Medians are used to help define roadway use and to provide separation and guidance for motorists.  They can be raised via use of curbs or can be flat or near flat, using color and texture.  Flat medians are commonly used on our local area streets to provide bike traffic buffers, center turn lanes, and even crosswalk medians (see Santa Cruz Ave at N.Lemon ).

Our Santa Cruz/Alameda Safety task force members, met several times with the Menlo Park Fire District chief and he strongly supported the use of flat (or slightly raised) medians made of color and texture.  His experience is that raised medians, when struck by a vehicle, often cause that vehicle to lose control and either veer into oncoming traffic  or veer towards the bike lane and sidewalks, putting those people at risk. He points out that from an emergency response route perspective, flat medians are easier for emergency vehicles as they allow motorists to move out of the way and they allow  emergency vehicles to cross at speed.

He pointed out that, while firetrucks and other ER equipment can cross over raised medians, it incurs a cost in both response speed and to the equipment, as heavy equipment having to drive over raised medians and curbs often will cause damage to the vehicles.

Flush median with color-texture
Flush median with color-texture
Flush median and pavement treatments

There are several advantages for using flush medians:

  • Provide safer and faster emergency response without damage to ER vehicles
  • Maintenance costs are much lower
  • Pavement texture/coloring provide clear direction to motorists
  • Eliminate collision risks caused by raised medians – Eliminates property damage
  • Requires less construction structure

Issues with Raised Medians

FHWA guidance identifies raised medians as being used when traffic speeds are above 40 mph, roadway is over 75 ft. wide, and traffic volume is 20,000+/day. While our Alameda section near Liberty Park doesn’t meet that criteria, it doesn’t mean that raised medians aren’t used for roadways like ours, its just that they need to be properly used. 

One key point is that raised medians are NOT recommended on roadways where raised medians can’t easily be seen, nor where they are placed in the middle of a traffic lane causing motorists to veer with little notice.  One would assume a visibility requirement of at least 800’, not the few seconds as is planned at the Liberty Park intersection.

The medians designed for Liberty Park are hidden from view, both in the SB and NB directions, due to the crest of the hill on Alameda. This is even true under the best of lighting conditions like mid-day. Consider when the sun glare is blinding motorists, or when visibility is additionally limited by rain or nighttime conditions. The County design calls for medians to be placed in the middle of the expected traffic lane: They will cause accidents.  Property damage costs will be high — Cost of injury: Incalculable. 

For those that remember a few years ago, Santa Cruz, between Hill View school and downtown, had a nightmare implementation of raised medians that cause so many problems that they were immediately removed. 

A current local example of raised medians is on Junipero Serra between Stanford’s Campus Drive and Page Mill Road. While these sets of medians are visible from a great distance, the frequency of collisions with the medians remains high.

One benefit goal for the medians at this Junipero Serra location is that they separate cyclists from traffic. That is NOT the case for the planned medians at Liberty Park intersection with Alameda, where the medians force vehicles towards cyclists.


When a Car Hits a Median

When a car strikes a median in the roadway, it can cause the vehicle to lose control due to several factors.

Firstly, the impact with the median can cause the wheels of the vehicle to lose traction with the road surface, especially if the median is made of a rigid material such as concrete. This loss of traction can cause the vehicle to slide or spin out of control, making it difficult for the driver to maintain control of the vehicle.

Secondly, the impact with the median can cause the vehicle to change direction suddenly, which can catch the driver off guard and cause them to overcorrect their steering or braking. This can also cause the vehicle to lose control and potentially collide with other vehicles, cyclists, or pedestrians using the roadway.

Additionally, the force of the impact with the median can cause damage to the vehicle’s suspension, steering, or tires, which can further impact the vehicle’s ability to maintain control on the road.

Finally, the psychological impact of a collision with a median can also play a role in causing the driver to lose control. A sudden and unexpected collision can cause the driver to panic or become disoriented, making it difficult for them to make quick and effective decisions to regain control of the vehicle.

Overall, when a car strikes a median in the roadway, it can cause a variety of factors to come into play that can impact the vehicle’s ability to maintain control. Drivers should be aware of the potential hazards associated with medians and take precautions to avoid collisions, such as staying alert, following posted speed limits, and avoiding distractions while driving.

Common Accidents with Medians

The most common type of accident involving raised medians is a sideswipe collision, which occurs when one vehicle drifts into the adjacent lane and strikes another vehicle traveling parallel to it. These types of accidents can be caused by driver distraction, fatigue, or impairment, as well as poor road conditions or road design.

Another type of accident involving raised medians is a rear-end collision, which can occur when a driver suddenly slows down or stops to avoid hitting an object in the road or a vehicle that has stopped in front of them. The median forms a channel where the only direction is forward. This can be particularly dangerous for cyclists that might be riding in parallel and they also get tangled in the accident.

Updated April 2023,

One thought on “Medians: Flush vs Raised”
  1. Ok, some sense there, but one does have to ask, what sort of drivers are we allowing on our roads that can’t see those raised medians and keep hitting them. I could argue that this makes it safer to be a crappy driver. Wouldn’t it be better up upgrade everyone’s driving skills?

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