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Raised Pavement Markers (RPM)
A raised pavement marker (RPM) is a safety device used on roads. These devices are usually made with plastic, ceramic, or occasionally metal, and come in a variety of shapes and colors. Raised pavement markers include a lens or sheeting that enhances their visibility by reflecting automotive headlights. RPMs can be used to show roadway alignment or to replace or supplement other pavement markings. More frequently, however, retroreflective RPMs are used in conjunction with retroreflective striping for longitudinal delineation. Retroreflective RPMs provide increased visibility at night, especially during rain to provide wet weather visibility.
Snow Plowable Raised Pavement Marker (SPRPM)
A snow plowable raised pavement marker (SPRPM) serves the same purpose as an RPM but is designed to withstand the impact of snow plowing operations. The devices are usually made with a cast iron housing which holds and protects a plastic reflective lens. They are placed into a saw cut reservoir and are secured to the pavement using epoxy adhesive.
Currently, NTPEP evaluates the performance of manufacturers’ RPMs and SPRPMs on both asphalt pavement and concrete pavement on a busy interstate. Adhesives that hold the RPMs in place may also be evaluated. The testing includes field evaluation and laboratory testing. Installation and testing protocols are described in the “Project Work Plan.” All sampling and testing requirements conform to the latest version of ASTM Standard Specifications (D4280 and D4383).
The NTPEP Technical Committee is responsible for authoring the Project Work Plan convenes yearly at the NTPEP National (Annual) Meeting. During this working meeting, the Project Work Plan is discussed; changes made, and shortly thereafter balloted for adoption. Improvements are immediately implemented in the next testing cycle.
NTPEP Designated Labs:
- RPM Test Deck Host State: Georgia Department of Transportation
- SPRPM Test Deck Host State: Ohio Department of Transportation
- Light Tunnel Testing: Florida Department of Transportation
NTPEP - Raised Pavement Markers
Annual meeting minutes are combined with attendance sheets and, if available, presentations.
2020 Summer Conference Call
2020 Annual Virtual Meeting
2019 Fall Conference Call
2019 Annual Meeting Big Sky, MT
2019 Spring Conference Call
2018 Winter Conference Call
2018 Annual Meeting Norfolk, VA
2017 Summer Conference Call
2017 Annual Meeting Boston, MA
2016 Fall Conference Call
2016 Annual Meeting Grand Rapids, MI Webinar
2015 Summer Conference Call
2015 Annual Meeting Scottsdale, AZ Webinar (includes attendance, Round Robin, Survey)
2015 Winter Conference Call
2014 Summer Conference Call
2014 Annual Meeting Greenville, SC
NTPEP tests products according to a Project Work Plan, which describes the laboratory and/or field test protocols used to conduct the evaluation. The Project Work Plan is a consensus-based document and includes peer review and input from industry experts. Each Project Work Plan is adopted after receiving at least two-thirds affirmative support from 52 AASHTO member states. The Project Work Plan is the basis for host states to conduct their testing and evaluation. When implemented by state DOTs, their own state standard specifications may supersede the NTPEP Project Work Plan. Industry is advised to be aware of state-level requirements, which may supersede basic NTPEP testing.
RPM Work Plan – updated August 2015
SPRPM Work Plan – updated February 2014
2011 RPM and SPRPM Work Plan – contains procedures still valid for evaluating Temporary Raised Pavement Markers, Temporary Chip Seal Markers, and the Adhesives
Round Robin Testing Results
NTPEP Round Robin Testing-2010
Control Marker Data
Data for 2010 Control Markers – GA DOT – PDF
Raised Pavement Markers (RPM) Snowplowable Raised Pavement Markers (SRPM)
Evaluations are based on:
- ASTM D4280, “Standard Specification for Extended Life Type, Nonplowable, Raise Retroreflective Pavement ”
- ASTM D 4383, “Standard Specification for Plowable, Raised Retroreflective Pavement Markers.”
RPM types evaluated include:
- Standard Raised Pavement Markers (RPM)
- Snow Plowable Raised Pavement Markers (SPRPM)
- Temporary Raised Pavement Markers
- Temporary Chip Seal Markers
RPM adhesives are also evaluated. Adhesive types include:
- Standard Bituminous Adhesive
- Flexible Bituminous Adhesive
- Non-Bituminous Hot Melt Adhesive
- Epoxy Adhesive
It is recommended that products be re-evaluated every 4 years.
Initial evaluations are performed on randomly sampled RPMs. Nonplowable and Snow Plowable RPMs are evaluated for:
- Dimensional Measurements
- Compressive Strength
- Lens Integrity
- Temperature Resistance
- Flexural Strength
- Abrasion Resistance
Snow Plowable RPMs will also be evaluated for Holder Ramp Hardness.
Temporary RPMs and Chip Seal Markers are tested for retroreflectivity and hardness
- RPM/SPRPMs are placed on a roadway and exposed to traffic and environmental conditions.
- RPM/SRPM products are evaluated over a 2-year period at intervals of 6, 12, 18, and 24 months.
- Temporary RPMs are evaluated over a 6-month period at monthly
- Chip seal markers are evaluated for 1 month at weekly
Additional information about this evaluation can be found at: http://www.ntpep.org/Pages/RPM.aspx
AASHTO National Transportation Product Evaluation Program (NTPEP) www.ntpep.org
AASHTO NTPEP DataMine https://data.ntpep.org/
- Alabama procedure for evaluation of pavement markers
- Ohio SRPM supplemental spec
- West Virginia spec for RPMs