Grissom-Widening-PSJ-Fay-30-PER-App6-Roundabout-Feasibility-20250225.pdf
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- Solicitation number
- RFQ-7-26-03
- Issued by
- Brevard County, Florida
About this file
This is an engineering feasibility analysis prepared by DRMP for Brevard County Public Works Department regarding the evaluation of roundabout design alternatives at the intersection of Grissom Parkway and Bridge Road as part of the Grissom Parkway Widening project. The analysis examines three distinct roundabout design alternatives to improve operations at this intersection, with each alternative evaluated against standardized design criteria including an inscribed circle diameter of 150 feet, 14-foot lane widths, a design vehicle of WB-62FL, a 6-foot truck apron, and a maximum entry design speed of 25 miles per hour. Alternative 1 centers the roundabout at the intersection with aligned approach legs, requiring right-of-way acquisition from all four corner properties. Alternative 2 shifts the roundabout center northward, maintaining centered Grissom Parkway approaches while shifting Bridge Road approaches north, requiring acquisition of both northeast and northwest corner properties plus corner clips from the southeast and southwest properties. Alternative 3 shifts the roundabout center southward with similar property impact requirements as Alternative 2 but presents challenges in meeting speed control objectives.
Based on the feasibility analysis, DRMP recommended against implementing any of the three roundabout alternatives due to the requirement for right-of-way acquisition from residential properties, which would significantly increase project costs and extend the project schedule. Instead, the recommendation is to proceed with the current 30 percent plan design treating the intersection as a full median opening with added turn lanes on Grissom Parkway for left-turning movements onto Bridge Road. The analysis further recommends that following completion of the widening project, a reevaluation of intersection performance and a signal warrant analysis be conducted to determine if signalization becomes necessary.
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APPENDIX SIX:
ROUNDABOUT FEASIBILITY
ANALYSIS.
941 Lake Baldwin Lane, Orlando, Florida 32814 Phone: 407.896.0594 | Fax: 407.896.4836
1.833.811.3767 | www.DRMP.com
Brevard County Public Works Department Attn: Eric Burnie, PE 2725 Judge Fran Jamieson Way Viera, Florida 32940
Project: Grissom Parkway Widening Subject: Evaluation of different alternatives of Two-Lane Roundabout at the Intersection of Grissom Parkway and Bridge Rd.
DRMP evaluated three alternative roundabout designs to improve operations at the intersection of Bridge Road and Grissom Parkway. The same criteria and characteristics is used for all alternatives (See table below).
The design of a roundabout is based on design decisions that include the size and location of the roundabout and the alignment of the approach legs. The main objective is to meet the design criteria, reduce vehicle speeds, and accommodate traffic volumes while designing within the constraint in the project site.
Roundabout Characteristics Value Reference Limits (Min-
Max)
Design Vehicle WB-
62FL
From Grissom
Parkway Feasibility
Study
Inscribed circle diameter 150' NCHRP672 Exhibit
1-9
Lane width 14' NCHPR672-Section
6.5.3
Range 14’-
16’
Total number of lanes entering and existing Grissom Parkway South
Total number of lanes entering and existing Grissom Parkway North
Total number of lanes entering and existing Bridge Road East
Total number of lanes entering and existing Bridge Road West
Splitter Island 50’ min NCHPR672 Section
6.4.1
100' desirable
Truck Apron 6' NCHPR672
Section6.4.7.1
Range 3-15'
Entry Width 24 NCHPR672 Section
6.5.2
24-30
Desirable maximum entry design speed 25 Exhibit 1.9 25-30
Description of Alternatives
Alternative #1: The roundabout is centered at the intersection of Grissom Parkway and
Bridge Road. and as shown in Exhibit (1). The alignment of the approach legs on both
All engineering and land surveying services in North Carolina are provided by DRMP NC, Inc.
P:\Projects21\21-0700.019_Grissom_Pkwy_Widening\_CADD\roadway\Roundabout Exhibit\Draft Roundabout analysis\draft memo-103124-TW.docx
Grissom Parkway and Bridge Road pass through the center of the roundabout’s inscribed diameter.
Using the centered approaches reduces the amount of alignment changes. This alternative also provides more curvature to the existing approach legs which allows drivers to maintain lower speeds. This alternative does impact all the corner properties and will require the
County to acquire right of way from the four properties.
Alternative #2: The center of the roundabout is shifted to the north. The Grissom Parkway approaches remain centered with the roundabout’s inscribed circle, while the Bridge Road approaches shift to the north of the roundabout. This option allows for a larger entry radius while maintaining speed control. However, it will increase the exist radius and reduce the speed control. The County will need to acquire both the northeast and northwest corner properties and a corner clip at the southeast and southwest properties. The shift to the north is maximized without having to impact more than one property on each side (Refer to
Exhibit 2).
Alternative #3: The roundabout center is shifted to the south. The Grissom Parkway approaches remain centered with the roundabout’s inscribed circle while Bridge Road is shifted to the south. This alternative has challenges to meet speed control objectives. The
County will need to acquire both corner properties at the southeast and southwest and a corner clip right of way at the northeast and northwest properties. The shift to the north is maximized without having to impact more than one property on each side (Refer to Exhibit
3).
Recommendation
Based on the analysis of the three roundabout design alternatives all three will impact the four residential properties in order for the roundabout to be constructed. The proposed roadway improvements currently do not require right of way acquisition along the project corridor. This will increase the cost of the project and likely extend the project schedule.
We recommend that this intersection be treated as a full median opening with turn lanes added on Grissom Parkway for left turning movements onto Bridge Road as shown in the 30% plans. We also recommend that after the widening project is completed, a revaluation for the intersection performance should take place and a signal warrant analysis be conducted.
PI STA. 1049+36.21
PI STA. 1046+84.21
700 701 702 703 704 705 706
EXIST. R/W
EXIST. R/W
EXIST. R/W
EXIST. R/W
EXIST. R/W
EXIST. R/W
EXIST. R/W
EXIST. R/W
CONST. 12' CONC. SEPARATOR
CONST. 5' CONC. SEPARATOR
REMOVE & REPLACE
EX. CONC. DRIVEWAY TYP.
CONST. 8' CONC. SW
CONST. TYPE F C&G
CONST. TYPE F C&G
CONST. TYPE F C&G
CONST. 6' CONC. SW
CONST. 6' CONC. SW
CL BRIDGE RD
CL GRISSOM PKWY
11'
CONST. 8' CONC. SW
BEGIN PAVT.
STA. 700+80.00
REMOVE & REPLACE
EX. CONC. DRIVEWAY TYP.
PI STA. 702+16.08
PI STA. 703+65.87
EXIST. EOP
EXIST. EOP
CONST. TYPE RA C&G
CONST. TYPE D CURB
CONST. 6' CONC. TRUCK APRON
11'
6.5' SHOULDER
11'11'6.5' SHOULDER
14' 14'
11'11'11'11'
CONST. 6' CONC. SW
CONST. 6' CONC. SW
END PAVT.
STA. 705+00.00
SHOULDER STRIPING SHOULDER STRIPING
∅7
6'
∅150'
PLAN SHEET BRIDGE ROAD
OPTION 1
SHEET
NO.
C:\Users\lbrambach\Desktop\Grissom 21-0700.019 Desktop\_CADD\roadway\PLANRD03 BRIDGE RD ROUNDABOUT OPT 1.dwg
Leesa Brambach 10/18/2023 3:43:04 PM
N
1"
0'
SHEET
NO.
REVISIONS
SHEET
NO.
DATE BREVARD COUNTY
PUBLIC WORKS DEPARTMENT
ROAD RSQ NO.
DATE:
100 PARNELL STREET., SUITE A
MERRITT ISLAND, FLORIDA 32953
P 321.453.0010 F 321.454.6885
CERTIFICATE OF AUTHORIZATION NO. 2648
SCIENTISTSENGINEERSSURVEYORSPLANNERS
GRISSOM PARKWAY
PI STA. 1049+36.21
PI STA. 1046+84.21
700 701 702 703 704 705 706
EXIST. R/W
EXIST. R/W
EXIST. R/W
EXIST. R/W
EXIST. R/W
EXIST. R/W
EXIST. R/W
EXIST. R/W
CONST. 12' CONC. SEPARATOR
CONST. 5' CONC. SEPARATOR
REMOVE & REPLACE
EX. CONC. DRIVEWAY TYP.CONST. 8' CONC. SW
CONST. TYPE F C&G
CONST. TYPE F C&G
CONST. TYPE F C&G
CONST. 6' CONC. SW
CONST. 6' CONC. SW
CL BRIDGE RD
CL GRISSOM PKWY
11'
CONST. 8' CONC. SW
BEGIN PAVT.
REMOVE & REPLACE
EX. CONC. DRIVEWAY TYP.
PI STA. 702+16.08
PI STA. 703+65.87
EXIST. EOP
EXIST. EOP
CONST. TYPE RA C&G
CONST. TYPE D CURB
CONST. 6' CONC. TRUCK APRON
11'
6.5' SHOULDER
11'11'6.5' SHOULDER
14' 14'
14' 14'
11'11'11'11'
CONST. 6' CONC. SW
CONST. 6' CONC. SW
END PAVT.
STA. 705+89.60
SHOULDER STRIPING SHOULDER STRIPING
∅150'
PLAN SHEET BRIDGE ROAD
OPTION 2
SHEET
NO.
C:\Users\lbrambach\Desktop\Grissom 21-0700.019 Desktop\_CADD\roadway\PLANRD03 BRIDGE RD ROUNDABOUT OPT 2.dwg
Leesa Brambach 10/18/2023 3:25:53 PM
N
1"
0'
SHEET
NO.
REVISIONS
SHEET
NO.
DATE BREVARD COUNTY
PUBLIC WORKS DEPARTMENT
ROAD RSQ NO.
DATE:
100 PARNELL STREET., SUITE A
MERRITT ISLAND, FLORIDA 32953
P 321.453.0010 F 321.454.6885
CERTIFICATE OF AUTHORIZATION NO. 2648
PI STA. 1049+36.21
PI STA. 1046+84.21
700 701 702 703 704 705 706
EXIST. R/W
EXIST. R/W
EXIST. R/W
EXIST. R/W
EXIST. R/W
EXIST. R/W
EXIST. R/W
EXIST. R/W
CONST. 12' CONC. SEPARATOR
CONST. 5' CONC. SEPARATOR
REMOVE & REPLACE
EX. CONC. DRIVEWAY TYP.
CONST. 8' CONC. SW
CONST. TYPE F C&G
CONST. TYPE F C&G
CONST. TYPE F C&G
CONST. 6' CONC. SW
CONST. 6' CONC. SW
CL BRIDGE RD
CL GRISSOM PKWY
11'
CONST. 8' CONC. SW
REMOVE & REPLACE
EX. CONC. DRIVEWAY TYP.PI STA. 702+16.08
PI STA. 703+65.87
EXIST. EOP
EXIST. EOP
CONST. TYPE RA C&G
CONST. TYPE D CURB
CONST. 6' CONC. TRUCK APRON
11'
6.5' SHOULDER
11'11'6.5' SHOULDER
14' 14'14' 14'
11'11'11'11'
CONST. 6' CONC. SW
CONST. 6' CONC. SW
SHOULDER STRIPING SHOULDER STRIPING
∅150'
PLAN SHEET BRIDGE ROAD
OPTION 3
SHEET
NO.
C:\Users\lbrambach\Desktop\Grissom 21-0700.019 Desktop\_CADD\roadway\PLANRD03 BRIDGE RD ROUNDABOUT OPT 3.dwg
Leesa Brambach 10/18/2023 3:33:35 PM
N
1"
0'
SHEET
NO.
REVISIONS
SHEET
NO.
DATE BREVARD COUNTY
PUBLIC WORKS DEPARTMENT
ROAD RSQ NO.
DATE:
100 PARNELL STREET., SUITE A
MERRITT ISLAND, FLORIDA 32953
P 321.453.0010 F 321.454.6885
CERTIFICATE OF AUTHORIZATION NO. 2648
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