Unclogging Busy Roads and Bridges to Keep America Moving
Keeping vehicles moving along heavily-traveled highways is a constant challenge for transportation agencies as population growth continues to outpace transportation systems, particularly in urban areas. And keeping traffic moving during reconstruction projects is even more challenging.
Today, many interstate routes serve as the primary corridors for commuters, long-distance travelers, and truckers carrying freight. But many of these vital corridors are seriously congested. During the past 20 years, the annual delay per peak traveler on interstates and the amount of wasted fuel has nearly tripled. For trucks carrying freight on busy commuter routes, traffic congestion means increased travel time and costs causing less reliable pick-up and delayed delivery times.
Interstate 95 from Houlton, Maine, to south Miami, Florida—sometimes called the east coast’s Main Street—is the longest north–south interstate route, passing through 15 states. To keep pace with constant traffic growth and related congestion, many states have invested in upgrading their segments of this east coast transportation lifeline.
The Delaware Department of Transportation (DelDOT) widened a four-mile stretch of I-95 that carries nearly 230,000 vehicles per day with no alternative routes for interstate travel or construction detours. In 544 calendar days, DelDOT widened the corridor without closing any lanes during peak travel while minimizing impacts to all adjacent wetlands. DelDOT used a cost-plus-time bid process to speed up construction, reduce the impact on the traveling public, encourage innovative construction techniques, and reduce traffic control costs on the $89 million project.
In Florida, the Department of Transportation’s 95 Express project built high-occupancy-toll lanes (HOT) with congestion pricing in the Miami-Dade/Broward County area to relieve chronic congestion. The $62.9 million project included innovative design, a transportation demand management system, rapid transit improvements for dedicated low-emission buses, electronic toll collecting systems, aggressive community outreach, a comprehensive signage plan to inform drivers about HOT-lane access and pricing, and a three-language marketing strategy. Existing highway lanes and shoulders were narrowed and reconfigured to add a new HOT lane in each direction within existing rights of way. 95 Express established a carpool registration process to enhance enforcement and reduce the number of vehicles on the road.
As part of its I-95 New Haven Corridor Improvement Program, the Connecticut Department of Transportation reconfiguring two interchanges into one, added two travel lanes on each side of the highway, replaced five bridges, constructed one new bridge, and added full inside and outside shoulders and a new median barrier along a congested one-mile stretch of I-95. The $75 million project was finished nine months ahead of schedule.
On the other side of the country, two states carried out successful projects to ease traffic congestion and improve mobility on busy Interstate 5.
The Washington State Department of Transportation’s I-5 Everett Freeway Expansion project widened 18 bridges, built five new bridges, added more than 11 lane-miles of high-occupancy-vehicle (HOV) lanes, built a new interchange, and reconstructed two more—all to unclog a notorious traffic chokepoint. The six-mile segment of I-5 is the major north–south backbone of Snohomish County’s transportation system, built to carry 60,000 vehicles per day. It now carries an average of 170,000 vehicles per day. The project successfully eliminated chronic stop-and-go conditions with drivers saving an average of 8 to 10 minutes on their daily commutes. The project also added the latest intelligent transportation system (ITS) features to capture traffic volumes for online traveler information.
The California Department of Transportation repaired drainage systems and replaced pavement on a busy section of I-5 in downtown Sacramento that carries more than 190,000 vehicles each day. The work was completed in 71/2 weeks by completely closing one side of the freeway twice during the duration of the project. During construction, more than 3.8 million trips were detoured with delays averaging only 5 to 10 minutes.
Many other transportation agencies have completed successful projects to ease chronic congestion.
The design-build Glenn-Bragaw Interchange project in Alaska eliminated severe congestion, delays, and rear-end collisions. The Alaska Department of Transportation and Public Facilities built a grade-separated intersection with three lanes in each direction and new ramps to ensure smooth traffic movement through the busy intersection—even with projected growth from 50,000 vehicles daily to 100,000 over the next 20 years.
Reconstruction of an interchange along with an extension of the high-occupancy-vehicle (HOV) lanes on I-85 at Gwinnett County in Georgia improved mobility. Post-construction data shows that traffic speeds have increased closer to standard limits even during high-commuter time periods—and even though typical traffic volumes are now 8 percent higher than before construction.