Medians (access management)

Using medians to support safety and local businesses

When installed as part of a toolkit of street design elements, medians can improve safety and support nearby businesses. Portland crash data indicate that multilane streets with medians experience crash rates that are 40 percent lower relative to similar streets lacking medians.* National data mirror these local safety benefits, and also indicate that businesses do as well or better following median installation.

Example street: No median	Example street: Median with other safety tools

Safety impact: Medians make streets safer for all people

A median is a barrier between opposing lanes of auto traffic (see illustration above). Gaps in the median allow people to drive onto and off of a street and to make U-turns. Engineers refer to medians as "access management," which also includes driveway design and placement.

Streets featuring medians in Portland include large segments of SW Macadam Ave., NE Martin Luther King Jr. Blvd. and SE Powell Blvd.

Street segments with medians in Portland experience significantly lower crash rates relative to similar streets lacking medians. As Figures 1 and 2 show, the rate of deadly and serious injury crashes is 38 percent lower on Portland street segments with medians, while the overall crash rate is 40 percent lower.

Portland’s experience with medians is backed by national findings. The Federal Highway Administration notes that medians may reduce crashes involving people walking by 46 percent and those involving people driving by 39 percent.

The FHWA explains the crash reduction effect of medians by pointing to the following impacts:

• Reduce conflict points for people driving by helping people make turns safely
• Provide people walking with a safe place to stop at the midpoint of a street before crossing the remaining distance
• Enhance visibility of crosswalks, particularly at unsignalized crosswalks
• Can support safe driving speeds approaching crosswalks
• Provide space for safety signage

In addition to enhancing safety, medians can make streets more attractive by providing a place to plant trees or other vegetation. While visibility can be a concern when adding vegetation, a Washington Department of Transportation study of 13 major urban arterials found that the presence of small trees in medians had no significant effect on crash rates.

Economic results: Generally positive experiences from business owners & customers

Studies have found that medians generally have neutral to positive economic effects on local businesses (see Table 1). 

The Federal Highway Administration has found the following effects based on before-and-after studies of medians from across the country:

• Higher sales: The “vast majority of businesses do as well or better” after medians are installed.
• Positive driving experience: Business customers report that their drive became “quicker, easier, and safer.”
• Easy U-turns: “A majority of drivers have no problem making U-turns at median openings to get to businesses on the opposite side of the road.”
• Continued deliveries: “Truck deliveries may be inconvenienced, at worst, but may in fact benefit from improved opportunities resulting from a change in access.”

An Oregon Department of Transportation report summarized a number of studies examining the economic impact of medians. Among the findings:

• Ivey, Harris and Walls Inc. (1995) surveyed business operators following construction of medians, and found that more than half of the business owners reported no change or an increase in their sales after the median construction.
• Frawley and Eisele (1998) found that between 16 and 22 percent of business owners believed that their gross sales decreased following median construction. Eisele and Frawley (1999) later determined that those same corridors actually experienced an 18 percent increase in property values following median construction.
• Stover & Koepke (2000) found that 68 percent of business owners who participated in a survey reported little or no economic impact to their businesses following median construction, although 27 percent reported some type of loss following the closure of select median openings.

Research indicates that the economic effects of medians vary but are largely positive. For example, one study found that gas stations and auto-repair shops experienced slight declines in gross sales, but concluded that “in almost all cases, employment increased in businesses surveyed” following installation of a raised median (Frawley, W.E. and W.L. Eisele (2000).