23. Too Hot to Shop and Other Inclemencies

A successful Downtown is measured today principally by its popularity as a pedestrian precinct. The more people who walk to work. shop. dine or  entertainment or for sheer pleasure. the higher regard Americans have for central business places. Conversely. empty sidewalks by day or night are associated with Downtown failures. If the commercial district isn’t considered appealing to workers. visitors and residents on foot, the public doesn’t care how high the new office towers soar.

This is a widespread and unrelenting standard. So important has it become that urban critics have come to venerate sidewalk activity almost as an end in itself. Street vendors are more readily tolerated now than before because they add essential sidewalk activity. Skywalks and underground concourses, on the other hand, are now thought to do more harm than good because they divert pedestrians from the sidewalks.

Without question, the curbed pavement at the street’s edge is the most important transportation guideway affecting Downtown commerce, more important even than interstate highway ramps, attached parking garages, synchronized traffic lights and illuminated signs that say, “Don’t walk.” Shoppers walk from transit or parking; Downtown employees overwhelming walk to midday shopping and dining destinations. The more attractive, wider sidewalks that speed pedestrian flows attract more Downtowners than ordinary sidewalks. The civility of Downtowns depends on the convenience, safety and amenities of the walking environment. So does Downtown commerce.

Urban walking is severely constrained by the time available for trips and the speed of walking. Few Downtowners will or can walk more than 1000 feet from work place to shopping, according to research by the International Council of Shopping Centers. Eighty percent of Downtown office workers will walk no more than nine minutes to dine or shop. Little wonder; the average lunch period is 54 minutes.

These useful rules of thumb, however, are further constrained by various weather conditions. Available research confirms common sense conclusions. Substantially fewer and shorter walking trips downtown are made during extremes of heat and cold and during periods of precipitation. New York, a city whose climate is tempered by proximity to the ocean, nevertheless records temperature extremes during a fifth of all daylight hours (Pushkarev and Zupan). Precipitation occurs roughly one in ten of all daylight hours there, although New York is also not noted for extremes of rain or snow.

These data, indicating the frequency with which weather can take the fun out of Downtown, also suggest the impact of meteorological variables on Downtown commerce. While it is impossible to specify how much of the Christmas sales surge, for example, is diverted to climate controlled malls, it is difficult to avoid the conclusion that significant market potential is lost simply because many walking trips are shortened or abandoned when it is unacceptably cold and wet on the sidewalks

Research on New York weather patterns has limited direct application to inland and southern cities although it suggests the potential brake on Downtown commerce where climate protection is not available and it provides a basis for local studies that will permit Downtowns to be planned based on a realistic understanding of weather constraints.

As an illustration of how weather can affect behavior, Pushkarev and Zupan established temperatures above 80 degrees and below 32 degrees as the points at which walking trips in New York City are significantly constrained. Manhattan has “uncomfortable” temperatures for 22% of the daytime hours of the year, producing reduced pedestrian circulation.

Based on a four year average of temperatures and inches of precipitation during twelve hours of daylight, their data reveal when such extremes are most frequent. (Figure 1) All months except September and October experience either extremes of heat and cold or substantial precipitation during the hours that men and women are walking to and from work or optional destinations such as shopping and dining. January, February and December experience extremes of both cold and precipitation.

A companion study of recreational daytime trips indicates the importance of a threshold temperature of about 55 degrees at which point a significant amount of pleasure walking (in this case to a midtown park) begins to occur (Pushkarev and Zupan).

Rain is Main Pain

Precipitation has an even more disruptive effect on pedestrian movement than temperature. Pedestrian counts on days of varying rainfall reveal a reduction in the number of walkers ranging from 24% to 55%, depending on the intensity of the rain (the study did not include a period of snowfall or sleet). Another study, testing the effect of rain on walking distances, indicates a reduction of 25% in trip length during the 9:30 to Noon period when a half inch fell. The study suggests that alternative destinations are selected by those who do travel during rainy weather — a closer restaurant is chosen or the trip to a more distant store is forgone. New York, with 44 inches of precipitation per year, is in the upper middle range of cities, along with Northeastern neighbors Boston and Baltimore (both 43 inches) and Philadelphia (41).

Other weather factors affecting the propensity to walk include wind, sunlight and humidity. While a breeze may lessen the impact of a torrid Houston summer day, winter winds can seriously aggravate a cold day in a Northern city. National Science Foundation research notes that tall buildings increase wind speeds and thereby lower body temperatures. At 20 degrees (F) even a moderate ten mile an hour wind produces the effect on humans of minus five degrees, the so-called wind chill effect. Cities known for severe winds, including Cleveland, Chicago and Buffalo, have this fourth weather factor with which to contend. Humidity compounds the effect of urban heat, further reducing the appeal of sidewalk strolling in, for example, Dallas.

William H. Whyte describes the steady erosion of sunlight downtown as taller buildings block winter rays. Downtowners go to considerable lengths to experience sunlight, suggesting that its absence can negatively affect attitudes toward the workplace. Dr. Norman Rosenthal of the National Institute of Mental Health notes that sunlight produces chemical changes that bring oxygen to the brain and produce “expansive and upbeat feelings.” As the mercury keeps climbing, however, temperature and humidity excesses in effect “force the body to boil over”, producing pent-up exasperated feelings. As the barometer drops, oxygen levels in blood fall, too, and the brain become sluggish. Rosenthal advises taking a brisk walk in sunlight to give a boost to oxygen in the brain and improve human functioning. The immense popularity of glazed skywalks, winter gardens and food court atria is in part associated with a desire to see and share sunlight and certainly helps stir hibernating office workers to stroll and browse.

Although weather is certainly not the only factor that influences Downtown pedestrian movement and therefore shopping — lack of places to go and time to get there are certainly the major factors in many places — it is more important than the attention it receives. Annual heating and cooling degree days and inches of precipitation provide a means of identifying locations where weather problems are the most severe and can prove most troublesome for Downtown commerce. l Eight of the largest 45 U.S. cities record more than 6000 heating degree days annually; nine cities record more than 2500 cooling degree days and four cities record more than 50 inches of precipitation. Three cities (Miami. New Orleans and Jacksonville) make both the hot and wet lists (Figures 2. 3. 4).

Other than subtropical Miami, none of the Atlantic and Pacific coastal cities are on these lists. Indeed, the moderating effect of the oceans is reflected in an extreme contrast. San Francisco, which records abnormally low numbers of heating and cooling degree days and inches of precipitation. It is probably not a coincidence that San Francisco has been created and redeveloped into our most enjoyable Downtown, San Francisco’s favorable “retail climate” can be seen in comparison with other major U. S. cities. With less than half the precipitation of Houston, Cincinnati, Miami, New York or Boston, Downtown San Francisco workers and visitors are more inclined to venture out and to take longer walking trips. Moderate temperatures also help. San Francisco has less than half the heating degree-days as Minneapolis and is well below Omaha, Boston, New York and Cincinnati. Even the extensive Embarcadero skywalk system is principally out of doors, emphasizing commercial and transportation values, rather than unneeded weather protection.

Two of the nine hottest cities, however, have extensive Downtown tunnel networks, and two have embryonic automated transit systems that provide some relief from the heat and humidity. Three of the eight coldest cities have extensive enclosed skywalk systems and two have high capacity specialized transit systems that help move pedestrians during severe winters. Three of the wettest Downtowns also have or plan special transit systems.

Houston is second only to Miami in cooling degree-days, a condition that has led developers since the 1950 ‘ s to construct 5.5 miles of pedestrian tunnels. Minneapolis ‘ top position for heating degree-days underscores the rationale for climate resistant skywalks connecting restaurants, retail centers, office and apartment buildings and other destinations.

Off-street pedestrian systems consist of bridges or tunnels above or beneath streets, corridors within buildings and activity centers. They range in type from the extensive skywalk networks of Cincinnati, OH and St. Paul, MN to Houston’s below grade “Connection” and Philadelphia’s transit-related underground Concourse. The largest connect more than fifty blocks.

St. Paul’s 1986 survey of 24 skywalk and tunnel systems in the U.S. and Canada asked respondents the principal purposes for the initiation and extension of their systems. While most first choices were to support retail and development, weather was more important where climatic conditions are most extreme. Thus, Dallas ranked weather second as the reason for expanding its mostly tunnel system and Duluth, MN (9901 heating degree days) ranked weather second for launching and for expanding its wholly skywalk system.

The distinction between development and weather protection objectives, however, is misleading and tends to focus on cold weather, only one of several climate conditions that affect Downtown commerce. Terry Jill Lasser, for example, writes that recent construction “has been largely motivated by economics rather than weather.” These are five economic development benefits derived from skywalks and tunnels, of which weather protection is an important one.

1. During commutation or midday trips, the small amounts of time saved passing under or over vehicular traffic can add significantly to pedestrian trip length or can shorten trip time, adding incentives for office, hotel or retail development. This gain is more important as the networks expand, adding more origins and destinations. Many cities with small networks have skywalk connections to parking garages, where both time savings and security benefits are influential with office developers.

2. Scattered studies indicate that sidewalk-related fear shortens, modifies or eliminates many Downtown-walking trips. Skywalks, however, are generally perceived to be safer than sidewalks. While some tunnels include portions perceived anxiously by Downtowners, there appears to be few such concerns within the glazed, highly visible skywalks. The resulting perceived security certainly benefits retail. It is probably of greater importance, however, to office development because of the necessity and difficulty of attracting skilled white-collar workers to Downtown jobs.

3. Many experts believe that pleasant, easy to navigate pedestrian features actually increase the number of men and women who walk about during the day. Virtually all skywalks offer pleasant views and constantly changing surroundings and therefore probably produce a net gain in walkers simply because of the visual environment. This ultimately translates into sales potential.

4. For retail, generally the highest priced commercial space, the most important benefit of skywalks and tunnels, however, is their capacity to channel large numbers of potential consumers past shops, dining and consumer services. This is especially true where the networks connect subways, bus or trolley systems with office and other destinations. Low density Downtowns often achieve their best pedestrian counts in systems limited to transit or parking. In addition, transit-linked networks typically experience three daily peak use periods, while those without transit links draw significant crowds only at midday.

5. Weather protection is an important element of economic development, not a factor apart. Climate controlled passages can be assumed virtually to erase the commercial losses associated with extremes of hot and cold and precipitation, putting more Downtowners into the commercial environment for longer periods. Such protection also provides a competitive advantage for office and hotel projects.

While all off street pedestrian systems provide protection from wind and rain, virtually all also provide heat and cooling. Of the 24 cities surveyed by St. Paul, only two (Lexington, KY and Syracuse, NY) provided neither heating nor cooling. Cincinnati, Duluth and St. John, NB reported no cooling systems. All of the tunnel systems were heated and cooled. The infrequency of exceptions suggests that the additional capital and operating expenses required to provide full climate control were considered essential to the desired quality of life Downtown, There appears to be no differences associated with whether the cost of skywalks or tunnels is borne by the public (e.g., St. Paul) or by the private sector (e.g., Houston). Virtually everywhere, these expensive pedestrian facilities are expected to have complete weather protection.

Published pedestrian counts from off street networks are rare. Minneapolis reported in the early stages of its skywalk system that one of the first bridges recorded 7000 pedestrians on a typical summer day and 18,000 a day during winter. People using skywalks in five Midwest cities (Robertson) overwhelmingly report that they prefer to use skywalks when the temperature drops to 20 degrees (96% of respondents) and even when the temperature has reached 50 degrees (81% of respondents). Reflecting the importance of convenience, however, more than 70% still prefer skywalks when the temperature reaches 80 degrees. In Duluth, 99% say they use the system in the coldest weather and only 31% say they do in warm weather. The latter result may, as Robertson suggests, reflect Duluth residents’ yearning for summer fresh air. More likely, however, it is because the small system has few origins and destinations: walkers are impelled to use it by extreme cold, rather than by convenience.

Despite the influence of precipitation on walking, critics tend to equate weather problems with the single factor of low temperature. “In contrast to Charlotte,” Lasser writes, “Cincinnati’s seasonal extremes may more readily justify climate controlled tubes… ” In fact, Charlotte has more precipitation that Cincinnati (43 inches vs. 40 inches) and its cooling degree days are substantially greater than Cincinnati’s (1546 vs. 1159). Cold weather is not the only reason for investing in off-street facilities.

Under the Weather

St. Paul1s survey revealed three Texas cities (Dallas, Houston and Fort Worth) and three in Canada (Montreal. Toronto and Edmonton) with networks of sixteen to more than 50 tunnels. The Montreal and Toronto systems connect extensive subway systems with major shopping and workplaces.

Houston’s Downtown Connection links 88 buildings. 70% of the total, principally by tunnels. Among the hottest of our cities. Downtowners find refuge in the naturally cooler passageways beneath the streets. The Houston Post reports, moreover, that pedestrian traffic in the tunnels swells almost 30% when it rains, suggesting that climate controlled walkways provide an important service beyond temperature moderation. (Use of midtown Manhattan1s subways similarly increases with substantial precipitation.)

Philadelphia1s underground Concourse network connects three subway lines and two major commuter rail depots. The main stems extend ten blocks below Market Street, linking The Rouse Company1s Gallery shopping center with Penn Center1s food and retail near Suburban Station. Despite these destinations, Philadelphia1s tunnels lack the critical mass of activities and crowds needed to reassure pedestrians concerned about personal security. Vacant storefronts and closed or restricted accessways to private buildings in the tunnels both reflect limited pedestrian traffic and contribute to it. Still, for its devotees, it provides shelter from wind. rain or snow. moderates temperatures and speeds trips to shopping or dining destinations otherwise beyond reach. Something of an orphan, the Concourse needs powerful friends to realize its enormous potential.

Skywalks and tunnels are successful to the extent that they provide three fundamental conditions required of Downtowns generally — convenience, security and amenity. The economic development benefits are simply a reflection of how workers, visitors and shoppers rank off-street systems in those three terms.

Convenience means that time can be saved, requiring easy access and important origins and destinations — shopping, dining, workplaces, public facilities. Security is a pervasive Downtown test, so finely applied that pedestrians will avoid using small segments of a tunnel system because it appears less safe than others. Amenity means that the environment is generally pleasant; but primarily it means weather protection. With these personal and economic benefits so evidently associated with tunnels and skywalks, it may be hard to understand why so much recent criticism is negative.

Critics repeat the warning that skywalks are ~not a panacea. Lasser reports ~increasing disenchantment with skywalks,~ that they are not an economic ~quick fix. II She says that Charlotte’s Overstreet Mall ~may have helped to persuade two department stores to remain downtown,~ but says that the system nevertheless has ~mixed reviews.~ Carol Morphew claims that skyways ~have created a wasteland for street level shops” and threatens that an “extensive and unchecked skyway system can (result in) a downtown comprised exclusively of large department stores and major corporate businesses that can afford the high rents.

Baltimore, Omaha and others that have lost their last department stores may find these admonitions less ominous than the authors intended. Indeed, skywalks do appeal to department stores and Downtown leaders would do a lot to retain or attract one.

Robertson says that the ~most pressing problems” associated with skywalks is their “tendency to exert a negative effect on retail sales and property values on the ground floor.~ His charge is based on reported differences in commercial rents in St. Paul and on survey responses indicating that those interviewed in skywalks prefer skywalk businesses. The survey responses are hardly surprising considering the location of the respondents. The conclusion, however, that skywalks depress other property values assumes that there is a fixed amount of potential consumer patronage upon which to draw. The best Downtown consumer research, however, makes clear that this is not true. The ICSC data demonstrates that among the factors that induce more office employees to shop Downtown is the amount of potential shopping and dining available to them. Puskarev and Zupan make clear that weather heavily influences trip numbers and lengths and thus potential Downtown sales. It is reasonable to assume, therefore, that skywalks that offer or connect with more retail suited to office workers· preferences will attract additional consumers who would not otherwise leave their offices. Many Downtowns with or without off street systems have lost so much ground floor retail that it is no longer worth the trip for time-pressed workers, especially when sidewalk level travel is slower and/or subject to various inclemencies.

Skywalks and tunnels generate Downtown sales that otherwise would be lost to highway shopping centers and they attack the office hibernation problem by offering convenient, safe, attractive walkways to commercial offerings selectively pegged to the office market. Perhaps skywalks do not “depress” real estate values at street level as claimed, but simply warrant higher rents at the second story level. Even the critics agree that skywalks add value to the commercial scene. Why should this not be reflected in higher rents? It is a mischievous leap of logic, however, to claim that the rental difference is the necessary result of a negative effect caused by skywalks.1

It would be a mistake for city leaders to assume that off street pedestrian systems simply “redistribute” commercial benefits, as Robertson and others warn. Indeed, the overwhelming success of the largest suggests just the opposite. Fine tuning improvements may be useful — the publicly owned sections of some tunnels could be cleaner, access to some skywalk systems could be easier and neglected sidewalk-level commercial areas could be upgraded. We lack evidence, however, that off-street systems are anything other than essential transportation systems that, if only because of their climate control, generate business and pedestrian traffic, the popular test of Downtown success.

Downtown retailing is a fragile sector generally operating in far less customer-friendly circumstances that the highway competition . Off-street pedestrian systems are the single most effective counter measure adopted by cities to halt the loss of market share . Despite the recent criticism. they are observably necessary commercial life lines. especially when it so frequently is too cold. too wet or too hot to shop.


Alexander, Larry. “CBD Analysis,” Downtown Idea Exchange, July, 1977.

“Drab Roslyn Needs a Little Space”, The Washington Post, 1990.

“Houston Underground”, The Houston Post, September 14, 1986

Lasser, Terry Jill. Carrots and Sticks: New Zoning Downtown, ULI, 1990

Lasser. “The Prose and Cons of Downtown Skywalks”, Urban Land, ULI, 1988

Morphew, Carol. “The Ins and Outs of Skyways”, Planning, March, 1984

“No Snow Job”, Planning, March, 1984

“Office Workers Retail Spending”, ICSC, 1989

Pushkarev, Boris and Jeffrey Zupan. Urban Space for Pedestrians, MIT, 1978

“Reta il Feasi bil i ty Study: South Broad Street Concourse”, PIDC, 1975

Robertson, Kent A. “Pedestrian Skywalk Systems: Downtown’s Great Hope or Pathways to Ruin?”, Transportation Quarterly, July, 1988

Robertson. “Downtown Danger: When Pedestrians Remain Above It All”, Minneapolis Star and Tribune, November 18, 1986

“Survey of Grade Seperated Pedestrian Circulation Systems”, City of St. Paul, 1986.

“The Minneapolis Skyway System, What It Is and Why It Works”, City of Minneapolis, January 1982

“To Your Health”, Nation’s Business. April, 1990

“Twin Cities Skywalks Are a Soaring Success”, The Washington Post, December 13, 1984

“Under the Weather”, Philadelphia Inguirer, February 24,1989

Whyte, William H. City: Rediscovering the Center. Doubleday, 1988

%d bloggers like this: