“难以置信”。这就是他叫明沟Wooten Corp .)vy highway project manager Matthew Davis characterizes the daily crush of more than 106,000 vehicles along a 13-mile stretch of Interstate 40 outside of Raleigh. And it’s the main reason why his company is in the midst of a four-year, $360-million design-build corridor upgrade that will add two travel lanes in each direction, 15 new and revamped bridges, and two diverging-diamond interchanges.

Davis adds that not even a pandemic-altered economy offered much of a respite for the project, which got underway in fall 2018.

“The traffic eased for a few months last spring, but it quickly came back,” he says.

North Carolina Dept. of Transportation resident engineer Robert Bullock explains that while commuter traffic accounts for much of the routine volume between the I-40/I-440 junction and NC Route 42 in Garner, congestion significantly worsens during spring and summer with the addition of travelers bound to and from the state’s beaches.

由于走廊的交通量预计到2040年将增加65％，因此必须尽快实施升级，而不必限制I-40的现有容量。

“That made maintaining all lanes of traffic during peak travel a priority from the outset,” Bullock says.

To tackle the project’s complex traffic maintenance and phasing issues, S.T. Wooten and design partner RK&K divided the corridor work into six separate work areas that are being executed west to east.

Davis says the strategy minimizes the potential for disruptions and helps synchronize concurrent activities, from clearing and utility relocations to integrating a new 1,050-ft-long flyover structure at the I-440 interchange to accommodate wider eastbound lanes.

但是，尽管经过精心测序的车道班次使走廊肩膀和中位数可以安全地容纳大量扩大和桥梁的重建工作，但项目团队仍然受到挑战，以防止材料供应卡车和其他建筑工具的数量添加到添加到拥塞。

Fortunately, the old real estate adage about the importance of location can sometimes work for construction. In this case, the project’s western section runs near an industrial cluster that includes a quarry and concrete and asphalt plants. Adapting an overpass with temporary fabric ramp structures gives supply trucks direct access to median and shoulder work areas. Davis says the interim access point will support construction activity along more than half of the corridor.

“We have only small windows when we can haul materials on the interstate itself, so the temporary access helps expedite the project and makes things safer for everybody,” he says.

随着扩大工作进入走廊的东部部分，S.T。Wooten将采用创新的材料运输技术，该公司用于另一个Raleigh Area I-40扩大项目，这是一个跨高速公路的280英尺长的输送机系统，将相邻沥青工厂与中位数工作区连接起来。配备加热的油线以保持热混合温度，传送带还将将石头引导到等候卡车上。

“As with the other measures, it keeps a significant number of construction vehicles out of the travel lanes,” Davis adds.

Innovative interchanges

Not all the project’s challenges are at highway level. A busy conventional interchange at NC Route 42 is being converted into a diverging diamond configuration, with the existing interstate overpass replaced with two 330-ft-long bridges.

While the goal is to provide safer, more efficient traffic movements in the densely developed area, RK&K design manager Brandon McInnis says the close proximity of businesses left little space to incorporate new lane configurations, a sequence that had to be revised to accommodate multiple underground utility relocations.

“That’s why we decided to do two new bridges across the interstate,” McInnis says, adding that along with helping with construction staging, the longer dual structures will also make it easier to incorporate 1.4 miles of new two-lane collector/distributor roads that will serve both the NC 42 exit and nearby Cleveland Road at the project’s western terminus.

Although diverging diamond interchanges are relatively new to North Carolina’s road projects, the I-40 corridor will have the distinction of hosting two such structures. Just after the contract for the widening project was let in summer 2018, Amazon announced that it would construct a 680,000-sq-ft distribution center on Jones Sausage Road, which at the time connected with I-40 with a conventional diamond interchange.

Given the anticipated high volume of heavy truck traffic to be generated by the distribution center, NCDOT modified the S.T. Wooten/RK&K widening contract to include an interchange upgrade that had to be expedited in order to coincide with the new facility’s scheduled late 2020 opening.

麦金尼斯说，由于现有的350英尺长的互换桥已经足够宽，可以容纳五个旅行车道，因此项目团队可以将钻石配置融合在一起，只有较小的结构修改，而无需额外的通行权。

“We’re installing a median railing to separate traffic and a new sidewalk/pedestrian railing on one side,” he says. “The interchange is ready-made for Amazon’s trucks and workforce as well as future development in the area.”

戴维斯说，项目团队能够快速将最后一刻的交换升级升级到整个项目的能力是对设计建设的信用，该构建以许多其他方式证明了其价值。他引用了一个机会，可以推进计划中的车道转移到高速公路的外部部分，以便在该部分的中位数上进行工作。

他说：“能够与工程师联系并进行更改，这将在计划和现实世界不匹配或有人有更好的主意时进行更改。”

天气困难

Design-build has also helped the team find a measure of schedule flexibility to handle unexpected challenges. Rain events have occurred with increased frequency and intensity over the past two years, slowing progress in some parts of the project as areas dry out.

Bullock recalls one rainstorm that caused Swift Creek to rapidly fill its floodplain approximately 20 ft below the project’s new 270-ft-long bridges. Although the structures weren’t threatened with flooding, the event offered a reminder that road and bridge infrastructure needs to be ready for the uncertainties of a changing climate.

“The pavement design raises the interstate by approximately 1 foot, which will help,” he says. “We’re also installing a lot of bores and culverts that will help with drainage and minimize flooding.”

戴维斯不确定持续的降水中断是否会影响该项目预定的2022完成日期的进度。另一个复杂的因素是在走廊东端的公用事业工作缓慢进展。麦金尼斯（McInnis）引用了一个看似简单的气体传输线搬迁，该搬迁变成了重大变化，需要新的许可证和施工测序的变化。

“One of the biggest lessons from this project is the need to get as much information from utilities during the proposal process so you can get a better idea of the time needed for that work,” he says,

Bullock补充说，尽管公用事业问题存在问题，但在公众对项目进度的看法方面，新的I-440天桥桥的开放是一项重大成就。那以及新的纹理噪声墙和其他功能的安装提供了视觉证明，可以预示更好的旅行体验。

他说：“一切都完成后，这绝对是另一个走廊。”