6-37 Section 610 – Gnss Construction Equipment
610.01 DESCRIPTION . This work shall consist of using grading equipment controlled with a global navigation satellite system (GNSS) machine control system in the construction of the roadway design and building the required surface models to facilitate GNSS machine control grading. This work shall also consist of furnishing, configuring, installing, maintaining, and removing GNSS units as needed for use by the Engineer and their inspection staff, including building the required surface models and loading them into the Contractor prov ided data collectors, and the training of the Engineer and their representatives on the use of the GNSS units provided. 610.02 EQUIPMENT . The Contractor may use any type of GNSS machine control grading equipment and systems which will generate end results meeting the Contract requirements. The Contractor shall supply GNSS construction inspection units for use by the Engineer. Each unit shall include all necessary components, communication devices, integrated antennae and receiver and cables, data collecto rs, operating manuals, attachments, and fastening hardware to meet the minimum requirements described below .
a.GNSS units provided for a single Contract shall be the same model and manufacturer and shall include, and be licensed to operate, the same version of GNSS planning software and data collection software to be used by the Engineer for data collection. Units shall be capable of tracking multiple constellations and allow for software updates within two years from the time of delivery. At the time of delivery of the GNSS units, all software provided (including firmware) shall be the most current available from the manufacturer and shall not be more than two years old. The Contractor shall provide a printed copy of the date of software installation for verification.
b.The Contractor shall provide the Engineer with a GNSS rover (with the same capabilities as units used by the Contractor) for use during the duration of the Contract. At the end of the Contract, the GNSS rover unit will be returned to the Contractor .
c.GNSS units shall include both standard USB cable and Bluetooth wireless technology for data transfer between the GNSS units and the data collectors.
d.GNSS units shall be equipped, at a minimum, to receive GPS and GLONASS data.
6-38 (e) GNSS units shall be equipped to receive, and be capable of using, real time kinematics (RTK)
correctional data (current version of RTCM format) through internet protocol provided from the VT Continuously Operating Reference System (VT CORS) Network. Th is shall include all necessary communication devices, repeaters, and systems, data service plans, and communications to meet the minimum required accuracy and not exceed 2 second latency at the rover. Whichever communication method is used by the Contracto r to broadcast the VT CORS RTK correctional data, the Contractor shall ensure that the RTK data shall be available at all locations across the entire Contract site during all hours of construction and inspection operations.
f.GNSS units shall include eit her an integrated or modular communication device capable of receiving RTK correctional data to satisfy the requirement of using VT CORS RTK corrections.
g.GNSS units shall be capable of collecting dual frequency GPS data.
h.The minimum required kinema tic accuracy relative to primary project control (CORS) shall be 0.033 feet + 1.0 ppm horizontally and 0.065 feet + 1.0 ppm vertically.
i.Necessary hardware and software shall be included (including communication drivers) to connect the GNSS units to an Agency -provided PC and communicate and exchange positional data with that Agency PC.
j.GNSS units shall have an internal, or modular, rechargeable battery system capable of operating through all active working hours (may include interchangeable batteries ), including the battery charger.
k.GNSS units shall include a hard or soft shell carry case, and all appropriate operation manuals.
l.GNSS data collectors shall have a touchscreen with a minimum size of 7 inches.
m.GNSS rover units shall include one fixed height rover rod of 6.56 feet in length, one attachable bipod which is compatible with the rover rod, one bracket connecting the data collector to the rover rod, and one topo shoe.
n.A GNSS unit set up to operate as a base station shall include al l necessary additional cables, hardware, fasteners, or accessories necessary to install it in a fixed semi -permanent location. This setup will not be considered as a rover unit and therefore will not require a rover rod, a bipod, a data collector bracket, or a topo shoe.
6-39 610.03 Construction Requirements .
a.GNSS Machine Control Grading .
1.Agency Responsibilities .
a.Control Points . The Engineer will set the initial horizontal and vertical control points in the field for the project as indicated in the Contract.
b.Localized Coordinate System . The Engineer will provide the project specific localized coordinate system. The control information used in establishing the localized coordinate system, specifically the rotation, scaling, and tra nslation, can be obtained from the Engineer upon request.
c.Electronic Data Files . Following the award of the Contract, the Agency will make available the following electronic data files. The files that will be made available were originally created with the computer software applications MicroStation (CAD software) and InRoads or OpenRoads (civil engineering software). The data files will be in the native formats and other software formats as described below.
1.CAD Files .
i.InRoads or OpenRoads DTM files representing the design surfaces. ii. InRoads or OpenRoads ALG files containing horizontal and vertical geometry. iii. MicroStation alignment design file. iv. MicroStation cross section design files.
v.MicroStation ROW design file. vi. MicroSta tion existing ground topography design file.
2.Machine Control Surface Model Files .
i.LandXML (ASCII format).
3.Alignment Data Files .
i.Alignment geometry report (ASCII report format). ii. LandXML (ASCII format).
6-40 The Contractor is notified that the Agency uses the US survey foot as a basis for all
engineering work. Particular care shall be taken to ensure that the US survey foot is used in any conversion or evaluation of the files provided. This includes any required conversion from MicroStation DGN to AutoCAD DWG, or from InRoads or OpenRoads to other engineering formats. The XML files shall also be checked to ensure that the US survey foot is used. Information shown on the Plans governs over the provided electronic data. The electronic information shall not to be considered a representation of actual conditions to be encountered during construction. Providing the Contractor this information does not relieve the Contractor from the responsibility of making an investigation of conditions to be encounte red, including but not limited to site visits, and basing any bid on information obtained from these investigations and their professional interpretations and judgment. The Contractor assumes all risk of error if the information is used for any purposes for which the information was not intended. Any assumptions the Contractor makes from this electronic information are at their own risk.
d.Spot Checks . The Engineer will perform spot checks of the machine control grading results, surveying calcul ations, records, field procedures, and actual staking .
2.Contractor Responsibilities .
a.The Contractor shall review and apply the data the Agency has provided to perform GNSS machine control grading and build the 3D model to do the same.
b.The Contr actor shall bear all costs, including but not limited to the cost of actual reconstruction of work, that may be incurred due to errors in the application of GNSS machine control grading techniques. Grade elevation errors and associated quantity adjustments resulting from the Contractor’s activities shall be corrected at no cost to the Agency.
c.The Contractor shall convert the Agency’s electronic data into a format compatible with the machine control grading system.
d.Manipulation of the Agency’s elect ronic data will be at the Contractor’s own risk.
6-41 e. The Contractor shall check the GNSS machine control system at the beginning of
each work day and recalibrate if necessary.
f.GNSS machine control grading shall meet the same accuracy requirements as conventional grading construction as required by the Standard Specifications.
g.The Contractor shall establish secondary control points at appropriate intervals and at locations along the length of the project and outside the project limits or where work is performed beyond the project limits as required at intervals not to exceed 1,000 feet. The horizontal position of these points shall be determined using static GNSS sessions or by traverse connection from the original baseline control points. The ele vation of these control points shall be established using differential leveling from the project benchmarks, forming closed loops. A copy of all new control point information shall be provided to the Engineer prior to construction activities. The Contract or is responsible for all errors resulting from their efforts and shall correct all deficiencies to the satisfaction of the Engineer at no additional cost to the Agency.
h.All reference points and monuments that are established by the Engineer within the project limits shall be preserved. Reference points that have not been preserved shall be reestablished at no additional cost to the Agency.
i.The Contractor shall set hubs at the top of the finished subgrade at all hinge points on the cross s ection at 1,000 foot intervals on mainline and at least two cross sections on the side roads and ramps. These hubs shall be established using conventional survey methods for use by the Engineer to check the accuracy of the construction.
j.The Contractor shall provide controls points and conventional grade stakes at locations such as, but not limited to, PCs, PTs, superelevation points, and other critical points required for the construction of drainage and roadway structures.
k.At least one week prior t o the preconstruction conference, the Contractor shall submit to the Engineer for review a written machine control grading work plan which includes the equipment type, control software manufacture and version, and the proposed location of the local GNSS ba se station used for broadcasting differential correction data to rover units.
6-42 (b) GNSS Construction Inspection Equipment .
1.The Contractor shall furnish, configure, install, maintain, and remove the GNSS units, and provide the Engineer and their representatives with training on the operation of the GNSS units. The Contractor shall ensure all GNSS units are fully operational and training has been provided before construction begins. The Contractor shall maintain all GNSS unit s and software in good working condition and shall provide replacement due to breakdown, damage, or theft within 2 working days. The Contractor shall retain ownership of all supplied GNSS units at the end of the Contract.
2.All projects shall use VT CORS as the spatial reference network from which RTK corrections are derived. The Contractor shall choose which communication technique and devices will be used which will ensure the consistent and reliable delivery of RTK correctional data from VT CORS to the GNSS units. When geographic locations or lack of a reliable communications network prohibit the use of the VT CORS directly, the Engineer may approve the use of a survey grade GNSS inspection unit as a base station in place of the VT CORS, which will be p aid for separately through a change order.
3.The Contractor shall semi -permanently mount the base station in a stable and secure location where it shall not be disturbed by construction activities nor be easily damaged by vandalism, and where it will be capable of providing radio signal coverage over the entire Contract area. If the base station cannot broadcast a signal that covers the entire site, the Contractor shall provide adequate repeater radios or other communications at such frequency and locatio ns such that a minimum of 90% signal strength is maintained throughout the project site. A GNSS unit installed as a base station for inspection operations shall only be moved with the approval of the Engineer.
4.For all construction grade GNSS units, the Engineer and their representatives shall be provided with a minimum of 16 hours of training on the use and operation of the GNSS equipment and software. Initial training shall occur within one week of delivery of GNSS units to the site unless otherwise di rected by the Engineer. The remainder of the training hours shall occur at the request of the Engineer. If a Contract has multiple years of work, an additional 8 hours of training shall be provided every additional year at the request of the Engineer. All training shall be performed by a manufacturer -verified trainer who is approved by the Engineer. The training shall occur at the Engineer’s field office or at a location agreed to by the Engineer.
6-43 (5) The GNSS units shall be maintained and remain in service until either a maximum of one
week after the Engineer requests its removal in writing, or the Agency relinquishes the Engineer’s field office.
c.GNSS Construction Inspection Surface Models .
1.The Contractor shall build the required GNSS construction inspection surfac e models using the data provided by the Agency as described in Subsection 610.03(a)(1) c. The Contractor shall load the models onto the provided data collectors to facilitate construction inspection by the Engineer.
2.At a minimum, the following GNSS cons truction inspection surface models shall be provided by the Contractor.
a.Proposed finish grade
b.Existing ground 610.04 METHOD OF MEASUREMENT . The quantity of GNSS Machine Control Grading to be measured for payment will be on a lump sum basis in the co mplete and accepted work. The quantity of GNSS Construction Inspection Equipment to be measured for payment will be the number of each GNSS Construction Inspection Unit provided and operational in the complete and accepted work. The quantity of GNSS Constr uction Inspection Surface Models to be measured for payment will be for all required GNSS Construction Inspection Surface Models on a lump sum basis in the complete and accepted work. 610.05 BASIS OF PAYMENT . The accepted quantity of GNSS Machine Control Grading will be paid for at the Contract lump sum price. Payment will be full compensation for furnishing all labor, equipment, and material necessary in preparing the electronic data files for use in the Contractor’s machine control system, the required s ystem check and needed recalibration, training of the Contractor’s staff, machine control equipment, maintenance, and for furnishing all materials, labor, tools, equipment, and incidentals necessary to complete the work. The accepted quantity of GNSS Const ruction Inspection Equipment will be paid for at the Contract unit price per each. Payment will be full compensation for furnishing all equipment, support, training for the Engineer, maintenance, and for furnishing all materials, labor, tools, equipment, a nd incidentals necessary to complete the work.
6-44 The accepted quantity of GNSS Construction Inspection Surface Models will be paid for at the Contract
lump sum price. Payment will be full compensation for furnishing the required surface models , performing corrections and updates to the models if issues are discovered, and for furnishing all materials, labor, tools, equipment, and incidentals necessary to complete the wo rk. Delays due to satellite reception of signals to operate the GNSS machine control system or inspection equipment will not result in adjustment to the Contract unit price for any Contract items or be justification for granting Contract time extensions.
a.Partial payments for GNSS Machine Control Grading will be made as follows:
1.The first payment of 75% of the Contract lump sum price will be made with the first biweekly estimate as determined by the Engineer pending progress on other Contract items.
2.The second payment of 25% of the Contract lump sum price will be made on the first estimate following the completion of 50% of the Contract.
b.Partial payments for GNSS Construction Inspection Equipment will be made as follows:
1.The first payment of 75% of the Contract unit price will be made once the equipment has been delivered to the Engineer and is fully operational.
2.The second payment of 25% of the Contract unit price will be made on the first estimate following the completion of 50% of th e Contract.
c.Partial payments for GNSS Construction Inspection Surface Models will be made as follows:
1.The first payment of 75% of the Contract unit price will be made once the model has been delivered to the Engineer and installed on the equipment .
2.The second payment of 25% of the Contract unit price will be made on the first estimate following the completion of 50% of the Contract. Payment will be made under: Pay Item Pay Unit 610.1000 GNSS Machine Control Grading ................................ .............................. Lump Sum 610.2000 GNSS Construction Inspection Equipment ................................ .............. Each 610.2500 GNSS Construction Inspection Surface Models ................................ .......Lump Sum
6-45 Sectio N 613 – Ston E Fill and Riprap
613.0 1 DESCRIPTION . This work shall consist of furnishing and placing protective material s. 613.0 2 MATERIALS . Materials shall meet the requirements of the following subsection s: Sand Borrow and Cushion ................................ ................................ ......................... 703.03 Stone for Riprap, Heavy Type ................................ ................................ ................... 706.03(a) Stone for Riprap, Light Type ................................ ................................ ..................... 706.03(b) Stone Fill, Type I ................................ ................................ ................................ .......706.04(a) Stone Fill, Type II ................................ ................................ ................................ ......706.04(b) Stone Fill, Type III ................................ ................................ ................................ .....706.04(c) Stone Fill, Type IV ................................ ................................ ................................ ....706.04(d) E-Stone Fill, Type I ................................ ................................ ................................ ....706.05(a) E-Stone Fill, Type II ................................ ................................ ................................ ..706.05(b) E-Stone Fill, Type III ................................ ................................ ................................ .706.05(c) E-Stone Fill, Type IV ................................ ................................ ................................ .706.05(d) E-Stone fill shall be of the type specified on the Plans, supplemented with material excavated from the channel or the tailings of a topsoil screening operation. Bed material shall be approved by the Engineer and the Vermont Agency of Natural Resources prior to use . Similar sized river sediment is an acceptable alternative as is a mixture of angular material and river sediment. 613.0 3 PREPARATION . The areas to be protected shall be constructed and graded to the lines shown on the Plans or as directed by the Engineer and, if a fill area, shall be compacted . All slope s shall be maintained to the neat lines shown on the Plans prior to the placing of filter or bedding material , stone fill, or riprap. 613.0 4 PLACING .
a.E-Stone Fill and Stone Fill . The specified stone fill shall be placed as shown on the Plans in a manner that will result in a reasonably well graded surface. Care shall be taken in the placing to avoid displacin g the underlying material . Stone fill placed inside of a closed structure shall be placed such that the structure is not damaged. The stones shall be so placed and distributed that there will be no segregation of either the larger or smaller sizes of stone .
Source: Vermont Standard Specifications for Construction, 2024 Edition. Pages 811–818 of 1,380.