JOB BB0414 PORTER RD. HWY. 112/71B WIDENING & INTCHNG. IMPVTS. (S) AUGUST 10, 2016

Transcription

1 JOB BB0414 PORTER RD. HWY. 112/71B WIDENING & INTCHNG. IMPVTS. (S) AUGUST 10, 2016 Is it allowable to substitute the WF beams to Plate Girders on Bridge 05692? The substitution of a plate girder with flanges and webs identical in size to the proposed w-beam would be acceptable. Are design files available for this project? The design files can be found at the following link: ftp://arkansashighways.com/outgoing/electronic Design Files The concrete median barrier walls shown on the plans include sections that are of variable height. The note on the plans instructs contractors to see the cross sections for information regarding the heights of these walls. Most of the cross sections do not list top of wall, bottom of wall, or edge of pavement elevations. Is it possible to obtain a profile of the walls with this elevation information? The height of the wall will vary based on the existing profile grade, which will be established by the Contractor and reviewed/approved by the Engineer during construction. The electronic design files have been made available and could be used to estimate the wall heights. Is it permissible for the contractor to obtain all or part of the material needed for the bid item Compacted Embankment from the state Right of Way (ROW) outside the project grading limits? What are the state regulations regarding obtaining borrow material from Arkansas State ROW? If permissible, what would be the requirements on the contractor in regards to the grading and finishing of the ROW borrow site? Page 1 of 6

2 On-site borrow will not be permissible for this project. Will the Department consider revising the DBE goal set for this project? The DBE goal will be 8% for this project. Please verify that the maximum incentive and disincentive is 10 days at $192,000 per calendar day. The number of maximum incentive and disincentive days has been revised. An addendum has been issued. Is a detail for Concrete Barrier Wall Median Type SP-3 available? The pay item for Concrete Barrier Wall (Median Type SP-3) has been deleted from this job. An addendum will be issued. The Bridge Quantity sheets and General Notes sheets call for all piling on these Bridges A7380 and B7380 to be HP12x53. On the bridge plan sheets for Int. Bent 2A and Int. Bent 2B the piling is shown as HP14x73. Which is correct? The pile size for bridges A7380 and B7380 Int. Bents has been revised on Plan Sheets An addendum has been issued. The Modification of Existing Barrier Wall Special Provision states the method of measurement includes demo related work, new reinforcement and Structural Concrete. This leads the Contractor to believe the plan quantity for this contract item (654 LF, 3 Work Locations) includes all Demo and Replacement Structural Concrete and Reinforcing. However, Note #7, Detail Sheet #72, indicates the 75 LF Transitions are paid for under Page 2 of 6

3 Contract Item Median Type C. Please clarify if the 75 LF Transitions are paid as Median Type C or is the intent of Contract Item Modification of Existing Barrier Wall to include Demo, Structural concrete and Reinforcing Steel. Yes it includes everything including the transitions. Also, please be aware an addendum has been issued concerning the MSE Retaining Walls. In reference to the Special Provision for MSE Retaining Walls, Page 4 of 8, (f), is there a min. gage wire size for the Soil Retaining Screen? The design of the wire fabric for the MSE Wall portion of Wall No. 1 will be the responsibility of the Contractor s MSE Wall designer. Also, please be aware an addendum has been issued concerning the MSE Retaining Walls. Is the Buy America Requirement applicable for this material? Yes. Please provide the assumed unit weight and friction angle for the compacted embankment or SM-1 material required for the retained fill behind the Reinforced Zone of the MSE Retaining Walls. MSE walls retaining constructed embankments should be designed based on the properties of the material provided by the contractor. Please provide the friction angles that should be assumed for the MSE Wall Foundation material. MSE wall designers typically assume a friction angle of 25 deg. for foundation material. This can be increased to the friction angle of backfill material in undercut situations. Page 3 of 6

4 Special Detail Sheet no. 57 has a detail showing the half-section of Bridge End Embankments showing embankment constructed out of SM-1 material. Special Provision Excavation and Embankment describes that the SM-1 used for fill (along with the underdrain and clay plating shown in the detail) will be paid for as Compacted Embankment (cy). My question is that there are no quantities listed in the summary of quantities for this SM-1 embankment at the bridge ends. Where on this job does the detail shown on Sheet no 57 apply? Also, Sheet No. 57 shows a detail of the undercut areas. These quantities are clearly marked and shown as included in the pay quantities of excavation and embankment. However, the detail sheet shows that the undercut areas are to be backfilled with embankment fill as directed by the engineer. The special provision, Excavation and Embankment, requires the undercut locations where significant seepage is encountered shall consist of Selected Material (Class SM-1). What material are we to backfill the undercut areas with, embankment fill (i.e., clay) or SM-1? The half-section shown on page 57 applies to the bridge locations where we have MSE walls that have SM-1 material behind the reinforcement zone. These locations are shown on the MSE wall sheets that accompany the applicable bridge layouts. The intent is to make sure that any areas that have exposed SM-1 material also have the plating material so that there are not any erosion issues. We also want to make sure the SM-1 material can drain, so the underdrains are shown for those locations as well. As noted by the contractor, the SM-1 material incorporated into the Excavation and Embankment SP is to be paid for as compacted embankment, and it is tabulated as compacted embankment in the quantities. For undercut locations, it is expected that ordinary compacted embankment will be sufficient at most locations. Per the SP, only locations that experience significant seepage should be backfilled with SM-1 material. Since there is a total quantity of approximately 500,000 CY of compacted embankment, the SM-1 material is going to be a very small percentage of the compacted embankment quantity. ASTM A847 pipe in the sizes shown is very difficult to acquire without a very large order. Will A500 Grade B pipe with a 3 coat paint system be allowed as a substitute for the ASTM A847 grade pipe? This substitution will be allowed provided the bearing stiffener weld details on the approved shop drawings show a grind to bear fit and a fillet weld. In addition, the color of the paint Page 4 of 6

5 shall be Brown and shall match Federal Standard 595B, Color Chip No and shall be painted in accordance with Subsection of the Standard Specifications. Under item Modification of Existing Barrier Wall the specification states: The top 6 inches of the existing anchor bolts shall be cut away and new anchor bolt extensions with threaded ends shall be welded on to the existing anchor bolts with full penetration butt welds performed by a certified welder to provide 6 inches of protrusion from the top of the modified median foundation columns. Damaged galvanized coatings to the anchor bolts shall be repaired as specified in Subsection of the Standard Specifications. All new materials shall meet the requirements of the Standard Specifications. This exact method was attempted on project in Miller Co. (bid date 2008) due to the change from aluminum to steel structures when it was found the drawings had not reflected the additional bolt projection needed to accept the new structures. The state certified welder was not able to provide a weld that would bond the bolt sufficiently to pass X-ray examination. It was determined that the thickness and grade of the overhead structure bolts would not allow for a penetrating enough weld to weld splices. The tower of the structure footer was then removed and new bolts installed and the top of the footer re-poured. The work can be accomplished through the method detailed by the Department. The anchor bolts specified in this instance are designated to be weldable per AASHTO M314. Once the contract has been executed, the Contractor can propose an alternative method to accomplish this work. On the Bridge Hwy112 to NB I-40 Ramp the bearing stiffeners on Sheet 436 are shown as grade A & 14 split pipe. We were just informed the Pipe mill will only roll these with a minimum order greater than 200 tons for each size (I.E. 400 tons minimum). Can these be substituted by A709 Grade 50W plate that is step bent to the corresponding size? Yes, under the following conditions: 1) The fabricator needs to make sure there won t be any issues with meeting Charpy V-Notch requirements after cold-bending. As specified in the superstructure notes, these stiffeners are main load-carrying members and shall meet the Longitudinal Charpy V-Notch Test specified in Subsection of the Standard Specifications Page 5 of 6

6 2) The plates shall meet minimum bend requirements per the LRFD Construction Spec (see snippet below) and Subsection of the Standard Specifications. 3) The fabricator needs to make sure the connection plate, oriented per the plans, will attach to one of the flat surfaces of the bearing stiffener (and not at a bend point). Based on the proposed schematic (shown with 9 equally-spaced bends), this requirement would be met. Page 6 of 6