621.01  Description

621.02  Materials

621.03  Layout

621.04  Installation RPM Casting

621.05  Installation RPM Retroreflector

621.06  Reflector Replacement

621.07  Reflector Color

621.08  Raised Pavement Markers Removed

621.09  Method of Measurement

621.10  Basis of Payment


621.01  Description.  This work consists of preparing the pavement and furnishing and placing plowable raised pavement marker castings (RPMs) and prismatic retroreflectors, and removing existing RPMs for disposal.

621.02  Materials.  Furnish materials conforming to:

Castings................................................................... 721.01

Prismatic Retroreflectors and Adhesive................... 721.02

Casting adhesive...................................................... 721.03


621.03  Layout.  Before placing RPMs, lay out the location of all RPMs.  Locate RPMs within 5 percent of specified spacing.  Do not place RPMs under the following conditions:

A.      On pavement surfaces with cracking, spalling, or failure of underlying base material.

B.      Within 1 foot (0.3 m) of active signal detector loop wires.  Exercise care to ensure that detector lead-in cables are not cut.

C.      Over pavement markings except with the Engineer’s approval.

D.      Closer than 2 inches (50 mm) to a pavement construction (transverse or longitudinal) joint or within an intersection.

E.      Within 3 feet (1 m) of a bridge expansion joint.

If the initial location of a RPM is determined to violate one of the aforementioned conditions, relocate the affected RPM longitudinally.  Relocate the RPM within a distance not exceeding 25 percent of the specified RPM spacing.  If necessary to relocate the RPM to a distance greater than 25 percent of the specified RPM spacing, do not install the affected RPM.

RPMs along double yellow centerline are to be placed in line or on line, but no closer than 2 inches (50 mm) to a pavement construction (transverse or longitudinal) joint.  RPMs installed along a channelizing line are to be placed no more than 1 inch (25 mm) from the edge of the painted line and no closer than 2 inches (50 mm) to a pavement construction (transverse or longitudinal) joint.   Place the RPMs installed along a lane line or dashed yellow centerline between and in line with the dashes no closer than 2 inches (50 mm) to a pavement construction (transverse or longitudinal) joint.

Install replacement RPMs within 3 feet (0.9 m) longitudinally of the damaged or missing RPM.

621.04  Installation RPM Casting.  Cut parallel slots with 1/16 to 1/8 inch (1.5 to 3 mm) clearance on each side for installing RPM castings. 

Pavement cuts should be inspected prior to adding casting adhesive.

When a casting is inserted in the cut without casting adhesive to test proper cut, at least 3 of the 4 leveling lugs/tabs must contact the pavement surface and all four keel-ends of castings must be below the pavement surface.

Each casting must be centered lengthwise and should have 1/16 to 1/8 inch (1.5 to 3 mm) clearance between pavement cut and casting for casting adhesive to bond properly.  Only the leveling lugs/tabs should be in contact with the pavement surface after insertion of casting in pavement so that a minimum of 1/16 inch (1.5 mm) of casting adhesive is the bonding adhesive between the casting and pavement.  The casting adhesive must fill all voids.

The pavement cut must be completely dry and free of dust, dirt or any other material that will interfere with the adhesive bond to the casting and the pavement.  Casting adhesive on the active reflector face must be removed immediately.

Install the RPM casting within 24 hours after cutting the slots into the pavement.  On new pavement surfaces, the Contractor may begin RPM placement as soon as the pavement markings for that section are completed and dry.

Ensure that the RPM casting is free of dirt, dust, oil, grease, rust, moisture, or any foreign matter that impairs adhesion to the pavement.

Place RPMs when the pavement surface temperature and the ambient air temperature are at least 40 °F (5 °C) and the pavement is dry.  Heat both parts of the RPM casting adhesive to 100 ± 10 °F (38 ± 5 °C) during installation when either the pavement surface or ambient air temperature is between 40 and 50 °F (5 and 10 °C).

Ambient Air


Minimum Period

Protected from Traffic


























Do not allow traffic on the RPMs until the adhesive has cured.

Two component approved casting adhesive is used to fill the pavement cut to within approximately 3/8 inch (9 mm) of the top of the pavement cut.  A minimum of 3 of the 4 leveling lugs/tabs must be in contact with the pavement surface and the casting adhesive should ooze out from under the casting from all sides filling all voids around the casting and be level with the pavement surface.

Mix the casting adhesive according to the manufacturer’s recommendations.  Complete the mixing operation and placing of the RPMs rapidly.  Do not use any mixed batch that becomes so viscous that it cannot be readily extruded from under the RPM with light pressure.

621.05  Installation RPM RetroreflectorAttach the reflector to the casting before installation or after the adhesive in the pavement slots has cured. 

Remove all dirt, dust, oil, grease, rust, moisture, parts of damaged reflectors, or any foreign matter that impairs adhesion of the reflector to the casting.

Peel the release liner from the back of the reflector with butyl pad.  Apply a wide bead (approximately 3/8 inch (9 mm)) of  reflector adhesive sufficient to squeeze out on all sides when pressure is applied to seat the reflector.

Apply approximately 100 pounds (45 kg) of pressure on the reflector or foot pressure for 1 to 3 seconds.  Do not allow adhesive material on the reflective surface of the reflector.  Any adhesive on the active reflector must be removed immediately.

Apply the reflector when the pavement surface temperature and the ambient air temperature are at least 35 °F (2 °C) and the casting surface is dry.  Do not attach the reflector to the casting when rain over the work site is imminent.

621.06  Reflector Replacement.  Replace damaged, non-retroreflective, or missing reflectors within the existing marker installations where the casting remains intact with the appropriate reflector type.  The Engineer will determine the location of replacement reflectors.

Perform the cleaning and attachment procedure for replacing reflectors within existing RPM installations according to 621.05.

621.07  Reflector Color.  Use the appropriate reflector color for the following applications:

A.      Channelizing Lines.  White/red two-way reflectors with white facing traffic.

B.      Lane Lines.  White one-way or white/red two-way reflectors as specified, with white facing traffic.

C.      Edge Lines.  One-way reflectors facing traffic matching the edge line color or two-way reflectors with the edge line color facing traffic and red in the opposite direction.

D.      Center Lines.  Yellow two-way reflectors.

621.08  Raised Pavement Markers Removed.  As designated, remove existing raised pavement markers.  Fill all depressions caused by removing the castings with asphalt concrete by the end of the next workday.  Remove all standing water from the hole before filling.  Compact the asphalt concrete flush with the pavement.  Removed raised pavement markers become the property of the Contractor.

621.09  Method of Measurement.  The Department will measure RPMs by the number of each furnished, complete with reflectors, in place, and accepted.

The Department will measure RPM, Reflectors by the number of each, complete in place, for use on existing RPM castings in the pavement, and accepted.

The Department will measure Raised Pavement Markers Removed by the number.  Payment will include the cost of asphalt concrete to fill depressions caused by removal of the castings.

621.10  Basis of Payment.  The Department will pay for accepted quantities at the contract prices as follows:

Item           Unit                                Description

621             Each                                RPM

621             Each                                RPM Reflector

621             Each                                Raised Pavement Marker Removed