Skip to content
by Tanya Snyder
RE Texas speedlimits. Per the article and EPA:
While each vehicle reaches its optimal fuel economy at a different speed (or range of speeds), gas mileage usually decreases rapidly at speeds above 60 mph. You can assume that each 5 mph you drive over 60 mph is like paying an additional $0.24 per gallon for gas.
When people will drive out of their way to pay 1 penny or 10 cents per less per gallon… what if you told them going 70 was costing an extra 50 cents per gallon!
Correction on your headline about New Mexico. Gov. Martinez did not veto a vulnerable user law. That bill, HB 68, never made it out of committee in the State Senate. She vetoed a bill that would have established a statewide five foot overtaking distance when motorists pass cyclists. Her veto message is here:
Regarding Texas speed limits. If you don’t live in the Southwest, you might not understand why high rural speeds are popular. Distances out here are huge. I live 100 miles from the nearest real airport in Albuquerque. “Reasonable and prudent” has its place, but the caveats are “reasonable” and “prudent”. Both concepts lost on a lot of Americans.
A few things: One, a high speed limit doesn’t mean you have to drive that fast. In 2008, I noted a lot of motorists driving slower than our Interstate speed limit of 75 mph in New Mexico in order to save gas. Two, I hope these ultrahigh speed limits are on limited access highways only, where head on crashes or overtaking crashes with bicyclists are rare. Finally, if we are going to see higher speed limits, we will need more competent motorists and more enforcement of keep-right laws so motorists are not weaving back and forth between lanes. Otherwise, 85 mph will introduce real carnage.
Kinetic energy goes as speed squared. A car travelling at 85 mph is carrying 2.4 times the kinetic energy as one travelling at 55 mph; this can be expended on deforming the car. Also, the energy required to overcome aerodynamic drag rises as the square of speed. Hence the massive loss of fuel economy at high speed.
Having said all that, I think it would be foolhardy to seriously suggest re-instituting double nickles out here. Its not going to happen without a huge fight. Rather, let gas prices rise so people drive less or drive more frugally or switch to smaller, more aerodynamic cars. Driving a shopping-utility vehicle long distances at 85 mph is dangerous (these vehicles were not designed to handle well at high speeds) and hugely wasteful of gas.
“Street designers seem to be asking themselves, "How can I make it less unpleasant for pedestrians to interact with cars on this street"?, when what they should be asking themselves is "Is there a need for us to have cars on this street at all?"”
– Joe B
In response to "Shared Space: The Case for a Little Healthy Chaos on City Streets"