Retroreflective lane markings and raised pavement markers: guiding drivers at night
How lane lines and markers stay bright at night, in rain and after snow plowing
Safety Behind the Wheel Foundation built this guide from Federal Highway Administration (FHWA) research and guidance, the Manual on Uniform Traffic Control Devices, Insurance Institute for Highway Safety (IIHS) data, federal regulations and published studies. Every source is listed at the end.
Why lane lines matter after dark
IIHS says about half of U.S. traffic deaths happen in the dark or at dawn or dusk [6]. Rural roads add to the risk. In 2024, 41% of crash deaths happened in rural areas [7]. Per 100 million miles driven, the death rate was 1.56 in rural areas and 1.01 in urban areas [7].
Many of these collisions start when a vehicle leaves its lane. FHWA calls it a roadway departure crash when a vehicle crosses an edge line or center line, or otherwise leaves the traveled way [8]. From 2016 to 2018, roadway departures caused an average of 19,158 deaths a year, or 51% of all traffic deaths in the country [8].
On an unlit road, the painted line is often the main guide. A line cannot stop a vehicle. It can give early, low cost information that helps a tired or distracted driver correct sooner.
This article covers lines and markers that run along the road. Rumble strips, curve chevrons, lighting and crosswalk markings have their own guides. For other fixes on your street, see Safer road design. For driver habits after dark, see Night driving safety.
How a marking sends light back
A marking works at night because it is retroreflective. That means it returns light toward its source. Headlight beams strike the line and bounce back toward the driver’s eyes [1].
Most lines get this effect from tiny glass beads. Crews set the beads in a binder, which is the paint, plastic or other material that holds them. The beads must stay partly exposed to work [1]. FHWA says a marking loses brightness faster than it disappears. Traffic, debris and especially snow plowing can scuff or knock out beads. The line is still there, but it returns far less light [1].
Brightness is measured in millicandelas per square meter per lux, written mcd/m²/lx. A higher number means a brighter line [1].
The Manual on Uniform Traffic Control Devices (MUTCD) is the national rulebook for signs, signals and markings. Markings that must be seen at night shall be retroreflective, unless street or highway lighting makes them clearly visible [4]. The manual also sets minimums. On roads with speed limits of 35 mph or more, agencies must use a method designed to keep longitudinal markings at or above 50 mcd/m²/lx in dry conditions. A longitudinal marking runs the same way as traffic, such as a lane line, edge line or centerline. At 70 mph or more, a 100 mcd/m²/lx method should be used [4].
FHWA added these provisions in a rule published August 5, 2022, and effective September 6, 2022. The 11th Edition places them in Section 3A.05 [9]. FHWA’s guide says the minimum levels match the night vision needs of a 62 year old driver [1].
Wider edge lines
An edge line is the solid line along the side of the road. White marks the right edge. Yellow marks the left edge of a divided highway or one way road [4]. The manual requires edge lines on freeways, expressways and rural arterials that are at least 20 feet wide and carry 6,000 or more vehicles a day [4]. A rural arterial is a major through road outside town.
A normal line in the manual is 4 to 6 inches wide [4]. FHWA calls an edge line wider when it grows from 4 inches to 6 inches [2]. The manual says this change can help on all road types [4].
FHWA lists wider edge lines as a proven safety countermeasure. It reports 37% fewer non intersection fatal and injury collisions on rural two lane roads [2]. It reports 22% fewer fatal and injury collisions on rural freeways [2]. For fatal and serious injury crashes on rural two lane roads, it gives a benefit cost ratio of 25 to 1, or about $25 in crash savings for each $1 spent [2]. Results vary, as the table shows.
Comparison compiled by Safety Behind the Wheel Foundation
Wider edge line results by road type
| Road type | What research found |
|---|---|
| Rural two lane roads | 37% fewer non intersection fatal and injury collisions [2] |
| Rural freeways | 22% fewer fatal and injury collisions [2] |
| Rural two lane roads, state studies of all crashes | 6% to 16% fewer collisions in Illinois, Kansas and Michigan analyses [10] |
| Multilane divided highways | No significant safety gain found in a 2015 review [3] |
Why would more paint help? Part of the answer is detection. A 2001 study found that 6 inch lines were seen from farther away than 4 inch lines at night in dry conditions, for older and younger drivers alike [3]. A driving simulator study found that wider lines changed lane position at night but not by day. As an edge line wore away, drivers moved farther from the centerline, closer to the shoulder [11].
Cost is low. FHWA says crews can use existing equipment during restriping and resurfacing, and the only added cost is material [2]. Still, a wide line that has lost its beads is a dim line.
Raised pavement markers
A raised pavement marker, or RPM, is a small device fixed to the road surface. Most have a reflective lens that faces approaching drivers. Research papers call these RRPMs. Some markers contain their own light, which must stay steady and not flash [4].
The manual sets plain rules for how markers are used [4]:
- Their color must match the line they support, by day and by night.
- Their spacing should follow the dash and gap pattern of the broken line.
- They may add to a line or, in some cases, take its place.
- A plain, nonreflective marker cannot replace a line on its own. Reflective or lit markers must be added.
- Right hand edge lines should not get markers, or be replaced by them, unless an engineering study shows the gains outweigh the effect on bicyclists.
An engineering study is a review by a qualified engineer of the road, its traffic and its collisions.
Where do markers shine? On wet nights. FHWA’s 2015 research review says wet pavement at night can strip a traditional marking of most or all of its reflective power. It names markers as the long standing answer for wet night visibility [3].
The crash record is less clear. An NCHRP report found that putting markers on two lane roads without picking sites made no significant difference in total or nighttime collisions. On four lane freeways, markers did not help or hurt those crash counts [3]. That points to selective use, such as places with a history of wet night lane departures.
There are two cautions. First, markers can be much brighter than the painted line, which makes the line hard to judge in a night inspection [1]. Second, markers are bumps. That is one reason the manual treats right hand edge lines with care. It also asks agencies to consider marking materials that limit tripping and loss of traction for pedestrians, bicyclists and motorcyclists [4]. Riders can learn more in Motorcycle riding in rain, wind, cold and darkness.
Rain and wet nights
Rain can hide a problem that a dry check will not show. FHWA’s review finds that a line almost always returns more light when dry than when wet. It also says wet performance cannot be predicted from dry readings [3]. The MUTCD minimums apply only to dry conditions [1]. A line can pass the dry check and still fade out on a wet night.
Some products are made to return more light when the road is wet. FHWA studied wet reflective markings, applied as paint, tape or thermoplastic, in Minnesota, North Carolina and Wisconsin [12]. On multilane roads, it estimated 30.4% fewer nighttime collisions and 24.9% fewer wet road crashes [12]. On freeways, it estimated 12% fewer injury collisions and 14% fewer wet road crashes [12]. The two lane sample was too small to show an effect [12]. A separate before and after study in one Texas district also found positive safety effects [13].
The 2015 review adds that wet night markings do not replace markers in visibility or in cost per mile [3].
Snow, plows and choosing materials
Snow country adds a hard test. FHWA names snowplowing as a major cause of lost brightness [1]. The MUTCD admits that snow maintenance can push brightness below the minimum. It says an agency still meets the rule if it takes a reasonable course of action to resume maintenance [4].
In one study FHWA’s review describes, the six sections still above 100 mcd/m²/lx after one winter were all grooved. The review says setting a marking in a groove can shield it from plows [3].
The federal wider line study reports non winter results. It ties that choice to the effect of snow removal on marking visibility and durability [10].
Markers face the same plows. FHWA’s review notes that its marker cost figures assumed surface applied markers, which are mostly used where there is little or no plowing [3]. Where plows run, ask whether a marker is made for plowing and whether it sits in a cut in the pavement.
No single material wins everywhere. FHWA’s 2022 guide lists these service life ranges [1].
Comparison compiled by Safety Behind the Wheel Foundation
Service life ranges for marking materials
The ranges are wide because traffic, climate, pavement type and plowing all change how long a marking lasts. The 2015 review favors performance based specifications, which set the result a marking must deliver instead of naming a material [3]. Safety Behind the Wheel Foundation supports that approach.
Who chooses, buys and installs them
The MUTCD is the national standard for traffic control devices on any street, highway or bicycle trail open to public travel. States must adopt changes within two years of a final rule’s effective date [5]. The rule’s definition of “open to public travel” reaches some privately owned places the public can use, such as shopping centers and airports [5].
The road owner makes the choices. That may be a state agency, county, city, campus or private company. Staff or a traffic engineering firm study the road, pick the lines and markers, and write the specifications. An approved installation contractor applies them. Infrastructure suppliers provide the beads, paints, tapes and markers.
Public traffic control devices must be selected, designed and installed by authorized agencies. Residents and neighborhood groups should never paint lines or glue markers onto a public road. Send a request to the owner instead.
Private owners, such as campuses, may not be covered if the public cannot travel there. Many still follow the manual, because drivers expect familiar colors and patterns.
How agencies keep markings bright
The manual says the upkeep method should be one or more of those in FHWA’s 2022 guide, or one built from an engineering study [4]. The guide describes five methods [1].
Comparison compiled by Safety Behind the Wheel Foundation
Five ways agencies keep markings bright
| Method | In plain words |
|---|---|
| Measured retroreflectivity | Crews measure brightness with an instrument [1] |
| Nighttime visual inspection | A trained inspector aged 60 or older checks the lines from a vehicle after dark [1] |
| Inspection with reference markings | The inspector compares lines on the road with calibrated samples [1] |
| Service life from past records | Crews restripe on a schedule built from documented history [1] |
| Service life from monitored sections | The agency tracks sample sections and times work for similar roads [1] |
In a night inspection, the inspector asks one question. Can an older driver see the lines far enough ahead to make good decisions [1]? The guide says inspection frequency, such as once or twice a year, is part of the method [1].
Common mistakes weaken a marking program:
What drivers and residents can do
Slow down when lines fade, in rain and in snow. Look farther ahead and leave extra space.
Do not count on lane keeping technology to fill the gap. IIHS says these systems read lane lines or the pavement edge, and that can be a problem on poorly marked or snow covered roads. The same page credits them with lower rates of several police reported crash types, including head on and sideswipe collisions [14].
Residents can help owners find problems:
- Note the road name, the nearest cross street or mile marker, and your direction of travel.
- Write what you saw, such as a missing edge line on a curve or dim lines in rain.
- Find the owner. State routes belong to the state, and FHWA keeps a directory of state transportation websites [15]. County and city roads belong to those governments.
- Send the report through the agency’s online form or phone line. Have a passenger take photos. Never stop in a travel lane.
- Ask when the next striping is planned.
Frequently asked questions
What does retroreflective mean?
It means a surface sends light back toward its source. A retroreflective lane line returns headlight beams to the driver’s eyes, usually with small glass beads set in paint or plastic. If beads wear away, a line may look normal by day and still be dim at night [1].
Are wider edge lines worth the cost?
On rural two lane roads, FHWA reports a 25 to 1 benefit cost ratio for fatal and serious injury crashes [2]. Crews can widen lines during restriping, and the main added cost is material [2]. The gain is not proven on multilane divided highways [3]. An owner should check its own crash history first.
Do raised markers replace painted lines?
Sometimes, with limits. The manual lets reflective or lit markers add to a line or take its place, but plain markers cannot do this alone [4]. Right hand edge lines need an engineering study first [4]. Crash results on two lane roads are mixed [3].
Why do lane lines seem to vanish in the rain?
On wet nights, a traditional marking can lose most or all of its ability to return light. Dry readings do not predict wet results [3]. Slow down and leave extra space. If one stretch is always bad, report it to the road owner.
Can my neighborhood paint lines or place markers on a public road?
No. The national standard covers traffic control devices on public roads [5]. Road owners choose and install them, or hire approved contractors. Homemade lines can confuse drivers, so send your request to the owner. The agency can study the site and add the right marking.
Will lane keeping technology work on faded lines?
It may not. IIHS says these systems read lane lines or the pavement edge, and that can be a problem on poorly marked or snow covered roads [14]. Treat the system as a backup, not a guide. Keep your own eyes on the lane and slow down when markings are poor.
The bottom line
Recommendation from Safety Behind the Wheel Foundation
Safety Behind the Wheel Foundation encourages drivers to slow down when lines fade and to report weak stretches to the road owner. Lane lines and raised markers are low cost tools that guide drivers when it is dark or wet. They work only while they stay bright. Good programs pick materials that fit local traffic and plowing, inspect lines on a schedule, and fix weak stretches fast.
You cannot fix a public road yourself. You can slow down when lines fade, report weak stretches and ask the questions in this guide.
Related articles
- Safer road design: a field guide to the safety fixes on your street
- Night driving safety: how to see hazards and stop in time after dark
- Roadway departure safety: curves, drop offs and how to recover safely
- Rural road safety: why country roads are deadlier and how to drive them
- Motorcycle riding in rain, wind, cold and darkness: stay in control
Sources and further reading
- 1Federal Highway Administration (FHWA). Methods for Maintaining Pavement Marking Retroreflectivity (FHWA-SA-22-028). Published July 2022. highways.dot.gov/media/20751
- 2Federal Highway Administration (FHWA). Wider Edge Lines. Proven Safety Countermeasures. Reviewed October 2026 (no update date shown). highways.dot.gov/…/wider-edge-lines
- 3Federal Highway Administration (FHWA). Synthesis of Pavement Marking Research (FHWA-SA-15-063). Published June 2015. highways.dot.gov/…/pvmnt_mrkg_synth.pdf
- 4Federal Highway Administration (FHWA). Manual on Uniform Traffic Control Devices, 11th Edition, Part 3: Markings and Other Delineation. Published December 2023. mutcd.fhwa.dot.gov/pdfs/11th_Edition/part3.pdf
- 5Electronic Code of Federal Regulations (eCFR). 23 CFR 655.603 Standards. Current as of October 2, 2026. ecfr.gov/current/title-23/section-655.603
- 6Insurance Institute for Highway Safety (IIHS). Headlights. Updated July 2026. iihs.org/research-areas/headlights
- 7Insurance Institute for Highway Safety (IIHS). Fatality Facts 2024: Urban/rural comparison. Posted June 2026. Data year: 2024. iihs.org/…/urban-rural-comparison
- 8Federal Highway Administration (FHWA). Roadway Departure Safety. Updated August 25, 2023. Data year: 2016 to 2018. highways.dot.gov/safety/roadway-departure-safety
- 9Federal Highway Administration (FHWA). Pavement Markings Regulations / Standards. Updated February 15, 2024. highways.dot.gov/…/pavement-markings-regulations-standards
- 10Carlson P, Park ES, Pike A, et al. Pavement Marking Demonstration Projects: State of Alaska and State of Tennessee (FHWA-HRT-12-048). Federal Highway Administration, November 2013. Data year: varies by state analysis (Michigan 2001-2009 among them). fhwa.dot.gov/…/12048.pdf
- 11Chang K, Ramirez MV, Dyre B, Mohamed M, Abdel-Rahim A. Effects of longitudinal pavement edgeline condition on driver lane deviation. Accident Analysis & Prevention, 2019;128:87-93. PubMed record. pubmed.ncbi.nlm.nih.gov/30991291
- 12Federal Highway Administration (FHWA). Safety Evaluation of Wet-Reflective Pavement Markings (FHWA-HRT-15-065). Published September 2015. Data year: not stated on the report page (Minnesota, North Carolina and Wisconsin crash data). fhwa.dot.gov/…/index.cfm
- 13Park ES, Carlson PJ, Pike A. Safety effects of wet-weather pavement markings. Accident Analysis & Prevention, 2019;133:105271. PubMed record. Data year: not stated in the abstract (Texas DOT Atlanta District crash data). pubmed.ncbi.nlm.nih.gov/31586823
- 14Insurance Institute for Highway Safety (IIHS) and Highway Loss Data Institute. Advanced driver assistance. Updated September 2026. iihs.org/topics/advanced-driver-assistance
- 15Federal Highway Administration (FHWA). State Transportation Web Sites. Updated February 5, 2024. fhwa.dot.gov/about/webstate.cfm
This article reflects the safety priorities of safer road design and clear lane guidance at night and in bad weather. It is general education, not legal or engineering advice, and it does not replace the plans, standards or engineering judgment for a specific road. Rules change, so verify details with official sources. For your own situation, contact your state, county or city road agency or an approved marking contractor. Reviewed October 2026.
Cite this article: Safety Behind the Wheel Foundation. “Retroreflective lane markings and raised pavement markers: guiding drivers at night.” drivewithcare.org, https://drivewithcare.org/retroreflective-lane-markings-raised-pavement-markers/. Reviewed October 2026.
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