2545.01 GENERAL.
This specification covers the overlaying of existing Type B signs. The signs to be overlaid will be identified in the contract documents.

This work is intended to be done by applying retroreflective sheeting, as specified in Article 4186.03, to sheets of thin aluminum and applying to existing sign panels with pop-rivets.

2545.02 MATERIALS.
The retroreflective sheeting used in the overlay material shall meet the requirements of Article 4186.03.

The thin aluminum sheets shall have a thickness of ± 0.063 inches (1.6 mm) and shall meet the requirements of ASTM B 209/B 209M, Alloy 6061-T6 with no specified limit for yield strength of bend test.

The retroreflective sheeting, as specified in Article 4186.03, shall be applied to the thin aluminum sheets in accordance with the recommendations of the sheeting manufacturer.

2545.03 PREPARATION OF PANELS.
The sign panel to be overlaid shall be left in place on sign supports while the work is in progress. If an alternate method requiring removal of the panel is proposed by the Contractor, the procedure shall be submitted for approval by the Engineer prior to beginning work.

All existing legends, symbols, shields, and borders shall be removed from the sign panel without damage to the aluminum extrusions. Removed items shall become the property of the Contractor. Rivets protruding from the surface of the sign panel shall be removed. Additional preparation work may be shown in the contract documents.

2545.04 APPLICATION OF ALUMINUM OVERLAY STRIPS.
The thin overlay aluminum strips with retroreflective sheeting shall be applied in uniform width vertical strips not less than 1.5 feet (0.5 m) wide except the last strip may be of lesser width. Vertical joints shall be made by butting aluminum strips together as close as possible without overlapping.

Edge molding on the panel is to remain in place. The overlay strips shall be indented 3/4 inch (20 mm) from the left and right edge of the sign face to allow the edge molding to grip the extrusions.

With the sign 4 feet (1.2 m) or less in height, the overlay strip shall be placed horizontal in one piece.

The overlay sheets shall be attached with rivets. Rivets shall be aluminum pull through, hollow blind rivets with a diameter of 1/8 inch (3 mm) and a brazier head with an appropriate grip range. The maximum spacing between rivets is 12 inches (0.3 m) both vertical and horizontal. The maximum spacing that the rivets may be indented is 3 inches (75 mm) from edge of the overlay strips.

Color matching of pieces of overlay shall be controlled by maximum use of overlay from a single lot number on each sign. When overlay from different lots is to be used on a sign, the colors shall be matched. In matching, the overlay pieces shall be placed side by side and inspected visually in existing light from a 10 foot (3 m) distance perpendicular to the faces of the pieces; if a difference in color is perceptible at that distance, the pieces are not to be used on the same sign.

2545.05 APPLICATION OF LEGEND.
Legend to be placed on refurbished sign panels shall be retroreflective sheeting applied to an aluminum base, in accordance with Type B sign layouts on the plans. All legends shall be of the detachable type. New material meeting requirements of Article 4186.05 shall be used. Legends shall be attached to the sign panel as specified in Article 4186.06, D.

2545.06 LIMITATIONS.
The sequence of overlay work and the time requirements for each sign are subject to limitations shown on the plans.

2545.07 METHOD OF MEASUREMENT.
The Overlay of Type B Guide Signs will be computed in square feet (square meters from measurements to the nearest 0.1 m) for the area of the vertical, front face of the signs, as specified in the contract documents, in accordance with Article 2524.12.

2545.08 BASIS OF PAYMENT.
Payment for Overlay of Type B Guide Signs will be the contract unit price per square foot (square meter) of sign area overlaid. This payment shall be full compensation for sign panel preparation, furnishing and applying overlay sheeting material to existing sign panels, and furnishing and applying all legend, border, and symbols in accordance with the contract documents.