Discussion: Increasing job opportunities in a subregion for region-wide fuel conservation and air-quality improvement

Abstract

The authors have examined the transportation implications of alternate development scenarios of some interest in the Ottawa-Carleton region. However, their conclusions and interpretation require some critical review before being accepted as the basis for any planning decisions. Although the authors do not always make the distinction, it must first be recognized that the results of the study can only be interpreted in terms of the specific scenarios investigated for Kanata rather than being interpreted as the demonstration of a general model via a case study. The paper presents neither the elements of a generalized approach that can be utilized in similar cases nor an attempt to compare results with similar cases elsewhere. Land use planning on a regional basis obviously involves a complex set of socioeconomic choices and desirable outcomes. Increasingly, the shortand long-term environmental implications of planning choices are becoming a factor in the decision making process. This paper suggests that the air quality implications of the scenarios investigated are significant enough to be a factor in the decision making and may in fact be important enough to be the prime motivating factor for the study of alternate scenarios in the first place. It is these interpretations and (or) conclusions that will be critically examined in this discussion which will be presented around three main points: 1. Given the uncertainties involved in the socioeconomic factors governing the scenarios investigated, and the level at which emission modelling has been attempted, the only conclusion that can be drawn from the results of the study (a maximum difference of 2.8% in pollutant emissions on a regional basis) is that the scenarios investigated do not show sufficient difference in terms of their transportation-related emissions on which planning choices can be based. The authors themselves seem to recognize this in their Conclusion 6 where they acknowledge other more significant factors in controlling air pollution in urban areas. On the other hand, they go on to suggest that land-use policies and corresponding transportation system developments are endeavours that "go beyond technology and regulations in order to reduce fuel consumption and emissions." No discussion is offered concerning the myriad of other issues that a re likely to be affected much more directly and strongly by the scenarios investigated, which involve up to 25% increase in employment in selected districts in the study. It should not come as a surprise that less travel and emissions result in general when people live closer to where they work, but one hardly needs a study at this level of detail to make this point. 2. If the authors attach any significance to the 1-3% calculated reduction in emissions between some scenarios on a regional basis, then they also ought to be pointing out the much higher relative increases of 3 -9% in Kanata for the same scenarios and emissions. In their Conclusion 3 the authors acknowledge the increases in Kanata in a qualitative way but then go on to justify these in terms of the decrease in the "main city centre" and the net reduction overall. Since the paper does not present any calculations pertaining to the "main city centre," it is difficult to determine which reductions are being referred to. However, using the methodology in the paper, the increases shown in Table D l and Fig. D l for Kanata can readily be calculated. It should also be remembered that the relation between total emission levels and the ambient air quality in a particular location is far from a simple one. For example, the ambient concentrations of CO, NO.,, and HC in highly populated micro-environments such as core business districts can show large temporal and spatial variations for the same level of total daily or annual emissions. While the reductions in total emissions (reported in Table 9 in the paper) for the investigated scenarios will be realized mostly along the routes connecting Kanata to other centres involving very little pedestrian traffic, the increases in the attached table will mostly be realized along the populated streets of Kanata, which can already be expected to exverience ambient concentration levels of vollutants similar