When it comes to placing concrete barriers, or K-Rail, the work can be done by cranes or forklifts. But when the wrong tool is chosen for the job, the consequences can be fatal. Colorado state highway officials issued a stop-work order for a rough-terrain crane earlier this month, after the second accident in five weeks took place on the Colorado Springs Metro Interstate Expansion (COSMIX) project.
The CDOT stop-work order applies only to the 30-ton Grove rough-terrain crane. The crane, used primarily on the project to place concrete barriers (or K-Rail), toppled over in both incidents. OSHA is investigating, and area director John Healy made this statement to the Gazette in Colorado Springs, Colo. “We're very concerned when a crane tips over,” he said. “To have two on the same project in a little more than a month is highly unusual.”
Read the full news report here.
In the April accident, in which crane operator Humberto Rodriguez was crushed when the crane tipped over, the crane was being used to move the K-Rail. It was the second incident involving a crane and K-rail in that month. The first happened when a crane in another state struck a power line while performing similar K-Rail work at night.
These incidents can raise awareness among job site decision makers of the hazards associated with K-Rail work and their many options for placing it. While in some cases a crane is the only option for placing K-Rail, crews often mistakenly choose cranes when other equipment might be better suited.
How does placing K-Rail with a crane compare to placing the barriers with, say, a tracked excavator or similar machine? Here are key questions to consider before making that machine choice:
1. Center of gravity
Given the choice between a tracked excavator and a modern rough-terrain crane, which machine do you suppose has a lower center of gravity? Which, then, can better navigate and maintain stability on marginal ground or - in this case - a sloped and turning roadway?
2. Working width
Compare the excavator with the crane again. Which machine typically has the need for room to deploy outriggers on solid ground while under load, and which one doesn't? And even if the crane is within its chart for on-rubber conditions, which machine is more likely to remain upright in the event of an unexpected out-of-level condition?
3. Site conditions
Compared to a tracked excavator, how often are cranes faced with marginal or no outrigger room during K-Rail placement on highway jobs? And which machine is more suitable for roadway conditions such as soft shoulders and uneven ground?
4. Working boom height
When comparing boom heights required in picking and setting the load, which machine requires a high-angle and high boom tip elevation that is more likely to tangle with difficult-to-see power lines, especially during night work conditions? And which machine offers a lower profile and a much greater chance of avoiding power line contact, even when the boom is raised to its maximum height?
5. Load handling
Which condition creates a greater hazard to employees who must maneuver heavy K-Rail when setting the pin: K-Rail that is freely suspended from 15 or 20 feet of wire rope or K-Rail that is closely coupled with a short sling or a direct boom-knuckle-clamp application?
Which machine is more likely to be affected by weather, including wind that could compromise stability in marginal chart conditions?
In marginal conditions on a piece-per-hour basis, which machine most likely has the ability to place more rail in a given amount of time? A crane that requires deployment and retraction of boom sections and outriggers and leveling within 1percent of level every time it moves, or an excavator that operates in typical out-of-level conditions that can freely travel at will?
Both cranes and excavators do great work when the work they do is suited for their intended purpose. But it sometimes takes a decision maker with just a little bit of extra awareness to make sure the match between the work and the machine is the best it can be.