Urban Design Strategies for the Built Environment: a case Study Analysis

Downtown San Diego is a much more walkable city than Southeastern San Diego not through population density (since the majority of the buildings are office space), but through its built form. Buildings typically over 20 stories cluster together which does not allow as much room for automobile right-of-way and surface parking. Blocks are significantly shorter, leading to more connective streets for both pedestrians and automobiles, sidewalks are wider, and roads are narrower for the pedestrian to cross. These design elements all come together to create a urban environment where walking is the main form of mobility within the neighborhood.

Similarly in Portland, the blocks sizes in the city center are uniformly distributed throughout the city center, measuring at a short size at approximately 215” x 200” ft. The average street has only one lane in each direction with additional setback for side-street parking on each side. The width of lanes measures at only 10 ft. from the beginning of the street-parking setback to the middle lane divider, below the standard of 12 ft. found in San Diego lanes. The total width of the automobile right-of-way measured approximately 35 ft., the same length found in Downtown San Diego intersections with bulb-outs in place. With the intersections involving bulb-outs in Portland, such as 5^th St. and NW Couch St. (Figure 2), the entire length of right-of-way a pedestrian would have to cross to reach the other end of the bulb was only a little over 24 ft., compared to 100 ft. to cross Market St. in Encanto.

Sidewalk widths in the same intersection of Portland measured 26 ft., compared to 4.75 ft. on the southbound side of Euclid Ave. Some differences in context may apply when comparing streets in Portland to Encanto, since the Euclid and Market intersection is a major corridor in the area. However, when analyzing Portland’s main corridors, such as Burnside St., measurements in street length were also significantly smaller than Encanto. Burnside St. consisted of two lanes in each direction, with three lanes measuring 10 ft. in width and the furthest right lane on the eastbound side measuring the standard 12 ft., and leading to a total right-of-way width of approximately 43 ft. considering lane paint buffers.


Figure 2. Source: (Google Maps).

Portland’s elements of the built environment are extremely designed towards accommodating alternative modes as the highest priority. The design throughout the city center almost never prioritizes the automobile above others, and this is evident in the mere lane width of lanes measuring only 10 ft. in non-major corridors like NW Couch St. Combined with bulb-outs, the average roads of Portland are narrow enough that a pedestrian only has to travel 24 ft. of automobile right-of-way to cross the street, the lowest of any case study. These strategies can be considered when applying context-appropriate strategies to Market and Euclid.

In the Midtown Manhattan neighborhood of New York, NY, the intersection of 48^th St. and Park Ave. is one of the busiest in the city in terms of vehicular traffic. There are 3 lanes on each side of Park Ave., with a separate fourth lane as a loading zone and side street parking for vehicles, making a total of 8 lanes for both north and south. Even at this site of extreme density in vehicular traffic, the block sizes in Midtown are uniformly at 230” x 420” ft. All lanes measured approximately 11 ft., slightly below the standard of 12 ft. The sidewalk setback along Park Ave. measures 15 ft., which allows the sidewalk to accommodate the appropriate capacity of pedestrians for this level of density.

Between the 8 lanes is a middle island refuge for pedestrian crossing that spans 20 ft. wide and large amounts of shrubs, trees, and potted plants planted along the stretch of the island. The middle island includes its own pedestrian signal light, so pedestrians have the option to cross Park Ave. in 2 increments before reaching the other side. The crosswalk section of the automobile right of way is also marked repeatedly with thick white lines on the pavement to catch drivers’ attention to the area that pedestrians cross (Figure 3). A pedestrian crossing Park Ave. would have to cross 45 ft. of automobile right-of-way to reach the middle island, and another 45 ft. to reach the other end of Park Ave.

Figure 3. Source: (Google Maps).

Without the installation of the middle island, this road would have more automobile right-of-way than either Euclid Ave. or Market St. However, with the design features such as wide sidewalk setbacks, the middle island for refuge, trees and shrubs planted to enhance aesthetics, and boldly marked pavement for pedestrian crossing, this large corridor serves to successfully facilitate both a high volume of vehicular traffic while still accommodating the pedestrian. Park Ave. in New York proves that large vehicular corridors can still serve as highly walkable environments, as long as proper design strategies are in place.

Interviews were conducted with Susan Peerson, professor of Urban Design at the University of California, San Diego and Planning Commissioner to the city of San Diego; Jeff Howard, Senior Project Manager at Parsons Brinckerhoff; and Nancy Lytle, Assistant Vice President of Civic San Diego. Professional input was given about urban design strategies that promote walkability and problems with the design around the Euclid and Market neighborhood.

She states that the one of the features of walkability from physical planning is the length of blocks. Blocks that are long and stretch for miles do not form a hospitable environment for the pedestrian because the streets are not connective to many destinations. Shorter blocks create both a perceived sense of shorter distance as well as creating a more connective street grid that is in line with the human scale and allows the pedestrian to get to a destination in a more direct fashion.

Howard states that a walkable urban space should ideally have 20-25” ft. of sidewalk space, which he considers very generous. However, most environments that are considered walkable will typically have only 10-12” ft. Driving lanes should be 11 ft. at the lowest, with the standard being 12 ft. Protected left turn lanes can lower to 10 ft., but right turn lanes need to be wider of at least 11 ft. Side street parking lanes can be lower at 8 ft., and bike lanes can be 7 ft.

Lytle states that implementing side street parking also promotes walkability by promoting a greater sense of safety. One of the greatest concerns to pedestrians is the sense of safety and not having to compete with automobiles. Parked cars along the curb provide parking spaces and also serve as a barrier that block pedestrians from automobile traffic. She claims “pedestrians want to know there’s a buffer” when perceiving a sense a safety. The side street parking buffer also helps to naturally slow down cars, since it creates a perception of a smaller space for the vehicle to maneuver. Lytle claims this perception to drivers is more effective at traffic calming than lowering speed limits.

Proper street frontage

Peerson states that the view from the curb to the first 30 ft. of a building is what defines the urban form. This is the design of street frontage that is important to creating a pedestrian-oriented development. Automobile-oriented developments, such as the Market Creek Plaza retail center in Encanto, have a street frontage that consists of a parking lot, where the storefront is a full 400 ft. away from the street-side curb. This type of development favors entering the street frontage through an automobile and parking your car before entering the stores, instead of designing a street frontage where the pedestrian enters from the street. Peerson adds that good urban design also happens to follow a 5 ft. setback required by the Americans with Disabilities Act (ADA). She cites Portland, OR as a very good American example of walkable urban design, especially with the implementation of complete streets to accommodate all users of the street.

Howard emphasized the importance of street frontage to aesthetic value that contributes to walkability. For proper street frontage that promotes walkability, he recommends a 10 ft. building setback from the beginning of the sidewalk. He identifies to the pedestrian sidewalk as consisting of 2 zones: the “café zone” and the “active zone.” The active zone is where the walking takes place on the sidewalk. Proper street frontage takes place in the café zone, which is the inner 8”-10” ft. of the sidewalk, between the active zone and the automobile right-of-way. Street frontage can be enhanced in this zone by a strategy Howard refers to as “activating the street.” This involves the placemaking strategy of “putting things there to make it happen.” Examples of features include “café seating and water features,” and general street furnishings that make “people linger.”

Green infrastructure

Lytle stressed the importance of green infrastructure to the promotion of walkability. This includes the biological components of the built environments, such as street trees, shrubs, and permeable surfaces. She states that these features enhance the quality of the built environment by serving multiple purposes. Trees provide aesthetic complements to the sidewalks, as well providing shade and protection from the elements for pedestrians and transit riders waiting at stops. One constraint she regularly runs into when implementing green infrastructure in her projects is deciding who pays for the routine maintenance and irrigation. She states that there are ways in which the irrigation water usage for public green infrastructure can be calculated based on property lines and billed to the appropriate property owner.

Specific comments about the street design of the area around Euclid Ave. and Market St. Problems Peerson identifies with site photographs are the sheer overabundance of pavement, creating a very inhospitable environment tailored only for the fast transport of the automobile. Street frontage was also lacking anything oriented towards the pedestrian, such as Market Creek Plaza as mentioned earlier. There was also a lack of “site furnishings,” a term used to describe decorative elements of the public space, such as street trees, light poles, and again active storefronts to create a destination along the street for people to walk to.

To enhance aesthetic value and enhance safety to promote walkability, Lytle recommends planting street trees along Market Ave., but emphasizes to place them in the “urban order” rather than the “suburban order.” The suburban order involves planting trees, shrubs, and greenery along the property frontage side of the sidewalk, rather than the side facing the street (Appendix D). In suburban design this typically involves plantings serving as a buffer between the narrow sidewalk a property line, such as the entrance to a parking lot. The urban order involves planting the greenery on the sidewalk between the pedestrians and the street. This serves as a natural barrier that further enhances the pedestrians’ sense of safety.

Suggestions Peerson gives to this particular site involve the inputting basic design infrastructure that was missing, such as a sidewalk, which was missing on the eastern end of Market St. A few feet towards the east of the intersection on Market St. the sidewalk turned into an unpaved dirt road due to the underutilized or vacant parcels of land. Other design mechanism to enhance safety and accessibility was to provide greater shelter at bus stop areas, so that riders are not exposed to the elements when waiting for public transit, especially with some of the narrow sidewalk curbs found in the area and nowhere to sit.

Accessibility issues could be addressed through greater sidewalk connection, which could be different after the existing street grid is already laid out. Peerson stated that when the block size or the width of the sidewalk can’t be changed, a design technique called the “road diet” that aims to reduce the excess space set aside for vehicles on the road that often go underutilized. These would include slimming down the number of lanes and their widths, to a suggested two lane street of 10 ft. each way, and 10 ft. setbacks on either side for street-side parking, that can also serves as a barrier between vehicles and pedestrians. Then similar to complete street design, an additional 7 ft. can be set aside for a bike lane, behind the parked cars for protection, and at curb level instead of at street level to enhance bicyclist safety. At least additional 10 ft. should be set-aside on each side of the street for the pedestrian sidewalk, but without the bike lane could allow for an extra space. This is wider than the current sidewalk widths of 4.75-7.75 ft. found in the existing infrastructure. Howard recommends against installing bulb-outs because both Market and Euclid are such large corridors. He states that bulb-outs only work when there is street side parking to utilize the space before the bulb, since they can no longer be lanes used for thorough traffic. Additionally, he stated most bulb-outs are not able to effectively accommodate bike lanes since they block existing bike paths at the intersection. Being able to accommodate biking infrastructure is still an important objective in walkability so these issues will need to be considered when applying context-appropriate strategies.

As for actually bringing pedestrians to stroll on the street, both Peerson and Howard recommended proper destination objects to be in place, such as patio seating from a café or public sidewalk benches and trees to allow people to congregate. This creates the placemaking effect of creating a sense of meaning on the street, rather than a desolate urban space that pedestrians would avoid.

Given all the findings about design strategies that will encourage walkability and reduce automobile dependence, it is apparent that the Euclid and Market neighborhood lack many elements that would facilitate pedestrian activity, especially with the dramatic differences found in the case study analysis. The design features of its existing conditions inhibiting walkability were the large block sizes, narrow sidewalks, lack of site furnishings, and the sheer width of the roads to facilitate large volumes of vehicular traffic and the narrow width of sidewalks exposing pedestrians to the dangers of moving cars. Second is the lack of proper store frontage along the street that is oriented towards pedestrians. The neighborhood is not shy of destination centers due to Market Creek Plaza, but that development does not have proper street frontage for the pedestrian.

Block sizes may not be feasible to change with the already developed grid plan and infrastructure in place, but adaptive changes can be made. Pedestrian comfort and safety can be addressed through reducing the amount of right-of-way pedestrian has to cross on either Euclid Ave. or Market St. The road diet strategy may not work on Euclid Ave. since it is a major corridor for vehicular entering and exiting the CA-94. Reducing the number of lanes on Euclid may create greater traffic congestion that can diminish quality of life.

The best strategy to work with this context is to install a middle island refuge at each intersection crossing so that pedestrians are able to cross in two increments if needed (Appendix E). This can be done on Euclid Ave. by eliminating just the additional left turn lane on the southbound side before the intersection and instead using that space to expand the middle island to create a refuge point in the middle of the road. The left lane of Euclid Ave. on the southbound side can be slimmed from 14.5 ft. to the standard 12 ft. as well. The furthest right lane on both sides of the road can also be slimmed down from 20 ft. to the standard 12 ft., so there isn’t extra setback space for right-turning vehicles. Instead, that extra space can add additional sidewalk width of 8 ft. or bicycle lane can be installed.

A bulb-out strategy may not be the best option for this area, since prioritizing bike lanes are important to promoting alternative modes of transportation. Instead, sidewalk space should be widened to create more comfortable access for pedestrians and not have them feel exposed to vehicular traffic (Appendix E). Since Market and Euclid are high traffic corridors, lanes cannot be eliminated or else traffic congestion would worsen, with the exception of the additional left turn lane on southbound side of Euclid.

These strategies, if implemented on Euclid Ave., have the potential to reduce the amount of automobile right-of-way needed to cross by a pedestrian from 96 ft. down to 75 ft. on the south side of Market and 93 ft. down to 67 ft. (down to 52 ft. if excluding the middle island refuge), on the north side of Market (Appendix F). The length is still large compared to the 35 ft. measured in Downtown San Diego, but may be the best option given the large volume or vehicles utilizing the corridor for CA-94.

Aesthetics enhancements

Aesthetic features to “activate the street” may be the most feasible to implement in the area in order to promote walkability. These would include site furnishings such as benches and patio seating along the “café zone” in front of the street frontage. Green infrastructure such as trees and shrubs can be easily installed on all sides of Market and Euclid. They would be planted in the “urban order,” lining the edge of the sidewalk that faces the street, to create a natural barrier between pedestrians and vehicular traffic (Appendix E).

In addition to the aesthetic enhancements, proper placemaking also needs to occur for pedestrians to actually have destinations to walk to. Otherwise, the built environment may be perfectly suited for potential for walkability, but is not utilized because of the lack of placemaking. This would involve fewer design elements and more economic development strategies to attract businesses to open up destination spots along the street. However, design techniques can be utilized to ensure proper setback and store frontage for buildings expected to house these businesses. This would include proper orientation, where buildings entrances directly front the sidewalk, rather than being hidden behind a large parking lot utilized in the suburban method. Market St. is a good corridor to build these pedestrian-oriented frontage as demonstrated in Appendix F).

The Euclid and Market area is lacking many urban design elements that allow it to be friendly for pedestrians and cyclists. Although numerous design strategies have been identified through case studies and consultations, many context-specific constraints prevent the area from being as walkable has the case studies analyzed. The constraints are largely due to the existing block sizes in place, as well as the area serving as a major corridor off two major freeways of the city. Strategies involving eliminating the number of lanes would severely impact the circulation networks in the region, with many automobile commuters from around the region using the corridor daily. Improvements can still be made to the existing infrastructure to enhance walkability, especially with the potential from the nearby transit center to facilitate a high volume of transit riders. The most appropriate design strategies from the case study analysis came from Midtown Manhattan, since its context was most similar to Market and Euclid, being a heavy traffic corridor with a large number of lanes. Widening sidewalks and installing a middle island and green infrastructure were all design elements that existed along Park Ave. in Midtown Manhattan, and all these strategies were appropriate to the Euclid and Market area in helping to improve walkability.

In regards, to reducing automobile dependence, it may take a transportation level-of-service (LOS) analysis to estimate the reduction in vehicle usage after more transit-oriented type developments take place in accordance to the vision of the Euclid and Market Land Use and Mobility Plan. Walkability of the built environment around the immediate area of study will be greatly enhanced with these strategies, but automobile dependence may not necessarily decrease because drivers drive through Euclid and Market to reach other destinations. However, trips made within the study area will have a reduction in automobile usage. If more communities aim to achieve the same vision as the Euclid and Market Land Use and Mobility Plan, more destinations in San Diego can be connected through public transit and have similar walkable neighborhoods. This will result in an overall reduction in automobile dependence, as more trips to more destinations can be traveled without a car and these destinations are designed to accommodate safety and comfort for the pedestrian.

Promoting walkability and reducing automobile dependence can be achieved through various design strategies and placemaking. To achieve this on a regional scale, planners and policy makers will need to emphasize the importance of pedestrian-oriented design and the human scale when developing new projects and retrofitting old ones.

A. CONTEXT MAP FOR SOUTHEASTERN SAN DIEGO REGION