Robert Peccia & Associates.

Environmental assessment and nationwide section 4(f) evaluation Canyon Ferry Road : STPS 430-1(5)1; CN 4480, Lewis and Clark County, Montana (Volume 2003) online

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be relocated. Reconstmction of tlie Canyon Feny Road/Spokane Creek Road intersection would
also require the relocation of residents &om four homes and possibly one mobile home adjacent
to the existing road.

The existing bridges over the Helena Valley Canal (at RP 4.77 on Canyon Ferry Road and at RP
4.70 on Spokane Creek Road) would be replaced witli new structures and the present bridge at
"No Name" Spring Creek (RP 8.68) would be removed and replaced by a large diameter culvert.
These new structures and pipe installations would accommodate a wider roadway. The existing
double culvert installation at Spokane Creek would also be replaced due to tlie proposed offset

Advisory and regulatory signs, as well as appropriate pavement markings would be installed
according to standards outlmed in the Manual on Uniform Traffic Control Devices (MUTCD).
Guardrail would be placedmlocations warranted by the presences of roadside obstacles or steep
slope conditions.

Estimated current construction costs for the proposed Canyon Feny Road project would total
about $9.6 million, mcludir^ traffic control durmg construction and construction engineermg.
Due to the cost of the project and the limited availabihty of fimdir^, rebuilding tlie entire project
at once is unlikely. Therefore, MDT would implement tins reconstruction proposal under two or
more projects. However, the necessary additional right-of-way and associated access
management for tlie entue Canyon Ferry Road comdor would be secured under one project.
Contmued use of the existing highway corridor and appropriate signing, flagging and detoms
would be used to minimize delays and mconveniences for highway users during conshTiction.


Horizontal and vertrcal alignments as well as all other design features for Canyon Ferry Road
withm the commercial/residential section of tlie corridor would be designed to meet the criteria
for a design speed of 90 km/h(55 mpli) wliichis consistent with the classification of a Rural
Collector road in level terrain and yet recognizes the level of roadside development in this
portion of the corridor. Fromjust east of Lake Helena Drive to tlie project end, the new road
would be designed as a Rural Collector m rolling terxain using an 80 km/h (50 niph) design

The posted speed limit for Canyon Ferry Road is typically 90 or 1 00 kiMi (55 or 60 niph) with
stretches of 70 km/li (45 mph) posted near tlie eastern end of the route . The current posted speed
limits in the project area would remain unchanged wrth the Preferred Action; however, the
horizontal curves posted for 70 km/h (45 mph) would be reconstructed to provide consistency
witli the selected design speed in tlie iiiral sectron. Lewrs and Clark County could ask MDT to


Canyon Ferry Road; STPS 430-1(5) 1 Envirortmental Assessment

conduct an engmeeiing investigation of tiavel speeds aftei reconstiuction project is completed to
determine if posted speed lunits for Canyon Ferry Road should be revrsed based on the speeds at
wlirch motorists drrve on the newly constructed facility.


Horizontal Alignment . Canyon Ferry Road would be designed to follow the existmg
horizontal aligranent as much as possible to minrmize the need for new rrght-of-way and avord
impacts to adjoinir^ developed properties. The proposed new centerhne of Canyon Feixy Road
would closely follow the existing roadway's centerline from the project's beginning to about the
Helena Valley Canal brrdge (RP 4.77) where along set of reverse curves would be introduced to
shift tlie proposed ahgnment south of the existmg liighway.

From about RP 5.0 easterly to about RP 7.25 (near Hart Lane) tlie new aligranent would
generally be parallel to but offset from the existmg centerline of the road by some 16 to 26m (52
to 85 feet). East of Hart Lane, the existmg horizontal curve would be flattened and the new road
would shift to the north side of the existing alignment. The proposed centerline would be about
11.4 m (37 feet)northof and parallel to tlie existir^ alignment to near Fames Lane (RP 8.2) at
whrch the new aligmnent would nearly cross over the existing roadway. East of Fames Lane, the
new aligranent of Canyon Ferry Road would be modrfred to flatten horizontal curves and
accommodate the proposed reconfiguration of the route's intersection witli Spokane Creek Road.

Realigranents of the road have been proposed for parts of the highway in the rural section to
eliminate substandard geomefric features, reduce fraffic confrol needs and conflicts between
motorists, and maintain fraffic during the route's reconstruction. Using an offset ahgnment would
help avoid conflicts between the fraveling public and constmction peisoraiel and also make it
easier to install new drainage structuies. Shifting the ahgnment towards tire south m the rural
section would also tend to impact fewei pioperty owners and lesser-developed properties. The
presentiy fraveled way would be obhterated where it cannot be incorporated into the fomidation
of the new roadway. The ground would be contomed to match existing terrain and seeded m
areas where tire old road is obliterated.

FIGURE 4 shows tlie proposed aligranent for the new road.

Vertical Alignment . The vertical aligranent of the road would be similar throughout the
commercial/residential sechon.

Improvements to the vertical ahgnment would be made where feasible in the Riral section of the
corridor to provrde desirable stopping sight distance and passmg zones. Maintaining acceptable
intersection grades, "balancmg" earthwork quantities (tlie amount of cut and fill) and minimrzmg
right-of-way impacts would dictate the vertical aligmnent in many areas within the rural section
of the corxidor. The existmg steep grade begmnmg east of the Helena Valley Canal crossing
(near RP 4.8) would be reduced to a grade of approximately 5 percent and the vertical curves
would be lengthened.


Canyon Ferry Road; STPS 430-1(5) 1

Environmental Assessment


The intersection of Canyon Ferry Road and Spokane Creek Road would be totally rebuilt with
tlie Preferred Action. The intersection would be reconfigured to make Spokane Creek Road the
stop-controlled leg of the intersection and allow for through traffic moveiuent on Canyon Ferry
Road. The preferred layout for the intersection would straighten Canyon Ferry Road by
eliminating unnecessary horizontal curves and shift the roadway sfightly north of its present
location. Spokane Creek Road would be altered to mtersect Canyon Feny Road in a "T"
configuration just west of tlie Glass Slipper Lounge. This section of road already exists as a
"short-cut" around the existing intersection and would be altered to become the main road under
tiie prefeiied treatment. Tliis would allow tire grade on Canyon Feny Road to be flattened and
would completely elimmate the existing substandard intersection at the top of the hill.

Keir Lane would intersect directiy to Canyon Ferry Road in a "T" configuiation and would be
shifted slightiy to the soutii and several otiier approaches near the new intersection would be
eliminated, reahgned or combined to better manage access.

TheinigationcanalbndgelocatedonCanyonFerry Road east of the present intersection would
also have to be replaced because the existing bridge could not accomiuodate the necessary
physical clianges to the roadway m the vicinity. The existing bridge is located on tire approach to
a curve, and the deck is sloped (superelevated) and constiucted at an elevation incompatible with
the new alignment.

FIGURE 5 shows tiie proposed alignment and reconfiguration of the intersection of Canyon
Ferry Road and Spokane Creek Road.

It IS important to note that reconstruction of the Canyon Ferry Road/Spokane Creek Road
intersectionisunlikely to be part of an initial reconstiuction project within the coiiidor. Initial
reconstinction efforts would probably be devoted to improving Canyon Feixy Road between the
western project termmus and tiie Helena Valley Canal bridge at RP 4.77. Reconstruction of the
roadway east of RP 4.77 would be unlikely until some years after tiie completion of the western
section when additional fiuiding becomes available.


Most of tiie mtersections within tiie Canyon Ferry Road project area are configured as square
"T" or as intersections with four approach legs. The Preferred Action would generally maintain
tiie location and layout of all public road approaches. Auxiliary lanes for left or right turning
tiaffic are proposed for side road approaches at the following locations:

Wylie Drive

Left turn lane and combined througMight turn lane for SB tiaffic
Left, through, and right turn lanes for NB tiaffic

Valley Drive Left turn lane and combined througli/right turn lane for SB tiaffic

Left turn lane and combined thi'ougMight turn lane for NB traffic
Due to the proposed ahgnment shifts in the rural section of tiie corridor, most public and private

-31 -

Canyon Ferry Road; STPS 430-1(5) 1 Environmerital Assessment

road approaches would require minor modifications to intersect with Canyon Ferry Road at
acceptable grades and angles.

Public and private approaches would be designed and leconstructed to fit local conditions and in
a manner that would ensure safe entry and exit fiom the highway. Appioaches would typically
be aligned to mtersect the roadway at angles between 75 and 90-degrees to provide adequate
sight distance. MDT typically paves public and private approaches to the nght-of-way limit.
Farm field approaches (those appioaches that piovide access only to pasture oi faimland)
typically receive a narrow paved ship adjacent to the highway shoulder and gravel suifacing to
tlie new right-of-way fine.


Since tlie project coiiidor consists of two distinct sections - a commercial/residential section and
a niral section - the proposed load design should also be lesponsive to the notable variance m
land uses and roadside environment.

The reconstructed highway would be built with a plant mix bituminous (asphalt) surface over the
top of a crushed gravel base course. Surfacing deptiis would be determmed after tiie completion
of detailed soils investigations and pavement design activities. The pavements of thenewioad
would be designed to last foi at least 20 years with regular maintenance and preservation
activities based upon projected traffic demands.

The pioposed typical load cross-sections for each section of tire corridor are described below and
are also shown in FIGURE 4.

Commercial/Residential Section (RP 1.00 to 4.201. Between the project's beginning and
Baldy Drive (near RP 1.6), the newioad would be rebuilt to provide two 3.6 m (12-foot) wide
tiavel lanes and two 2.4 m (8-foot) paved shoulders. In addition, separate 4.2 m (14-foot) wide
left him lanes would be provided at the approach to Helena Sand and Gravel (RP 1.2), Tizei
Road (RP 1.4), and Baldy Drive (RP 1.6). The poition of the roadway between Tizer Road and
Baldy Drive where left timi lanes are not provided would be stiiped as a painted median. With
the exception of the section of loadway between the beginnmg of the project and the approach to
Helena Sand and Gravel, the new road's top width in this area would be 16.2 m (54 feet). The
roadway would be 12.0 m (40 feet) wide fiom the project's beginning to RP 1 .2 and would
giadually increase in width to 16.2 m (54 feet) east of Tizer Road.

FIGURE 4 shows tiie proposed alignment and typical sections foi the Canyon Ferry Road

Between Baldy Drive and Wylie Diive, Canyon Ferry Road would be reconshucted to include
turn lanes for left and right tiiming vehicles fiom Canyon Ferry Road onto Wylie Drive. A 4.2
m (14-foot) wide centertwo-way left turn lane would be provided west of Wylie Drive.


Canyon Ferry Road; STPS 430-1(5) 1

Environmental Assessment

Canyon Ferry Road/Wylie Drive Intersection

Install traffic signalization and crosswalks

Provide left, Itirough, and righl turn lanes for EB traffic

Provide left turn !ane and combined througti/riglit turn lane for

WB traffic

Provide left turn lane and combined through/riglit turn lane for

SB traffic

Provide left, through, and riglit turn lanes for NB traffic

Project Location Map

Project Beginning to Baldy Drive

Rebuild following existing centerline

Provide two 3.6 m (12-foot) wide travel ianes and two 2.4 m

{8-foot) paved shouiders with striped median & center ieft

turn ianes

Provide 4.2 m (14-foot) wide ieft turn lanes at Helena Sand

and Gravel (RP 1 .2), Tizer Road (RP 1 .4), and Baldy Drive


Baldy Drive to Wylie Drive

a Rebuild following existing centerline

Provide two 3,6 m (12-fool) wide travel ianes, two 2.4 m
foot) shoulders, and a 4.2 m (14-foot) wide continuous two-
way ieft turn lane
Provide overhead lighting at Wylie Drive Intersection

Figure 4

Proposed Alignment and

Typical Road Cross Sections

Map Not To Scale

Press nl localian of
roadside Is nee

Wylie Drive to Lake Helena Drive

a Rebuild following existing centerline

Provide two 3.6 m [12-foot) wide travel lanes, two 1.8 m {6-foot)

shoulders, and a 4.2 m [14-foot)

wide continuous two-way left turn lane
a Provide curb and gutter and a storm runoff collection system
□ Consider reducing travel lanes to 3.3m {1 1-foot), while

increasing shoulder widths to 2.1m (7-feet)
a Eliminate sidewalk alternative under this project to reduce

overall construction width and cost. Sidewalk can be built under

.ftiture project when property owner consensus is strong

Present lacaSoi
of yoLir
roadsidB rence

Vanes I

Ejisling Right-of-Way Width ^ 60' (18.3m}

■J €-oi'

6' (1.8m)


^ — >


14'[4.2iti|Turn Lane


Trairai Lane


0-5'-^ 1^

nollo scale

A future sidewalk can be
builr in Itirs localirjn to
provide separation of
pedestnens and traffic

Canyon Ferry Road/Spokane Creek Road
Intersection (See Figure 5)

□ Reconfigure to a "T" intersection and make Spokane Creek Road
the stop-controlled leg of the intersection
Shift intersection location to west of Glass Slipper
Change grades to provide adequate sight distance
Provide left turn lane and through lane for WB traffic on Canyon
Ferry Road

Provide left turn lane for EB traffic at Kler Lane
Lengthen Kler Lane approach, create standard "T" intersection
Provide overhead lighting at intersection
Add transverse rumble strips on Spokane Creek Road

Lake Helena Drive to Spokane Creek Road

D Rebuild following existing centerline to Helena Valley Canal Bridge at RP 4.77

Rebuild offset from existing centerline east of Helena Valley Canal, modify curves and
grades to meet MDT standards

Provide two 3.6 m [12 foot) wide travel lanes and two 2.4 m (8-foot) paved shoulders
Utilize V-type ditches to minimize new right-of-way needs

I Venes


- Concrete
CurbSGuttBf ,


Canyon Ferry Road; STPS 430-1(5) 1

Environmental Assessment











-f -

_ —






















Figure 5:

Proposed Reconfiguration of

Canyon Ferry Road/Spokane Creek



Canyon Ferry Road; STPS 430-1(5) 1 Environmerital Assessment

Dedicated turn lanes would also be provided at the mtersections of Canyon Ferry Road and
Dusty Maiden Drive (RP 2.7), Valley Drive (RP 3.1), and Lake Helena Drive.

Curb and gutter and a storm water runoff collection system would be piovided along tlie
roadway fiom Wylie Drive to Lake Helena Drive. This segment would consist of two 3.6 m (12-
foot) wide travel lanes and a 4.2 m (14-foot) vvdde continuous two-way left turn lane.
Consideration IS being given to reducing tlie width of travel lanes to 3.3 m (1 1 feet) and
providing paved shoulders with vndtlis of 1 .8 to 2. 1 m (6 to 7 foot) fiom tlie edge of the travel
lane to the face of curb between Wyhe Drive and Lake Helena Drive. Reducing the widtli of
travel lanes may provide some "traffic calming" benefits in this area. A 2. 1 m (7 feet) wide
shoulder would also provide more clearance between thi'ough lanes and occasional disabled
vehicles and mail deliveiy vehicles.

The pioposed typical load cioss-sections within the commeicial/residenfial section of the project
coiridor are presented in FIGURE 4.

Rural Section (East of RP 4.201. East of Lake Helena Drive, Canyon Feriy Road would
typically be reconstructed to apaved width of 12.0m (40 feet) accommodating two 3.6 m (12-
foot) wide travel lanes and two 2.4 m (8-foot) paved shoulders. MDT's geometric design criteria
indicate tliat shoulders within tliis portion of tlie project area should be at least 1.2 m (4-foot)
wide based on current traffic volumes. Howevei, 2.4 m (8-foot) paved shouldeis have been
pioposed in response to projected future (design yeai) traffic on the route and to allow a disabled
vehicle to pull to tlie side of the load vvdthout bemg witliin traffic lanes. Providing 2.4 m (8-foot)
wide shoulders would eliminate tlie need for mailbox turnouts or additional surfacing widening
to accommodate future pavement overlays.

The project would provide 3.6 m (12 feet) wide left hirn lanes at the intersections of Lake Helena
Drive, Spokane Cieek Road and Keir Lane.

V-ditches would be provided throughout this section of the project and standard cut and fill
slopes would be consfiucted based on MDT's standard cut and fill slope guidelines and in
accordance with geoteclmical recommendations. V-ditches have been proposed instead of flat-
bottom ditches in response to public concerns about minimizing new right-of-way acquisition
and to reduce excavation costs. In general, V-ditches are about 3.0 m (10 feet) narrower than
standard flat bottom ditches. Flat-bottom ditches, however, would likely be used in deeper cut
sections to alleviate snow-drifting problems.

The proposed typical road cross-section within the rural section of the comdoi is shown in

Rumble Strips. Rmnble ships would be installed viithin the rural segments of tins project m
accordance with MDT's current policy that calls foi 300 mm (1-foot) long rumble strips to be
cold-milled at an offset of 150 mm (6 mches) outside tiie edge of tiavel way (shoulder stripe).

Transverse nmible strips extending across the full widtii of one tiavel lane would be piovided on
tiie Spokane Creek Road approach at the reconfigured intersection of Canyon Feixy Road.
Incoiporating tiansverse rumble stiips prior to tiie mtersection is a safe and cost-effective means


Canyon Ferry Road; STPS 430-1(5) 1

Environmental Assessment

to warn diivers of the approacliing stop control. Rumble strips are viewed as beneficial in this
instance due to the lack of otlier stop controls on this roadway, hi addition, stop ahead waiTiing
signs and oversized stop signs would be used to leinforce tlie stop condition.


As duected by the Bureau of Reclamation and tlie Helena Valley Irrigation Distiict, the
existing bridges over tire Helena Valley Canal at RP 4.77 on Canyon Feny Road and at RP 4.70
on Spokane Creek Road would be replaced with new stmctures that completely span the canal.
Letters fiom the Bureau of Reclamation and tire Helena Valley liiigation District concerning
tiieu' requuements foi the biidges can be found m APPENDIX B. The proposed bridges would
likely have cast-in-place concrete decks with conciete barrier rails similar to the bridge recently
constructed over Prickly Peai" Creek under MDT's "One Mile East of Helena" project. The new
bridges would be sized to accommodate the proposed 12.0 {40-foot) wide roadway.

The existing timbei biidge ovei "No Name" Spiing Creek would be replaced with an adequately
sized pipe. The existing dual culveit installation at Spokane Creek would tikely be replaced smce
tiie present pipes are not compatible witii the proposed design. Appropriately sized culverts
would be installed at other intermittent diainages within the project conidoi to maintain surface
drainage patterns and provide flood rehef

A new storm water runoff collection system would be provided between Wylie Drive and Lake
Helena Drive where curb and gutter is proposed. The system would include drop inlets and an
outfall line(s), where possible, for stormwater collected fiom the roadway surface. The roadside
in this portion of tiie corridor is moderately developed with few natural drainages for outfall
locations. For these reasons, a stormwater infiltiation/detention/retention system to handle runoff
would also be a necessary part of the proposed project.


The intersection of Canyon Ferry Road and Wylie Drive would be signalized vvith this proposed
project. Overhead lighting would also be installed m conjunction with signahzation at the
intersection. As mdicated in Part II, signal wairants were reviewed for the Canyon Feny
Road/Valley Drive inteisection but anticipated conditions would not be expected to satisfy any
warrants for at least ten more years (possibly five years after reconstruction of the highway).

MDT would reconstruct tiie intersection to include appropriate timi lanes and tiie necessary
underground conduits to facihtate the installation of a fiiture signal at Valley Drive once
warrants are met. Valley Drive cunentiy has a flashing beacon with amber fiashers for through
tiaffic and red fiashers for stop-contiolled tiaffic to heighten motorist awareness of traffic
contiol at the intersection. A similar fiashing beacon was installed at the Canyon Feny
Road/Lake Helena Dnve mtersection m 2002. These beacons would be perpetuated undei this
pioject and similar' beacons would be considered at the reconfigured mtersection of Spokane
Creek Road and Canyon Feny Road.


Canyon Ferry Road; STPS 430-1(5) 1 Environmerital Assessment

In addition to tlie intersections listed above, the Preferred Action would provide lighting at all
major intersections on Canyon Ferry Road. The intersections where lighting is proposed include
Lake Helena Drive, Valley Drive, Keir Lane, and Spokane Creek Road.


Limited access contiol and access management would be incorporated as part of tlie proposed
Canyon Feny Road reconstruction project. Access management has been proposed for tliis route
in response to the docmnented problems of traffic congestion, confhcts, and motor veliicle

Access management involves the establishment of guidelines for managing access points and
spacing along a liighway, adding tiun lanes, mcorporating tumir^ restrictions, consohdating
accesses, eliminating unnecessary accesses and implementing traffic control measures to
maintain the desired operational characteristics of tlie highway. The goals of access management
are to improve tlie safety, fluiction, and opeiation of the roadway, and to ultimately provide a
traffic facility that better serves both local and legional users. MDT will ensure tliat all residents
or businesses have leasonable access to tlieu pioperties. However, some residents may be
required to access their properties fiom alternate routes as MDT tries to eliminate unsafe access
points and reconfigiue imdemsed accesses.

An Access Management Plan would be prepared showing tlie specific location, configuiation,
ownership, land use type and level of use (volume) for each mdividual property access witlun tlie
coiTidor. Themtent of the Access Management Plan would be to identify and perpetuate
necessary existing access pomts, shift or combine approaches where practical; and eliminate
unneeded approaches. Access Management Gmdelines would be developed for the project with
tlie following classifications:

Developed Access Control for use m developed or developing areas where a high degree
of access is requned.

Intermediate Access Control for use in areas where developed ends and before rural

Rural Access Control for use in primarily undeveloped areas that exliibit an agricultural
or natural character.

Aset of Access Control Plans would be developed and tlie locations where these specific
classifications apply would be shown on the plans.

The Access Management Guidelines are mtended to provide "reasonable" access to all existing
properties/parcels. To the extent possible, existing accesses would be made to conform to the

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Online LibraryRobert Peccia & AssociatesEnvironmental assessment and nationwide section 4(f) evaluation Canyon Ferry Road : STPS 430-1(5)1; CN 4480, Lewis and Clark County, Montana (Volume 2003) → online text (page 4 of 19)