Stopping before you cross the line
On median barriers, the value of a human life, and the types of interventions that even strident libertarians ought to approve
In built-up urban areas, lanes of opposing traffic on expressways are usually separated by concrete median barriers. Ugly but effective, they keep mishaps from escalating -- which represents a victory for safety. A single-vehicle collision at 60 mph can be terrible, but the consequences are certain to be worse if it cascades into a head-on collision at a closing speed of 120 mph.
■ But concrete barriers are material-intensive, and the vast majority of American highway miles pass through rural areas, where traffic densities are lower than on urban expressways and sloping medians between opposing lanes of traffic offer little suitable space to set down heavy concrete blocks. The increasing adoption of cable barriers for separating traffic on rural highways addresses the problem both more cost-effectively and more suitably to conditions.
■ Median barriers installed on rural highways are credited with slashing head-on crashes by 97%. Considering that 8% of deaths on those types of highways happen in head-on crashes, median barriers installed everywhere would have a multiple-percentage-point effect on those deaths.
■ Rural cable-style median barriers stand up well as a metaphor for a certain ideal of government intervention: Generally speaking, they are high-return investments that impose no active restraint on motorists except when things have already started to go wrong, at which time they serve almost exclusively to keep a bad situation from escalating into a catastrophe.
■ While they cost a mighty sum to install (upwards of $80,000 per mile), their payback value is estimated to be a 16:1 return on investment. That return assumes a value of $4,500,000 on a human life -- an actuarial assumption that actually sounds extremely low if you're putting a price on the life of someone you love.
■ As a standard for gentle government interventions in other areas of life, it would be hard to beat the example of a non-intrusive, nearly fail-safe, 16-to-1 investment. If we could find more of those, even the most ardent libertarian ought to be persuadable.