Glenn Highway MP 49 Blowhole Realignment

By: John Fuller

David Darrington Andrew Pavey

CE 425 Highway Design

Spring 2013

Contents Introduction .................................................................................................................................................. 3

Figure 1 - Location Map ........................................................................................................................ 3

Methodology ................................................................................................................................................. 4

Design Controls and Criteria ..................................................................................................................... 4

Consideration of Alternate Routes ........................................................................................................... 5

Horizontal Alignment ................................................................................................................................ 6

Vertical Alignment .................................................................................................................................... 7

Cross Section ............................................................................................................................................. 8

Structural Section ...................................................................................................................................... 9

Earthwork Quantities .............................................................................................................................. 10

Mass Haul Diagram ................................................................................................................................. 10

Intersection Design ................................................................................................................................. 11

Analysis of Results ....................................................................................................................................... 11

Level of Service ....................................................................................................................................... 11

Cost Estimate .......................................................................................................................................... 12

Conclusions & Recommendations .............................................................................................................. 13

Appendixes .................................................................................................................................................. 14

Horizontal Alignment .............................................................................................................................. 14

Vertical Alignment .................................................................................................................................. 15

Superelevation ........................................................................................................................................ 16

Earthwork Quantities .............................................................................................................................. 18

Intersection Design ................................................................................................................................. 19

Introduction

The Glenn Highway MP 49 has a large erosion feature just east of the existing alignment. This erosion feature is threatening the road at two locations. The first location is just north of Farm Loop Road going into the horizontal curve and this erosion feature is within approximately 15 feet of the road, just off the side of the eastern shoulder.

The second erosion feature is just south of Archie Road at the scenic turnout. This erosion feature is undercutting the turnout but is still 100 feet away from the horizontal alignment and does not pose an immediate threat to the Glenn Highway.

This report will discuss Team Awesome's proposed two lane highway realignment to address these erosion problems while adhering to the appropriate design criteria.

Figure 1 - Location Map

Methodology

Design Controls and Criteria

The design controls and criteria for this project come from the Alaska Highway Preconstruction

Manual. Page 1100-14 of the manual contains the design particulars, and the Glenn Highway

MP 49 realignment falls under the rural new construction category.

The sources of the design controls for this project are as follows:

• Highway Capacity Manual 2000 (HCM)

• A Policy on the Geometric Design of Highways and Streets (The Green Book)

• Alaska Preconstruction Manual (PCM)

The specifications used from those sources are as follows:

Design Particular Source Capacity HCM2000 LOS GB Design Vehicle GB Design Speed GB Sight Distance GB Grades GB Alignment GB Roadway Cross Slope PCM Sec 1130 Superelevation Rate GB Ex 3-17, 3-22 Superelevation Transition

GB Ex 3-27,28, Eqn 3-25,26

Foreslopes PCM Sec 1130 Intersection Design GB

The values obtained from the above sources are as follows:

Criteria Value Used Design Functional Class Rural Interstate Design Year 2029

Present ADT 3870 (from

2011) Directional Split (%) 50/50 Trucks (%) 12.5 Design Vehicle Design Speed (mph) 65 Stopping Sight Distance (ft.) 645 Passing Sight Distance Not Allowed Max Allowable Grade (%) 3 Min Allowable Grade (%) 0.35 Min Radius of Curvature (ft.) 1645 Min K Value for Vertical Curves (sag) 157 Min K Value for Vertical Curves (crest) 193 Width of Traveled Way (ft.) 40 Width of Shoulders (ft.) 8 Side Slope Ratio (foreslope) 4:1 Side Slope Ratio (backslope) 2:1

Consideration of Alternate Routes

Alternate routes for this project were considered. The primary alternate considered was to the

west of the historic structures in the project area. The other alternate considered was the

existing route.

The primary reason these routes were not chosen is cost and safety. The alignment to the west

of the historic structures would require larger amounts of right-of-way and the cost would be

significantly higher due to a longer project length.

The existing alignment is unacceptable due to the risk of the erosion feature. The Glenn

Highway is the primary access to everything northeast of Anchorage and an extended closure of

the road is unacceptable.

Due to these considerations the alignment presented in this report was chosen.

Horizontal Alignment

The design of the horizontal alignment primarily came from The Green Book. The primary

design considerations were the erosion feature to the east of the existing alignment and the

historic buildings to the west. The toe of the erosion feature appears to be stable since the

railroad embankment at the bottom of the slope does not appear to have moved.

Geotechnical engineers reviewed this erosion feature and decided that the Matanuska River

does not appear to be the cause of the erosion and natural erosion due to wind and rain is the

most likely cause. This means the base of the existing slope is unlikely to move and an extent of

erosion can be determined based on the soil types in the valley and the road realignment can

be placed outside those limits.

The minimum radius of curvature for the horizontal alignment was calculated to be 1,657ft and

is based on:

• Design Speed – 65mph

• Maximum Superelevation – 0.06

• Friction Factor – 0.11

The stopping sight distance was calculated to be 645 ft. and was taken from the Green Book.

The other consideration for the horizontal alignment was the horizontal sight offset. For the

two horizontal curves used in this design the required HSO was determined to be:

• Curve 1 – 27ft

• Curve 2 – 26ft

The horizontal alignment parameters using this design criterion is presented in the following

table.

Type Length Radius Min Radius

Start Station

End Station

Delta angle

Chord length

External Tangent PI Station

Line 759.99' 5+00.00' 12+59.99' Curve 1 770.23' 1927.00' 1660.00' 12+59.99' 20+30.22' 22.9015 (d) 765.12' 390.33' 16+50.32' Line 340.83' 20+30.22' 23+71.06' Curve 2 792.05' 2023.00' 1660.00' 23+71.06' 31+63.11' 22.4327 (d) 787.01' 401.17' 27+72.22' Line 38.25' 31+63.11' 32+01.36'

The maximum superelevation was set to 6% for the two horizontal curves and the roadway was

rotated about the centerline. The superelevation design can be found in the appendices.

Vertical Alignment

The primary concerns for the vertical alignment was the minimum length of the vertical curves,

the allowable percent grade and balancing the cut and fill.

For the minimum length of curves the following criteria was checked:

• Sight Distance

• Comfort

• Appearance

• Drainage

The results of this analysis are shown below:

Required Length on Criteria (ft.)

A (Grade Change)

Curve Type SSD Comfort Appearance

Profile Curve Length (ft.)

Curve 1 2.94% Crest 567 267 294 589 Curve 2 4.37% Sag 682 397 437 691 Curve 3 2.04% Crest 394 185 204 409

For all three curves the minimum length of curve was based on sight distance criteria. After the

minimum length of curve was determined the vertical alignment was designed in AutoCAD Civil

3d with a focus on balancing the cut/fill.

The surface used for this purpose was derived from the Mat-Su boroughs 2011 LIDAR (Light

Detection and Ranging) collect that was 1’ resolution and this might account for cut/fill

differences between Team Awesome and other groups.

At this point the corridor had been constructed, the assemblies built in AutoCAD and a sight

analysis was run on the corridor to identify problem areas. While AutoCAD did not find any it is

possible that a blind corner may still exist and the vertical alignment may need to be adjusted

accordingly.

Cross Section

Typical cross sections were designed for areas of both cut and fill. The cross sections were

designed to AASHTO specifications for rural principal arterials in level terrain. 2 percent lane

slopes were used for the 12 foot lanes. Four percent cross slopes were used for the 8 foot

shoulders. This meets AASHTO standards but it was revealed to the team after the final design

that the Alaska standard is to continue the 2 percent grade through the shoulder to the edge of

pavement. In cut a 4:1 foreslope and 2:1 backslope was designed. In fill, the slopes for lanes

and shoulders were the same as in cut as well as the foreslope. No backslope was designed for

fill sections. The total right of way width totaled 102’ giving 30 feet of clear space from the edge

of pavement. (See Figure xx)

Figure xx

Using Alaska Department of Transportation standards a structural cross section was designed

for this project. The surface layer consisted of 2” of type II asphalt concrete. The base layers

consisted of 4” asphalt treaded base and 2” of D-1 base course. The final structural layer

consisted of 36” select material type A. (See Figure xx)

Structural Section

Earthwork Quantities

With the proposed alignment for the new road, we determined the amount of cut and fill

required at each station throughout the length of the project. This was done by finding the

total amount of ROW required and using our typical cross sections determining what was

needed at that particular station. At the beginning of the project after station 06+00 there is a

hill that is going to be cut into that will provide a large amount of the fill required for the

project. All of the material from the hill will fill a depression that starts between stations 13+00

and 14+00. After the depression some more cutting will be required between stations 20+00

and 21+00 and at the end of the project will have an estimated amount of 2,000 cubic yards of

material to be removed from the project site. For more details on the calculations used to

determine that amount of cut and fill at each station refer to appendix xxx.

Mass Haul Diagram

The balance points for the length of the project were determined to be at station 06+00, station

15+04, and station 30+90. From figure xx you can see the cut and fill for the whole project. For

this project the length of the project is our free haul distance, what this means is that it will not

cost the client more money to move material back and forth from part of the job to another.

This is important for this design because most of the material that will be cut will be used

further down the project. The overhaul quantity that there will be is the 2,000 cubic yards of

material that has to be removed at the end of the project. This material will be hauled away to

the nearest available dump site which was determined to be approximately 5 miles from the

beginning of the project. The total cost to remove the material came to approximately $79,000

and this was determined by the cost of the truck multiplied by half an hour for time multiplied

by the number of truck loads to remove the material.

Figure xx

Intersection Design

For our intersection design we decided to keep the existing design the same with one

modification. The only thing that was changed is just north of Palmer Fishhook Road we

changed the highway into two lanes instead of three lanes in that section of the highway. The

intersection design can be found in appendix XX.

Analysis of Results

Level of Service

Level of service for the Glenn Highway Milepost 49 project was developed using the Highway

Capacity Software. The program required several inputs to calculate the level of service for the

project. The majority of the data was obtained through Alaska Department of Transportation

resources but, due to lack of time for research, a few assumptions were needed to receive an

output. AADT, traffic distribution, and the percentage of heavy vehicles data was gained from

the AKDOT database. Lane width, shoulder width, no passing percentage, and access points per

mile were calculated from the roadway design. The percent hour factor and terrain were

assumed to be .83 and level respectively.

The HCS test was run twice. The first neglected the passing lane that extends the length of the

project, while the second included the passing lane. The results concluded that project

produced a level of service of B for the design that included the passing lane and a level of

service of a C for the design that neglected the passing lane.

Please refer to appendix XX for the entire output information from the software.

Cost Estimate

The cost estimate for this project primarily consisted of right of way acquisitions and

construction line items.

Right of way acquisitions consisted of acquiring land from two parcels for a total acquisition

area of 12 acres. Land costs in the area of the project averages $13,000 an acre. The total cost

for acquiring the land required for this project totals $156,000.

The majority of the costs for the project were from construction bid items. Accurate costs for

bid items were developed using the average of similar projects in the area and conference with

local engineers. The largest expense for this project is for unclassified excavation at $350,000

followed by asphalt treated base at $296,000. For additional line item costs please refer to

appendix XX. The total cost of line items for the project is $3.07 million.

A 15% contingency is industry standard to account for unforeseen costs. Due to the minimal

time available to prepare this cost estimate, a contingency of 20% was used.

The total for this project included ROW, line items, and the contingency. The total project cost

is estimated at $3.87 million or $7.56 million per mile.

Conclusions & Recommendations

This project needs to go forward in order to keep the Glenn Highway corridor open in the long

term. There is no doubt that this erosion feature is threatening this road and realignment

needs to take place.

There are potentially a few issues that need to be addressed in this design if it were to be used.

These issues include the following:

• A potential blind corner generated from the horizontal/vertical alignments. The grade of the

road may need to be reduced going into and out of the sag curve to eliminate the blind corner.

This would increase the required fill for the project and increase the project cost.

• There is minimal distance between the superelevated sections in this design. Either the tangent

in between the superelevated sections should be increased to 500’ or the tangent should be

removed to turn it into on continually superelevated section of road.

• While the overall cost estimate may be close some of the lump sum costs may be high.

Given the proposed design the road would operate at a level of service of C. This means that

the Glenn Highway would operate at near free flow operations. If a passing lane were to be

included then it would operate at a level of service of B, which would be desirable.

The grade should be raised in the sag curve to increase the sight distance to remove any

potential blind corner and increase the sight distance to where a passing lane is allowed. This

design would also remove the need for longer superelevated sections and remove any issues

with the superelevation. This would increase the cost of the project but make the project much

more worthwhile.

Appendixes

Horizontal Alignment

Vertical Alignment

Superelevation

Superelevation Design - Curve 1

Superelevation Curve Start Station

End Station Length

Left Outside Lane

Right Outside Lane

Transition In Region 10+92.98' 13+15.65' 222.67' Run out 10+92.98' 11+48.65' 55.67' End Normal Crown 10+92.98' -2.00% -2.00% Level Crown 11+48.65' 0.00% -2.00% Runoff 11+48.65' 13+15.65' 167.00' Level Crown 11+48.65' 0.00% -2.00% Reverse Crown 12+04.32' 2.00% -2.00% Begin Curve 12+59.99' Begin Full Super 13+15.65' 6.00% -6.00% Transition Out Region 19+74.56' 21+97.23' 222.67' Runoff 19+74.56' 21+41.56' 167.00' End Full Super 19+74.56' 6.00% -6.00% End Curve 20+30.22' Reverse Crown 20+85.90' 2.00% -2.00% Level Crown 21+41.56' 0.00% -2.00% Run out 21+41.56' 21+97.23' 55.67' Level Crown 21+41.56' 0.00% -2.00% Begin Normal Crown 21+97.23' -2.00% -2.00%

Superelevation Design - Curve 2

Superelevation Curve Start Station

End Station Length

Left Outside Lane

Right Outside Lane

Transition In Region 22+07.19' 24+25.05' 217.86' Run out 22+07.19' 22+63.05' 55.86' End Normal Crown 22+07.19' -2.00% -2.00% Level Crown 22+63.05' -2.00% 0.00% Runoff 22+63.05' 24+25.05' 162.00' Level Crown 22+63.05' -2.00% 0.00% Reverse Crown 23+18.91' -2.00% 2.00% Begin Curve 23+71.06' Begin Full Super 24+25.05' -5.80% 5.80% Transition Out Region 31+09.12' 33+26.98' 217.86' Runoff 31+09.12' 32+71.12' 162.00' End Full Super 31+09.12' -5.80% 5.80% End Curve 31+63.11' Reverse Crown 32+15.26' -2.00% 2.00% Level Crown 32+71.12' -2.00% 0.00% Run out 32+71.12' 33+26.98' 55.86' Level Crown 32+71.12' -2.00% 0.00% Begin Normal Crown 33+26.98' -2.00% -2.00%

Earthwork Quantities

ft (yd3)1 2 3 4 5 6 7 8 9 10

(5) * 10/100 (5) + (6) MassTotal Shrinkage Total Fill Cut Diagram

Station Cut Fill Cut Fill 10 Fill (-) (+) Ordinate(+) percent (-) Cum. Vol

600 473.2 20.47 - - - - - - 0700 787.3 23.89 2334.30 82.15 8.21 90.36 0.00 2243.9 2,244800 809.8 0 2957.69 44.24 4.42 48.7 0.0 2909.0 5,153900 588.5 148.59 2589.54 275.17 27.52 302.7 0.0 2286.9 7,440

1000 452.6 267.29 1928.02 770.15 77.01 847.2 0.0 1080.9 8,5211100 448.9 366.64 1669.48 1173.94 117.39 1291.3 0.0 378.1 8,8991200 791 95.44 2296.20 855.70 85.57 941.3 0.0 1354.9 10,2541300 743.8 787.32 2842.22 1634.74 163.47 1798.2 0.0 1044.0 11,2981400 0 1875.6 1377.33 4931.28 493.13 5424.4 4047.1 0.0 7,2511500 0.1 1556.5 0.19 6355.74 635.57 6991.3 6991.1 0.0 2601600 0 1344.4 0.19 5372.04 537.20 5909.2 5909.1 0.0 -5,6501700 0 1105.4 0.00 4536.59 453.66 4990.3 4990.3 0.0 -10,6401800 1.12 615.95 2.07 3187.67 318.77 3506.4 3504.4 0.0 -14,1441900 0 431.6 2.07 1939.91 193.99 2133.9 2131.8 0.0 -16,2762000 25.21 179.39 46.69 1131.46 113.15 1244.6 1197.9 0.0 -17,4742100 475 17.47 926.30 364.56 36.46 401.0 0.0 525.3 -16,9492200 666.4 0.12 2113.61 32.57 3.26 35.8 0.0 2077.8 -14,8712300 655.6 3.27 2448.00 6.28 0.63 6.9 0.0 2441.1 -12,4302400 588.8 0.24 2304.43 6.50 0.65 7.2 0.0 2297.3 -10,1322500 344.4 0.65 1728.19 1.65 0.16 1.8 0.0 1726.4 -8,4062600 304 19.37 1200.67 37.07 3.71 40.8 0.0 1159.9 -7,2462700 355.7 129.2 1221.57 275.13 27.51 302.6 0.0 918.9 -6,3272800 431.1 52.81 1456.93 337.06 33.71 370.8 0.0 1086.2 -5,2412900 515.7 6.42 1753.31 109.69 10.97 120.7 0.0 1632.7 -3,6083000 531.9 22.42 1940.00 53.41 5.34 58.7 0.0 1881.3 -1,7273100 528.5 0.3 1963.57 42.07 4.21 46.3 0.0 1917.3 1903200 457.8 0.02 1826.43 0.59 0.06 0.7 0.0 1825.8 2,016

End Area (ft2) Volume (yd3) Net Volume

(4) + (7)

Intersection Design