2410.01 GENERAL.
This construction shall consist of furnishing and installing either treated or untreated single or double plank floors in accordance with the contract documents.

2410.02 MATERIALS.
All materials used in the construction of plank bridge floors shall meet requirements of the contract documents.

A. Lumber.
Lumber shall be treated or untreated, as specified. Section 4163 shall apply to treated lumber, and Section 4162 shall apply to untreated lumber.

B. Hardware.
Hardware shall meet requirements of Article 4153.07.

2410.03 CONSTRUCTION.
Rough planks shall be laid with not more than 1/4 inch (5 mm) opening between the planks. Adjacent planks laid in the floor shall not vary more than 1/4 inch (5 mm) in thickness. Surfaced planks shall fit tightly together and shall present a smooth, uniform surface without variation due to difference in thickness or surfacing of the plank.

When the design requires wood stringers or nailing strips on steel beams, each plank shall be securely spiked to each nailing strip or joist with not less than two wire spikes. The length of spikes used shall be 3 inches (75 mm) greater than the nominal thickness of the plank.

All shims and scupper blocks shall be fastened securely to the plank floor. Ends of the plank shall be cut to a true line parallel to the center line of the roadway.

Unless otherwise provided, the floor may be attached to steel stringers or joists by pins driven through the flange, using a process subject to approval of the Engineer, or by steel clips. Clips shall be securely held between the planks by double pointed nails or by hooks or fins on the clips which engage both adjacent planks. When double pointed nails are used, they shall be 20d for 3 inch planks and 40d for 4 inch planks (5.72 mm diameter by 100 mm long for 75 mm planks and 6.65 mm diameter by 125 mm long for 100 mm planks). Clips shall be positioned so that they will hold the plank in close contact with the top flanges of beams to prevent the planks from working loose due to relative movement between the planks and flanges.

If methods used by the Contractor for driving adjacent planks onto double pointed nails indicate damage to the plank or unsatisfactory joints, the Engineer may require the Contractor to jack the plank into position hydraulically with not less than three jacking points per plank. Sledges and blocks may be used to facilitate jacking.

Timber for subfloors for asphalt wearing surface or for double plank floors shall be given full pressure preservative treatment as specified in Section 4161, unless otherwise indicated in the contract documents.

A. Single Plank Floors.
Single plank floors shall consist of a single layer of wood planks of the size and type specified. When the plank floor is to be covered with asphalt wearing surface, the floor planks shall be surfaced on at least one side and one edge.

B. Double Plank Floors.
Double plank floors shall consist of two layers of planks supported by stringers or joists. The lower course of planks shall be laid parallel to bridge abutments and the top course parallel to the roadway center line. Each top course plank shall be fastened to the lower course by spikes placed in pairs at intervals of not more than 4 feet (1.2 m). The spikes shall be 3 inches (75 mm) longer than the nominal thickness of the plank. At bridge ends, planks shall be beveled in a manner to provide a smooth riding surface.

2410.04 METHOD OF MEASUREMENT.
The quantity of lumber used in plank floors shall be computed by the Engineer in thousands of board feet (cubic meters) as provided in Article 2409.16. Nails and miscellaneous hardware will be considered incidental and will not be measured separately for payment.

2410.05 BASIS OF PAYMENT.
Plank bridge floors built in accordance with the contract documents will be paid for at contract unit price per thousand board feet (cubic meters) for the types and grades of lumber specified in the contract. These payments shall be full compensation for furnishing all lumber, nails, miscellaneous hardware, and other materials, and for performance of all incidental work necessary to complete the structure in accordance with the contract documents.