04-043934

CONTRACTOR'S INQUIRY RESPONSES NO. 2,

APRIL 27, 1998


APPARENT LOW BIDDERS
BALFOUR BEATLY CONST. INC.$ 62,253,191.00
CALIF. ENG. CONTRS. & A.G. TADRES$ 63,282,515.00
AMERICAN BRIDGE CO.$ 64,745,414.00

MORE INQUIRIES

46) Reference Plan Sheet 149 of 555, Section A-A, Stage 3, Sequence note #4: "Provide temporary cover opening resulting from removed finger joint"... Is this temporary cover (Steel Plate?) to be paid for as incidental item 29 (Salvage & Reinstall Structural Element) or item #5 (Temporary Bridge Decking).

Temporary cover to span over the removed finger joint may be a steel plate and shall be paid as incidental to "Temporary Bridge Decking".

47) What provisions are there in the contract to cover up the open excavation formed by drilling for the CIDH piles or precast abutment cap?

Standard Specification 7-1.09, Public Safety, governs open excavation protection.

48) Reference drawing sheet 161 of 555, (Pier #2-Top Plan).... the nearest reference dimensions at Section E-E, are 2'-1" and 5'-1". The corresponding dimension shown on Section E-E, sheet 164 of 555, (Pier #2 Sections) is 6'-9". Please confirm the accuracy of these dimensions and clarify their correlation.

All dimensions shown are correct and are clarified as follows: The 2'-1" and 5'-1" dimensions as shown on sheet 161 of 555 detail the location and size of the flare in the new concrete bolster. The 6'-9" dimension shown on Section E-E on sheet 164 of 555 is intended to show the limits of the #8 x 6'-0" drill and bond.

49) On drawing 392of 555 (Restrainer Plan 1, "D" Line) it clearly calls out a quantity of four (4) Prestress Anchor Beams with notes refering to a schedule on drawing 384 of 555 ( Column Post Tensioning Details). Close review of the "Column Post Tensioning Detail" drawing failed to locate a schedule identifying quantities for Bents D5 & D6. Drawing 374 of 555 shows two (2) anchor beams each at Bent D5 and Bent D6. Please confirm the following anchor beam quantities are correct:

Bent D4 - Four (4) Anchor Beams

Bent D5 - Two (2) Anchor Beams

Bent D6 - Two (2) Anchor Beams

The schedule referred to is not on the plans. There should be 4 anchor beams each at Bent D4, Bent D5, and Bent D6. Place at all locations as detailed for Bent D4 on sheet 392 of 555.

50) Reference contract Drawing sheet #171 of 555... The base plate detail shows a new plate 3/4" x 42" x 3'-6" to be installed and welded inside the tower columns. There is no access to insert the new plate from inside the column. Even if it were possible to insert the plate inside the column, it would be impossible to weld to the base plate since access would be immediately cut off upon mating with the tower column. Additionally, American Bridge Co. Drawing #118 AC dated 6-20-56 shows three horizontal stiffener plates inside the tower leg which would interfere with placement of the 3/4" x 42" x 3'-6" plate. Please clarify detail and advise.

Base plate detail on sheet #171 of 555 has been modified for weld access. See Addendum No. 5 for modifications.

51) Reference Special Provision 10-1.60 Steel Structures, subtitle Removal....The second paragraph on page 177 states "The design calculations shall be adequate to demonstrate the stability of the structure during all stages of removal operations. Calculations shall be provided for each stage of structural steel removal".... Is it the intent of the contract that the truss be modeled for each piece removed or series of pieces removed?

The Contractor's engineer shall demonstrate by calculation, using engineering principles, that the structure remains stable during all stages of structural steel removal. The Contractor's engineer needs to determine which portions of the truss to analyze for demonstration of structural stability during removal of individual members or series of members.

52) Please detail the sequence for the installation of the shock transmission devices @ piers as they relate to the sliding bearing devices and truss chord shock transmission devices.

There is no specific requirement for staging regarding installation of the shock transmission devices (STD) in the truss chords or at Pier 5.

53) Reference sheet #171 of 555... A detail of the masonry plate and anchor bolt detail shows only 4" x 3/4" dia. anchor bolts with 9" embedment for each tower leg. Is this really the intent of the contract?

Detail is correct as shown.

54) Reference contract drawing #160 of 555... The double tendon at each TS 16 x 16 x 5/8 sliding bearing support requires a minimum of 28 strands each. The manufactured anchor heads closest to this required number of strands is drilled for 31 strands. The bearing plate associated with this anchor head is 20" square. It is impossible for one anchor to fit down through the 16 x 16 tube (14-3/4 x 14-3/4 inside dimension) much less two anchor heads. Please clarify and advise.

Our calculations indicate that one anchor head can provide the required prestress force. It is not required that the anchor head fit through the TS section. The anchor head and associated bearing plate sit on top of the TS section. The diameter of the trumpet should be less than 10, so there should not be any problems placing the duct through the TS section.

55) Reference contract drawing sheet #149 of 555... A call out for concrete filled steel grid deck appears in section A-A, stage 3. There is no material or erection specification in the Special Provisions. Sections 10-1.08, 10-1.60, or 10-1.72 (Temporary Deck Bridging, Steel Structures or Miscellaneous Metal Bridge, respectively). Additionally it is not defined how the Contractor is to be paid for this item of work. Please clarify and advise.

The special provisions for the concrete filled steel grid are contained in 10-1.40, "Concrete Structures".

56) Reference contract specification section 10-1.08 "Temporary Deck Bridging" and sheet 149 of 555... The contract specification calls for the deck bridging to be "designed, furnished, constructed, monitored, maintained, and removed in accordance with the requirements of these special provisions". Detail L on sheet 149 of 555 clearly shows a design of deck bridging required for abutment 1. Are we entitled to rely on Caltrans design or are we to redesign the deck bridging? Page 62 of the contract specifications requires a detailed procedure and design criteria for deck bridging. Can the contractor forgo the deck bridging submittal if we use the Caltrans design? Also, does Caltrans require Professional Liability / errors & Omissions Insurance for the contractors' furnished design? If so please provide clarification and details.

The temporary deck bridging can be used as shown on sheet 149 of 555 without a contractor provided design. At the Contractors option, the deck bridging may be redesigned as specified in special provision 10-1.08 "Temporary Deck Bridging". Professional liability/Error & Omissions insurance is not required for contractor furnished designs.

57) Reference Addendum # 2, Page 6 paragraph starting with "this work includes the modification...." Is it the intent of the contract to have the Contractor design access ladders and platforms as stated? If so, the following information is not provided in the contract:

i. Location plan of new ladders and platforms.

ii. Design criteria and service loading for ladders and platforms.

iii. Whether Caltrans will "hold harmless" the general contractor for errors & omissions / professional liability or must the Contractor purchase these policies and furnish Caltrans with certificates of insurance.

Refer to Section 10-1.28U, Bridge Utility and Maintenance Equipment Work, pp. 111-112, 3rd paragraph, and as amended in Addendum 2, page 6, is the Special Provision that relates to the design modifications to existing access ladders and their associated platforms. A location plan is not required because no new ladders are required - only modifications to existing ones as needed to make them usable after the pipeline relocation and any other retrofit work is done. The Contractor is referred to the fourth paragraph (as amended in Addendum 2) of this Special Provision that "The locations, types, and configurations of the facilities are indicated on the plans and on the Materials Information Handout, entitled "Existing Bridge Utilities and Maintenance Equipment on Eastbound (1958) Carquinez Bridge", based on record drawings and visual inspections. ..."

The Contractor shall match the existing design to accommodate the changed location of the pipeline. However, where a new type of platform or special structure is required, he must follow applicable OSHA standards. Professional liability/Error & Omissions insurance is not required for contractor furnished designs.

58) Is CIDH drill spoil material to be classified as hazardous, contaminated or common material for disposal.

The CIDH drill spoils are to be classified based upon the depth from which they originate. Material removed from within the depth of the footing are to be handled in accordance with the material classification indictated in the contaminated and hazardous material excavation special provision. Material below the extent of the known information should be considered "clean," but the material is to be segregated for testing to determine appropriate disposal."

59) Section 10-1.28G states that excavation required for removal of drainage facilities will be paid for as drainage excavation (hazardous). However, the drainage quantity sheets don't show any pay quantity for these removals. Where is the breakdown for drainage excavation for removing drainage facilities? Is there a breakdown for hazardous or contaminated excavation for the drainage removal facilities?

Relating to drainage excavation ... There is no pay quantity when the drainage facility is located within areas of structural excavation. For all other areas, drainage quantity tables have been provided and will be updated in Addendum 5. The Contractor is referred to Special Provision 10-1.31C, "Contaminated and Hazardous Material Excavation."

60) Section 10-1.13,"Obstructions," in Addendum #3 states that the contractor must excavate and backfill trenches for new Pacific Bell duct banks. Is this excavation paid for as roadway excavation (hazardous material)? Where are the plan and profiles for these trenches? What are the trenching and backfill specifications for these trenches?

Relating to the excavation associated with the PacBell ductbank... The excavation work is to be performed by the Contractor as shown on plan sheets C-14 and Q-3 to be provided in Addendum 5. The quantity is included under roadway excavation (Hazardous) for Vista del Rio. The contractor is also referred to the Standard Specifications for trenching relating questions, and to Special Provision 10-1.13, "Obstructions," which indicates that PacBell will be responsible for the backfill.

61) Drainage quantities shown on Sheets D-9 through D-12 only breakdown hazardous materials. Where is the breakdown for contaminated materials?

Drainage quantity tables have been provided and will be updated in Addendum 5. The Contractor is referred to Special Provision 10-1.31C, "Contaminated and Hazardous Material Excavation."

62) Sanitary sewer quantities on SS-6 only breakdown hazardous materials. Where is the breakdown for contaminated materials?

Sanitary Sewer quantity tables have been provided and will be updated in Addendum 5. The Contractor is referred to Special Provision, 10-1.31C, "Contaminated and Hazardous Material Excavation."

63) We attended the site inspection meeting for the above job on 2/18/98. At Bents 3A and 3B we observed through a vent hole that there was water inside the cofferdam. Our question is this: Can the leaks be sealed? How many leaks are there and where are they? Does the 5 gallon /8 hour/square yard specification apply?



Water has been present inside the cells of the pier since it was constructed. It is not known if there are leaks in the cell walls. It is anticipated that the cells are capable of being dewatered to the depth necessary to place the concrete bolster inside the cell. It is not expected that the piers need to be completely dewatered.

64) Also at Bent 5 Sheet 185, 186 etc. access seems to be a problem. Does Caltrans have a right of way to cross the Union Pacific tracks? If so where? can we build a haul road between the tracks and the high water line? It appears that we may have to use the area that is now occupied by one of the spur tracks.

See Addendum No. 6 coming up soon.

65) Ref sheet 174 of 555, Section B-B and sheet 216 of 555, key index and temporary Brace note #1...does the addition of the temporary brace shown on the key index (sheet 216 of 555) allow the removal of both diagonals and transverse strut shown on sheet 174 of 555? The note under Temporary Braces leads you to believe that this is possible, however our cursory investigation shows otherwise. Please confirm.

The addition of the temporary brace as shown on sheet 216 of 555 does not allow both Pier 3 lower tier diagonals to be disconnected. Per the A4E Main Span Order Of Work special provision (page 54 in original special provisions), only one diagonal may be disconnected at a time.

66) Ref sheet 210 of 555, exterior gusset elevation... The note calls out for removal of a portion of the existing strut. How much of this existing strut is to be removed?

On sheet 210 of 555,disregard the note "Remove portion of exist strut". No existing strut shall be removed.

67) Ref sheet 253 of 555, note #8 ... The note calls out "L29 shown, L86 similar". The geometry and panel point loadings are not similar. Should the note read "L29 shown, L87 Similar"? Please clairify.

Note 8 on sheet 115 of 227 should read "L29 shown, L87 similar".

68) Ref sheet 165 of 555, note #6... The note calls out "Remove existing strut, see Pier 2 & 4 - Bearing Details Sheet". On sheet 171 of 555 titled "Pier 2 & 4 - Bearing Details" there is no reference or call out for the removal of an existing strut. Please clairify.

On sheet 171 of 555, the "Tower Base Removal" detail shows the shape of the existing strut. The size of the existing strut is: Web Plate 1" x 24" plus or minus, Flange Plates 1" x 36" plus or minus.

68) Ref sheet 161 of 555 ... The "concrete blocks, typ". called out on the right hand side of the bridge centerline, along the centerline of the longitudinal shear lock appear to be shown in the wrong location. The correct location of these blocks are critical for jack placement and we have included a sketch (SK-1) showing where we believe the correct location of the blocks should be. Please confirm/ clarify this detail.

Concrete blocks are shown in the correct location on sheet 165 of 555. The dimension to the concrete block on sheet 161 of 555, measured from the centerline pier along the centerline longitudinal shear lock (N-S direction), should be 5'-6"(corresponds to intersection of centerline tower anchor and centerline longitudinal shear lock (N-S direction)).

69) Ref sheet 165 of 555... Both the " Part Elevation" and "Section B-B" show the point of temporary support at the intersection of the centerlines of the transfer girder and the tower anchor. Section D-D on sheet 167 of 555 shows the centerline of temporary support (shown near the call out for section F-F) more than 2'-0" from the aforementioned location. Please clarify this discrepancy.

The temporary support location shown on sheet 165 of 555 is correct. Temporary support location on sheet 167 should point to centerline tower anchor line.

70) Reference contract specifications page 178, "Sequence of Removal Operations" and contract drawing sheet 165 of 555, inset "Temporary Vertical Support Loads"... The specification specifies that all work must be completed at the base of the tower including shearlocks, bracing and transfer girder prior to jacking "One tower leg at a time".

A.) Please confirm that there is sufficient headroom and area at the prescribed jacking location to jack and support over 5,400 kip.

B.) Do the loads given on sheet 165 of 555 include the resistance from the other three tower legs being tied down and chevron bracing being bolted? If so please provide us with the calculated deflections and shortening of members?

The loads shown on sheet 165 of 555 do not include the resistance from other components of the tower. The deflections and shortening are not calculated as it is anticipated that the tower leg will be raised minimally (just enough to take the load off the existing bearing).

71)Please provide verification on the amount of railroad insurance the contractor must provide for the above referenced project. The specifications state on page 215 (see attached) that 50% of the work is over or under or within 50 feet of the railroad tracks. If this number is correct please provide clarification of how the department arrived at it so the contractor will not have to include money for more insurance than is necessary.

Please see Addendum No. 7.

72)Pay Item #70, Structure Excavation (Contaminated), is not a Final Pay Quantity as of Addendum #3 (page 6 of the Engineers Estimate). All other structure excavation quantities in the proposal, as is the Caltrans custom, are Final Pay. Is this your interYt on this project?

Please see Addendum No. 7.

73)Pay Item 211, Vehicle arresting Barrier (Net Type, Dragnet) wvas deleted in Addendum #5, but page 13 of the Engineer's Estimate on which the item appears was not revised in Addendum #5. May we bid this item at $0.00 cost ?

Please see Addendum No. 7.

74)We are unable to find the definition of the classification of the following Bid Items:

Item 71, Structure Excavation (Type DH)

Item 72, Structure Excavation (Type H)

Item 71, Structure Excavation (Type DH): Structure Excavation with water and Hazardous Material

Item 72, Structure Excavation (Type H): Structure Excavation Hazardous Material

75)Addendum No. 5 revised Section 10-1.60, "Steel Structures," but it did not include "Measurement and Payment."

See Addendum No. 8.

75)Internet posted question #45 and the given response address the condition of the travelers. What is the condition of the rail the travelers ride on and its connection to the bridge structure?

Addendum number three, page two, modified the provisions of Section 10-1.28 of the Special Provisions. This addendum gives allowable loads that may be placed upon the existing traveler rail.

76)Further clarification to previous question and answer # 51 on the net. The response does not satisfy our concerns. We wish to clarify the intent of our question and hereby present the following:

i.) Typically on steel rehabilitation work, the Owner's Engineer has performed a comprehensive analysis of the structure prior to determining what work is actually required and in what sequence the work can be performed.

ii.) The specifications clearly dictate that "the contractor shall proceed with the removal of the existing structural steel in accordance with the sequence of work shown on the plans and in the special provisions", which is consistent with point (i.) above.

iii.)The specifications and drawings include bid items and details for areas of work which require temporary support and temporary bracing of the structure to allow the work to be performed while maintaining the stability of the structure, which is also consistent with point i. above.

iv.) The standard specifications, as amended by this contract, are clear in defining the requirements for falsework design and drawings when required.

v.) Elsewhere in the special provisions it is stated that "in the event that removal of any element of the bridge may weaken the structure, the contractor shall provide additional shoring, falsework or bracing as required to maintain structural stability".

vi.) The specifications direct the contractor to submit design calculations for falsework and bracing which are "adequate to demonstrate the stability of the structure during all stages of the removal operations".

vii.) Points v.) and vi.) contradict points ii.) and iii.).

The only practical way to satisfy points v.) and vi.), would be to create a comprehensive model of the bridge which would allow analysis of the impact of removing "any element of the bridge". It would seem superfluous to expect the contractor to redo the Engineer's work, especially since this is a very long and very costly procedure. We therefore reiterate our original question... Is it the intent of the contract that the truss be modeled for each piece removed or series of pieces removed?

The sequence of construction and order of work, as specified on the plans and in the special provisions, protects the global stability of the bridge. Retrofit modifications detailed on the plans, which threaten the global stability of the bridge have temporary bracing locations and loads shown. In these areas, it is not necessary that the Contractors Engineers provide calculations to verify the global bridge stability during member removal. However, the Contractor shall demonstrate through engineering calculations that the shoring and bracing is sufficient to satisfy the loads and maximum deflection specified on the plans and in the special provisions.

In removal locations where there is no temporary support or bracing shown, the locations of temporary support or bracing and the loads for which it shall be designed shall be determined by the Contractor, subject to approval of the Engineer. The purpose of this is to give the Contractor flexibility to propose specific means and methods for individual removal locations. Temporary support will be necessary during removal where lack of support could cause damage to adjacent elements of the bridge or be a safety hazard. The Contractor is responsible for providing calculations prepared a Licensed Civil Engineer in the State of California, demonstrating that the specified temporary bracing requirements have been satisfied, and that other areas of removal are adequately supported during removal. This shall be submitted as part of the Structural Steel Removal Plan as specified in special provision 10-1.60, Structural Steel. It is not our intent to require a comprehensive structural model of the entire bridge to demonstrate the temporary support requirements.

77) Reference Internet question and answer #50.

i.) The American Bridge drawing #118 AC dated 6-20-56 shows internal stiffening and continuity plates inside the tower leg at the location of the proposed new plate.

ii.) Furthermore, access / clearance is required inside the tower leg for a welding stinger as well as a person's arm and head (with helmet) to perform the full penetration weld attaching the internal plates to the base plates per the base plate detail on sheet #171 of 555.

We therefore rephrase our original question... 1. How does the proposed new plate fit into the column?...... 2. How do you suggest that the welding of the plates inside the tower leg be performed?

Note that sheet 167 of 555, provided to the Contractor in Addendum 5, specifies the removal of the two existing horizontal stiffener plates inside the tower leg. Once these are removed, the new plate can be inserted from under the leg and the welds placed with access into the leg from underneath and inside from existing perforations above the new plate.

78)Reference Internet question and answer #70.

We wish to expand our original question as follows: Even without taking into account the significant additional resistance forces introduced by the new shear locks, bracing and transfer girder, the jack load will be in excess of 5,400 kip. (breakout force > 8,000 kips).We have contacted several jack designers / manufacturers and have been unsuccessful in locating a low clearance jack of adequate capacity, that will fit within the headroom available, and at the location shown on the drawings. please provide us with a description as to how the Engineer envisions this work being performed as well as potential suppliers / manufacturers of jacking equipment known to the Engineer for providing this equipment.

It is not required that the jacks used to raise Towers 2 and 4 fit under the temporary support location. The jacks can straddle the support location and use a cradle, strong-back with high strength rods, to apply the jacking load to the temporary support location.

79)Reference Internet question and answer #54.

We wish to expand the original question as follows: Please provide details with respect to the manufacturer, # of strands and model number of anchor materials that the Engineer has determined will work within the design.

From sheet 160 of 555, the required force per Abutment 1 tiedown anchor tendon is 850 kips. Based on this, and the equation for As(min) shown on this same sheet, the minimum area of prestressing steel is 6.1 sq. in. This can be provided by a 43-0.5" strand, or 29-0.6" strand tendon. Based on discussions with prestressing manufacturers, these will have a maximum diameter of approximately 12 in. and will fit inside of and on top of the TS 16 x 16 section.

80)Reference contract drawing sheet 319 of 555.... Section A-A calls out to ream the existing 2" diameter drain holes to 6" diameter and insert the upset rods shown in detail B. The upset rods in detail B are 6-1/2" diameter. Please clarify the discrepancy.

See Caltrans question and response # 36 on the Carquinez web page, and revised sheet 319 of 555 as per addendum 6. The hole size has been increased to 6-5/8" diameter.