Improving Safety and Reducing Crashes
The Federal Highway Administration (FHWA) encourages the addition of medians and refuge islands, due to the increase in safety for pedestrians and motor vehicles.
Benefits
30%
Head-on crash rate for divided highways was 30% of the rate on undivided highways
24%
Intersection crash rate was 24% of the rate on undivided highways
42%
Total crash rates on divided highways were 42% less than on undivided highways
24,000
On roads with traffic > 24,000 VPD, reducing unrestricted left turns is key to reducing crashes
78%
Improved lighting at pedestrian crossing locations has shown to reduce nighttime pedestrian fatalities at crossings by 78%
What are Medians?
A portion of the roadway that separates opposing streams of traffic. Medians convert a “two- way” movement into two “one-way” movements. There are three types of medians: Raised, Flush and Depressed. Median types are selected based on criteria.
Raised Median
Raised medians manages access and improves safety. Also, provides pedestrian refuge.
Criteria
- Arterials with traffic volume of > 18,000 and future volume projected at > 24,000 vehicles per day
- High turning volumes
- High crash rates
- Number of driveways
- Pedestrian crossings
Benefits
Raised medians concentrate left turn movements and provide the following benefits.
- Reduce motor vehicle crashes by 15%
- Decrease delays (>30%) for motorists
- Increase roadway capacity (>30%)
- Reduce vehicle speeds on the roadway
- Provide space for landscaping within the right-of-way
Flush Median
Flush medians use “two-way left-turn lane” (TWLTL) in urban /suburban areas.
Criteria
- Design speeds of 45 mph or less
- Current traffic volume of < 18,000 and future traffic volume projected at < 24,000 vehicles per day
Research Data
- Capacity increased by 30%
- Delay decreased by 30%
- Total crashes were reduced 35%
Depressed Median
Depressed grass medians allow higher speeds on state “through” routes.
Criteria
- Typically rural setting
- Higher speeds, with greater recovery area
- Most effective for reducing crashes
Benefits
- Provide greater safety at high speeds
- Provide a larger recovery zone
- Reduce crashes and improve survival rates
- Provide landscaping opportunities
Pedestrian Safety
Rates for vehicle crashes involving pedestrians on urban arterials are 5 times higher on undivided roads than on roadways with medians. Pedestrian-vehicle crash rates were higher at mid-block on undivided highways than at mid-block in raised median sections.
Raised Medians
- Provide pedestrians refuge from traffic
- Allow safer crossings in areas of pedestrian activity
- Protect pedestrians by minimizing vehicle left turn movements