Thursday, April 22, 2010

Pocket bike lane (between thru lane and RT lane), Galileo Way SB approaching Main St., Cambridge

Submitted By: Liana Afuni

Galilei Way is a multilane, median-separated roadway that intersects with Main Street, in the city of Cambridge, MA . Both these streets are strategic because not only do they serve the Massachusetts Institute of Technology (M.I.T) area, but also they are in close proximity to the “Mass Ave” bridge, which carries Massachusetts Avenue, from Back Bay, Boston to Cambridge, MA, and is the longest bridge over the Charles River.

Locus of Area

On the southbound approach of Galileo way, the bicycle lane is located alongside the curb until it nears the intersection at Main Street, for which a traffic calming measure is implemented.  In order to maintain safety for bicyclists, consideration needs to be taken in regards to vehicular right turns being allowed off of Galileo Way. There needs to be a transition from the thru lane in order to allow right-turning vehicles to merge. Since there is adequate curb to curb width, the bicycle lane is dotted approximately 20 ft from the stopline, The key is for the dotted stripping not to occur too far back from the stop line, because then vehicles would have enough room to accelerate at high speeds within the right turning lane, which could compromise the safety of the cyclists. This approach results in a “pocketed” bicycle lane, in between two travel lanes.

 Galilei Southbound Approach

One would argue that the merging stage would be unsafe for the bicyclists since vehicles have to maneuver into the right turn lane. But the question is, who has the right of way? After having researched online, an anonymous blogger, who is clearly a cyclist expressed that, “I tend to give the car the right of way because I assume everyone in a car wants to kill me.” In this particular case, the right of way is not unambiguous, because the blue paint delineates the separation. However, I would recommend that the right of way be clarified further at this intersection by perhaps a warning sign, placed a couple of feet ahead of the dotted lines, that gives the right of way to the cyclists. According to AASHTO, a recommended configuration for bike lanes with right turning traffic is identical to that located at Galilei Street. 

To further ensure the safety of the cyclists at the merge intersection, blue paint is used to illuminate the merging right turn lane. This color treatment has been used for a "test trial" in only two cities in the U.S, Cambridge and Portland. Galilei happens to be one of the streets that utilizes a change in pavement coloring. This kind of treatment helps in establishing a right of way for cyclists in such cases. The results of the added blue paint in several cities have reached such conclusions as:

  • Significantly more motorists yielded to bicyclists and slowed or stopped before entering the blue pavement area;
  • More bicyclists followed the colored bike lane path.
  • Fewer bicyclists turned their heads to scan for traffic or used hand signals, perhaps signifying an increased comfort level or lower level of caution.

The benefit of having a bicycle lane “pocketed” in between a thru and right turning lane, is this prevents the “right hook” problem that cyclists can face. The right hook occurs when a car passes a cyclist and then tries to make a right turn directly in front of or into the cyclist. Vehicles don’t assume that cyclists are going very fast, so it never occurs to them that they can pass the cyclist in time. However, with the right turning lane being placed by the curb, and a prior merge dotting, vehicles will no longer turn in front of the bicyclist, which eliminates this collision.

Demonstrating a "Right Hook"

Another important factor of a bicycle lane, especially if pocketed, would be the width of the lane. The striped off pocketed lane is approximately 6 ft, which is enough space for a cyclist to ride comfortably. Furthermore, since the curb is brought back in closer to the landscape medians, there is more than enough space to fit in a right thru lane without compromising the widths of the remaining travel lanes and bicycle lane. So although the cyclist will be in between traffic, it is not for a long portion of the trip, neither is the cyclist lane jeopardizing the safety of the rider.

In essence, "a pocketed bike lane" is the perfect traffic calming measure for both cyclists and vehicles, especially with a clearly defined merge lane that leaves no room for ambiguity. 


  1. Good analysis. I corrected the opening -- this multilane road is not a local street.

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