fixing the crash barrier to the existing slab.

• Pier (dimension) mismatches in GAD itself (600 and 900) as well as in dimension detail drawing of pier.

• Maximum scour level should be shown in GAD.

• What do Max FRL and Min FRL mean?

• A buried-type expansion joint is used. In drawing no. Misc-01 expansion joint shall be provided as per revised MORT&H specifications letter no. RW/NH-34059/1/96-S&R dt. 30th November 2000.

• Note no. 35 (Drg No. G-01-Sht 1) to be reviewed after ascertaining the founding level of the existing bridge.

• Note no. 36: Details of floor protection should be done as shown in the drawing.

• Drawing E-01 The approach slab appears to be either resting on the dirt wall or is integral with the dirt wall. Normally, a separate bracket is provided for resting the approach slab. Please review the arrangement and design and provide details in the drawing.

• In GAD, wearing a coat seems to be provided below the crash barriers. Please rectify.

• H.F.L. mentioned in the drawing (77.501 m) mismatches with the value considered in design calculations (77.547 m).

• Camber shown in drawing (4.235%) mismatches with design (3.76%) 21. Return wall (dimension) be checked-drawing no. E-01 Section Z-Z.

• Eccentricity of concrete component considered in design to be checked. (Page No. 4 of abutment design calculation)

• Joining detail of existing and proposed bridges to be shown.

Observations on Abutment design:

• Maximum Scour Level (73.075 m) is higher than LWL (70.825 m) on Page 1 of the design cal of the abutment design. Please verify.

• Centrifugal force considered in the design shown as NIL. Please verify. (Page 11).

• The design of the abutment appears incomplete, as the design for the cracked section is not done.

Observations on Pier design:

• Formation level considered in design (79.223 m) mismatches as shown in GAD (79.269 m).

• H.F.L. mentioned in the drawing (77.501 m) mismatches with the value considered in design calculations (77.547 m).

Observations on Geotechnical and hydrological data:

• A geotechnical investigation report is required to check the SBC considered in design and mentioned in GAD.

• Hydrology report to be submitted to check maximum scour level considered in design.

B. MNB at Ch: 52+75

• A soft copy of the staid file is required to check the stresses considered in design.

• Detail of existing bridge is required.

• A geotechnical investigation report is required to check the SBC considered in design and mentioned in GAD.

• Bore hole detail to be furnished in CAD.

• HFL to be shown in GAD.

• G.L. with FRL to be shown in GAD.

• The coefficient of active earth pressure considered in design is 0.5. Please clarify.

• Reinforcement detail (mostly) mismatches between design calculations and drawing.

• Depth of foundation (dimension) to be shown in GAD.

• Arrangement and methodology of joining existing and proposed new structures are shown/mentioned.

• In GAD, curtain walls are not provided on both sides U/s and D/s of the box structure to protect it from scoring. Please clarify.

• In GAD, toe walls are not provided on both sides U/s and D/s of the box structure to protect embankments from falling in the waterway. Please clarify.

• Base width considered in design mismatches between design (5.50 m) and drawing (5.0 m).

• Height of return wall above G.L. mismatches between design (4.650 m) and drawing (4.16 m).

• Reinforcement detail of heel and toe slab mismatches between design and drawing.

So you are being instructed to comply with his observations and resubmit the same for his final review.

Thanking you

To

The Concessionaire

Subject: Submission of GFC Drawings for Minor Bridge at Ch. XX+XXX-Reg

With reference to the above-mentioned letters and subject, the revised drawing has been reviewed by us, and we have no objection to accepting the same, following Submitted the compliance of specific instructions as mentioned below:

1. Substructure The dimensions of the pier should match the existing structure.

2. Drainage spigots shall be provided as per the reviewed plan and profile of highway drawings.

3. Expansion joints have to be provided per the MORT&H guide lines. (Vide letter no. RW/NH-34059/1/96-S&R dated 30-Nov-2011)

This is for your information and necessary action.

Thanking You,

To

The Concessionaire

Subject: Review on Compliance Report of notified observation for the Minor Bridge at Km. 14+745 & 14+805-Reg

Dear Sir,

Under the above cited subject and your above reference letter, the Compliance report submitted, are being reviewed by us and we have got no objection in accepting the same for submission of GFC drawings in the required format

Thanking you,

The Concessionaire

Subject: Submission of GFC Drawings for Minor Bridge at Km 16+978-reg

Ref: Your Letter submission

Dear Sir,

Under the above cited subject and your above reference letter, the Drawings submitted, are being reviewed by us and we have got no objection in accepting the same following the compliances of under mentioned observation.

“If there is any variation between the GFC issued and the site data, then the same must be notified to us immediately, for further review.”

Thanking you,