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4-1 Transportation Master Plan 4.0 2020 MAJOR THOROUGHFARE PLAN 4.1 Study Area The study area for developing an updated Major Thoroughfare Plan for the Brighton area is bounded by the following facilities: • Yosemite (on the west) • I-76 (on the east), including industrial developments immediately east of I-76 • Weld County Road 4 (on the north) • 120th (on the south) The study area is depicted on Figure 4-1, along with the traffic analysis zone structure used in the transportation modeling process. The traffic analysis zone structure corresponds with the structure used in the Denver Regional Council of Governments (DRCOG) regional traffic model. To accurately model trips between Brighton and outlying areas, the overall area that was modeled was somewhat larger than the study area for defining needed transportation improvements. 4.2 Transportation Modeling Process Land uses for the transportation modeling process were based on the DRCOG sketch-planning travel model. For each of the traffic analysis zones (Figure 4-1), the DRCOG data set included 2001 and 2020 land uses for each of the model zones. Land uses were defined in six categories: low, medium and high income housing and employment divided into production, retail, and service jobs. Working closely with City of Brighton planning staff, the DRCOG land uses for the model area were updated to reflect current development proposals and other anticipated developments. The land uses assumed in the modeling effort are summarized on a table in Appendix 1. Some of the larger development plans that have been incorporated into the 2020 land use plan are: • Mountain View Estates I & II • The Preserve • Chapel Hill • Carma • Brighton East Farms • Todd Creek • Pheasant Ridge • Platte River Ranch • Sugar Creek • Parkside • The Village • Bromley Park • Hishinuma ---PAGE BREAK--- 4-2 Transportation Master Plan • Palizzi • Case Farm • Indigo Trails • Diedrichs Farm • Davis • Prairie Center • Silver Peaks - Lochbuie The following table below summarizes the population estimates used in the transportation model for the model area depicted on Figure 4-1. The table further divides the data for those zones within the study area boundary and those zones within the model but outside of the study area boundary. As shown on the table, there is a several fold increase in both population and in employment assumed in the 2020 land use forecasts. 2001(1) 2020 Population Employment Population Employment Within Study Area 22,868 8,002 95,205 61,655 Outside Study Area 7,788 2,419 63,289 48,371 Total 30,656 10,421 158,494 110,026 Year 2001 population and employment estimates are per the DRCOG model land use database. The traffic modeling program TMODEL2 was used to develop traffic forecasts on the study area street system based on forecast land uses. Daily and A.M./P.M. peak hour trips were estimated using trip generation rates defined in the Denver Regional Council of Governments Sketch Travel Model manual (March 1998). Using a modeling process generally referred to as a “Gravity Model Distribution,” the travel demand between each pair of traffic analysis zones was computed. The result is a “trip table” that identifies the desired trips between each zone and the “external stations” at the edges of the model area that link the study area to the surrounding urban area. These trips were then assigned to the roadway network in an iterative process that takes into consideration congestion on the various roadway links. The resulting trip distribution of model area generated external trips was North 15.1%, South 44.9%, East 5.2%, and West 34.8%. Models were developed for the A.M. and P.M. peak hours. An off-peak model was also developed to evaluate conditions for the remaining 22 hours of the day. Capacity evaluations were conducted using the peak hour traffic models of directional traffic flows. Assumed directional roadway capacities for arterials and collectors were 900, 1,800, and 2,700 vph for one, two, and three lanes per direction respectively. Models of year 2001 traffic conditions were developed to calibrate the traffic model to existing conditions. Using the calibrated model, the year 2020 peak hour models were developed using forecast future land uses to iteratively test alternative roadway networks. ---PAGE BREAK--- 4-3 Transportation Master Plan 4.3 2020 “Base Case” Analysis The initial or “base case” roadway network that was analyzed was the current transportation plan from the 1999 Comprehensive Plan (Figure 4-2). The initial test network also included all of the ultimate US 85 access recommendations contained in the US 85 Access Control Plan, I-76 to WCR 80. For roadways outside of the study area and for freeways passing through the study area, the 2020 Transportation Plan roadway laneages were taken from the April 1996 Adams County Transportation Plan. Figure 4-2 shows the daily forecasted traffic levels for this initial test network. Daily traffic was estimated from the P.M. peak hour model and this daily traffic forecast is depicted on Figure 4-2. Figure 4-3 depicts those facilities anticipated to operate above or near capacity during either of the peak hour periods. The facilities forecasted to operate above the capacity with the initial test transportation plan are: • Bridge Street – Yosemite Street to 4th Avenue. • Bridge Street/US 85 interchange. • Bromley Lane – US 85 to 4th Avenue, and I-76 to Gun Club Road. • Bromley Lane/I-76 interchange. • 150th Avenue – Tower Road to I-76. • Collector (138th Avenue) – 27th Avenue to I-76. • 136th Avenue – US 85 to I-76. • 136th Avenue/I-76 interchange. • Henderson Road – Brighton Road to Yosemite Street. • 120th Avenue – Quebec Street to east of Tower Road. • 120th Avenue/E-470 interchange. • Yosemite Street – 128th Avenue to Henderson Road. • 4th Avenue – Bridge Street to 136th Avenue. • Sable Boulevard/I-76 interchange. • Buckley Road – 144th Avenue to 120th Avenue. • Telluride Street – 144th Avenue to I-76. • 45th Avenue – Southern Street to Bromley Lane. • Picadilly Road – I-76 to Baseline Road. ---PAGE BREAK--- 4-4 Transportation Master Plan 4.4 Recommended Major Thoroughfare Plan Based on the deficiencies noted in the “base case” analysis, an iterative analysis of required transportation network improvements needed to serve 2020 travel demands was performed. The resulting recommended Major Thoroughfare Plan and the forecast 2020 traffic demand on the proposed roadway network are shown on Figure 4-4. Changes between the recommended Major Thoroughfare Plan and the “base case” plan are depicted on Figure 4-5. To be consistent with new City-adopted cross-sections, all 6-lane facilities are now classified as “Major Arterials”, all 4-lane facilities are “Minor Arterials”, and all 2-lane streets are “Collectors.” The changes in laneage from the “base case” are summarized below, with the former classification in parentheses: • Bridge Street – 27th Avenue to Tower Road, 6-lane Major Arterial (previously: 4-lane Major Arterial). • 136th Avenue – Brighton Road to US 85, 4-lane Major Arterial (previously: Collector/Minor Arterial). • 136th Avenue – US 85 to I-76, 6-lane Major Arterial (previously: Collector). • Henderson Road – Brighton Road to Yosemite Street, 4-lane Minor Arterial (previously: 2-lane Minor Arterial, agreement with City of Thornton necessary for completion). • 120th Avenue – I-76 to the east, 6-lane Major Arterial (previously: 4-lane Major Arterial). Reclassification of 120th Avenue to a six-lane facility is in part due to increased DIA activity. • Brighton Road – Bromley Lane to south, 4-lane Minor Arterial (previously: 2-lane Major Arterial). • 4th Avenue – Bridge Street to Bromley Lane, 4-lane Minor Arterial (previously: 2- lane Major Arterial). • 4th Avenue (Sable Boulevard) – 144th Avenue to 136th Avenue, 6-lane Major Arterial, 45,000 trips per day (2020) forecasted (previously: 4-lane Major Arterial). • 27th Avenue – Bridge Street to Baseline Road, 4-lane Minor Arterial (previously: 2- lane Major Arterial). • 45th Avenue – Southern Street to I-76, 4-lane Minor Arterial (previously: Collector). • Picadilly Road – I-76 to Baseline Road, 4-lane Minor Arterial (previously: Collector). • Westside I-76 Frontage Road – Baseline Road to 144th Avenue, 4-lane Minor Arterial (previously: Collector). In addition to the changes in roadway classification described above, there are several new roadways that were not on the “base case” plan: • 148th Avenue – 27th Avenue to I-76, 4-lane Minor Arterial. West of 27th Avenue, Collector. • I-76 Frontage Road (East side) – Baseline Road to Bromley Lane, 4-lane Minor Arterial. This facility is needed to serve industrial development in Bromley Park. • Bromley Lane – I-76 to Picadilly Road, 4-lane Minor Arterial. • WCR 2.5 - US 85 to I-76, Collector. • 7th Avenue – Baseline Road to WCR 2.5, Collector. • 11th Avenue – Baseline Road to WCR 2.5, Collector. ---PAGE BREAK--- 4-5 Transportation Master Plan • Himalaya Street (50th Avenue) – Baseline to WCR 4, 4-lane Minor Arterial. • Picadilly Road – Baseline to WCR 4, Collector. • Tucson Street – Bridge Street to Baseline Road, Collector. • Longspeak Street/164th Avenue. Shift the transition from the 164th Avenue alignment to the Longspeak alignment east of 19th Avenue instead of west of 27th Avenue in order to avoid some stormwater detention areas. • Chambers Road aligned with 8th at Bromley Lane and extended as a Collector from 144th Avenue to Prairie Center Parkway. • Fulton Avenue – Bromley Lane to 148th Avenue. • Frontage Road on east side of US 85 – 148th to 132nd, Collector. It should be noted that this frontage road is not part of the US 85 Access Control Plan and as a result, will be a City street. • Potomac Street – 136th Avenue to 144th Avenue, Collector. • 132nd Avenue – Proposed US 85 Frontage Road to Buckley Road, Collector. • Prairie Center Parkway. A new 6-lane Major Arterial through the Prairie Center from Sable Boulevard to 144th Avenue. • Sable Boulevard Interchange with E-470 to align with Prairie Center Parkway. A total of nine facilities were removed or realigned from their location in the “base case” plan. Two of these were as a result of the recommendations of the US 85 Access Control Plan. They are: • WCR 4 – Main Street to US 85. • Henderson Road – Peoria Street to Brighton Road. Four facilities were removed or realigned at the request of the City. They are: • 19th Avenue – Southern Street to Bromley Lane. • Southern Street – Himalaya to Bridge Street. • 150th Avenue – A collector alignment was previously identified on 150th Avenue. The 150th Avenue alignment has be removed from the plan and replaced by the 148th Avenue alignment. This was done to provide a more regular spacing (on the half mile) of planned streets and better serve the needs of future development between 148th and 144th Avenues. • Realignment of Longspeak Street. As a result of the inclusion of Prairie Center Parkway, three other facilities are removed from the plan. These three are: • Telluride Street south of 144th Avenue. • 138th Avenue from 27th Avenue to I-76. • I-76 frontage road (west) between 136th and 144th Avenues. ---PAGE BREAK--- 4-6 Transportation Master Plan 4.5 Analysis of Proposed Transportation Network 4.5.1 Capacity and Level of Service The planning of roadway network improvements, including new roadway segments and the widening of existing roadways, is based in large measure on an evaluation of the traffic-carrying capacity of the individual roadway segments in the network. As discussed in Section 2.2 of this report, traffic engineers define the quality of traffic flow on a roadway as “level of service” (LOS) using letter designations ranging from LOS (best) to LOS (worst). Level of service considers such factors as speed and travel time, freedom to maneuver, traffic interruptions, and comfort and convenience. In the Denver metro area, LOS is the typical minimum level of service standard for roadway planning. LOS represents a prudent design minimum that balances acceptable traffic flows with the cost and feasibility of roadway improvements. Higher level of standards can be used for roadway planning, for example, LOS is adopted by some jurisdictions. Although LOS can provide improved peak hour traffic operations, the tradeoff of this higher level of service standard can be the requirement for wider roadways and more intersection lanes (providing an excess of facilities to serve traffic demands for non-peak periods). Although the proposed Major Thoroughfare Plan makes significant enhancements to the Brighton transportation network and meets a considerable portion of the forecast traffic demand, there remain several facilities under the recommended transportation plan that are anticipated to operate above or near capacity during either of the peak hour periods. The facilities, shown on Figure 4-6, forecasted to operate above capacity are: • Bridge Street – Yosemite Street to 4th Avenue. • Bridge Street/US 85 interchange. • Bromley Lane/I-76 interchange. • 120th Avenue – Quebec Street to Peoria Street, and Buckley Road to Tower Road. • 120th Avenue/E-470 interchange. • Yosemite Street – 128th Avenue to Henderson Road. • 4th Avenue – Southern Street to E-470. • Buckley Road – 136th Avenue to 120th Avenue. • Westside I-76 Frontage Road – Picadilly Road to Bridge Street. • Picadilly Road – 164th Avenue to I-76 frontage road. • Prairie Center Parkway – 132nd Avenue to 136th Avenue. • 136th Avenue – 4th Avenue to Prairie Center Parkway. There are three major reasons why these facilities have not been upgraded in the recommended transportation plan: ---PAGE BREAK--- 4-7 Transportation Master Plan • First, on some facilities, only short segments are overcapacity and it would not be cost-effective to upgrade a long segment to a higher functional classification. • Second, on some facilities, it is anticipated that additional right-of-way needed for a higher classification cannot be obtained. • Finally, at some locations the forecast exceeds the capacity of the highest capacity classified facility. For roads, it would be a traffic forecast exceeding the capacity of a six-lane Major Arterial. Construction of eight-lane arterials is not recommended due to the difficulty pedestrians have crossing such facilities, the difficulty of left turn access in driveways, and their negative impact to adjacent land uses. For freeway interchanges, there are no current plans to construct anything other that diamond interchanges at the identified locations. The facilities depicted as being over capacity are over the capacity of a diamond interchange. Other types of interchanges, such as those with direct connectors, could be considered in the future if the actual need for these special treatments is deemed necessary. Bridge Street remains as a four-lane facility consistent with its classification in the North Metro Major Investment Study. Facilities that are depicted as being over capacity should be carefully monitored as traffic volumes grow. As not all streets that will be constructed were modeled, it is possible that future parallel streets and roadway networks internal to developments can distribute traffic in a more efficient manner. In some cases, auxiliary turning lanes and access control can help alleviate forecasted over-capacity conditions. 4.5.2 Air Quality After the passage of the federal Clean Air Act in 1970, the Environmental Protection Agency designated the Denver metropolitan area as a non-attainment area for several federal health-based air quality standards. Over the years, the region frequently violated the standards for carbon monoxide, ozone, and particulate matter. However, in the early 1990's, air quality improvements resulting from federal, state, and local air pollution control programs gradually began to bring the area into compliance with federal standards. The Denver metro area has not violated federal standards since 1995. According to the Regional Air Quality Council’s (RAQC) Blueprint for Clean Air, with ongoing implementation of current or equivalent programs, and further federal regulation of motor vehicle emissions, the Denver metro area should remain in compliance with the federal standards for carbon monoxide, ozone, and PM-10 through 2020, even with the significant increases in population and vehicle travel expected during this period. The RAQC indicates that motor vehicles are the largest source of air pollution along the Front Range. Not only do gasoline and diesel vehicles emit a number of pollutants from their tailpipes, they also kick up street sand and dust from the region's paved and unpaved roadways. These pollutants are responsible for approximately 70 percent of the Brown Cloud and can lead to violations of the federal health standards. Coal-fired ---PAGE BREAK--- 4-8 Transportation Master Plan power plants also are significant contributors to the problem. Other sources include wood burning, restaurant grills, construction equipment, and commercial and industrial sources. Congestion and delay that occurs during the commute hours on our transportation system can exacerbate air quality problems. The recommended Major Thoroughfare Plan reduces the total vehicle miles traveled during the peak hours in congested conditions by nearly 13,000 vehicle miles, or a roughly 8 percent reduction over the “base case” previous transportation plan. The recommended plan also reduces the daily amount of vehicle hours traveled by over 2,400 vehicle hours per day. 4.5.3 Traffic Noise As traffic volume builds on highways and arterials, local and state officials can often anticipate an increase in noise complaints. Land uses that are particularly sensitive to increasing noise levels include residences, picnic areas, recreation areas, playgrounds, active sports areas, parks, motels, hotels, schools, churches, libraries, and hospitals. As a rule of thumb, traffic is not usually a serious problem for people who live more than 500 feet from heavily traveled freeways or more than 100 to 200 feet from traveled roads. Land use planning should require that new developments are planned, designed, and constructed in such a way that noise impacts are minimized. Highway noise impacts may be subject to federal noise mitigation requirements. General requirements for planning projects subject to federal requirements include: • Identification of existing activities, developed lands, and undeveloped lands for which development is planned, designed and programmed, which may be affected by noise from the highway; • Prediction of traffic noise levels; • Determination of existing noise levels; • Determination of traffic noise impacts; and • Examination and evaluation of alternative noise abatement measures for reducing or eliminating the noise impacts. 4.6 Functional Street Classifications The Major Thoroughfare Plan is based on the street classification system of Major Arterials, Minor Arterials, and Collectors. City-adopted cross-sections for each roadway classification are included in Appendix 2 to this report. It is recommended that the following street cross- sections be used for the following street classifications: • Major Arterial, six lanes. Major Arterial Revised Cross-Section, Page 13-B, 130–foot right-of-way/easement combination. • Minor Arterial, four lanes. Minor Arterial Revised Cross-Section, Page 13-A, 110– foot right-of-way. • Collector. Any of the applicable collector street sections (Pages 12-A, 12-B, or 12-C). ---PAGE BREAK--- 4-9 Transportation Master Plan Rights-of-way in excess of these standard may be needed at intersections between streets depicted on the proposed plan to allow for addition turn lanes (dual left turn lanes on minor arterials and exclusive right turn lanes). A traffic engineering analysis should be conducted prior to the design of these intersections and dedication of adjacent right-of-way to determine if additional turn lanes are needed. 4.7 Downtown Parking and Circulation Both parallel and angle parking configurations are used for on-street parking in downtown Brighton. Locally, as well as nationally, there is an ongoing debate about the merits of retaining or expanding the use of angle parking in downtown areas. Proponents often cite the increased parking supply afforded by angle spaces, while opponents we express concern about the safety issues associated with the restricted visibility for backing-up movements. Angle parking is best suited for low-volume, low-speed roads that have adequate width to accommodate both the wider parking area and the through travel lanes. Angle parking stalls must provide for adequate corner clearance from intersections, driveways and crosswalks. Since restricted visibility is a concern with angle parking, the volume of bicyclists in the through lanes should be particularly considered. Parking-related accident rates have been used by some jurisdictions in evaluating whether to retain or remove existing angle parking. Using this measure, elimination of existing angle parking is warranted if the parking-related accident rate is greater than the rate on similar streets that have parallel parking. While quantitatively the overall parking supply in downtown Brighton is adequate, the quality and convenience of many of the spaces is perceived to be low, leading to a daily competition for the best parking spaces between employees, customers, and other downtown visitors. Additionally, the downtown park-and-ride lot is also too small to accommodate the parking demand. As discussed in other sections of this plan, RTD is actively looking for addition park-and-ride lot capacity. The street network in the downtown area is primarily on a grid and posted speeds are generally 25 or 30 mph. Residences and businesses directly access the streets within the grid. The locations of many of the stop signs within the downtown Brighton street grid follow an every other street pattern commonly found in many communities with similar networks. A grid street system provides ample capacity to the areas they serve. Therefore, roadway widening is not warranted other than on the streets previously mentioned (Bridge Street and 4th Avenue). However, the City often receives complaints of speeding and cut-through traffic in the downtown area. These complaints are common in other communities with similar grid street networks. While members of the public have a right to use public highways without obstruction and interruption, this right is subject to the power of local governments to impose reasonable restrictions for the protection of the public. Residential streets should be protected from vehicular traffic moving at excessive speeds (greater than 25 to 30 mph) and from parking unrelated to residential activity. ---PAGE BREAK--- 4-10 Transportation Master Plan Traffic calming measures have been implemented in other communities with grid networks to deal with these concerns. Traffic calming involves changes in street alignment, installation of barriers, and other physical measures to reduce traffic speeds and/or cut-through volumes, in the interest of street safety, livability, and other public purposes. Some of the more commonly used traffic calming devices are street undulations, chokers, mini roundabouts, full or partial street closures, turn prohibitors, and chicanes. Before any traffic calming measures are implemented, an engineering study should be undertaken to determine if traffic calming is warranted and the appropriate locations and method of traffic calming to be employed. Consideration has to be given to the legal, access, and public safety ramifications of implementing such a program. Stop signs are persistently requested by citizens with the expectation that they will control speeds or reduce traffic volumes and accidents in residential neighborhoods. Although there may be some effect on volume and accidents in certain instances, there is little effect on traffic speeds attributable to stop sign placement except within about 200 feet on the intersection controlled. Indiscriminate use of stop signs and multi-way stops signs should be avoided. It should be noted that there are warrants for stop sign installations that should be met before they can be installed.