February 28, 2022 | Vaughn J. Mantor
Rest easy; there’s no fight – figurative or literal – between Missoula and the behemoth of the East.
It’s about traffic.
Missoula has been growing. From 1990 to 2021 Missoula’s population grew 58.5%, from 48,430 to 76,784. That’s about 9,500 new households. That’s more than 10,000 additional cars. The roadways and traffic flows that worked in 1990 are not sufficient for 2022 and beyond. So a few years ago, the city government began to plan changes to the area North of the Clark Fork River near the Higgins Avenue Bridge as a part of Missoula’s redevelopment plan.
Documents written by the engineering company HDR show the extent of the area slated for change. A map of the area, extracted from the HDR documents, is shown below. The broad, pink lines show the primary traffic routes. The total length of the roadway affected by the proposed changes is 1.4 miles and includes eleven intersections – identified by the blue, dashed circles – all of which are on primary vehicular routes.
In projects like this, the number of competing and interrelated interests increases exponentially as the size of the project. In this medium-sized project, just the traffic design must take into account the interrelated concerns of:
intersection geometry,
turning movements,
the number of accidents at intersections and roadway locations,
parking,
pedestrians’ and bicyclists’ movements,
public transit operation,
air quality regulations,
the very close Interstate 90 connection,
and the concerns of the residents.
Even simple-looking projects are complex.
For the reasons outlined below, the city of Missoula and the surveyor, IMEG Corp., asked Verify 3D to laser scan the eleven affected intersections.
No one who is familiar with such urban projects will be surprised that surveying the area is an essential part of the work. However, many might be surprised to learn that the laser scanning of the area preceded the survey. The mathematics we apply to the data obtained from laser scanning makes this possible, even desirable in some cases.
How does this work? When Verify 3D laser scans the area, we pay close attention to certain, immovable locations such as the corner of a building’s foundation, and we leave permanent markers for the surveyors. The permanent markers are mathematically connected to all the laser scanning data. When the surveyor determines the coordinates of the markers, based on the coordinate system in use for the area, e.g. state plane, then all the laser scanning data is mathematically adjusted and aligned with the surveyor’s work. The wonders of computers.
But the question might be posed, “Why laser scan at all if surveying is to be done?” Safety. Accuracy. Completeness.
Safety. As we have done on similar projects, we can laser scan when traffic is light, and because we almost never leave the public sidewalks, we have no effect on traffic; no orange cones, no closure of lanes. (See the 90 second video, Hot, Cold, Far, Dangerous here.) This allows the surveyor to focus his attention on the precise alignment of the coordinate system, and then the laser scanning data, aligned to the coordinate system, fills in many details that would be tedious or time consuming or dangerous for the surveyor to do.
Accuracy. A million measurements per second, each with an accuracy of 1/4 inch (6.4 mm), gives everyone working on the project a much more accurate understanding of the area. For example, as you look at the first image below, from Google Earth Pro, can you tell exactly how long is the opening below the curb that directs water into the storm drain? It’s the part that’s painted yellow under the stop sign. And what is its spatial relation to the manhole cover? Looking at the point cloud (the next image) or the CAD model on a computer screen, a couple of mouse clicks answer these and many more questions.
Completeness. Notice the irregular, overhead wires in the images above and below. These are generally not surveyed, and usually not needed in the CAD models of intersections and roadways, but they are in the point cloud, along with everything else. So when engineers plan and constructors erect, they know what heights may lead to problems at any intersection. The same goes for overhead branches and signal lights. And all of these questions are answered without the need for a trip to the site. The savings in travel time alone are substantial.
Another advantage of this technology. There is no more accurate, faster method of building the computer models that have become essential to design, engineering, and construction in civil and urban settings. Any other approach is deficient in one way or another.
Hey, New York! Missoula is using the most advanced, sophisticated technology available anywhere to plan their downtown traffic flow and the changes to their town. The Big Apple has nothing on Missoula, except it does not sit inside the biggest volcano on the continent. (See Faithful to Old Faithful here.)`
If you’d like a personal exploration or demonstration of the ways laser scanning can help you, or if you’d like to speak with one of our clients, see our contact information below.
Because our experience in this technology dates to 2002, Verify 3D knows the most appropriate equipment to use on each project and how to use it for the best benefit to our clients. For this project we used a Leica laser scanner, a P-30, and Leica Cyclone software for registration. Per contract, Verify 3D delivered ReCap point clouds, and an AutoCAD Civil 3D Surface model with feature lines.