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Alternative Options

Alternative 1

This Alternative has a total of 13.7 miles beginning at the intersection of NW 137th Avenue towards SW 136th Street in West Kendall. Alternative 1 is an alignment parallel to east of SW 177th Avenue, Krome Avenue, which is also known as SR 997, is a two lane undivided rural principal arterial which runs in north-south direction. It provides limited access to industrial areas that are spread out throughout the area. It terminates at US 1 south of Florida City. This alternative include interchanges with some streets:

· SW 8th Street, major east-west controlled access, four lane divided arterial, which has a posted speed limit of 55 mph as it reaches Krome Avenue. On the north side, the Tamiami Canal runs parallel to the SW 8th Street and on the south side we have businesses and residential housing exist.

· SW 42nd Street, Bird Road, major east-west controlled access, four lane divided arterial; it currently ends at SW 157th Avenue. The canal runs parallel along the south side of it. This is residential and businesses area presence has made it difficult to widen SW 42nd Street.

· SW 88th Street, Kendall Drive, is an east-west, six lane divided arterial and it is one of the most traveled arterials in Southwest Miami Dade County. It provides access to many residential and commercial areas and to major expressways such as SR 874, and SR 826. It has a posted speed limit of 50 mph around Krome Avenue and it terminates there as well.

· SW 104th Street, Killian Parkway, is an east-west, two-lane roadway as it approaches Krome Avenue. It has a posted speed limit of 45 mph. It provides access to many residential, educational and small commercial areas.

Alternative 2

This alternative covers 4.2 miles connecting of SW 177th Avenue, Krome Avenue to NW 12th street via SW 8th Street. SW 8th street is a six lane divided arterial east of SW 157th Avenue, which then reduces to four lanes between SW 157th Ave. and SW 177th Ave. The posted speed limit on SW 8th St. is 45 mph east of SW 157th Ave. and 55 mph from SW 177th Ave. to SW 157th Avenue. SW 8th St. also has interchange with Homestead Extension of Florida’s Turnpike (HEFT) and direct connection to SR 836 via a tolled ramp from the HEFT.

This alternative includes an interchange at SW 157th Avenue. SW 157th Ave. is a four lane divided arterial, which currently has construction going on which has been creating many breaks. It is mostly a residential area with a few businesses here and there. The posted speed limit is 30 mph on SW 157th Ave. and it passes through three school zones.

Alternative 3

The third alternative would extend the SR 836 in the southwest direction, which connects SW 136th Street to NW 12th Street via SW 157th Avenue. This alternative would include interchanges between SW 8th St., SW 42nd St., and SW 88th Street.

As mentioned before, SW 8th St. is a major east west traveled arterial and it continues through Miami Dade County into Collier County located on the West coast of Florida. SW 8th St. consists of six divided lanes on the east side of SW 157th Ave and are then reduced to four lanes on the west side of SW 157th Ave. SW 42nd St. terminates at SW 157th Ave. and it has full interchange with the Homestead Extension of Florida’s Turnpike (HEFT).

Alternative 4

The fourth alternative would extend the SR 836 in the west and south direction, and connect NW 12th Street to SW 136th Avenue. It begin at NW 12th Street connects to SW 157th Avenue, runs west along SW 42nd Street towards SW 162nd Avenue where it will run through until Krome Avenue its terminating point at SW 136th Street. This alternative will have a length of 14.6 miles and have some interchanges located at SW 8th St., SW 26th St., SW 42nd St., SW 56th St., SW 88th St., and SW 104th St. Interchange of SW 26th St., also known as Coral Way, is an east west access-controlled four lane divided arterial, which extends west to SW 157th Ave. It is primarily residential between SW 137th Ave and SW 157th Ave.

SW 162nd Ave is an undivided arterial, which begins at Bird Road and continues south to Kendall Drive. Residential areas surround a school zone located at SW 69th Terrace and SW 162nd Avenue.

Do Nothing

Do nothing is an alternative to keep existing conditions as it is. A no build alternative must be analyzed for comparative reasons. It will not address the purpose and need of the project, which in turn will not help in improving the traffic congestion and traffic demands existing now in the southwest area of Miami Dade County. The no-build alternative will not create any additional environmental impacts and will not spend funding.

3. safety analysis

After analyzing the different possible alternatives for alignment that PCG group have been presented with, the team got to the conclusion that safety was not going to be a decisive factor. For any alignment that the team decides, it is the group’s responsibility to make it safe. In order to do that, PCG will follow FDOT manuals and specifications for the design. The focus of this study is going to be lighting, and conflict points, which refers to severe curves.

· In summary, as depicted in the previous table Prime alternative has been created to provide the best alignment taking into consideration as a number one priority the public and the environment, as well as thinking and carefully analyzing the cost to make sure it is reasonable. In continuation a detailed explanation of how PCG analyzed every criterion will be specified in every section, the calculations, tables and reasons for all decisions will be related.

3.1 lighting

3.1.1 Types of Lighting Poles

There are two types of poles used for conventional lighting: “non-breakaway” and “breakaway.” Non-breakaway poles are rigidly mounted, typically remaining upright when hit by a vehicle. Breakaway poles are designed so that the base will shear easily on impact. The following table briefly explains the advantages and disadvantages of both when stroke by an errant vehicle.

Table 3-1 Types of poles

Type of pole	Advantage	Disadvantage
Non-breakaway	Normally does not fall down and causes further damage to surrounding people and property	May cause great injury to the occupants and damage vehicles
Breakaway	Less likelihood of damage to impacting vehicle and injury the occupants	Falling pole may be a hazard to surrounding traffic and properties

Source: FDOT manuals

· Breakaways Poles Preferred

Because of their respective advantage and disadvantages, both types of poles have appropriate use. However, unless special circumstances exist, breakaway poles are preferred over the non-breakaway type.

· Falling Area for Breakaway Poles

To understand the use and placement of breakaway poles, it is important to be familiar with the concept of “falling area.” Research shows that most errant vehicles striking light poles are traveling at an angle less than 20 degrees from their original path and that light poles fall within one mounting height from the foundation along the direction of vehicle travel. A breakaway pole falls within 40 percent of its mounting height in a direction perpendicular to and away from the lane in which the errant vehicle was traveling. Therefore, to prevent knocked down poles from encroaching onto other traffic lanes, breakaway poles should be placed so that they have a falling area of at least 2/5 of the mounting height behind the poles and one mounting height on the side of the pole.

· Use and Placement of Breakaway Poles

Unprotected roadway lighting poles located inside the clear zone should be breakaway, unless conditions dictate otherwise. Breakaway poles placed on the house side of interstate highways should be 15 feet from lane edge and should provide a clearance behind the pole of 2/5 of the mounting height. For highways other than interstates, breakaway poles placed on the house side of travel lanes should be 15 feet from lane edge where practical. If sufficient right-of-way does not exist for this clearance, the poles may be placed just inside the right-of-way line but not closer than 2.5 feet from lane edge.

· Median Lighting

Breakaway poles placed in medians should not be closer than 2/5 of the mounting height from either main lane edge. Breakaway poles should not be placed in medians less than 30 feet wide, except as noted in the following paragraph.

Median lighting in narrow medians should be avoided. If no other alternative is possible, an exception may be made for divided city streets with curbed medians, speed limit of 45 MPH or less, and where pedestrian traffic allows the use of breakaway poles. In this situation, breakaway poles may be used if placed at least 2.5 feet from any curb face, the pole height should not exceed 30 feet and pole mast arm lengths should not exceed 4 feet. Light poles should not be installed in urban median areas less than 30 feet wide if any other design is practical.

· Median Lighting Design Examples

The following illustrations show typical median lighting designs for various controlled access roadway sections.

· Example 1 — Unprotected Median: shows a typical median lighting design for a controlled access roadway having an unprotected median 30 feet or greater in width. Here breakaway poles should be used.

Figure 3-1 Unprotected Median

· Source: FDOT Manual

· Example 2 — Concrete Median Barrier: Figure shows a typical median lighting design for a controlled access roadway having a concrete median barrier. Median width in this situation is typically 20 feet.

Figure 3-2 Concrete Median Barrier

Source: FDOT Manual

· The following table shows the recommended lighting for concrete median barriers:

Table 3-2 Recommended Light

NUMBER OF LANES	LUMINARIES	MOUNTING HEIGHT	SPACING
2 or 3 in each direction	250 watt HPS	40 feet	Varies
4 or 5 in each direction	400 watt HPS	50 feet	Varies

Source: Fdot Manual

3.2 CURVES

3.2.1 General Considerations for Horizontal Alignment

There are a number of general considerations, which are important in attaining safe, smooth flowing, and aesthetically pleasing facilities. These practices as outlined below are particularly applicable to high-speed facilities.

· Flatter than minimum curvature for a certain design speed should be used where possible, retaining the minimum guidelines for the most critical conditions.

· Compound curves should be used with caution and should be avoided on main lanes where conditions permit the use of flat simple curves. Where compound curves are used, the radius of the flatter curve should not be more than 50 percent greater than the radius of the sharper curve for rural and urban open highway conditions. For intersections or other turning roadways (such as loops, connections, and ramps), this percentage may be increased to 100 percent.

· Alignment consistency should be sought. Sharp curves should not follow tangents or a series of flat curves. Sharp curves should be avoided on high, long fill areas.

· Reverse curves on high-speed facilities should include an intervening tangent section of sufficient length to provide adequate super elevation transition between the curves.

· Broken-back curves (two curves in the same direction connected with a short tangent) should not be used if possible. This type of curve is unexpected by drivers and is not pleasing esthetically.

· Horizontal alignment and its associated design speed should be consistent with other design features and topography. Coordination with vertical alignment is discussed in Combination of Vertical and Horizontal Alignment in Section 5, Vertical Alignment.

3.2.2 Curve Radius

The minimum radii of curves are important control values in designing for safe operation. Design guidance for curvature is shown in the following Table:

Table 3-3 Horizontal Curvature of High-Speed Highways and Connecting Roadways with Super elevation

Design Speed (mph)	Usual Min.1,2 Radius of Curve (ft)	Absolute Min.1,3 Radius of Curve (ft)
[based on emax = 6%]
45	810	643
50	1050	833
55	1635	1060
60	2195	1330
65	2740	1660
70	3390	2040
75	3750	2500
80	4575	3050
[based on emax = 8%]
45	740	587
50	955	758
55	1480	960
60	1980	1200
65	2445	1480
70	3005	1810
75	3315	2210
80	4005	2670
1For other maximum superelevation rates refer to AASHTO’s A Policy on Geometric Design of Highways and Streets. 2 Applies to new location construction. For 3R or reconstruction, existing curvature equal to or flatter than absolute minimum values may be retained unless accident history indicates flattening curvature. 3 Absolute minimum values should be used only where unusual design circumstances dictate. Source: PCG

Table 3-4 Horizontal Curvature of Highways without Super elevation

Design Speed (mph)	6% Min. Radius (ft)1	8% Min. Radius (ft)1
15	868	932
20	1580	1640
25	2290	2370
30	3130	3240
35	4100	4260
40	5230	5410
45	6480	6710
50	7870	8150
55	9410	9720
60	11100	11500
65	12600	12900
70	14100	14500
75	15700	16100
80	17400	17800
1 Normal crown (2%) maintained

Source: FDOT Manual

3.2.3 Sight Distance on Horizontal Curves

Where an object off the pavement, such as a bridge pier, bridge railing, median barrier, retaining wall, building, cut slope or natural growth restricts sight distance, the minimum radius of curvature is determined by the stopping sight distance.

The following equation applies only to the circular curves longer than the stopping sight distance for the pertinent design speed. For example, with a 50 mph [80 km/h] design speed and a curve with a 1150 ft [350 m] radius, a clear sight area with a middle ordinate of a approximately 20 ft [6.0 m] is needed for stopping sight distance.

3.2.4 Vertical Curves

Minimum lengths for crest and sag vertical curves are provided in the following table (K values for crest vertical curves are based on eye height of 3.5’ and object height of 6”)

Minimum Lengths of Crest Based Vertical Curves Based on Stopping Site Distance

Table 3.5

K Values for Crest Curves

Design speed (mph)	Interstate	All other facilities
55	245	185
60	313	245
65	401	313
70	506	401

Source: FDOT Manual

Length, L=KA

Where L = minimum length

K= constant A= Algebrais difference in grades

· Lengths of crest vertical curves on Interstate mainlines are not to be less than 1000 ft. for open highways and 1800 ft. within interchanges.

· K values for ramp crest vertical curves at interstate terminals are not to be less than the Interstate K values. K values for other ramp crest vertical curves are not to be less than the K values for All Other Facilities.

· Arterials and Collectors: The minimum lengths of crest vertical curves for highways with design speeds of 50 mph or greater are as follows:

Table 3.6

Minimum Lengths of Crest Vertical Curves

Design Speed (mph)	50	55	60	65	70
Minimum Length (ft.)	300	350	400	450	500

Source: FDOT Manual

· The lengths of crest vertical curves are not to be less than 3 times the design speed (mph) expressed in feet.

· Minimum Lengths of Sag Vertical Curves Based on Stopping Sight Distance and Headlight Sight Distance

Table 3.7

K Values for Sag Curves

Design speed (mph)	Interstate	All other facilities
55	135	115
60	157	136
65	181	157
70	206	181

Source: FDOT Manual

Lengths of sag vertical curves on Interstate mainlines are not to be less than 800 ft.

· K values for ramp sag vertical curves at interstate terminals are not to be less than the interstate K values. K values for other ramp sag vertical curves are not to be less than the K values for All Other Facilities.

· K values for all sag vertical curves on systems interchanges are not to be less than the K values of the higher system.

· The minimum lengths of sag vertical curves for highways with design speeds of 50 mph or greater are as follows:

Table 3.8

Minimum Length for Sag Vertical Curves

Design Speed (mph)	50	55	60	65	70
Minimum Length (ft.)	200	250	300	400	450

Source: FDOT Manual

4. Social aspect

Transportation agencies around the world decide to create new roads or to expand old ones based on how it will positively affect the public. The extension of the 836 was not an exception to this, the Miami-Dade Expressway Agency (MDX) decided to go ahead with this project in order to both help relieve the traffic in the Southwest Area and accelerate the urban development.

The public’s opinion is always of great importance to MDX. The agency organized several meetings in the Southwest Area because they wanted to hear what the future users of the roadway had to say regarding the project. The response was positive; drivers communicated how tired they are of spending long hours in their cars due to traffic congestion.

4.1 Alternative 1

The social impact was very important during the comparison between alignments. The first alternative considered on the Project Report made by MDX has a strong point on its favor which is that the part of the roadway that is parallel to Krome is located near the 2025 urban development area. Thus, it would bring great long-term benefits. However, the first part of this alternative crosses an area, yet to be developed, diagonally which would affect negatively the urbanization in that area.

4.2 Alternative 2

The second alternative instead of going diagonally, it traverses the area yet to be developed in a vertical manner. After meeting with Mark Plass, a traffic operations engineer from the FDOT, he suggested that crossing vertically through this area would be better for the future urbanization process. He explains that unlike alternative 1, this one has an interchange at SW 8th St and SW 157th Avenue that would be essential in the future for the people living in the squared area shown on the picture below. However, this alignment is too short. It only reaches SW 177th Avenue unlike the other alternatives that extend to the south supporting more the long-term urban development.

Figure 4.1

Urban Development

At the beginning of the project a new alternative was considered, it consisted of connecting the ending of alternative 2 with Krome Avenue, and expanding the lanes in Krome. However, it was discarded because this option would involve changing a roadway that does not charge the users with one that did. On the other hand, alternative 1 would be built parallel to Krome giving users the opportunity to decide if they want to use Krome or the new extension. Removing a free roadway with a charged one would provoke a negative response from the public without doubt.

4.3 Alternative 3

The construction of the 3rd alternative would not be easy at all. The public would react strongly against it because this alternative goes through urbanized areas and construction causes noise disturbances as well as traffic. The congestion problems that the drivers of the SW already have would worsen during construction. Also, the management of the project would be a great challenge for engineers. Especially the time management part, because they would have to coordinate the delivery of concrete trucks and other materials with the traffic congestion. This would not be an easy task and would not be well received by the public as it is happening right now with the construction on I-95. They close all lanes except one during the night and drivers around the county are criticizing these events strongly. This alignment also has a point against in the long-term development aspect because it goes through an already developed area.

4.4 prime alternative

The Prime alternative would be the best alignment socially due to several reasons. First, it wouldn’t negatively impact as much as alternative 1 the urbanization in the squared area at the beginning of the extension because the first part of the Prime alignment is the second alternative, which traverses this area vertically. It also has an interchange as mentioned before unlike alternative 1. Second, regarding long-term development, the prime alternative is the one closest to the undeveloped land so it will be used constantly during that areas’ urbanization and development. Third, the construction process will be easier with this alignment because the noise and traffic congestion won’t affect the public as much as the 3rd alternative because there are less people surrounding the construction area. Fourth, it is a great alternative because it doesn’t involve forcing drivers to pay. It gives them the opportunity to use Krome and avoid fees or use the Prime alternative, which would involve a toll. This is really important because the population would see the 836-extension almost as a downgrade if they were forced to pay, even though the project would bring great benefits such as improving traffic congestion and support long-term development.

5. Traffic operations analysis

5.1 field trip

To make the study of travel time, the decision of Prime Consulting Group was to find the travel time from the end of SR 836 end to Krome Avenue and from SW 136th street to SW 8th street and the results were the following:

SR 836 end to Krome Ave (Total miles = 5.2 miles):

Friday February 6, 2015

· Level of Service (LOS): D

· Start Time: 2:34 p.m.

· End Time 2:47 p.m.

· Total Time: 13 minutes

·

Tuesday February 10, 2015

· Level of Service (LOS): E

· Start Time: 6:29 p.m.

· End Time 6:48 p.m.

· Total Time: 19 minutes

Wednesday February 13, 2015

· Level of Service (LOS): C

· Start Time: 12:54 p.m.

· End Time 1:05 p.m.

· Total Time: 9 minutes

SW 136th street to SW 8th street (Total miles = 8.5 miles):

Friday February 6, 2015

· Level of Service (LOS): D

· Start Time: 2:55 p.m.

· End Time 3:06 p.m.

· Total Time: 11 minutes

·

Tuesday February 10, 2015

· Level of Service (LOS): C

· Start Time: 6:52 p.m.

· End Time 7: 13 p.m.

· Total Time: 21 minutes

Wednesday February 13, 2015

· Level of Service (LOS): C

· Start Time: 1:08 p.m.

· End Time 1:19 p.m.

· Total Time: 11 minutes

For the first part of the studied area (SW 136th street to SW 8th street) the Average Level of service is D and the travel time average was 14.33 minutes or 14 minutes and 20 seconds.

For the second part of the studied area (SR 836 to Krome Ave) the Average Level of service is C and the travel time average was 13.67 minutes or 13 minutes and 40 seconds.

5.2 Project alternatives and goals

There are four viable alternatives that would alleviate the traffic and reduce travel time when traveling in the southwest direction.

5.2.1 Alternative 1

The first alternative consisting of continuing the SR 836 from its current location at NW 137th Avenue up to SW 136th Street in West Kendall. This road would run parallel to and east of Krome Avenue. The interchanges for this option are SW 8th Street, SW 42th Street, SW 88th Street, and SW 104th Street. This alternative would alleviate the north-south traffic congestion by providing a separate road for travel.

5.2.2 Alternative 2

The second alternative consists of connecting SR 836 to the existing Krome Avenue through SW 8th Street. The option includes an interchange with SW 157th Street. This project would allow for more movement in the area, but would require improvements to Krome Avenue.

5.2.3 Alternative 3

The third alternative proceeds from SR 836 west and south following the partially built corridor and direction of SW 157th Avenue up to SW 136th Street. Like the first alternative, this would alleviate north-south traffic and going to have interchanges with SW 8th Street, SW 42th Street, SW 88th Street

5.2.4 Prime Alternative

The forth alternative is a hybrid between alternative 1 and 2, this project consists of continuing the SR 836 from its current location as the alternative 2 and before connecting the Krome, it is going to transform to alternative 1 and run parallel to Krome Avenue. The interchanges with SW 157th Street, SW 8th Street, SW 2th Street, SW 88th Street, and SW 104th Street. This alternative would alleviate the congestion in north south traffic as alternative 1 and

5.3 traffic benefits

5.3.1 Alternative 1

· This alternative has less traffic than alternative 3.

· It is expected to carry traffic volumes approximately 25,00 vpd (vehicles per day) in this year, and a prediction of 36,000 vpd in 2030.

· Alleviate traffic on SW 88th Street from LOS E to D, removing 6,500 vpd this year.

· Decrease of traffic in Bird Road (SW 40th Street) by removing 3,200 vpd this year.

Figure 5.1

Alternative 1 Traffic Analysis

Source: MDX report

5.3.2 Alternative 2

· This is the shortest alternative, so it is predicted to carry least amount of total traffic.

· The highest traffic volume expected for this alternative is estimated to occur between SW 157th Avenue and SW 137th Avenue with volumes of 10,000 vpd in this year and 17,000 vpd in 2030.

Figure 5.2

Alternative 1 Traffic Analysis

Source: MDX report

5.3.3 Alternative 3

· Highest traffic volumes 30,000 vpd in 2015 and 40,000 in 2030.

· Most impact on SW 137th Avenue south of SW 8th Street and north of SW 120th Street reducing 6,600 vpd

Figure 5.3

Alternative 1 Traffic Analysis

Source: MDX report

5.3.4 Prime Alternative

· As a mix of alternative 1 and 2 and one more interchange than alternative 1 it would carry more volume than alternative 1.

· Less traffic than alternative 3.

· Is expected to carry more traffic than alternative 1 and 2.

· As alternative 1, alleviate traffic on SW 88th Street from LOS E to D, removing 6,500 vpd this year.

· As alternative 1, Decrease of traffic in Bird Road (by removing 3,200 vpd this year.

5.4 travel time differential analysis

According to an analysis from WilburSmith Associates (WSA) in January 2008 of the travel time differential between the alternatives, using computer model results, they compare these travel times between two points along different routes during peak period in the morning, the measurements for all alternatives where performed for three point.

· Between SW 157th Avenue at 136th Street and Miami Intermodal Center, 21 miles long.

· Between SW 157th at 136th Street and 137th Avenue at SW 8th Street, 14 miles long.

· Between SW 157th Avenue at 88th Street and SW 137th Avenue at 8th Street,10 miles long.

These measurements of time were compared with the travel time from Homestead Extension Florida Turnpike and Krome Ave for alternative 1and 3. For alternative 2 just HEFT was used for comparison.

After the examination of the analysis, alternative 1, 3 and Prime Alternative demonstrate the best options according to time reduction in travel time. The analysis shows that in this year, 2015, If alternative 1, 3 or Prime Alternative were constructed, the reduction time from Kendall area to MIC is 28 minutes and alternative 2 by 6 minutes. Is expected that in 2030 alternative 1, 3 and Prime Alternative operates at significantly higher speeds and lower travel time than the no-build options, alternative 2 in 2030 the travel times will be the same as the non build option, this alternative does not add capacity for north-south travel and may be seen as temporarily alleviating congestions for the HEFT and may be anticipate that alternative 2 will not has a long term impact as alternative 1, 3 and Prime.

Even each project provides some benefits for the transportation; alternative 2 is the least likely because the long-term benefits, the travel time differential and the amount of traffic carried. Alternative 1 and Prime shows a positive travel impact and a grater capacity than alternative 2. Alternative 3 seems to be the best in impact on transportation network but the expenses to construct this alternative are very high. Comparing Alternative 1 and Prime Alternative, Prime Alternative would carry more vpd than Alternative 1.

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