Funky Intersections
Harvard GSD, fall 2021 & spring 2022
Cambridge, MA
Cities by Design Instructors: Peter Rowe & Rahul Mehrotra
Urban Theories & Interventions Instructor: Eve Blau
The writing below consists of two separate papers. First, an analysis of the unusual geometry and traffic patterns of intersections in Cambridge, MA, and second, a response with a critical lens questioning the authoritative and non-democratic aspect of this intersection redesign where an unintended consequence is the loss of public space.
Outline:
Funky Intersections of Cambridge
Wayfinding
East vs West Cambridge
Accident Rates
Existing Conditions
Ideal Diagram
Conclusions
Scales for the Public
Funky Intersections of Cambridge
Introduction
In the end of August, the cycle of academia returning to Cambridge means many experience the unusual nature of traffic patterns common in Cambridge (and the greater Boston area) for the first time. This sometimes has disastrous consequences. For example, navigating the construction and one-way flows around John F. Kennedy St. almost requires a lighthouse. In front of the Johnston Gate to Harvard Yard cyclists get clipped by a bus as they are directed by granite curbs into vehicle traffic lanes. At the intersection of Massachusetts Ave and Cambridge St, seven lanes from one direction confuse pedestrians and cyclists as to which cars to watch for. Is this level of chaos normal for Cambridge, and has it always existed?
Wayfinding
Kevin Lynch is well-known for his descriptions of wayfinding in cities. In particular, he describes legibility as a way of navigating the city with various modes of transportation and points out that “patterning” is a trait of human psychology. We seek out patterns to provide a framework for understanding our place in the world, and that eventually shapes our beliefs and values.
Lynch breaks down how legibility can be structured in a city into five concepts: paths, edges, districts, nodes, and landmarks. Although he refers to these at a city-scale, I believe they can also be applied at a smaller scale, even down to an individual intersection.
The Path is the sidewalk or lane that a user walks, bikes, or drives on; the Edge is a curb or lane stripe; the District includes the boundaries of an intersection (the point where a pedestrian looks up from their phone to begin navigating traffic;) the Node is a point of conflict where different modes of transportation cross; and finally the Landmark is an object by which a user navigates such as a traffic light, a building’s front door, a business down the street, or a playground in the park.
East vs. West Cambridge
East Cambridge streets are generally wider and straighter, so the street improvements are easier to design and construct. The streets themselves are not particularly dangerous but it is at the intersections where problems can occur. West Cambridge streets are far more complex, partially because they are narrower, leading to more points of conflict along travel routes. Here, destinations are not connected by straight lines, but rather wander geometrically in relation to the river and topography.
One place in Cambridge where east and west meet is between Harvard Yard and Cambridge Common. This large, twisted intersection along Massachusetts Avenue is worth studying due to its unusual geometry and confusing wayfinding features.
Accident Rates
While studying crash statistics in Cambridge, I discovered that incidents were lower than expected at this specific intersection. However, there was a cluster of crashes south near the Harvard Yard entrances and north along Massachusetts Avenue. Some of these collisions were with parked cars, but others were cases of rear-ending. I witnessed a cyclist get clipped by a bus in front of the Johnston gate at Harvard Yard so I do suspect bicycle crashes are underreported.
However, the general lower crash rates in the central portions of the intersection may be a result of heightened anxiety. The multiple Lanes of traffic directing people in all directions may cause people to pay more attention, but intersection design should not promote anxiety to reduce accidents. There are better ways to control traffic than through fear.
Existing Conditions
Originally, I had only planned to study one leg of the intersection where pedestrians cross Massachusetts Avenue after leaving Cambridge Common, but to fully understand the conditions of the intersection, one must look at the entire route around Flagstaff Park.
When looking at the Existing Intersection diagram above, there are a few noteworthy existing conditions. First, the total area that the intersection occupies is 5.09 acres (the gray area above.) There are approximately 92 points of conflict over the intersection, with many more unaccounted for due to implied merging points of both vehicles and bicycles not being marked. One particularly bad spot is where I witnessed the bicycle crash, in front of the Johnston Gate at Harvard Yard. The bike lane there is directed to cross the street with pedestrians, but then splits and continues along both sides of the street as it approaches Garden Street. This is incredibly confusing to both cyclists and motorists, which leads to navigation mistakes and dangerous conditions.
Since the level of pedestrian traffic in the area is particularly high due to the educational demographics of Harvard University, the commercial district at Harvard Square, and the neighborhood draw to Cambridge Common, different forms of mobility need to be accommodated. However, the infrastructure of this intersection still seems to favor vehicles, even while technically providing the capability for alternative modes of transportation. A new design to this intersection would greatly improve the safety, flow, and navigability for all people if it considered each complete path.
Ideal Diagram
The Ideal Diagram above illustrates a possible reconfiguration of the intersection. This simplifies many aspects of the current layout and frees up 2.31 acres of land to be better utilized by something other than pavement and lawn-planted island. The points of conflict are reduced significantly to approximately 49 points, down from the approximate 92. This could be further reduced with the application of different intersection configurations such as a roundabout.
The remaining land could be used to further improve the pedestrian, biking, and bus facilities, although some would need to be allotted to relocate the Flagstaff Park flagpole, the Charles Sumner Statue, and the Dawes Island plaza. This could be a great landscape architecture project to make this Harvard entrance equal to its historical significance. One possible funding source for the project could be Harvard’s acquisition of some of this remnant.
The largest constraint to the project moving forward is a topographic one, where the decent of Cambridge Street below the Science Center plaza would need to climb up to meet the new intersection. This then puts pressure on the underground facilities of the Red Line subway and bus tunnel. However, based on the presence of large trees and retaining walls near Flagstaff Park, I suspect there is enough below-grade flexibility for this road realignment to work. The relocation of the bus tunnel entrance is the greatest unknown, and future study would need to confirm the sectional possibilities here.
Conclusions
If the ideal intersection is built, nodes (traffic lights) are reduced from approximately five to two. A landmark is created at the entrance to the Harvard gate and strengthens the difference between Cambridge Common, Harvard Yard, and the commercial Harvard Square. The reorganization of the intersection could improve the legibility of the district in that it transitions from the residential West Cambridge to the educational East Cambridge with more than large rings of pavement. Each of these contribute to improved traffic flow for cars and busses and improves safety for bicycles and pedestrians by reducing the conflict points to one location.
Other analyses that may further improve this intersection could include an in-depth transit study to determine the directions in which busses should enter/exit the bus tunnel, whether the tunnel should be used at all, or if car traffic could be relocated to the tunnel to pedestrianize the Harvard Square area thereby reducing the at-grade vehicle conflict points altogether. To make this intersection navigable to both new and old Cambridge residents, then the dysfunctional aspects of Cambridge’s funky intersections would be resolved.
Bibliography
Barker, Roger G. Ecological Psychology: Concepts and Methods for Studying the Environment of Human Behavior. Stanford University Press, 1975.
Cambridge, City of. Harvard Square Design Project. June 2005, https://www.cambridgema.gov/CDD/Transportation/projects/completedprojects/harvardsquare.
“Crash Map - Demonstration.” Cambridge Open Data, https://data.cambridgema.gov/Public-Safety/Crash-Map-Demonstration/i8vh-vya9.
Earth Tech. “Harvard Square Priority Improvements.” 6 June 2005.
Knieriem, Declan J. Following Deadly Crash, Residents Reimagine Pedestrian Safety in Harvard Square: News: The Harvard Crimson. 27 Sept. 2019, https://www.thecrimson.com/article/2019/9/27/reevaluating-pedestrian-safety/.
Lynch, K. The Image of the City. MIT Press, 1977.
Slaughter, Jason. Not Just Bikes. https://www.youtube.com/c/NotJustBikes.
Scales for the Public
I analyzed one specific intersection at Massachusetts Ave and Cambridge St to understand how its history led to such an unusual and confusing layout. However, looking back at the process I went through to both critique the layout and produce an “ideal” diagram, I wonder if I was acting as a sort of Messianic planner and assuming a universal absolutism like Susan Fainstein mentions in her article “Planning and the Just City” (Fainstein, 2009) and created a miniature “utopia of spatial form [seeking] to suppress the force of historical change” like David Harvey and Caz Potter critique in their “The right to the Just City” (Harvey & Potter, 2009).
Kevin Lynch is well-known for his descriptions of wayfinding in cities. In particular, he describes legibility as a way of navigating the city with various modes of transportation and points out that “patterning” is a trait of human psychology (Lynch, 1977). In the analysis of this Cambridge intersection, I applied his five concepts of legibility (paths, edges, districts, nodes, and landmarks) to the way people interact at the scale of crossing a street. I surmised that the Lynchian psychology of patterning could work at scales of both the city and intersection.
However, is there a scale of urban intervention that should trigger the democratic process of public input? Is the reconstruction of an intersection large and impactful enough? Fainstein points out that injustices can still happen given the democratic process such as in her example of the Bronx Terminal Market displacing an existing set of merchants that were not given the chance to stay despite thorough municipal proceedings. In this case, leadership had already made up their minds as to the economic value of redevelopment and anything contrary to that position was dismissed. One could argue that an intersection’s realignment would improve the movement of goods thereby having an economic impact, but my original drive to redesign the intersection was not economic in nature. I was simply frustrated and scared every time I had to cross or travel through it as a pedestrian, cyclist, or driver. Is that enough to warrant a new design if the institutions responsible for the decision would most likely require an economic cost-benefit study, a series of public-private relationships, and possibly the sale of public lands, that each distance the process from the broader public?
One of the reasons to consider a redesign of this intersection is due to the 7 different lanes of traffic merging at the very point of a pedestrian crosswalk and two bike lanes
In my creation of a new ideal intersection diagram, I discovered a large amount of land could be reallocated to something other than asphalt and underutilized lawn. About 2.3 acres would be available for alternative uses with most of it adjacent to the central Harvard Yard. One could assume that this land could be a significant source of capital to finance the project itself if this was purchased by Harvard University or a private developer. But would this be the best use given the central and historic nature of the site?
Although I still believe in the organized layout of the ideal Massachusetts Ave and Cambridge St diagram, it is clear now that I was ignoring the possible futures resulting from such an intervention. Would this be opening the possibility of a new commercial corner between Harvard Yard and Cambridge Common? This would surely be a significant economic impact which would convince the City of Cambridge to embark in a costly reconstruction like this, but it would also be a symbol of furthering capital accumulation over historic and academic integrity. As Susan Fainstein quoted J.C. Scott saying “efficiency, order, and beauty through the imposition of reason” become the resultant goals of projects when a future context is not considered.
Bibliography
City of Cambridge. (2005, June). Harvard Square Design Project. Cambridge CDD. Retrieved from https://www.cambridgema.gov/CDD/Transportation/projects/completedprojects/harvardsquare
City of Cambridge. (2022). Crash Map - Demonstration. Cambridge Open Data. Retrieved from https://data.cambridgema.gov/Public-Safety/Crash-Map-Demonstration/i8vh-vya9
Earth Tech. (2005, June 6). Harvard Square Priority Improvements.
Fainstein, S. S. (2009). Planning and the Just City. Searching for the Just City, 19–39. https://doi.org/10.4324/9780203878835
Harvey, D., & Potter, C. (2009). The right to the Just City. Searching for the Just City, 40–51. https://doi.org/10.4324/9780203878835
Lynch, K. (1977). The Image of the City. MIT Press.
Slaughter, J. (n.d.). Not just bikes. Not Just Bikes. Retrieved from https://www.youtube.com/c/NotJustBikes
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