Effect of Street Pattern on Road Safety

Effect of Street Pattern on Road Safety
Shakil Mohammad Rifaat, Richard Tay, Alex de Barros

In the past 50 years, the loops-and-lollipops design has become the basic building block of many urban neighborhoods. In the field of traffic engineering, this combination of cul-de-sacs and loop streets is designed to discourage through traffic and improve road safety, and thus it has the support of many traffic engineers. Perhaps because of its intuitive appeal, few studies have examined the impact of this design on road crashes. The city of Calgary, Alberta, Canada, was used as a case study to examine the effects of neighborhood street patterns on the number of reported crashes. In the study, crashes were converted into equivalent property-damage-only crashes using various weighting factors to check the sensitivity of the finding. Results suggest that currently popular road patterns such as warped parallel, loops, and lollipops are safer than the traditional gridiron pattern. Moreover, this result is quite robust regarding severity weights or aggregation schemes, albeit with some variations in the absolute values of the estimated effects. However, changing the aggregation scheme had a significant effect on some of the control variables used in the model, especially the socioeconomic characteristics, although most of the road features and land use estimates remained robust.

(bad news for the New Urbanists, Traffic Engineers actually score a point).

Schoolhouse rock for transportation funding

What we need is a schoolhouse rock for transportation funding.
The public does not know where the money for roads comes from or goes to. It does not understand trust funds. It has no clue the magnitude of the gas tax or other transportation funding sources.
I could say the same about policy-makers.
Transportation funding is becoming a shell-game promulgated by Washington because of fear that elected officials have of being unelected by the mathematically illiterate.
It has to be cheaper to teach people math than to suffer through inadequate transportation funding out of general revenue because a general sales tax seems cheaper (at e.g. 1/2 percent) than a gas tax (at e.g. 20 cents / gallon) since 1/2 < 20.