A curvaceous conundrum

Safety improvements on California S.R. 299 hit a direct line toward success

Safety Article June 05, 2017
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California’s S.R. 299 is the main east-west artery between U.S.101 in Humboldt County on the northwest coast and I-5 in the northern Sacramento Valley.

 

Although it is one of the most beautiful drives in California, nestled within dense forest land, the Buckhorn Grade portion of the route has long been one of the Golden State’s more difficult roads to navigate. With its tight switchback turns, steep grades and narrow lanes, even those who travel it daily were relieved when funding was finally made available to make significant improvements after nearly eight decades.

 

“State highway officials have had improving this portion of road on the drawing board since the early 1930s,” said California Department of Transportation (Caltrans) Project Manager Chris Harvey. “It just all came down to securing an enormous amount of money for what was going to be a huge multi-year project, unlike anything this area has seen.”

 

It was unlikely that Caltrans District 2 could secure funding for the entire 7-mile stretch of Buckhorn Grade at one time, so the improvements would need to be broken up into fundable sections. Even though the improvements would be constructed in smaller segments, an environmental document needed to address cumulative impacts for the entire Buckhorn Grade corridor. Environmental studies began in the late 1990s.

 

Crews were persistently challenged with steep grade work.

 

Assessing the need

The Buckhorn Grade Improvement (BGI) project funded the environmental studies for an operational improvement project, but there was no funding for actual construction on the corridor. As part of the BGI project approval process, traffic studies were conducted. It was discovered that there was a higher-than-average accident rate for some segments of the corridor. As a result, District 2 was able to secure funding for three small safety projects. However, each of these projects only corrected one or two curves. There were more than 90 curves along the Buckhorn Grade.

 

As luck would have it, in 2004 Caltrans was challenged to expedite safety projects statewide. District 2, along with the North Region, elected to form a multifunctional safety team made up of highway designers, environmental coordinators, right-of-way agents and project management. The team developed goals to streamline the project development process. It immediately went to work on the Buckhorn Corridor safety projects. Its main goal was to take a project from conception (traffic identifies an accident concentration) to a programmed project to ready-to-list within 18 months. That was only if environmental permits were not needed or new right-of-way was not required. If right-of-way and permits were required, the goal was 36 months to ready-to-list. The team worked directly with the Traffic Department to develop the project concept and Project Initiating Document (PID), and completed fleshing out the project and environmental approval process. The team streamlined the project reports and other supporting documents, making them much easier for executive management to read and understand, and got the go-ahead to break ground on the first three smaller safety projects.

 

Going bigger

Near the completion dates of the three small safety projects, which had been executed to specs, the first of two larger safety projects, named Middle of Buckhorn (MOB), was programmed.

 

This project was approximately 2 miles long and about half way up the grade of the corridor. The safety program funding available for this project was only about $12 million. With this amount, District 2 really could not do a complete realignment with all the required safety features required. However, an extraordinary event happened: the economy collapsed in 2008, sending the entire nation into a recession.

 

Prior to the recession, construction projects were bidding at 30-50% higher than expected bids. With the recession, construction prices rolled back to levels not seen since the early 1980s. Earthwork went from $20 per cu yd to as low as $4 per cu yd. The cost to realign MOB prior to the recession was about $60 million. After the onset of the recession, the cost went down to about $15 million. Yet despite these sudden advantages, the project funding team was still short.

 

The success of the minor safety projects already in hand was a prime example of the power of great partnerships, and it set a exemplar course for pursuing the MOB project. Caltrans District 2 was able to meet the needs of Shasta, Trinity and Humboldt counties and the needs of drivers commuting daily from Redding to Weaverville by combining efforts with the local agencies. In partnership with the three counties, several of the safety projects were split-funded between the Caltrans Operational Improvement Program and High Priority Projects (HPP) funding, with Humboldt County as the implementing agency. Without this pooling of resources and the partnership between Caltrans and the counties, these projects would not have been realized. With the aid of local counties, an additional $3 million was secured through HPP funds to extend the climbing lanes within the MOB limits. The project was listed, bids came in 20% below the engineer’s estimate, and the project was awarded and constructed.

 

Soil erosion at grade decline was a primary challenge.

 

Further areas of concern

As MOB was designed, the traffic department identified two more accident concentrations below the project limits. The team developed a plan to realign this section, which included covering the old road up to 70 ft deep. Safety program funding allowed only about $15 million for these segments, forcing the team to expedite the approval process and design.

 

“As it turned out, the nation stayed in a deep recession for several years,” said Senior Design Engineer Al Trujillo. “As hard as it was on the country, this allowed us to get this fifth project, called Twin Gulches, listed and constructed, with our local partners again contributing some funding to construct a climbing lane.”

 

In addition to the financial challenge of funding the Twin Gulches improvements, it was a design/construction challenge that required some extremely creative thinking on the part of Caltrans engineers from the very beginning. The new alignment embankments required installing 1,040 ft of drainage structures in the gulches and covering the existing roadway with up to 70 ft of material at two separate locations, while still allowing traffic to travel through the area. Moving traffic through the construction safety zone required a very detailed staging plan. Some of the early solutions considered complete route closures with detours using alternate state routes. Another option was to close the road for up to four hours at a time. These solutions were very unpopular and were deemed to be too costly to the public. The alternate routes that could handle the type of traffic that S.R. 299 carries were hundreds of miles away—Rte. 20 to the south and Rte. 199 in southern Oregon.

 

The safety team developed a five-stage construction scenario that would provide for traffic moving through the construction zone safely. Even with the multiple stages developed by the design engineers, some of the planning was modified during construction to provide for a two-lane detour to minimize the time the roadway would be under 24-hour controlled traffic.

 

Material was used to control surface erosion.

 

The “Capstone”

The final financial challenge would be that of funding the remaining segments of the corridor. The first five projects made improvements to approximately half the 7-mile Buckhorn Grade.

 

“This was the ‘wow’ moment for our department,” said Trujillo. “Half the realignment of Buckhorn was under construction.”

 

District management went to Sacramento and lobbied to secure funding to complete the remainder of the Buckhorn Grade. The $25 million the district received for what was known as the Capstone Project was very tight and was based on low construction unit prices. Again, the only hope was to get this segment programmed, cleared and listed while the economy was still flat. The project was programmed, designed and listed between 2010 and 2013. Bids opened within 20% over estimate.

 

Once construction for the Capstone Project got underway, assuring that traffic could move safely through the 7-mile-long construction zone—where the contractor was excavating 200 ft above moving vehicles—became a serious concern. Earthwork operations involved bulldozers, excavators, scrapers, on- and off-highway trucks and as many as 50 workers, all of which were attempting to move as much as 15,000 cu yd of material each day.

 

Resident Engineer Sergio Mendoza was getting feedback from all sides. “The public, of course, didn’t want the road closed and weren’t happy with the delays. But the contractor, Steve Manning, was worried about the safety of his crews during this improvement project.”

 

Mendoza, working with both the Caltrans Traffic Management Center Supervisor and Steve Manning, came up with a solution that allowed the contractor to delay traffic up to 45 minutes while starting the above excavations. Excavations high on the slopes were only partially dug out to create a trench allowing the contractor to excavate within the trench while protecting traffic. Once the elevation of the trench met the final roadway grade, traffic was rerouted to allow the contractor to finish the roadway cut and complete any roadway embankment over the old roadway and drainage work.

 

Staying in touch with the public

Daily commuters between Redding and Weaverville knew there was a light at the end of a very long tunnel. A massive public relations campaign was launched, including mailers with maps showing how long each project was expected to take and the delay times drivers should expect. There also were daily email blasts, social media updates and even a hotline created so motorists could call in for project information. Weaverville resident Sarah Sheetz has been commuting from Weaverville to Redding for several years. “As a daily commuter, the construction delays tested my patience,” she said. “But the new road is wonderful! The elimination of curves and the addition of the passing lanes has improved safety tremendously.”

 

Getting people moving along the grade was not the only issue. The project also introduced environmental concerns. Early in the project development phase, Caltrans was informed that the California Department of Fish and Wildlife required project planners to provide an animal crossing. The logical solution was to use the deep creek culverts. In order to use these culverts, they had to be a specific ratio size of area in respect to their length of the culvert to allow natural light through the culverts to encourage the animals to cross. Engineering calculations based on this criteria determined that the 800-ft-long barrels would have to be approximately 50 ft in diameter, which made it impossible from a cost-resource standpoint. The solution turned out to be the installation of two animal crossings high above the creek, about 20 ft below the roadway pavement. Cameras were installed to monitor the usage. (Thus far, pictures have shown evidence of at least 10 different animal species using the crossings, including bears, foxes, squirrels and ringtail cats. Even an owl was filmed flying through the crossing.)

 

Crews were working with multiple material types, including decomposed granite and metamorphic rock, which presented unique respective challenges.

 

Upping the intensity

The sixth and final project, Capstone, proved in the end to be the most intense. It required moving approximately 1.3 million cu yd of material. The upper reaches of the project were comprised of decomposed granite, a highly erodible soil type which required extraordinary measures to reduce the erosion potential. The lower, or eastern end, of the project, was made up of metamorphic rock. To reduce erosion potential and to improve overall stability of the embankments, the rocky material from the lower reaches was transported to the upper areas to encapsulate the embankments of mainly decomposed granite soil. To further ensure control of surface erosion, Coir fabric material was embedded into the embankments and then draped over the exposed surface. Mulch derived from vegetation removed for the project was spread over the flatter slopes to also reduce surface erosion. Maintainable sediment traps were constructed below major cut slopes to trap material before reaching waterways.

 

When all the improvements on the Buckhorn Grade were completed, approximately 3 million cu yd of earth had been excavated, and the roadway length was reduced by 1.4 miles, from 7 miles to 5.6 miles. What used to take the public 20-30 minutes to travel now takes only 10. The recently completed sequence of projects reduced the number of curves on the roadway, increasing design speed, improving passing opportunities, increasing sight distance, providing standard shoulders, improving the super-elevation rates and transitions, and making slopes more recoverable to improve safety.

 

Not only was traveler safety addressed, but worker safety as well. Crews are now able to use consistent shoulder widths and catchment areas to respond to traffic- and weather-related incidents on the grade, which in the past often required temporary closures.

 

Other project features include a soft median, an improved clear recovery zone and increased sun exposure to mitigate ice and snow conditions. Those who used to avoid the road entirely because it was notorious for making people carsick can now cast that worry aside. But perhaps the best news for taxpayers and Caltrans alike was the final price tag. The total cost for all work including support, right-of-way, construction and environmental clearance was approximately $90 million. Prior to the Great Recession that estimate had been more like $250 million.

 

The new alignment in this area had many engineering challenges. But in the end, Caltrans working with six different contractors on each project were able to use creative design and construction methods to meet the project need and purpose, constructing the projects within budget for planned work and within the environmental requirements.

 

About the author: 
Coder is with Caltrans District 2.
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