272 ALASKA 2020 SECTION 520
520-1.01 DESCRIPTION . For each site where public traffic uses a temporary crossing or a
Contractor uses a temporary crossing that is elevated over a public route, construct and maintain the temporary crossing. Remove temporary crossings after use and cleanup the site. Design temporary bridges, change the preliminary design of approach roads to accommodate temporary bridges, and have an independent design check performed. Inspect and perform quality acceptance on temporary bridges.
520-1.02 Definitions .
DESIGNER OF RECORD ( DOR). A civil engineer registered as a Professional Engineer in the State of Alaska, and in responsible charge of the work described. The DOR must have adequate and relevant prior bridge design and inspection experience. The DOR may delegate portions of design, quality acceptance, and inspection work, to qu alified technicians. The DOR and qualified technicians must not be supervised by, or under the direction of the Contractor’s temporary crossing superintendent and work crew. INDEPENDENT ENGINEER (IE). An engineer registered as a Professional Engineer in the State of Alaska, and in responsible charge of the independent design check. The engineer responsible for the check must have adequate and relevant prior bridge design experience. The engineer responsible for the check shall not be employed by the Contr actor or the same firm as the Designer of Record; or employed by a firm managed or owned by the Contractor or the Designer of Record; nor shall the engineer performing the work manage or own the Contractor or the firm employing the Designer of Record. INDEPENDENT DESIGN CHECK (IDC). An independent design check of the temporary bridge package including but not limited to: design, location and dimensions of the foundation, structural members, connections, erection plan and temporary bracing (when required), safety barrier, and independent calculations of design loads, member stress, material properties, hydraulic capacity and scour protection. TEMPORARY BRIDGE. A temporary bridge used by the public or over a public route, including abutments, piers, safety ba rrier and railing, foundation scour protection, and other incidentals. TEMPORARY BRIDGE PAC KAGE (TBP). Design calculations from the DOR and IE, working drawings, specifications, load rating, and all items identified on Form 25D -080, necessary to construct a temporary bridge. TEMPORARY CROSSINGS. A detour route that includes temporary bridges, approach roads and other incidentals. MATERIALS AND DESIGN
520-2.01 MATERIALS. New or used materials must meet the requirements of the design and the
Contract. The DOR must verify the quality of temporary bridge materials before incorporation into the project.
520-2.02 GEOTECHNICA L DATA AND HYDROLOGY REPORT. The Department may provide
records of geotechnical investigations. The Contractor is responsible for obtaining all additional geotechnical data necessary for design and construction of the temporary crossings. The Department may provide a preliminary hydrology and hydraulics report. The Contractor is responsible for obtaining all additional hydrology and hydraul ics data necessary for design and construction of the temporary crossings. 273 ALASKA 2020 520-2.03 TRAFFIC CON TROL PLAN. Submit a traffic control plan for temporary crossing according to the Plans and Section 643.
520-2.04 DESIGN REQU IREMENTS. Retain the services of a DOR to design temporary bridges,
and to provide a TBP. When the temporary bridges are used as a construction platform for the Contractor’s equipment or workers, then design and construct temporary bridges that are wide enough for traffic lanes and construc tion areas, and strong enough to support design traffic and construction loads. The Department will provide preliminary designs for approach roads. The DOR may change the design of approach roads to accommodate temporary bridges.
1.Design temporary crossi ngs according to the following documents:
a.DOT&PF Standard Specifications for Highway Construction for recommended construction methods, material properties, and sampling and testing methods;
b.AASHTO LRFD Bridge Design Specifications, AASHTO Guide Specific ations for LRFD Siesmic Bridge Design, and the DOT&PF Bridges and Structures Manual for temporary bridge design criteria, as modified by Subsection 520- 2.04; and
c.DOT&PF Preconstruction Manual for design criteria for changes to approach roads.
2.Provide work ing drawings for temporary bridges including:
a.All information and details necessary to construct temporary bridges including all items listed on Form 25D -080;
b.All dimensions controlling the temporary bridge design and erection, including beam length and s pacing, post location and spacing, vertical distance between connections in diagonal bracing, height of bents, and similar design controlling dimensions;
c.All design loads and material properties;
d.The soil bearing values;
e.The openings required to allow the passage of traffic, including horizontal and vertical clearances, and the location of railing or barrier;
f.Water design flow, opening size and elevations under superstructure, the high water elevation, and the maximum water flow elevation, and vertical clearances; and
g.When a bridge is built over a traveled way show where temporary bracing is used during erection or removal of the bridge, show the sequence of erection and removal, and show details of the temporary bracing used.
3.Design temporary bridges t o conform to the following requirements:
a.To support 100 percent of HL- 93 live loads or the Contractor’s maximum construction load whichever is greater, without overstress. Indicate the HL- 93 live load and the governing live load (when different than HL- 93) on working drawings;
b.Design for half the seismic acceleration value of the permanent bridge shown on the Plans;
c.Include the capacities and demands of load- supporting members in the design calculations; SECTION 5 20 274 ALASKA 2020 d. Provide a clear roadway and clear pathway widths equal to or greater than the widths indicated on the plans. Construct the temporary bridge and approach embankments wide enough to provide the widths indicated on the plans, and to safely pass contractor’s equipment during all phases of constructing the ne w bridge;
e.Design vertical clearance for the life of the temporary structure. A minimum vertical clearance of 16.5 feet is required above a state highway, local road, or street open to the public. A minimum vertical clearance of 23 feet is required above the Alaska Railroad. For navigable waters a minimum vertical clearance of 17 feet is required between the low elevation of the superstructure and (1) the ordinary high fresh water elevation or (2) mean high salt water elevation;
f.Minimum vertical clearance of one foot between the low elevation of the superstructure and the maximum water flow elevation within the proposed construction opening. Calculate the design water discharge for each temporary bridge;
g.To support equipment used to install and remove the temporary bridge, and construct or renovate the existing bridge. List equipment type, size, capacity, lifting locations, and traffic patterns during lift on the working drawings. Indicate maximum construction loads and locations of applied construction lo ads;
h.Provide a concrete F -shape barrier system on the bridge and bridge approaches. Anchor barrier system to prevent deflection when impacted. Locate barrier so outside edge is setback a minimum of 12 horizontal inches from outside edge of bridge deck;
i.Construct roadway surface of concrete or asphalt. Construct skid- resistant bridge deck surface of concrete, asphalt, timber or steel;
j.Design to comply with the requirements of permits and environmental commitments, including time windows during which work m ay occur. Apply for and obtain additional permits or modifications to existing permits as needed;
k.Do not use existing bridge components on the project site for temporary bridge construction; and
l.To support loads from utilities identified in the Contract.
4.Provide load ratings of the temporary bridge according to the most recent version, including interim version, of the AASHTO Manual for Bridge Evaluation (MBE ) and the Alaska Bridges and Structures Manual . Do not submit a temporary bridge with load factors less than 1.0. Load rate steel and concrete bridges using the Load Factor Rating (LFR) and Load and Resistance Factor Rating (LRFR) methods. Load rate timber bridges using the Allowable Stress Rating (ASR) method and Load and Resistance Factor Rating (LRFR) methods. Include values for moment, shear and, where applicable, axial stresses. Specify live load type, placement for maximum stress, distribution, and impact. Do not include the Contractor’s construction loads. Include the following cases for LF R load ratings:
a.inventory and impact included
b.operating and impact not included
c.operating with one lane centered on the bridge and impact not included. Include the following LRFR load ratings: 275 ALASKA 2020 d. design inventory and impact included
e.design operating and impact included
f.design operating with one lane centered on the bridge and impact not included. Provide a LFR and LRFR load rating summary table with the general geometry of the structure, assumptions made, and each load rating value. Provide updated load rat ings as necessary to reflect the current condition of the temporary bridge.
6.Design changes to approach roads must conform to permit requirements, and Department design standards applicable to the design criteria listed on the plans.
520-2.05 DESIGN SUBM ITTAL AND REVIEW. Comply with the following:
1.Retain a DOR to design temporary bridges and design changes to the approach roads, and to provide load ratings for temporary bridges. The design drawings and load ratings in the TBP must be stamped with the seal of , dated by, and signed by the DOR;
2.Retain an IE to perform an IDC; and to stamp with their seal, date, and sign an IDC letter certifying: “The TBP meets the AASHTO LRFD Bridge Design Specifications and the Contract requirements”; and
3.Submit the IDC letter with the TBP (except calculations may be one set), and with three sets of design changes to the approach roads, to the Engineer for review and approval at least 30 days prior to beginning construction of the temporary bridge.
520-2.06 VALUE ENGIN EERIN G CHANGE PROPOSALS. Base your bid on supplying
temporary bridge structures according to the Contract documents. After Award you may submit construction value engineering change proposals to the Engineer. Proposals must include permitting requirements and t imelines for construction. The Department will consider value engineering change proposals in accordance with Subsection 104- 1.06. CONSTRUCTION REQUIREMENTS
520-3.01 TRAFFIC MAI NTENANCE. Protect and control traffic according to Section 643 and the
approved traffic control plan.
520-3.02 CONSTRUCTIO N AND MAINTENANCE RE QUIREMENTS. Construct temporary
crossings entirely within the right -of-way and within permitted areas. Construct the temporary bridge according to the approved TBP. Construct the approach roads according to the Plans and Specifications, as modified by the DOR and approved by the Engineer. Construct according to the Standard Specifications for Highway Construction with exceptions noted by the DOR and this Section 520. Bolted steel connections must use load indicating washers. Weld according to Subsection 504- 3.01.7 Welding. Maintain structure, safety appurtenances, and wearing surface of temporary crossings until substantial completion. Maintain temporary crossings in a safe and functional condition. Keep bracing and connections tight, and immediately replace any damaged members or damaged connections. Promptly remove debris caught against, under or inside, temporary bridges. Limit surface deviations to 3/8 inch, as measured from the testing edge of a 10- foot straightedge, between two contacts on the driving surface of the temporary crossings. SECTION 5 20 276 ALASKA 2020 520-3.03 WINTER MAIN TENANCE. The Department may accept the maintenance responsibility for winter snow and ice removal only. The Contractor retains responsibility for all repairs and maintenance, in accordance with Subsections 105- 1.13 and 107- 1.15.
520-3.04 INSPECTION. The Contractor is responsible for Quality Control, and for the
construction of temporary crossings, including temporary bridges and approach roads, to conform to the working drawings, specifications and the Contract requirements. The DOR is in responsible charge of Quality Acceptance and inspection, of temporary bridge materials and construction work. The DOR must verify in writing that the quality of bridge materials and construction work meet the design and Contract requirements. The DOR or qualified technician is required to be on- site and to inspect critical work including but not limited to abutments, piers, pile driving, welding, struc tural elements, fastening of structural elements, reinforcing steel placement, concrete pours, and foundation scour protection. The Engineer may sample and test materials, and may reject materials that do not meet the requirements of the design. The Engi neer may inspect the construction of temporary crossings at any phase of construction and reject unacceptable work. The Engineer will inspect the finished construction of temporary crossings before public use; however, inspection by the Engineer will not relieve the Contractor from any responsibility for defective work.
520-3.05 APPROVALS. Obtain the following written approvals from the Engineer:
1.TBP prior to beginning temporary bridge construction;
2.Design changes to temporary approach roads prior to const ruction of approach roads;
3.Temporary bridge construction prior to opening the bridge to traffic; and
4.Approach road construction prior to opening the road to traffic. Such approvals will not relieve the Contractor of the responsibility for defective work. The Contractor shall remain responsible for all aspects of the design, location and dimensions of the temporary crossing, including but not limited to materials, foundation, structural members, connections, safety barrier, and for satisfactory and safe c onstruction of all work. The Engineer’s review and approval of the TBP shall not be construed as a complete review, but will indicate only that the general method of construction and working drawings are acceptable to the Department, that the TBP appears complete, and that a certification of an IDC was provided. The request to open the temporary bridge to traffic must be supported by a final inspection report that is stamped with the seal of, dated by, and signed by the DOR; and that certifies: “The temporary bridge has reached Substantial Completion as defined in Subsection 101- 1.03, conforms to the requirements of the TBP and the Contract, and can support design traffic loads and construction loads, and is suitable for public use.”
520-3.06 CLEANUP. Remove temporary crossings, cleanup site, and stabilize site from erosive
forces before final completion. Return the site substantially to its original condition. Additional cleanup conditions may be listed in the permits. Remove piling to a minimum of one f oot below ground level.
520-4.01 METHOD OF M EASUREMENT. See Section 109.
520-5.01 Basis of Pa Yment.
Temporary Crossings . The lump sum payment is full compensation for all design, engineering, load rating, inspection, labor, equipment and materials neces sary to furnish, install, repair, 277 ALASKA 2020 maintain and remove temporary crossings in their entirety. The lump sum payment also includes all traffic control and traffic maintenance within the limits of the temporary crossings. Payment will be made under: PAY ITEM Item Number Item Description Unit 520.0001.____ Temporary Crossings LS 278 ALASKA 2020 SECTION 550 COMMERCIAL CONCRETE
550-1.01 DESCRIPTION . Furnish, place, finish, and cure Portland cement concrete for
manholes, inlets, sidewalk, curb, gutter and other minor structures and incidental construction as shown on the Plans.
550-2.01 MATERIALS. Use materials conforming to Subsection 501- 2.01.
550-2.02 COMPOSITION OF MIXTURE – JOB MI X DESIGN. Provide a Job Mix Design, JMD,
meeting the requirements of Table 550- 1 for each class of concrete included in the Contract. TABLE 550 -1 COMMERCIAL CONCRETE DESIGN REQUIREMENTS Class B W Water -Cement Ratio, lbs/lbs, maximum 0.45 0.50 Total Air Content, % 5.5 – 6.5 4.0 – 6.5 Coarse Aggregate Gradation, AASHTO M 43 No. 57 or 67 No. 7, 8, 57, or 67 Compressive Strength, psi, minimum 4,000 3,000 Alternative sizes of coarse aggregate, as shown in AASHTO M 43, may be used when approved in writing. Calculate the water -cement ratio based on the total weights of all water and all cementitious material. Portland cement, blended hydraulic cement, fly ash, ground granulated blast -furnace slag, and silica fume are cementitious materials. Fly ash, ground granulated blast -furnace slag, silica fume, and combinations of these materials may be used as a substitute for Portland cement provided the quantity meets the limits of Table
550-2 and the total combined quantity of fly ash, ground granulated blast -furnace slag, and silica
fume does not exceed 40 percent of the total cementitious materi al by weight. TABLE 550 -2 SUPPLEMENTARY CEMENT ITIOUS MATERIAL LIMI TS Material Max. Percent Fly Ash 35% Ground Granulated Blast -Furnace Slag 40% Silica Fume 10% Maximum percent includes initial quantities in blended cement plus supplementary cementitious materials.
1.Submittals . Submit a JMD and materials documentation at least 15 days prior to scheduled production.
a.JMD. Submit concrete mixture proportions per cubic yard and test results for the proposed JMD. Submit the following:
1.Weights of cementitious materials
2.Weights of aggregates in saturated surface dry condition
3.Volume or weight range of each admixture.
4.Weight of water
5.Water -cement ratio
Source: Alaska Standard Specifications for Highway Construction, 2020 Edition. Pages 300–305 of 584.