Welcome! The purpose of this slideshow is to outline the Parks Highway Alternative Corridor Development Process. Using maps and graphics, this slideshow will walk you through the corridor development methodology one step at a time.
Please scroll or use your keyboard arrows to navigate through this information. You may also use the links on the left and right of the screen to navigate through slides.
Note: To maximize your experience with this slideshow, it is best viewed from a laptop, desktop computer, iPad, or tablet.
On September 28, 2010, the Steering Committee recommended the project study area focus south of the Parks Highway Alaska Railroad corridor. North of the existing Parks Highway the project team found substantial obstacles to corridor development. Residential and commercial property is more densely developed north of the Parks Highway, including about twice the number of parcels as south of the Highway. The chain of lakes extending northeast of Wasilla also severely limit options for corridor development.
Because the likelihood of developing a viable corridor north of the Parks Highway was very low, the Steering Committee determined that continuing study in that area would consume unnecessary public resources and time. The study area was therefore limited to the area south of the Parks Highway and Alaska Railroad, as shown on the map.
The next step for the project team was to collect information on the natural and human environment within the study area. Geographic Information Systems (GIS) were used to collect information for mapping and planning purposes.
GIS technology uses an additive map layering process that enables planners to identify areas suitable and unsuitable for potential transportation corridor development. The information collected was selected based on constructability issues most important to highway development, environmental regulations, and community impacts. Readily available GIS data and other information that could be analyzed and displayed on maps included the following:
The purpose of a GIS “suitability” analysis is to determine where land is most and least suitable for transportation corridor development. Topography, land use classification, developed land, assessed property value, subdivisions, hydrography, and wetlands include resource categories that were mapped, weighted, and prioritized according to their respective importance to the final corridor decision. Highly weighted resource categories included severe slope limitations, high cost land, lake features, the highest function wetland classes, and special sites or community facilities.
The weighted values of multiple resource categories were then added together, cell-by-cell, to produce the final suitability map. Areas weighted highly in more than one resource category may overlap and exceed the high value of 15 (shown in red). Low values (shown in blue) represent areas with few impacts and were best suited for corridor development.
This type of mapping provides an intuitive method that allows planners to consider multiple layers of complex information at the same time. The following slides illustrate this map and data layering process, step by step.
Next, wetlands are added to the map. Wetlands are protected by the Clean Water Act. Construction in wetlands requires special permits from the U.S. Army Corps of Engineers to ensure that these areas are not needlessly impacted. Wetlands are divided into four categories based on their typical functions; these categories range from 1 (highest functioning) to 4 (degraded or lowest functioning). Highest functioning wetlands are shown in red, with lower functioning wetlands shown in yellow.
Developed Land is added next to the map, shown in yellow. This data was obtained from the 2013 Mat‐Su Borough Division of Assessment parcels GIS dataset and shows the extent of current development in the study area.
Steering transportation corridor development away from developed property has many advantages. Vacant land tends to be less expensive than already developed property, which reduces the right‐of‐way acquisition cost of the project. By avoiding developed areas as much as possible, impacts to existing businesses and residents can be minimized, fewer relocations are necessary, and the likelihood of other social concerns such as noise, vibration, and visual impacts are reduced.
Total cost (land value/acre + building value) is added to the map next. The 2013 Mat-Su Borough Division of Assessment data is used to determine a total property value for each parcel within the study area. The MSB data includes the tax assessed land and building values for each parcel.
Lastly, “special sites” are added to the suitability map. Special sites include community facilities and public sites that may include sensitive information. These sites should be avoided if at all possible. Facilities in this category include:
This slide shows the final Composite Suitability Map. The colors range from blue to red: darker blues representing the land most suitable for corridor development, darker red areas showing areas to avoid.
The highly weighted wetland and water features (constraints to development) are clearly visible in red on this map. Moderately weighted developed areas are visible in shades of yellow and orange. By looking at the blue areas on the map we see, according to the suitability model, land that would incur the least amount of impact as the result of transportation corridor development.
Guided by design criteria and the suitability map, the next step in the GIS analysis was to delineate a range of preliminary corridors. Starting with the eastern terminus at the Seward Meridian Parkway, corridors were drawn to the west simply by staying in the blue as much as possible. This approach of following the blue and avoiding the red is a very intuitive method of drawing a route that takes into consideration multiple layers of complex information, all previously analyzed in the suitability analysis. Because the suitability model weighted resource categories relative to their importance to the final decision, the blue areas show routes with the least amount of potential impact or cost to project development.
This delineation process produced 20 initial corridor alternatives. These preliminary corridors (at 450 feet wide) are shown on this map. The corridors are displayed on top of the suitability mapping results.
To evaluate the first set of preliminary alternatives, the project team performed an impacts analysis using GIS data. Impact categories such as wetlands, cost/acre, and land use were intersected with the corridor footprint, and the result is a quantitative measurement of impact that is specific to each alternative and precisely located.
Using the information from the impacts analysis, alternatives can easily be evaluated and compared side‐by‐side. Alternatives with substantially higher impacts in any category were examined more closely and further refined.
A decision matrix is an evaluation tool that prioritizes a range of corridor alternatives. The alternatives were evaluated using a list of criteria that were weighted based on their respective importance to the final decision. The impact analysis conducted earlier provided the data needed to quantitatively compare the alternatives.
An extensive public involvement process has been completed for the project and is still under way. Your input is valuable! Corridors are revised based on public input and new information. This map shows a revised set of corridor alternatives updated February 2014. Recommended corridors are still under study by the project team.