Enhanced Delineation 

for Horizontal Curves

Enhanced delineation at horizontal curves includes a variety of potential 

strategies that can be implemented in advance of or within curves, in 

combination, or individually.

Potential Strategies In Advance of Curve Within Curve

Pavement markings (standard width 

or wider) 

In-lane curve warning pavement markings 

Retroreflective strips on sign posts

Delineators

Chevron signs

Enhanced Conspicuity (larger, fluorescent, 

and/or retroreflective signs)

Dynamic curve warning signs 

(including speed radar feedback signs)

Sequential dynamic chevrons

Enhanced delineation treatments 

can alert drivers to upcoming curves, 

the direction and sharpness of the 

curve, and appropriate operating 

speed. 

Agencies can take the following 

steps to implement enhanced 

delineation strategies:

1. Review signing practices and

policies to ensure they comply

with the Manual on Uniform

Traffic Control Devices (MUTCD)

principles of traffic control devices.

Consistent practice for similar

curves sets the appropriate driver

expectancy.

2. Use the systemic approach to

identify and treat problem curves.

For example, Minnesota uses risk

factors that include curve radii

between 500 and 1,200 ft, traffic

volumes between 500 and 1,000

vehicles per day, intersection in

the curve, and presence of a

visual trap.1

3. Match the appropriate strategy

to the identified problem(s),

considering the full range of

enhanced delineation treatments.

Once the MUTCD requirements and

recommendations have been met,

an incremental approach is often

beneficial to avoid excessive cost.

FHWA-SA-21-035

Chevron signs with retroreflective strips on sign 

posts installed along a curve. Source: FHWA

Safety Benefits:

Chevron Signs

25% reduction in nighttime

crashes.1

16% reduction in

non-intersection fatal and 

injury crashes.2

Oversized Chevron Signs

15% reduction in fatal and

injury crashes.3

Sequential Dynamic Chevrons

60% reduction in fatal and

injury crashes.4

In-Lane Curve Warning 

Pavement Markings

35 - 38% reduction in

all crashes.5

New Fluorescent Curve Signs 

or Upgrade Existing Curve 

Signs to Fluorescent Sheeting

18% reduction in nonintersection, head-on, 

run-off-road, and sideswipe 

in rural areas.1

1 (CMF ID: 2439,2431,2432) Albin et al. Low-Cost Treatments for Horizontal Curve Safety 2016. FHWA-SA-15-084, (2016).

2 (CMF ID: 2438) Srinivasan et al. Safety Evaluation of Improved Curve Delineation. FHWA-HRT-09-045, (2009).

3 (CMF ID: 8978) Lyon et al. Safety Evaluation of Two Curve Warning Treatments: In-Lane Curve Warning 

Pavement Markings and Oversized Chevron Signs. Presented at the 96th TRB Annual 

Meeting, Paper No. 17-00432, (2017). 

4 (CMF ID: 10362) Hallmark, S. Evaluation of Sequential Dynamic Chevrons on Rural Two-lane 

Highways. FHWA, (2017).

5 (CMF ID: 10312,9167) Donnell et al. Reducing Roadway Departure Crashes at Horizontal 

Curve Sections on Two-lane Rural Highways. FHWA-SA-19-005, (2019).

OFFICE OF SAFETY

Proven Safety 

Countermeasures

For more information on this 

and other FHWA Proven Safety 

Countermeasures, please visit 

https://highways.dot.gov/

safety/proven-safety-counter 

measures and https://high 

ways.dot.gov/safety/rwd/

keep-vehicles-road/horizon 

tal-curve-safety.