Challenge Is To Facilitate Shorter Urban-Suburban Trips

America’s freeways are filling up. Indeed, they’re full much of the time, and they’re often not free. Ideally, cars and trucks drive smoothly on freeways, without intersections or traffic signals, from an entrance ramp to an exit.

But that ideal is disappearing. Traffic has tripled since 1960, as car ownership and use has skyrocketed. At the same time, new freeways have become almost unaffordable. So with more traffic, and fewer new roads, serious congestion is widespread.

What to do? One view is that we can’t build our way out of congestion, that we’ve got to wean ourselves from auto dependence. And this means building communities that are easier to serve with public transit. That may be part of the solution.

But another part of the solution should be changing the kind of highways we build. Too often, the roads we build to solve local traffic problems use designs that are not suited to local traffic, but rather to high-speed, intercity traffic.

What’s the difference? Most important is the road’s design speed. Generally, the higher the design speed, the greater the need for wide lanes, wider curves, longer grades, longer merging and exit areas and bigger interchanges.

But these features are expensive. Land, concrete, guardrails and noise barriers aren’t cheap. The two-mile “accessory lanes” being built between Exits 43 and 46 on the Long Island Expressway are to cost $95 million. Non-monetary costs - traffic disruption, road worker fatalities, and years of planning, hearings, lawsuits and wrangling over where to put them - are also high.

Most important, as design requirements ratchet up, designers have fewer options for fitting a highway to local conditions. It’s harder to dodge around a park or historic building with a 70-mph highway than a 40-mph highway.

While the costs of high-speed design are higher in metropolitan areas, the benefits are actually lower. Why? Most traffic is local: 10 miles or less. And speed matters less for short trips. An expensive interstate that lets you drive 70 mph instead of 45 mph saves you only nine minutes for a 20-mile trip, less than five minutes for a 10-mile trip, and that’s assuming you’re going 70 mph the whole way.

What are the alternatives? New York has an extensive system of suburban parkways, for example, which are much less massive in scale and impact than an interstate. These exclude trucks and buses, and have speed limits of 55 mph or less, but they’re quite useful for short trips. But highways like these couldn’t be built today because engineering standards require wider shoulders and other high-speed design features.

England offers an alternative: very few limited-access freeways of the interstate type, but many medium-sized highways, with traffic circles instead of traffic signals or interchanges. Interstate-style interchanges give the edge to traffic that’s already on the highway. If you’re entering, you have to wait for a break in the through traffic or bully your way in. On the English system, those entering the circle must yield to those already in the circle, so cars entering the circle from side roads have the same priority as those entering from larger routes. And why should through traffic have the edge, anyway?

Italy uses yet another system on many of its highways. Americans are rather formal about adding and dropping lanes along a highway. If we add a lane, we need space for the transition, and when we drop a lane, we need space for that transition.

The Italians are much more informal. When they have a short space that allows a little more pavement width, they just put it in. They may add a lane, or just widen the lane so that cars can pass within lanes for a short stretch, all the while flashing their lights at oncoming traffic. It’s somewhat unnerving for an American driver, but it has the advantage of adding a little road space at low expense. In America, we would add a full lane with transitions if we could afford it, or do without.

American-style highways consume a tremendous amount of land; in metropolitan areas, space is expensive and difficult to acquire even when you can afford it.

But, for the last half century, America has emphasized the interstate - no traffic lights from coast to coast, high speed, limited access and designed for worst-case safety situations.

We don’t like compromising safety in order to increase highway capacity. But highway engineers face the tradeoff all the time. One of the key ways we can increase mobility without sacrificing safety is to look for lower-speed, lower-scale highways that are safe and efficient for moving local traffic. These would include parkways and other smaller-scale highways that have fallen into disfavor during the interstate era. But the interstate is now finished. And we can’t afford to build interstate-like facilities to satisfy every local traffic need.

Congress has nearly completed work on a bill creating the National Highway System, the successor to the interstate. In the next year or so, it will need to reauthorize the federal highway program, which lapses in 1997. Part of this debate should be whether some of the canons of American highway policy ought to be reexamined.

Smart cars, smart highways and better transit and ridesharing will all provide some help in mitigating congestion. But the private automobile is likely to continue its dominance. While the English or Italian systems may not be right for us, they do show that there are alternative ways to design highway systems. Since most traffic is local, and most gas taxes are earned in local travel, maybe the highway system ought to be designed to serve local traffic well. It won’t be easy or cheap but it may well be worth the effort.

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