Land Consumption Impacts of a Transportation System on a City: An Analysis


Background Reading

Recently this document was cited in another by two researchers working for the Project for Transportation Reform with the Congress for the New Urbanism in Chicago. The abstract for this article reads as follows:

University of Pennsylvania Research Findings

Parking disrupts the urban fabric in places like Hartford, where it occupies more than 20 percent downtown land.

Parking disrupts the urban fabric in places like Hartford, where it occupies more than 20 percent downtown land.

The impacts of a changing transportation system on land consumption are analyzed. An analytical model with which to examine the intrinsic relationships between the volume of activities, the intensity of land use, and the modal split of generated trips is formulated on the basis of an idealized urban region that contains a city within radius R. The city land consists of that required for transportation and that for all other activities. Given hypothetical initial conditions, impacts of an increasing auto modal split are analyzed on the basis of three conceivable strategies to deal with the pressure to expand transportation facilities. The analysis shows that the modal split has a strong influence on volume of activities and land use intensity. A policy of infrastructure expansion to accommodate the increasing number of autos reduces the amount of land available for more fundamental activities that transport is intended to support, not displace. To prevent this displacement, land intensity of areas used for all other activities must increase. Otherwise, the options would be to relocate some activities from the city to outlying areas; such relocation could result in increasing traffic volumes in the entire region. Alternatively, the accommodation of other activities may encroach on previously protected or undevelopable land and lead to unsustainable development for the region. It is also shown that to maintain sustainability of a city, high-capacity transit modes with reserve capacity, such as rail transit systems, represent an efficient option in dense urban areas.

Fancy language that breaks down this way:

  • Cities imply high volumes of people working in close proximity to one another. In essence, a very dense land use situation.
  • If each person working in a given city were to bring their own vehicular transportation the number of vehicles would also be high in number.
  • Because automobiles are relatively large as compared with their occupants the land use required to house that many vehicles would overwhelm the land use for working space of the people using those vehicles.
  • As the authors of the (presumably computer model) point out to relieve the stress of land use reserved for parking workers would have to be redistributed away from the central city.
  • Such a redistribution would only spread the congestion further away from the city.
  • The solution is to employ high-capcity transit modes, i.e. trains, buses or planes.

I have no objection to the premise nor find fault with the solution. It seems obvious however that these conclusions would have been arrived at since the structure of American central cities and their collar suburbs have employed just this solution for the 50 years or more that the authors acknowledge was highlighted by increased use of highways (beginning in the 1960s).

What I do take exception with but only in a technical sense is the title on the Atlantic Cities article. To the lay person it seems to suggest that all cars (i.e. motor vehicles) are bad for cities. This is far from the truth. It is with respect to parking requirements that the underlying computer model comes to the conclusion that single occupancy cars with unused 6 passenger capacities represent a threat to the land use of cities.

Computer models like this can be comparatively stupid. For instance because what matters most in conserving land usage for things other than the parking of transportation you end up realizing that SUVs and Passenger vans are our “friends” and not our enemies because they represent the potential to carry more people into the city that just one. And despite their sizes they far outstrip the efficiency of having each of those people on board in his own car.

In fact under this model jumbo jets, mega-buses, ferry boats, commuter helicopters and limousines all qualify as more than adequate means of transporting greater numbers of people than the equivalent number of automobiles would. So each of these options represents the potential to save increasing amount of parking.

To take this a bit further and venture into cycling at the same time, it means that cyclists are better off traveling around the city on tandems, triples and quads than on single two-wheeled bicycles because of the space savings that these larger bikes represent on the parking end of things.

Where Does Cycling Fit Into The Model?

What is not clear however is how bicycling fits into this model. Bicycling is a fairly short distance option for commuting possibilities. Given the extremes of weather in the Chicago area it is also limited in its value to the workers who might undertake to use it on a year round basis. Chicago has a fairly robust number of commuters who are plagued with problems crossing bridges in bad weather. Traction plates have to be installed to make two wheeled bicycle use practical enough to be safe.

Given the volumes of snow and its depth it is imperative that high volume snow removal be adequate in order to even allow limited bicycle use for distances up to 10 miles. For cycling to be considered a reasonable alternative that in itself does not require much additional effort on the part of the commuter the bicycle may have to transform from something merely human powered into something with electrical assistance.

What is paramount in importance is that workers using bicycles not have the additional burden of having to:

  • find shower facilities
  • carry extra clothing
  • have sufficient load capacity that books, computers and other work product be easily transported

Bike share bicycles work for some of these situations but are not presently electric-assisted. Neither are two wheeled vehicles suited for all users. A fair number would require at minimum three wheels in order to feel safe on a typical urban street where potholes , debris and poorly installed pavement are the norm rather than the exception.

What is also quite interesting to consider is whether the SmartCar offers a solution to the problem proposed by the University of Pennsylvania researchers. The premise of this vehicle is that its size more closely approximate that of a velomobile (at least in terms of its footprint). You can easily get two of these vehicles into the parking space of one traditional mid-sized automobile. What it offers is greater convenience and safety than a bicycle and far greater range.

The real question is what sort of vehicle could tempt the greatest number of commuters who attempt the full distance of their commute in a uni-modal fashion. For folks traveling a scant mile or so to work a bicycle might be just the ticket. Outside the range of 10-20 miles something else is required for most commuters. It should also be understood that commuting is not always just a back and forth affair. Often workers are required to leave the office and head to a client site outside the city. That again requires something other a bicycle if the worker is wearing dress clothing and does not have the time to shower before consulting with clients.

Segway units are another option in the urban environment for distances in the 1-2 mile range. It has the advantage of being electric and not requiring costume changes or showers for its use. And further it is small enough to be stowed in limited spaces at either end of the trip.

Finding Good Quality Single Occupancy Vehicles Is Key

Bicycles are limited range vehicles at best. And that limited range presumes optimum riding conditions. We get perhaps 6 months of pleasant enough weather to warrant commuting by bicycle but even then only for distances of about a mile or two. The designs that cities across the country are working from do not include 25-30 mile trips on a regular basis. That is to day only the closer in suburbs like Evanston and Oak Park/River Forest make good candidates for bringing in large numbers of people via bicycle.

The way to extend that range is to improve the quality of the bicycle. Make it a hybrid that uses electricity and travels in a protected tube much like the one envisioned for use over the City of London. A protected environment means that snow, wind, rain and excessive heat are less likely to deter would be riders from venturing out on “bad weather” days. And if you provide the electrical assist you make it possible for riders to travel at predictable speeds for greater distances despite their age, gender or physical capacities.

Apart from this kind of bicycle then the next best approach is to put the American car on a diet. That is essentially what the German SmartCar represents. It is sized the way it is because of the cognizance that unused excess passenger capacity is the enemy of a thriving central city. What these vehicles bring to the table that electrified bicycles do not is the ability to be driverless drones that can be directed along their way via a central computing system that makes them cars in a “virtual” train as it enters the city. I really, really like where this is capable of taking us.

What would make this an even better vision for the future is the possibility of having these vehicles be either hybrid or fully electrical.