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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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luaintenance responsibihty. MDT completed a thm-hft overlay project on the route fiom the
project's beginning to Lake Helena Drive duiing 2000.

MDT lias implemented several spot improvement projects to increase safety in identified
accident clusters within tlie project conidor. No passing shipmg, delineation, and a fiasliing hglit
were installed between RP 1.7 and 3.1 during August 1996 as part of project STPHS 002(167).
Similar' unprovements were installed between RP 3.4 and 4.2 dming June 1998 under STPHS
002(318). A fiaslimg hglit was also installed at tiie intersection of Canyon Feny Road and Lake
Helena Drive during 2002.

Signs, guardrail, and bridge end tieatments were installed duiing October 1993 between RP 7.6
and 8.2 under project STPHS 430-1(1) 0. MDT identified tiie section of Canyon Feny Road
between RP 7.3 and 7.7 as an accident cluster location in 2001. Reconstinction of the roadway
was the recommended action for improving safety onthis section of the route. Similarly,
lueasmes to improve safety at the Canyon Ferry Road/Spokane Creek Road intersection have
been investigated but no major changes have been made at this conidor location. Problems at tiie
Canyon Feny Road/Spokane Creek Road intersection have not been previously remedied due to
the high cost of reconfiguring tiie intersection and impleiuenting other recommended tieatments.

Efforts to improve Canyon Feny Road (beyond typical maintenance activities) began in earnest
witii the completion of MDT's "One Mile East of Helena" project that reconstructed about 2.4
km (1 .5 miles) of the route fiom tiie Canyon Ferry Road/York Road intersection to the beginning
of this Canyon Feiry Road project. The "One Mile East of Helena" project mcreased the
roadway vvddtli, improved the intersection with York Road, eliminated a dangerous set of
horizontal curves and replaced a nanow bridge over Prickly Pear Creek.
Lewis and Clark County nominated this section of Canyon Ferry Road for reconstinction in
2000. After approval to proceed was received fi'oni the FHWA, a preliminary field review

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Canyon Ferry Road: STPS 430-1(5} 1



Environmental Assessment



attended by various staff &om MDT and representatives of Lewis and Clark County occimed on
July 21, 2000. A Preluninaiy Field Review Report siumnaiizing existing conditions in the
pioject area, identifying notable facility deficiencies, and outlining a proposed scope of work for
the project was approved on August 24, 2000. In April 2001, woik began to prepare tlie
necessary envuonmental docmnents, develop preliminaiy design and right-of-way plans, and
perform otlier necessary activities foi the pioject.



2. FUNCTIONAL CLASSIFICATION



The roads comprising Montana's highway system are classified by tiie cliaracter of service
(function) they provide. The functional classification system lecognizes tiiat each liighway or
street provides varying levels of access to property and tiavel mobility. Functional classification
also provides tiie fiamework for determining the geometiic design of individual liighways and
stieets. Once the function of tire liighway is defined, tire appropriate design contiols, roadside
safety elements, amenities, and other design values can be determined.

According to the STP Route Segment Plan in MDT's Road Design Manual, Canyon Feny Road
is classified as a Non-NHS- Secondary Rural Collector Road . Non-NHS- Secondary refers to
Secondary Routes not on tire National Highway System (NHS) in Montana. Collector routes are
characterized by a roughly even distiibution of tiien access to and from property and mobility
fimction. In rural areas, collectors sei"ve intia-regional needs, operate as farm-to-market roads,
and provide connections to the arterial system. Canyon Feny Road links Helena with outiying
residential and agricultural areas nortii and east of the City and serves as one of two luajor
roadway links between Helena and the Town of East Helena.



3. CURRENT AND PROJECTED ROAD USE



Road Use. Canyon Ferry Road is one of the major travel routes used by residents comruuting
between permanent or seasonal homes located m the east Helena Valley or along Canyon Feixy
Reseivoir and destinations witliin tiie Crty of Helena and tiie Town of East Helena . The
importance of tins road as a commuter route has increased over the years witii continued rural
residential development in outlying areas of the valley. Dmii^ much of tiie year, this route also
recerves significant use by recreational traffic heading to sites along Canyon Ferry Resen/on and
tiie Missomi River and wrthin tiie Helena National Forest. Agncultiire rs still the dominant land
use m much of the Helena Valley and Canyon Ferry Road serves as an important "faim-to-
niarket" road for many agircultiual operations.

The Helena area has steadily grown over the last several decades and should continue to see
sustained resrdential and commercial growtii. As development continues in the Helena Valley,
the importance of Canyon Ferry Road in the overall tiansportation system of the area has and
will increase. Improvements to the route are necessary to be responsive to the demands (and
impacts) that have occuned since tiie road was originally built and the upgraded facility must be
capable of meeting transportation needs over the next twenty or more years.

The proposed Canyon Feny Road project may contribute to further growth and development



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Canyon Ferry Road: STPS 430-1(5} 1



Environmental Assessment



along tlie route by providing a route that would make coiTunutiiig to and from Helena easier.
While tins rs a possrbility, there are too many other factors tliat promote growtli to make accurate
predictrons wrthin this docmnent about where and when such growth may occur'. The factors
include items such as the general econoiuy, land prrces, tax levels and the existence of services,
to name a few. Current land use planning policies of the County encourage new development to
locate in areas Irke the project corridor where county servrces and in&astnictiire exist to better
accommodate giowtli.

Current and Future Traffic Volumes. MDT's annual traffic counting program does not
include the segiuent of Canyon Ferry Road proposed foi reconstiuction. In order to develop
accurate tiaffic count information for this section of the route, ti'affic data infonuation was used
&01U the 1999 Montana Major Collector Study and &oiu maclime counts collected by MDT's
design consultant during 200 1 . This data was collected and refined to provide accurate Average
Daily Traffic (ADT) volumes for the different sections of Canyon Ferry Road. The current and
fiituie ADT voluiues for various sections of the project corridor aie presented m TABLE 1.
Year 2024 tiaffic voluiues for tiiese same sections were projectedbased on a 3.3% annual
grovrth factor for the road.



TABLE 1 : Current and Future Traffic Volumes


1 Canyon Ferry Road (S-430) - RP 1 .0 to RP 9.2




Location within Project Corridor


Current (2001)

Average Daily Traffic

Volume


Projected Year 2024

Average Daily Traffic

Volume


^West of Wylie Drive (RP 1.0 to RP 2.0)


6,000


12,600


East of Wylie Drive (RP 2.0 to RP 3.0)


6,100


12,900


East of Valley Drive (RP 3 to RP 4.0)


3,620


7,644


East of Lake Helena Drive


1,800


3,800


West of Spokane Creek Road


1,500


3,200



NOTE: Shading in Table 1 denotes locations within the "commercial/residential" section of the project corridor.

Other key characteristics of average tiaffic on thrs section of Canyon Ferry Road are listed
below:



Design Hourly Volume (DHV)
Directional Distribution
Percent Commercial Tracks



830 vehicles pei hour

55-45%

<3% of all veliicles



4. CURRENT AND FUTURE LEVEL OF SERVICE (LOS)



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Canyon Ferry Road: STPS 430-1(5} 1



Environmental Assessment



One of the major reasons for undertaking the proposed improvements to Canyon Ferry Road is to
provide for tlie safe and efficient movement of traffic. To accomphsh tliis, the proposed action must
ensure an acceptable level of service (LOS) under anticipated future tiaffic conditions. In this
instance, an acceptable level of service means that the proposed facility must operate at LOS C or
liigher under flitiue traffic conditions.

The LOS represents the operatmg conditions that occiu' on a highway mtersection or specific
segment of the highway when accommodating various tiaffic volumes. Factors affecting LOS
include speed and tiavel time, freedom to maneuver, tiaffic interruptions, comfort and convenience,
and induectiy, safety. LOS analyses provide a quahtativemeasurement of operational conditions
withm the tiaffic sti'eam and tiieir perception by motorists and/or passengers.

Levels of service for different types of facilities aie based on factors describing the quality of
operation on the facility. For two-lane highways, average tiavel speed and the time delay aie the
primary measures of effectiveness considered in LOS analyses. The operating conditions of a
liighway are measmed on the basis of sis levels of service, designated as LOS A through LOS F by
the Highway Capacity Manual (HCM). LOS A represents the best operating conditions (fiee-
flowing tiaffic) and LOS F tiie worst operating conditions (low tiavel speeds witli fiequent delays).
Levels of service for intersections are stated in terms of tire average stopped delay per vehicle
and is also categorized fiom LOS A to LOS F. Descriptions of operating conditions under
various LOS categories are provided in TABLE 2.



TABLE 2: Level of Service (LOS) Descriptions




LOS Category


Description of Operating Conditions


LOS A


Free flow. LOS A represents high speed, smooth flow with little or no interference
between vehicles.


LOSB


Lower speeds than LOS A, although flow is still good and httle congestion exists. In
urban areas, average over-all speeds di'op due to intersection delay and vehicular
conflicts.


LOSC


Lower speeds than LOS B, although flow is still good and little congestion exists.
Operation is still stable with acceptable delays, but becoming more critical.


LOSD


Level D shows still lower speeds than previous levels. There is some congestion, and
conditions become slightly unstable with respect to tiavel time and delay. The traffic
flow is beginning to tax the ci^abilities of the street section. In urban and suhurban areas,
delays at intersections may be extensive with some cars waiting two or more cycles.


LOSE


The traffic flow is unstable, and the traffic volumes are at capacity. Any momentaiy
stoppage may create an immediate and significant amount of congestion. Traffic is
backed up continuously at intersection ^proaches.


LOSF


Level of service F is demonstrated by conditions of heavy congestion and stop-and-go
tiaffic. All intersections are handling traffic in excess of edacity. Vehiculai' back-ups
extend back from signalized intersections, through unsignalized intersections.



The existing and fiitme LOS on Canyon Ferry Road was analyzed using cmrent tiaffic data and
projected tiaffic for the year 2024. MDT's design consultant followed procedures outlined in
tire Transportation Research Board's Highway Capacity Manual (HCM) - Special Report 209 and



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Canyon Ferry Road: STPS 430-1(5} 1 Environmental Assessment

used tlie Highway Capacity Software (HCSj to complete the LOS evaluations for road segments
and major intersections within the Canyon Ferry Road project corridor. The LOS analyses for
intersections considered tiafQc volumes, tuiiiing movement data, the types of vehicles using the
road, and geometric informahon for the current conditions and anticipated conditions in tlie year
2024.

Current and Future LOS for Roadway Segments. The LOS evaluatrons for the different
roadway segments along Canyon Ferry Road showed that the roadway currently fimctrons at
LOS C in tlie commercial/residential section and LOS B in the rural section of the conidor. If
improved as proposed under this project, tlie rural section of the project conidor would fluictron
at LOS B based on 2024 haffic conditions.

Current and Future LOS at Major Intersections. Due to the presence of nmnerous
closely spaced mtersectrons, it is not appropriate to use roadway segment analysis to estrmate the
future LOS wrthin the commercial/resrdential section of the corrrdor. Instead, unsignalized
intersection analyses were performed for allmajormtersectronsmthispart of the corridor.

The unsignalized intersection analysis shows that all of tlie Canyon Feny Road approaches at
stop-controlled intersections witliin tlie corridor, with tlie exception of rts approaches at Wyhe
Drive, currently operate at LOS A. All other stop-controlled side road approaches curxently
operate at LOS A or B, with the exception of Wylie Drive. The Wylie Drive approaches to
Canyon Feny Road currently operate at LOS C, whrcli rs considered acceptable by MDT for this
type of facility.

Based on year 2024 traffic data and unsignalized condrtrons, the LOS is expected to decrease at
most otlier intersections along the project conidor. The analysis showed tiiat Wyhe Drive's and
Tizer Road's intersections with Canyon Ferry Road would operate at LOS F and LOS E,
respectively, under peak-hour traffic conditions m the year 2024 if they continue to operate as
unsignalized inter sectrons. This poor level of servrce during peak hour tiaf&c conditions suggests
that tiaffic signals may be wananted at tiiese locations. Future tiaffic signal needs at these and
other major intersections in the corridor are discussed in the following section.

Traffic Siqnalization Needs. Wanants for tiaffic signals were reviewed at all mtersectrons
witiim tiie project corridor based on cunent and future tiaffic vohmies. The wanant analysis was
conducted using gurdelines outiined in the Manual on Uniform Traffic Control Devices
(MUTCD). The MUTCD describes each of the erght wanants necessary to assess the need for
intersection signalization. The warrants do not imply that a signal must be installed, but at least
one of the warxants must be met before a signal can be considered.

The wanant analysis showed that the Wylie Drive intersection may satisfy the requirements for
tluee of the eight wanants by the year 2024, with one of the wanants currently being met. An
additional warrant would likely be met by the time the proposed project is ready for conshuction.
The Valley Drrve intersection may also meet tiiree wanants by 2024. However, none of the
warrants would likely be met for at least ten more years from now. Therefore, signal warxants
would probably not be met until after tiie proposed Canyon Ferry Road project is built.

Altiiough the LOS analysis predicts the Trzer Road approach to Canyon Feny Road would

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Canyon Ferry Road: STPS 430-1(5} 1 Environmental Assessment

operate at LOS E by the year 2024, the intersection would be unlikely to meet any traffic signal
warrants by that time.

Left Turn and Right Turn Lane Needs. Major intersections in tiie project conidor were
also examined to determine tiie need for left and right timi lanes based on cun'ent and ftiture
traffic vohmies. Using guidelines from MDT's "Road Design Manual" (Figures 13. 3C and
13. 3E, "Volume Guidelines for Left-Turn Lanes at Unsignalized Intersections on 2-Lane
/f/gMffl>'j'"),it was determined that foiu' intersections would justify left-turn lanes on the Canyon
FeiTy Road approaches by 2024. These intersections include Tizer Road, Baldy Drive, Dusty
Maiden Drive, and Valley Drive.

None of the intersections studied have projected design-year tiaffic vohmies that indicate the
need for right-turn lanes.

A left turn lane for westbound motorists is considered prudent and was recommended on the east
approach to the intersection of Canyon Ferry Road and Spokane Creek Road. The provision of a
deceleration lane on tliis relatively steep downhill grade would and remove turning tiaffic
(seasonally includmg many RV's and vehicles with camping or boat tiailers) fiom tiirough tiaffic
on Canyon Feny Road.



5. ROADWAY AND BRIDGE DEFICIENCIES



Consistent and predictable driving characteristics are important featiues of a safe and convenient
road. Variances in tire physical conditions of the road or inconsistencies in the way the road is
designed can have a duect bearing on tiie overall safety of tiie roadway and the ability of
motorists to negotiate tiie facihty. PHOTO PLATES 3 and 4 illustiate some of the existing
problems and deficiencies vvdthin the Canyon Feixy Road project corridor.

The motorist's ability to see ahead is a primary consideration in the safe and efficient operation
of a vehicle on a highway. Sharp curves aiound terrain features or over the crests of hills do not
provide sufficient distance for a motorist to see an obstmction in the roadway and to stop if
necessary. Such curves are said to lack adequate stopping sight distance . The American
Association of State Highway and Transportation Officials (AASHTO) defines
stopping sight distance as the length of roadway ahead visible to the driver.

The amount of stopping sight distance reqmied depends mostly on the design speed (the selected
speed used to determine the various geometric features of the roadway). The design speed is
typically established based on tiie topography, anticipated operating speed, adjacent land use,
and the functional classification of the highway. All of the pertinent featiues of tiie lughway
must be related to the design speed to obtain a balanced and sound design for tiie facihty.

It should be noted that design speed does not equal the operating speed or running speed of
vehicles ontheroadway or the posted speed hniit. According to AASHT0'sy4 Po//cv oh
Geometric Design of Highways and Streets, the "operating speed" is the speed at which drivers
are observed operating their velncles. The "running speed" is tiie speed at which an individual

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Canyon Ferry Road: STPS 430-1(5} 1 Environmental Assessment

vehicle tiavels over a specified section of highway (i.e., a specified distance traveled divided by
tlie time taken by the veliicle to travel the specified distance) . Other tlian by state statute, the
"posted speed limit" is established based on the results of a special engineering and traffic study
to determine the speedat or below wliich 85 percent of all observed veliicles were traveling. The
85tli percentile of tlie distribution of observed speeds is also the most frequently used measure of
operating speed.

The appropriate design speeds for various functional classifications of roads in Montana have
been established and aie published in MDT's "Road Design Manual." Canyon Feriy Road is
classified as a Non-NHS- Secondary Rui'al Collector Road. Appiopriate design speeds for such
roads range fiom 80 km/li (50 mph) to 100 km/h (60 mph) depending on teiram features.

Requirements for stopping sight distance length, as well as other geometric features such as
horizontal and vertical curvature and superelevation (the degree of banking on curves), are
duectiy related to and vary substantially with design speed. Highway designers stiive to use as
liigh a design speed as piacticable to attain tiie desired degree of safety, mobility, and efficiency
withm the consti'aints of environmental quality, economics, aesthetics, and social impacts.

PRINCIPAL DESIGN CONTROLS

Canyon Feny Road passes tiiiough level terrain m the commeicial/residential section of the
coiTidor to lolhng terram in tire eastern and more rural portion of the project area. MDT's "Road
Design Manual" states that appropriate design speeds foi Ruial Major Collectors are 100 km/h
(60 mph) for roads in level terrain and 80 km/h (50 mph) for roads m rolling terrain. The
existing posted speed limit is 90 km/li (55 mph) within the commeicial/residential section and
1 00 km/h (60 mph) for most of tiie rural section with stietches of 70km/li (45 mph) near the
intersection of Spokane Creek Road and ai'eas witii sharper horizontal curves.

Based on these considerations, MDT's design guidance mdicates tiiat a design speed of 100 km/h
(60 mph) IS appiopriate foi tiie commercial/residential section of the coiiidor. However, based
on site constiamts and a review of tiavel speed data, MDT determined that a 90 km/li (55 mph)
design speed is appropriate for the commercial/residential section of Canyon Feny Road. The
appropriate design speed for the rural section of this project was established at 80 km/h (50
mph).

ContioUing geometiic standards for botii 90 km/li (55 mph) and 80 km/h (50 mph) designs are as
follows fiom Figure 12-5.- Geometric Design Criteria for Rural Collector Roads (Non-NHS -
Secondary) and Chapter 8 of MDT's "Road Design Manual"):

90 km/h (55 mph) 80 km/h (50 mph)

Minimum Radii 305 m (1 ,000 feet) 230 m (755 feet)

Maximum Gradients 5% (level terrain) 7% (rolling terrain)



Photo Plate 3: Existing Road Conditions and Geometric Deficiencies



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



Environmental Assessment



Photo Plate 3




Multiple utilities and steep roadsides adjacent to Canyon Ferry Road present hazards to motorists within
the commercial/residential section of the project corridor.




Looi<ing west down the steep approach of Canyon Ferry Road from the existing intersection of Spokane
Creek Road. The existing layout, steep approach grade, roadside developments, terrain, and multiple
approaches combine to make the existing intersection hazardous.

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



Environmental Assessment



Photo Plate 4




View of Canyon Ferry Road approach to Spokane Creek Road Intersection nearthe eastern terminus of
the project. The existing alignment closely follows the rolling terrain and contributes to limited sight
distance.




This photograph of the existing (timber bridge) approaches across "No Name Spring Creek" near RP 8.7
shows the poor condition of the road surface, limited sight distance, and the steep roadside slopes.



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Canyon Ferry Road: STPS 430-1(5} 1 Environmental Assessment

90 km/h f55 mph) 80 km/h (50 mph)

Minimum Passing Sight Distance 615 m (2,018 feet) 550 m (1,805 feet)

Desirable Stoppmg Sight Distance 170 m (558 feet) 140 m (459 feet)

Minimum Stopping Sight Distance 140 m (459 feet) 120 m (394 feet)

ROADWAY DEFICIENCIES AND ALIGNMENT IRREGULARITIES

Based on the geometric design criteria for Collector Roads (Non-NHS- Secondary) from MDT's
"Road Design Manual" and tlie selected design speeds for this project, the following geometric
defrciencies are evident.

Deficient Roadway Width. The existing roadway is cuirently only 7.2 m (24 feet) wide
tliiough tlie entue project area. According to MDT's geometric design criteria for Ruial
Collectors and cunent aveiage daily traffic, tlie recommended minimum widtli for the
reconstniction between the project's beginning and Lake Helena Drive is 1 2.0 m (40 feet). A
roadway of this width would accommodate two 3.6 m (12 foot) wide travel lanes and two 2.4 m
(8 foot) wide shoulders. The addition of any tiun lanes within tliis section of the conidor would
require additional widthof up to 4.2 m (14 feet) to accommodate left turn lanes, two-way left
turn lanes and stiiped medians or transitions between each. Theiefore, tiie minimum standaid
roadway widlh for tiie commercial/iesidential section of Canyon Feixy Road would be 12.0 m
(40 feet) or 16.2 m(54 feet) witii tire mclusion of turn lanes. Because of recognized site
constiaints, MDT is considering shouldeis withwidtiisof 1.8 to 2.1 m (6 to 7 foot) from the edge
of tiie tiavel lane to file face of curb between Wylie Drive and Lake Helena Drive.

MDT's geometiic design criteria for the rural section of the corridor (east of Lake Helena Drive)
indicates that tiie roadway should be at least 9.6 m (32 feet) wide based on current tiafBc
volumes. Aroadway of tins width would acconuiiodate two 3.6 m (12 foot) wide tiavel lanes and
two 1.2 m (4 foot) wide shoulders. If fixture (design yeai) tiaffic volumes are considered, tiie
minimum required roadway width for the luial section of the corridor increases to 12.0 iti(40
feet). The mcreased vvddtii would allow for the provision of 2.4 m (8 foot) wide shoulders.

Horizontal Alignment. The contiolling geometric design criteria listed above were used to
evaluate the existing road's aligmnent. Preliminary engineering analyses determined that the
existing horizontal alignment of Canyon Feixy Road west of Spokane Creek Road is generally
acceptable. The existing highway ahgnment tluough the commercial/iesidential section is nearly
tangent (stiaight) witii a few only slight deflections fi'oiii tangent. Horizontal curves witiun 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 2 of 19)