Today we review a background overview paper prepared by one of the world’s leading advocates for sustainable transportation, Todd Litman, at a United Nations conference aimed at developing best practices in Asia where major shifts to urbanization are taking place. His paper includes many tips and statistics such as better traffic congestion indicators and space requirements for various modes, the advantages of transportation demand management strategies, especially when different ones are combined.
Key Quotes:
“cities tend to experience significant traffic and parking congestion problems when ownership rates exceed about 200 vehicles per 1,000 residents.. In most cities traffic congestion maintains equilibrium; it increases to the point that residents fore-go some potential peak-period vehicle trips... Durable congestion reductions require changing the point of equilibrium by discouraging automobile travel and encouraging use of space-efficient travel modes, particularly public transit.”
“Space requirements tend to increase with vehicle size and speed.. For example, an automobile traveling at 40 kilometers-per-hour (Km/h) requires about 3.0 meters of lane width and 18 meters of lane length, or about 54 square meters of road space, but at 100 Km/h it requires 4 meters of width and 40 meters of length, or about 160 total square meters. A bus requires about three times a much road space … but during peak periods typically carries 30-60 times as many passengers ... Bicycles and automobiles also require space for parking, ranging from about 2 square meters for a bicycle to 40 square meters for a large off-street parking spaces”
“Public transit service improvements designed to attract discretionary travelers (people who would otherwise drive) are particularly effective at reducing urban traffic congestion … These become more effective if implemented with incentives to discourage peak-period automobile travel, such as efficient road and parking pricing and commute trip reduction programs.”
“Transit travel has about a tenth the traffic casualty rate per kilometer as automobile travel, and many factors that encourage transit travel (better walking and cycling conditions, lower traffic speeds, more compact and mixed development) also help increase traffic safety. “
“wider roads may help reduce traffic congestion, and more fuel efficient vehicles may help reduce air pollution, but these strategies tend to increase total vehicle traffic, a rebound effect, which reduces their net benefits and exacerbates other problems. Similarly, grade separated intersections and wider clear zones may help reduce some types of crashes, but they increase roadway costs, and automobile occupant protection such as heavier vehicles and airbags tend to increase production costs and fuel consumption.”
“Transportation demand management strategies tend to have synergistic effects: their benefits are greater if implemented together…by itself a bus service improvement might only reduce automobile commuting by 10%, and by itself parking pricing might only reduce automobile commuting 10%, but if implemented together they reduce automobile commuting 30% because they provide both a push and a pull to shift mode. “
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