Do Medians Actually Make Streets Safer for Pedestrians?

The median on Martin Luther King Jr. Boulevard in Stapleton has pedestrian crossings, but it's still a fundamentally dangerous, car-oriented street. Image: Google Maps
The median on Martin Luther King Jr. Boulevard in Stapleton has pedestrian crossings, but it's still a fundamentally dangerous, car-oriented street. Image: Google Maps

Some transportation engineers believe that raised medians — concrete strips dividing one side of a street from the other — are all you need to make a street safe for walking. But data from Denver Public Works shows it’s not that simple.

While medians can help, they’re no substitute for other aspects of safe street design, like lane widths that reduce speeding and crossing distances that aren’t too long for vulnerable pedestrians. Drivers still hit, injure, and kill people walking at locations with medians.

Take the project to widen Federal Boulevard between 5th Avenue and Howard Place. The Colorado Department of Transportation and DPW will add a sixth driving lane and widen the existing lanes on this stretch of Federal. Both changes will lead to more speeding on what’s already the deadliest street in the city.

But CDOT and DPW claim people on foot will benefit, despite the increase in speeding and longer crossing distances, thanks to medians. The idea is that people will use them as refuges halfway across the street, and drivers will have to turn more carefully to avoid going over them.

The data on medians in DPW’s Pedestrian Crash Analysis indicates that the safety benefit of existing medians on Colfax Avenue, Colorado Boulevard, and Federal may be real, but is definitely limited.

All three streets double as state highways. On each street, some stretches have medians and others do not. Eight of the 24 pedestrians killed on these streets between 2011 and 2015 lost their lives at locations with medians. Drivers hit pedestrians 43 times at the most common crash sites on Colorado, according to DPW’s analysis. A median was present each time.

As you can see in this diagram, the median did not guarantee pedestrian safety — quite the opposite:

Crashes on Colorado w: media presence and speed limit
The dots represent drivers hitting people walking, with black dots signifying a pedestrian fatality. Image: DPW

It’s important to distinguish between different types of medians, says Wes Marshall, a civil engineering professor at the University of Colorado Denver.

“I have mixed feelings,” he said. “Some [medians] are good and useful — such as when they provide a curb-cut and pedestrian refuge, which is especially important for mid-block crossings. Some are bad and create mini-highways — and without a curb cut, they can make for barriers — especially for bikes.”

Monaco Parkway is one example where the median makes the street a “mini-highway.” Here, the median is like a highway divider that induces higher driving speeds by eliminating “friction” between on-coming vehicles. Drivers can just step on the gas without a care.

The median also creates another barrier for pedestrians at some intersections, where traffic engineers have determined that people on foot don’t merit an official crossing:

Image: Google Maps
Image: Google Maps

One way to make medians more pedestrian-friendly, Marshall says, is to add crossings, like on Martin Luther King Jr. Boulevard in Stapleton (shown at the top of this post). Still, it’s a superficial improvement. The street is primarily designed to move cars at high speeds.

Marshall is a fan of Octavia Boulevard, an arterial street in San Francisco where trees and medians — three of them — slim down the roadway. The posted speed limit is 25 mph:

Image: Google Maps
Image: Google Maps

There’s a difference between accommodating pedestrians and prioritizing them. Medians can be part of a street engineering strategy that puts safe walking front and center, or they can be half-measures that merely mitigate an inherently dangerous design.

  • TakeFive

    With respect to Monaco Pkwy you must be driving it late at night or very early in the morning. I can’t recall Monaco being the least bit of a speedway unless I go back 25 years. Love those trees though.

  • Vooch

    Agreed 1000% with this article – medians are bad news. Much safer to widen sidewalks and narrow the roadbed.

    • Bernard Finucane

      Also wide medians and other “parkway” features tend to be wasted space, They may be green, but people are less likely to congregate there than in green spaces adjacent to human amenities.

      • Vooch

        good point – and space is scarce

  • Too bad we can’t go back and redesign much of Denver as early city planners here never envisioned the urban area growing to its current size. Medians work great in cities that have enough design width to put them in.

    Take Detroit for-instance, where city planners there in the 1800s planned boulevards of 180-foot right-of-way width, which is enough room for 8 lanes of traffic, 40-foot medians, and still have 12-feet of treelawn before reaching the sidewalk.

    So the design was a little wasteful on space until the urban area got to be 3 million people back in the 1950s. Such high speed boulevards facilitated rapid urban growth. Too bad that unfair free trade cost them half their middle-class jobs. Who would have known?

    Imagine an 8-lane boulevard with a 55 mph speed limit and computer-controlled stoplights designed to maximize traffic flow all the way to downtown Longmont from downtown Denver, or to Castle Rock from downtown, and yet only 44 feet of roadway to cross curb-to-curb to reach safety?

    That is what Woodward Ave is like from Detroit to Pontiac 28 miles away. Here in Denver we begrudgingly give up an extra inch on roads designed for a city with a population of 1/6th our current population, while forecast population growth through 2040 will make our city bigger than Metro-Detroit.

    Either we will have to build wider roads, greatly increase public transit capacity, or cut down on commuting. The Northeast Corridor has 4 train tracks side-by-side so that express trains can run up to 150 mph while local trains stop at every station, but with RTD flat broke until 2042 I don’t see that happening here.

    I don’t see DRCOG’s traffic demand forecasts as being too far off either, though I have plenty of experience living and working in urban areas much-larger than Metro-Denver too. About the only way to cut traffic much is to work away from commuting toward a design like Howard’s Garden Cities design where most people stay local to their own urban center rather than commuting long distance by car as is so common here, where 70% of all commuting is by car and doesn’t involve the central city.

    So figure 220,000 to 240,000 vehicles per-day on I-70 east of the Mousetrap plus another 60-70% of that on I-270 east of I-25 too. Back in 1975 the intersection of Woodward and Eight Mile Rd, two Detroit surface boulevards, carried 240,000 vehicles daily, when Metro Detroit was just 4 million people, with a lot of the traffic on Eight Mile Rd heavy truck traffic due to multiple large factories east and west of there.

    Why was MLK designed to move some traffic? Because Stapleton Airport used to be at the one end east of Quebec. Remember that California and Stout were once designed to move lots of airport traffic too. Still, now that the city has replaced Stapleton airport with a large urban neighborhood MLK still must move a fair amount of traffic.

    I say only a fair amount because MLK isn’t as wide as major boulevards in real big cities are. Roosevelt Blvd in Philadelphia is 12 lanes, 6 local and 6 express, the same number of lanes that the Jeffries Freeway in Detroit has. The Dan Ryan has 14 lanes. The Kennedy only has 12 lanes between downtown and the Edens cut-off, plus the Blue Line runs alongside the Kennedy and the Red Line in the median on the Ryan too.

    If Denver wants to be a big city it is going to have to make some big city design moves or DRCOG’s 2040 Fiscally-Constrained forecast will be realized and we will see a more than doubling of severe congestion, which won’t help some businesses dependent on commuting and/or freight access stay in the city.

    We have to add travel lanes, widen roads, perhaps add medians as pedestrian refuges as I have already proposed 2 years ago on Colorado, we have to finish the two unfinished FasTracks lines, add express trackage, as well as at-least a couple more lines to unserved parts of the Metro Area, we may as well consider downtown subways and/or elevated trains or bike lanes, and we still have to improve bike access and access for the transit-dependent if average bottom 90% income is going to remain as low as it is too.

    Slowing traffic down is the last thing we need to do as that will just drive-up living costs and likely result in businesses dependent on employee commuting and/or timely freight access possibly leaving the city. Already central-city Denver has much-higher living costs than most suburbs. How much higher can the cost of living in the central city go especially if the next generation doesn’t have enough income to move to the city?

  • Bernard Finucane

    Short crossings make pedestrians safer. It’s not that complicated.