Question

During the evening of November 24,2004 , an 18 -wheeler truck flipped over, forcing the closure of the westbound lanes of I-70 in Glenwood Canyon, Colorado. I-70 is the principal east-west route across the mountains west of Denver, and a high volume of traffic was expected the next day, Thanksgiving. That accident probably saved lives because at about \(7: 30\) the next morning, just up the road from the overturned truck, part of a cliff about 390 meters (1,300 feet) above the highway collapsed. A slab of rock 30 meters ( 100 feet) high by 10 meters ( 33 feet) across by 6 meters ( 20 feet) thick crumbled and crashed onto the roadway right between the accident scene and waiting vehicles. The massive landslide smashed holes in the highway and shut down the route for more than 24 hours. The rockfall damaged two bridges, mangled guardrails, and battered retaining walls. The construction of I-70 through Glenwood Canyon was a challenge because engineers had to replace a two-lane road with a modern four-lane highway in a narrow, deep canyon that also housed the Colorado River. Each day, 17,000 motorists travel the highway, risking injury or death from falling rocks. Two drivers died in separate incidents in 2003 when boulders crashed into their vehicles, and the Thanksgiving example illustrates the potential for significant loss of life from future incidents. Imagine that you work for a consulting company hired by the Colorado Department of Transportation to create a plan for protecting motorists on I-70 in Glenwood Canyon from future landslide hazards. Resources are finite and the budget for addressing the problem is limited. What would you suggest the Department of Transportation do to minimize damage and injury?

Short answer

Prioritize identified hazardous areas, enhance protective engineering solutions, implement monitoring systems, educate the public, and ensure regular maintenance.

Step-by-step solution

Identify the Problem Areas

Begin by analyzing the regions of I-70 in Glenwood Canyon that are most susceptible to landslides. Determine locations with steep slopes, weak rock structures, or frequent rockfalls. This helps prioritize areas for intervention.

Assess Current Protective Measures

Review existing protective measures such as barriers, retaining walls, and netting. Identify any deficiencies or areas where these measures are insufficient to handle potential landslides.

Propose Engineering Solutions

Suggest engineering methods like rock shed construction, slope stabilization through bolting or shotcrete application, and installation of advanced rockfall barriers, considering the budget constraints. These solutions aim to contain or redirect rocks before they reach the highway.

Implement Early Warning Systems

Recommend the installation of monitoring systems such as ground sensors, drones, or cameras to detect potential landslides in real-time. These systems can trigger alerts to close roads preemptively and help avoid traffic during rockfall events.

Develop a Public Information and Response Plan

Create a strategy to inform motorists about the potential hazards through signage, apps, or radio broadcasts. Include plans for emergency response to quickly clear roads and assist motorists in case of rock falls.

Prioritize Preventive Maintenance

Develop a maintenance schedule focused on clearing debris, inspecting structural integrity, and replacing worn-out barriers. Continuous maintenance ensures that protective measures remain effective.

Key concepts

rockfall engineering solutions

Rockfall engineering solutions are designed to mitigate the impact of rocks falling from slopes typically found near highways in mountainous areas like Glenwood Canyon. These solutions aim to prevent rocks from reaching the road, thereby protecting motorists from serious accidents. Common methods include:

• Rock Sheds: These structures serve as tunnels that deflect falling rocks over the highway, preventing damage to the road and vehicles.


• Slope Stabilization: Techniques such as bolting, which involves inserting rods into unstable rock, or applying shotcrete (sprayed concrete) to reinforce the rock face, are used to stabilize slopes and prevent rockfall.


• Rockfall Barriers: Barriers are designed to absorb and stop rocks before they can reach the road. Advanced barriers can withstand the impact of even large boulders.

These solutions not only provide immediate protection but also contribute to long-term safety. Engineers must consider factors such as the geography of the area, the size of potential falling rocks, and budget constraints when choosing the appropriate method.

landslide early warning systems

Landslide early warning systems are critical for preventing rockfall-related accidents and ensuring road safety. These systems use technology to detect potential landslides before they happen, giving time to respond and protect motorists.

• Sensors and Monitoring Equipment: Ground sensors that detect soil movement and pressure can provide real-time data on slope stability. If abnormal activity is detected, warnings can be issued.


• Drones and Cameras: Aerial surveillance via drones and fixed cameras can continuously monitor rock faces for changes or signs of instability, allowing for rapid assessment and response.


• Automated Alerts: Systems can be configured to send alerts via apps, text messages, or road signs, giving motorists and authorities timely warnings about potential rockfall risks.

The integration of these technologies helps minimize the risk of road closures and accidents by allowing preemptive actions when a risk is detected.

road safety in mountainous regions

Road safety in mountainous regions requires a comprehensive approach, given the unique challenges posed by such environments. Falling rocks, narrow roads, and steep slopes increase the risk for motorists, demanding targeted safety measures.

• Protective Infrastructure: Developing robust infrastructure like strong barriers, retaining walls, and adequate drainage systems can prevent accidents and improve safety.


• Traffic Management: Proper signage, speed control measures, and road layout can help manage traffic flow safely through dangerous areas.


• Motorist Education: Informing drivers about the potential hazards and how to react can greatly enhance safety. Campaigns and educational materials should focus on safe driving practices specific to these environments.

By implementing these measures, transportation departments can significantly reduce the risks associated with driving through mountainous areas and improve overall safety for everyone.