Division 13-14-002
Flagstaff Urban Trails System (FUTS)
Sections:
13-14-002-0001 Design Standards
13-14-002-0002 Trail Dimensions
13-14-002-0003 Structural Requirements
13-14-002-0004 Expansion and Contraction Joints
13-14-002-0005 Shoulders
13-14-002-0006 Street/Sidewalk Transitions
13-14-002-0007 FUTS Fencing
13-14-002-0008 Pedestrian and Bicycle Tunnels and Underpasses
13-14-002-0001 Design Standards
FUTS trails shall be designed in accordance with the most current AASHTO "Guide for the Development of Bicycle Facilities." (Ord. 2024-13, Enacted, 4/16/2024 (Res. 2024-15))
13-14-002-0002 Trail Dimensions
A. Trail Width. The minimum treadway width for a standard FUTS trail is ten (10) feet.
B. Shoulders. Two (2) foot shoulders are required along both sides of all FUTS trails for the entire length of the trail.
C. Parkways. Where FUTS trails are adjacent to streets, a minimum parkway of five (5) feet in width is required between the back-of-curb or street edge and the trail treadway. The trail shoulder may be located within the five (5) foot parkway.
D. Horizontal Clearance. A minimum of three (3) feet is required between the trail treadway and any vertical features or obstructions.
E. Vertical Clearance. Minimum vertical clearance from the trail surface is ten (10) feet across the width of the trail treadway.
F. Grades. Running grades shall not exceed eight percent (8%) without written approval from the City Engineer and upon documented evidence that flatter grades are not feasible or desirable in the present circumstance. When FUTS trails are aligned along public streets and replace the public sidewalk, the grade of the trail can match the grade of the adjacent street, even when the grade exceeds eight percent (8%).
G. Cross Slope. The cross slope of the trail treadway and shoulder is one percent (1%) minimum and two percent (2%) maximum.
H. Design Speeds. The design speed for a paved FUTS trail is twenty (20) miles per hour, and the design speed for an aggregate FUTS trail is fifteen (15) miles per hour.
I. Horizontal Curves. Minimum inside radii for horizontal curves are provided in the current AASHTO "Guide for the Development of Bicycle Facilities."
J. Vertical Curves. Vertical curves are required where there is a difference in grade of more than one percent (1%) between two (2) adjacent segments of trail at crests, sags, and grade breaks. The minimum length for vertical curves is provided in the current AASHTO "Guide for the Development of Bicycle Facilities." (Ord. 2024-13, Enacted, 4/16/2024 (Res. 2024-15))
13-14-002-0003 Structural Requirements
A. Paved Trails.
1. PCC (Portland concrete cement) is the only allowable material for a new paved FUTS trail.
2. Where a FUTS trail is constructed adjacent to a public street in lieu of the public sidewalk, the trail shall be constructed of PCC.
3. Trail sections with grades of ten percent (10%) or greater for more than fifty (50) feet shall be constructed of PCC.
4. The minimum structural section for a paved trail is six (6) inches of PCC on three (3) inches of ABC (aggregate base course).
5. Aggregate base course shall be compacted to ninety-five percent (95%) per MAG Section 301.3.
6. Trail subgrade shall be scarified to a minimum depth of eight (8) inches and compacted to ninety-five percent (95%) per MAG Section 301.3.
7. The base course and trail subgrade shall extend a minimum of one (1) foot beyond the edge of the trail treadway.
8. Where a trail segment across a commercial driveway is constructed of PCC, the concrete shall be nine (9) inches thick. A trail segment across a commercial driveway shall be constructed of PCC if:
a. The trail is adjacent to the edge of the driveway pan;
b. The driveway is constructed of PCC; or
c. The trail is paved and the driveway is unpaved.
B. Aggregate Trails.
1. The minimum structural section for aggregate trails shall be four (4) inches of aggregate surface course material over six (6) inches of dirty cinders.
2. Aggregate surface course material shall have a plasticity index of five (5) to twelve (12), and the gradation shall be as follows:
|
Sieve size (square openings) |
Percent by weight passing sieve |
|---|---|
|
1/4" |
100 |
|
No. 4 |
90 – 100 |
|
No. 8 |
65 – 95 |
|
No. 10 |
60 – 80 |
|
No. 16 |
45 – 75 |
|
No. 30 |
35 – 60 |
|
No. 40 |
30 – 40 |
|
No. 50 |
25 – 40 |
|
No. 100 |
20 – 30 |
|
No. 200 |
12 – 23 |
3. Aggregate surface course shall be compacted to ninety-five percent (95%).
4. Dirty cinders for the base course shall be compacted to ninety-five percent (95%) per MAG Section 301.3.
5. Dirty cinders shall comply with MAG Section 702 and City of Flagstaff Modification 13-21-001-0702.2.2, except that the Los Angeles Abrasion requirement is waived.
6. The base course and trail subgrade shall extend a minimum of one (1) foot beyond the edge of the trail treadway.
7. Trail subgrade shall be scarified to a minimum depth of eight (8) inches and compacted to ninety-five percent (95%) per MAG Section 301.3.
8. A nonwoven geotextile fabric is required between the subgrade and the base course when indicated by geotechnical investigation.
9. Should unsuitable material be encountered at subgrade elevation, the unsuitable material shall be removed and replaced with suitable fill material in accordance with MAG Sections 210 and 211.
10. Aggregate surface course material shall be a color compatible with the natural surroundings and acceptable to the City of Flagstaff. White, light gray or other visually incompatible-colored aggregates will not be accepted. Sample shall be provided for approval prior to placement. (Ord. 2024-13, Enacted, 4/16/2024 (Res. 2024-15))
13-14-002-0004 Expansion and Contraction Joints
A. Expansion Joints.
1. The maximum distance between expansion joints is fifty (50) feet.
2. Expansion material shall be one-half (1/2) inch thick, preformed, bituminous expansion joint board, ASTM D-1751, MAG Section 729.
3. An expansion joint is required at all cold joints.
4. Expansion joint requires a modified PVC joint seal (e.g., Greenstreak G-Seal or approved equal) be placed over the expansion material. Submit manufacturer’s specification cut sheet for prior approval by the City. The joint seal shall have a minimum of two (2) fins on legs that embed into the adjacent concrete for the purpose of anchoring, creating a water stop, and providing a smooth travel surface. The top surface of the joint seal shall be one-sixteenth (1/16) inch minimum to one-quarter (1/4) inch maximum below the finished surface. Joints shall be installed perpendicular to the trail.
5. Expansion joints require twenty-four (24) inch long by one-half (1/2) inch diameter smooth dowels at twenty-eight (28) inches on center, beginning four (4) inches in from the outside edges of the trail.
B. Contraction Joints.
1. Contraction joints shall be sawcut rather than troweled.
2. Contraction joint spacing shall be equal to the width of the trail, not to exceed twelve (12) feet.
3. The maximum width of a control joint is one-eighth (1/8) inch. Sawcut depth shall be one-third (1/3) the depth of the concrete thickness. (Ord. 2024-13, Enacted, 4/16/2024 (Res. 2024-15))
13-14-002-0005 Shoulders
Trail shoulders shall be graded and have a smooth surface. Rip-rap, rocks, cinders, loose gravel, landscaping, and other materials that could cause bicyclists to lose control, fall, or crash shall not be used on the shoulder. Shoulders shall be seeded along with other disturbed areas. (Ord. 2024-13, Enacted, 4/16/2024 (Res. 2024-15))
13-14-002-0006 Street/Sidewalk Transitions
A. Where a FUTS trail intersects with another FUTS trail, a radius of ten (10) feet shall be provided. Where a FUTS trail intersects a sidewalk, a radius of five (5) feet shall be used.
B. For aggregate trails, the first twenty (20) linear feet of the trail after an intersection with a sidewalk, paved trail, or road shall be constructed of PCC.
C. Vehicle crossings of trails shall meet City of Flagstaff driveway standards (include reference).
D. A sidewalk ramp shall be provided whenever a trail crosses or ends at a street or driveway with a curbed edge. Sidewalk ramps shall meet City of Flagstaff Engineering Standards, except that the width of the ramp pan shall be a minimum of ten (10) feet or match the width of the trail treadway. (Ord. 2024-13, Enacted, 4/16/2024 (Res. 2024-15))
13-14-002-0007 FUTS Fencing
FUTS fencing shall be located in accordance with the most current AASHTO "Guide for the Development of Bicycle Facilities." (Ord. 2024-13, Enacted, 4/16/2024 (Res. 2024-15))
13-14-002-0008 Pedestrian and Bicycle Tunnels and Underpasses
A. The minimum inside width of a tunnel or underpass is determined by its length according to the following table, or by the total width of the trail treadway plus two (2) foot shoulders on each side, whichever is greater:
|
Length |
Minimum Width |
|---|---|
|
Up to 60 feet |
16 feet |
|
61 to 120 feet |
18 feet |
|
More than 120 feet |
20 feet |
B. The minimum clearance from the floor of the tunnel or underpass to the ceiling is ten (10) feet across the entire width of the trail treadway. (Ord. 2024-13, Enacted, 4/16/2024 (Res. 2024-15))