Technical Memorandum Transportation Analysis Update County Road San Juan County, New Mexico

Transcription

1 Technical Memorandum Transportation Analysis Update County Road San Juan County, New Mexico NMDOT Control No. L5076 NMDOT Project No. HPP-7950(2) prepared for the San Juan County Department of Public Works 305 South Oliver Drive Aztec, New Mexico in cooperation with the Federal Highway Administration and the New Mexico Department of Transportation prepared by URS Corporation 6501 Americas Parkway NE, Suite 900 Albuquerque, New Mexico September 2012

2 INTRODUCTION The following technical memorandum has been prepared to provide an update and describe changes to previously produced transportation related documents on this project for improvements to San Juan County Road (CR) 7950, the primary northern access road to Chaco Culture National Historic Park (CCNHP). This memorandum supplements information presented in the report titled Transportation Needs Analysis County Road 7950, prepared by URS and Taschek Environmental Consulting, dated June 2008, and the Addendum to April 2008 Technical Memorandum on Park Visitation and June 2008 Transportation Needs Analysis Report, County Road 7950, prepared by URS and Parametrix, dated April These documents were intended to provide the engineering analyses and general project background to support an environmental assessment (EA) document for County Road 7950 improvements. The Environmental Assessment document was developed as a working draft only; it was not completed, nor was it signed by the participating sponsoring and oversight agencies, nor was it made available to the public. This Transportation Analysis Update will form the basis and provide supporting data for a renewed and updated EA document to be prepared for this project. The following is a listing of the various background documents referenced above and found elsewhere in this report, summarized here for clarification. Potential Impacts Associated with Improvements to County Road 7950, prepared for Chaco Culture National Historical Park by Jonathan Upchurch, NPS Transportation Scholar, draft June 2005, (referred to herein as the 2005 Upchurch Study ) 2

3 Technical Memorandum Estimated Changes in Visitation Patterns at CCNHP as a Result of Improving CR 7950, by URS, dated April 2008, ( the 2008 Technical Memorandum ) including Addendum: Visitation and Traffic Volume Prediction Model for Chaco Culture National Historic Park Transportation Needs Analysis County Road 7950, prepared by URS and Taschek Environmental Consulting, dated June 2008, ( the TNA ) Addendum to April 2008 Technical Memorandum on Park Visitation and June 2008 Transportation Needs Analysis Report, County Road 7950, prepared by URS and Parametrix, dated April 2009, ( the 2009 Addendum ) General Management Plan Amendment Transportation Data & Visitor Projection Analysis, Final Report, dated November 13, This document was prepared for the NPS by consulting engineers David Evans and Associates, Inc., ( the GMPA ) BACKGROUND The information presented herein primarily addresses the Proposed Action for road improvements to CR 7950 from the transportation and engineering perspectives. As described in more detail below, the overall limits of the environmental investigations and documentation remain unchanged. Refer to the map on the preceding page for the overall limits of the Study Corridor as defined by the logical termini for the EA, and the Limits of Proposed Action for actual roadway improvements. REVIEW OF TRAFFIC VOLUME FORECASTS Traffic volumes on CR 7950, both existing and forecast, have been the subject of much previous research and analysis. Traffic volumes were addressed in the Technical Memorandum Estimated Changes in Visitation Patterns at CCNHP as a Result of Improving CR 7950, by URS, dated April Findings from this Technical Memorandum were incorporated into the aforementioned Transportation Needs Analysis. The Technical Memorandum contained a Visitation and Traffic Volume Prediction Model for Chaco Culture National Historic Park. Following receipt of further information and statistics from the Public Use Statistics Office (PUSO) of the National Park Service regarding visitor usage, the Visitation and Traffic Volume Prediction Model was updated in the aforementioned Addendum. Following the development of these analyses and documents related to the initial CR 7950 Improvements Study, an additional analysis and study commissioned by the National Park Service (NPS) was also developed. This study is labeled as the General Management Plan Amendment Transportation Data & Visitor Projection Analysis, Final Report, dated November 13, This document was prepared for the NPS by consulting engineers David Evans and Associates, Inc. An earlier study and report was also prepared addressing traffic and visitation to CCNHP. This report, Potential Impacts Associated with Improvements to County Road 7950, dated June 2005, prepared by Jonathan Upchurch, also made predictions regarding the impacts of improving CR 7950 on CCNHP. Findings of some of these studies are somewhat inconsistent with each other, particularly the Upchurch Study, but for purposes of this project update, these previous studies are considered adequate to indicate the probable range of visits to CCNHP and the associated traffic volume forecasts that are associated with visitation. Brief excerpts of this 3

4 visitation and traffic data are included here. For greater detail, the original documents should be reviewed directly. The original URS document, the Technical Memorandum, utilized average park visitation data from 2004 to 2007, a predicted annual growth rate of 7.65% per year for two years immediately following CR 7950 improvements, and a leveled off 0.525% annual growth rate for the years beyond the two years following road improvements. The annual average daily traffic (AADT) on CR 7950 was estimated to be 284 vehicles per day (vpd) in 2009 and 404 vpd by Growth data and trends for the park itself were not available, since visitation counting methodology changed dramatically in the Park in It should also be noted that the forecasts and predictions made in this document were based on the assumption that the full length of CR 7950 would be improved with paving. The growth rates and trends previously defined can be assumed to be much reduced if only a partial segment of CR 7950 is improved as with the Proposed Action defined below, because the segment of roadway not being improved contains the Escavada Wash crossing, an arroyo crossing that is impassable during certain weather conditions and that can be difficult to cross for some vehicles (i.e. tour buses) even when it is dry. In addition, the growth rates and trends would also be much reduced if a lesser surface treatment is applied, i.e. where the roadway is not being paved, making the road possibly less attractive to some visitors. URS Addendum to the Technical Memorandum utilized the new (post 2005) NPS data for park visitation, and the same growth rates that had been previously established and used in the original Technical Memorandum (7.65% followed by 0.525%). Using much reduced park visitation numbers (due to the NPS revisions in the tracking / counting methodology), revised estimates were made for annual average daily traffic in the Addendum, with 2009 traffic estimated on CR 7950 west of CR 7900 to be 204 vpd, and with 2029 traffic estimated to be 305 vpd. Again, it should be noted that the forecasts and predictions made in this document were based on the assumption that the full length of CR 7950 would be improved. The growth rates and trends can be assumed to be reduced if only a partial segment of CR 7950 is improved. Another perspective on park visitation and traffic forecasts is made in the aforementioned General Management Plan Amendment (referred to following as GMPA). Following considerable independent study and analysis of recreational visitation at various national parks, the GMPA concludes that: there seems to be no universal relationship between access road or general transportation improvements and a substantial increase in recreational visitation that can be applied across park units. While some parks experienced an increase in visitation during the years following transportation improvements, variations in visitation at many individual parks seemed to follow general regional trends. The GMPA includes a predicted growth rate of 3% per year for the three years immediately following road improvements, followed by a leveled annual growth rate of 1% per year for the years thereafter. The growth rate of 3% per year influenced by the road improvements is less than half of that forecast by URS (7.65% per year), however, it applies to partial road improvements only i.e. no improvements on the segment of CR 7950 south of MP As stated in the GMPA, the lower percentage is due to the continued inability of tour buses to directly access the park as well as a lower annual rate of increase of vehicular access expected immediately following road improvements. The lack of crossing 4

5 improvements at Escavada Wash would have the largest impact to the expected increases in visitation resulting from the other road improvements. The GMPA goes on to state that: If CR 7950 is only partially improved, the annual recreational visitation may increase as little as six percent more than the expected base visitation increases by With application of an update to the previous URS traffic model, assuming road improvements take place in 2013, and incorporation of the GMPA growth rates as discussed herein into the URS model, traffic on CR 7950 west of CR 7900 in 2029 is forecast to be 308 vpd (as compared to previous URS findings of 305 vpd, a very negligible difference). An update to park visitation data was obtained from the PUSO website for the past four years from 2008 to The following table includes the number of park visitors in the recent past. Park use growth was flat between 2008 and 2009, dropping in 2010, and then increasing fairly dramatically between 2010 and Overall, the growth rate between 2008 and 2011 is calculated to be 1.75% per year for this short sample period, considered to be representative of only this period of time. Year Park Visitation 37,180 37,376 34,226 39,175 Taking the variations in previous studies and findings into account, park visitation and traffic predictions are less than an exact science. The data presented in the GMPA are considered reasonable and within the same order of magnitude as the previous URS data. An annual growth rate for park visitation of 1% appears reasonable taking into account the more recent data available in the GMPA, and with consideration of both visitation counting methodologies used by the NPS. The partial improvements related growth rate of 3% from that document also appears reasonable in light of URS previous findings of 7.65% when improving the entire roadway, including the Escavada Wash. In any event, these growth numbers, when applied to the present data for visitation, which is reported to be 39,175 visitors per year in 2011, do not suggest an overwhelming influx of visitors into the CCNHP with road improvements, nor a significant impact related to the improvements. It is not the objective of this current project update to generate yet another forecasting model that would have its own assumptions and results. Findings from these studies support the planned roadway improvements; CR 7950 can be considered as a low volume rural road with traffic forecast / AADT for the 2029 design year being approximately 308 vpd. PROJECT LOCATION AND LIMITS Corridor Study Limits / Logical Termini The logical termini of the environmental assessment study corridor remain as previously discussed in the aforementioned documents. The logical termini have been determined based on logical end points at primary traffic generators. The southwest terminus is the south end of CR 7950, at the CCNHP boundary, at MP 0.0. The northeast terminus is the north end of CR 7950, located at the intersection with CR 7900, at MP The intersection of CR 7950 and CR 7900 is located approximately five miles south of US 550. The overall length of the study corridor is miles. (Refer to the preceding map.) 5

6 Construction Project Limits /Proposed Action The construction of proposed improvements to CR 7950 is planned to begin at the north boundary of Navajo Tribal Fee lands, at Sta as shown on the adjacent figure. This location is 4.37 miles northeast of the CCNHP boundary (MP 0.0 / Sta assumed starting point for development of the roadway geometric layout) on CR This location has been established with property line mapping data; the begin station is the point where CR 7950 crosses from Navajo Tribal Fee lands and enters into the checkerboard area of land ownership. Lands within the checkerboard are owned by various entities, including the Bureau of Land Management (BLM), State of New Mexico (NMSLO), Navajo Tribal Trust lands, Navajo allotments and private ownership. Beginning at this location and continuing to the northeast, San Juan County generally has established right of way for CR Southwest of this point of beginning, the existing roadway is within the Navajo Tribal Fee lands where 6

7 no public right of way exists. Therefore, no work is planned for the southerly 4.37 miles of CR 7950 from the Park boundary. The northern limit of the improvements has been established by San Juan County and in previous studies as Sta , at the point where the roadway to the northeast was previously constructed with a chip seal surface treatment. This end location is miles from the CCNHP boundary, thus the total length of proposed roadway construction is 8.23 miles. It should be noted that the crossing of the Escavada Wash is not included within the limits of the Proposed Action. Remaining Roadway Segments and Right of Way The most southerly segment of CR 7950, from MP 0.0 (at the boundary to CCNHP) to MP 4.37 is within Navajo Nation lands, designated as Navajo Tribal Fee lands. Navajo Tribal Fee land is land purchased by the tribe similar to private property, rather than lands dedicated by some Federal action or within federally established reservation boundaries. Federal agencies such as the Bureau of Indian Affairs (BIA) have no jurisdiction over these lands; property taxes are paid on these properties as with private lands. No road right of way exists or has been established crossing this land. Ongoing maintenance of this segment of the roadway is assumed to be the responsibility of the Navajo Division of Transportation (NDOT). The segment of roadway designated for the Proposed Action includes a few land sections of Navajo Tribal Trust lands. The Tribal Trust lands have no individual land ownerships; all Tribal Trust land is owned in common and administered by the Navajo Nation's government, and is under BIA jurisdiction. No property taxes are paid on these lands. The ownership status makes acquisition of a roadway easement (or definition of prescriptive right of way) feasible within Tribal Trust lands, and infeasible within Tribal Fee lands. Right of way or easements will be acquired by San Juan County as necessary for the crossing of Navajo Tribal Trust Lands. The Proposed Action also crosses State lands administered by the New Mexico State Land Office. San Juan County purchased the road right of way crossing the State lands in 1998, recorded as Right of Way Easement No. RW The right of way across the Federal BLM land was assigned in 1981, in compliance with Federal Road Statute This right of way is 60 feet wide; recorded under Federal Permit No. NM The most northerly segment of CR 7950, from MP to MP has been previously improved by San Juan County. Chip seal surface treatment was constructed on this segment in 2006, prior to the inception of the current project, by the County. No changes or other improvements are currently planned for this segment of CR 7950, other than ongoing maintenance activities, on an irregular basis as needed. 7

8 CONSTRUCTION PROJECT ELEMENTS / PROPOSED ACTION Roadway Surface Treatment The previous Transportation Needs Analysis (TNA) included the development and analysis of six different roadway surfacing alternatives (refer to the TNA for details). The recommendations made in the TNA for further study (through the NEPA process) for roadway surfacing consisted of two alternatives: Stabilized Aggregate Surfacing (stabilized with lignosulfonate) and Chip Seal Surfacing. From the perspective of initial construction costs, these two alternatives were very similar, within 3-4% of each other. For various reasons, including the desire to minimize future maintenance, and to continue with the same surface treatment applied to the northerly three miles of CR 7950, San Juan County s previous preferred alternative had been Chip Seal Surfacing. However, through the previous project scoping and public involvement process, significant opposition has been recorded and the use of Chip Seal Surfacing ( paving ) has been the key point of contention. (Chip Seal Surfacing is considered by the public to be effectively the same as the placement of paving with a plant mix bituminous pavement, which is considered to be unacceptable by the public.) In response to the public opposition related to the Chip Seal Surfacing, San Juan County has revised the Preferred Alternative: the Preferred Alternative for roadway surfacing will be the Stabilized Aggregate Surfacing. In general terms, this will consist of an aggregate roadbase material with a stabilizing compound applied to increase the hardness, durability, and longevity of the surfacing. It will also reduce dust. Stabilization will consist of a mixture of 90% Magnesium Chloride and 10% Lignosulfonate. An appendix is included at the end of this memo containing data sheets describing the composition and handling of these materials. The above photograph illustrates the appearance of another County road with stabilized aggregate surface using the same materials planned here. This photo was taken on San Juan County Road 2770, aka the Hart Canyon Road, located north of Aztec. This surface treatment is projected to have a 3 to 5 year life, before additional maintenance action becomes necessary. This alternative is expected to be acceptable to the public since previous public input identified gravel as an 8

9 acceptable alternative, the roadway surface will not be striped nor appear as typical pavement, nor will this treatment result in the symbolizing of a paved road on future state highway or other maps. Roadway Surfacing Width The existing graded traveled way width is approximately feet. Roadside ditches are found adjacent to the traveled way, generally well defined and about 10 to 12 feet wide. The ditch flowlines are typically offset about 5-6 feet from the edge of traveled way, with an additional 5-6 feet of backslope. The TNA report reviewed the roadway design criteria of several national agencies that have jurisdiction or provide guidance over rural roadway design. These agencies included the Federal Highway Administration (FHWA), the American Association of State Highway and Transportation Officials (AASHTO), BIA, BLM, and the NPS. CR 7950 is considered to be a Primary Access Recreational Road in accordance with AASHTO definitions (refer to the TNA for more detail). Recommended roadway widths for such a road as summarized with data from the above agencies range from 20 ft. (BLM minimum) to 32 ft. (BIA). The conclusion reached in the TNA report was a recommendation for use of a 28 ft. design width. Taking into account the existing roadway dimensions, the previously conceived design width of 28 ft. appears to be somewhat extravagant, and would generate the need for complete regrading of the roadbed and ditches, and create additional environmental impact to the roadside. The proposed width of the roadway surface treatment will therefore be 24 feet. This will require some minor regrading of the existing roadbed and roadside ditches in areas where the width is less than 24 feet. Refer to the adjacent plan and typical section views for illustrations of the proposed road. 9

10 Roadway Geometry / Horizontal Curvature The existing roadway alignment was defined and analyzed as part of the 2008 TNA. Findings of the TNA were that the horizontal curvature of the existing roadway satisfied geometric requirements for an operating speed of 40 mph or greater, with the exception of seven specific curve locations. These curves were recommended for realignment in the TNA, by means of reconstruction with broader, flatter radii to allow for an increase in operating speed. Six of these curves are located between MP 0.0 and MP 4.37, and are therefore outside the limits of the Proposed Action. The final curve, labeled as Curve No. 7 in the TNA, is located at Sta , which is between MP 8.1 and 8.2, at what is known as Padilla Junction. This existing curve is a compound curve, with the shorter, sharper radius of the compound curves being 425 ft. In verifying the appropriate operating speed for this curve, the planned surface treatment of stabilized aggregate must be considered. Since the roadway surface material and texture results in different side friction factors, and use of the stabilizer results in a reasonably hard driving surface, the applicable side friction factor in the case of a stabilized aggregate can be assumed to be somewhat between that of a paved vs. an unpaved surface. Using a friction factor of 0.13 and assuming a superelevation rate of 6%, results in a safe operating speed of 35 mph for this 425 ft. radius curve. Since 35 mph is the current posted speed for the entire roadway, 35 mph can be considered as acceptable and this curve can be considered as adequate to remain in place as is. With posting of a new speed limit to be 40 mph, an advisory speed posting of 35 mph should be placed at this curve. Therefore, leaving this curve as is, and with no other substandard curvature, no adjustments or realignments are proposed for any of the horizontal curves within the limits of the Proposed Action. Curve No. 7 crosses an area previously identified to contain an archaeological site; this site is defined as LA_ There are reported to be 13 features at this site; Feature 7 (refer to Cultural Resources Report, September 2010, Parametrix) is located within the proposed construction footprint. This feature is located in the existing CR 7950 roadbed. An update to the Cultural Resources Report being developed by Parametrix indicates that impacts to this feature would have no adverse effect on the characteristics of the site that qualify it for inclusion in the National Register of Historic Places. Therefore, no realignment of the roadway is warranted in relation to this archaeological site. Roadway Drainage The existing roadside ditches are generally well defined and graded; widths vary but are generally about feet, including both foreslope and backslope. (The TNA has noted these ditches to be intermittent, which is generally true, but they appear to have been better defined and graded since the surveys that were done for the TNA.) The width of proposed surface treatment is 24 feet, which will be somewhat wider than the existing width (22-24 feet), thus requiring minor re-grading of the roadside ditches. Lead-out ditches (called bleeder swales in the TNA) continue to be used to direct ditch flows off of the roadway into low points or ponding areas. Culverts exist at minor drainage crossings as noted in the TNA, with existing culverts being 18 to 24 corrugated metal pipes (CMP). The design approach to be incorporated into the Proposed Action will be consistent with that described in the TNA. Roadside ditches will be maintained, with generally the same size and configuration as 10

11 currently exists (with use of approximately 4:1 side slopes). As discussed in the TNA, roadway surface treatment with stabilized aggregate will be more impervious than the current dirt road, and greater runoff will result in storm events. Rather than increase the number of lead-out ditches / bleeder swales to account for the greater volume of runoff, check dams within the roadside ditches were recommended in the TNA. Use of check dams will allow all work to be generally within the existing prescriptive right of way, avoiding the need for taking of wider right of way or obtaining easements for lead-out ditches / bleeder swales. Check dams will be used where roadside longitudinal ditch grades are between 2% and 6%. No check dams are needed where grades are flatter than 2%; grades steeper than 6% will require a higher level of protection, i.e. riprap armoring of the ditch. In a review of the roadway grades within the limits of the proposed action, the following are found: 5.87 miles of roadway with grades flatter than 2%, thus requiring no special treatment in the ditches; 2.31 miles of roadway with grades between 2% and 6% thus requiring check dams; and 0.08 miles (400 ft.) of roadway where grades are steeper than 6%, requiring riprap armoring. Based on spacing calculations related to runoff volumes for a one year storm, approximately 600 check dams will be needed (300 each left and right sides of the road). Culvert pipes will be replaced or extended where necessary to match the new graded width of the roadway and blend with the ditches. In some cases, existing culverts are buried, ends are damaged, or they are simply too short to accommodate the planned roadway width. Extension or replacement of culverts will be done with sizes in kind with existing and within the roadway footprint and right of way. Fencing CR 7950 traverses open range country as noted in the TNA report. The existing roadway is posted with signage noting the possible presence of livestock on the road, but there is no fencing of the right of way. Fencing would be required to keep livestock out, and to prevent them from entering onto the traveled way. With no existing right of way fencing, horses and cattle can and do cross and meander on the traveled way. This situation would not be acceptable in certain conditions, such as with high traffic volumes, high speeds, limited site distance and without driver awareness. However, traffic volumes are very light, site distance is generally very good, and with proper posting, drivers can be made aware of this situation. Current operating speeds are generally not high; the posted speed limit is 35 mph, and the presently poor roadway surface tends to slow down traffic speeds. With a stabilized aggregate surface, and posting for 40 mph (see below), speeds are expected to increase somewhat, however with consideration of the other factors, fencing of the right of way is considered to be unnecessary. Therefore, fencing is not included as a component of the Proposed Action. 11

12 Signing and Delineation A site review of the existing signage was conducted on June 26, 2012, as a means to supplement the information presented in the TNA report. Existing signage generally consists of the following: Two sets of regulatory 35 MPH speed limit signs County Route Signs identifying intersections of other county roads A few guide signs, directing traffic to CCNHP in the southbound direction, and to US 550 / NM 44 and Albuquerque / Farmington in the northbound direction A set of non-standard Livestock on Road Please Slow Down signs, one in each direction Chevron alignment warning signs at sharper horizontal curves Non-standard warning signs at Escavada Wash warning of the water crossing Improvements to this signage will be included as part of the Proposed Action. The following signage will be upgraded: Increase of the regulatory Speed Limit to 40 MPH reflecting the expectation that drivers will tend to travel somewhat faster on the improved roadway surface (Post R2-1 signs at four locations) Addition of Curve Warning Signs (W1-2) with 35 MPH Advisory Speed Plaques (W13-1P) for the curve at Padilla Junction (MP 8.18) Addition of Cow Warning signs (W11-4) (two or three sets) Replacement of the County Route Signs at intersections Replacement of Destination and Distance Signs using current highway designations (i.e. US 550 rather than NM 44) Addition of County Route Signs identifying (confirming for unfamiliar driver) CR The placement of traffic markers, known as delineators, will also be included in the Proposed Action. Delineators consist of roadside posts that extend 4 feet above the edge of the roadway surface containing a single reflector, used to identify the roadway edge. For roadways with lower functional classifications such as rural two-lane roads, the delineators are placed at the roadway edge, typically between 2-8 ft. from the outside edge of shoulder (or the traveled way as in the case of CR 7950). The delineators will be placed to identify curves in the roadway alignment, with spacing of the delineators 12

13 being a function of the radius of the curve (the smaller the radii, the shorter the delineator spacing), for all curves with radius less than 3000 ft. With placement on both sides of the curves on CR 7950, approximately 400 delineators will be placed. In addition to curve / roadway edge treatment, object markers, resembling the delineators but with three reflectors rather than one, will be placed to identify the location of culverts. These are used by both the traveling public and maintenance forces to clearly indicate the locations of culvert ends. Delineators and object markers will be placed in accordance with NMDOT Standard Drawing SAFETY CONSIDERATIONS The primary improvement to safety associated with the proposed action is the surface treatment itself. With the construction of a stabilized aggregate roadway, the driving surface of CR 7950 will be altered in that the current loose dirt and sand that exhibits a poor coefficient of friction will be replaced with a denser more stable material that exhibits an improved coefficient of friction. Therefore, drivers will be able to maintain better control of their vehicles with the improved friction characteristics i.e. there will be less tendency to experience the ball bearing effect of driving on loose material or the bouncing effect of driving on the washboard surface. Crash history data was obtained from the NDOT and the San Juan County Sheriff s Office and described in the TNA report. The data obtained at the time of the TNA was very limited and generally inconclusive. The NDOT has again been contacted with a request for an update to their crash reports for the period between 2008 and the present. With the crash history data provided by the NDOT in June 2012, no additional crashes have been reported. The San Juan County Sheriff s Office has also been recently contacted and they report that, due to the project s location on Navajo lands, the NDOT is the agency to contact for this information. New guidance regarding highway safety has become available from AASHTO since the original TNA report was issued in This guidance is in the form of the Highway Safety Manual, 1 st Edition, issued by AASHTO in The Highway Safety Manual (HSM) contains predictive factors to assess the quality of improved safety with respect to roadway improvements. The HSM was consulted regarding the planned improvements to CR It is the general intent of the HSM to address higher volume and higher function roadways than CR 7950, which is a very low volume, unpaved rural road. Because of this, most of the guidance has been found to be not applicable, or of negligible value in addressing the safety improvements being made to CR The foremost element of safety improvement that can be identified with the Proposed Action is the surface treatment; this type of improvement is not addressed in the HSM. Other improvements or elements of improvements can be found in the HSM with crash modification factors (CMF) identified. These CMF s are based on historical and statistical data collected by AASHTO from various studies that provide a statistical means of assessing or evaluating the benefit of implementing certain roadway changes quantified with the CMFs. Various Roadway Element Treatments, Roadway Sign Treatments, and Roadway Delineation Treatments included in the planned improvements / proposed action were reviewed as described below, with their associated CMFs. 13

14 Modify Lane Width. Very minor widening of CR 7950 is planned, with the establishment of the planned roadway cross section to consist of 24 feet of surface treatment. The existing roadway is somewhat less than that, often around 22 feet wide. Therefore, it can be stated that the road will be widened to (an average of) one foot on each side. Lane widening can reduce vehicle crashes such as single vehicle run off road, multiple vehicle head-on, opposite direction side swipe and same direction side swipe. However, with the information gathered from the NDOT and the San Juan County Sheriff s office, there is no proven history of vehicle crashes. Although AASHTO has identified CMFs for lane widening, they are noted to be of much greater effect for higher volume roadways, where traffic volumes exceed 2000 vpd. For the traffic volume associated with the project (less than 500 vpd), the CMF improvement between an 11 ft. lane and a 12 ft. lane is 1% (1.01 to 1.00). With this low CMF, and effectively no crash history, the results is negligible. Install Combination Horizontal Alignment / Advisory Speed Signs. New signage is planned, however, this will be an upgrade and expansion of existing signage; CR 7950 is currently signed. The CMFs associated with this improvement are those compared to a base condition with no signage at all, the absence of any signage. The CMF for this case is 0.87, or a 13% improvement over the condition of no signage at all. Since this is not the case with CR 7950, some lesser degree of improvement might be assumed with the planned signage, such as 5% or so. Install Post Mounted Delineators. The installation of roadside delineators is included as part of the proposed action (refer to previous section). AASHTO s findings on the benefits associated with delineators is not conclusive, however. This type of improvement, when compared to a base condition being the absence of any post-mounted delineators, results in a CMF of 1.04 or 1.05, a greater crash probability. AASHTO notes that Observed variability suggests that this treatment could result in an increase, decrease, or no change in crashes. These findings do not provide a warrant for use of delineators, however, this may be due to the size of the population sample and data available to AASHTO in this first edition of the HSM. Delineators are considered to be a nominal cost for a potential high value gain. Summarizing the above safety findings, there is little to no crash history on CR 7950, therefore little or no opportunity to quantify the improvements relative to trends or crash modification factors. In addition to the primary improvement to safety provided by the surface treatment, the proposed improvements to signage and delineation are also expected to yield safety benefits. Increasing driver awareness of the hazards present and safe operating speeds, as well as providing clear guidance to destinations and identification of the roadway edge, has the potential to reduce crashes on CR CONCLUSIONS AND RECOMMENDATIONS This Technical Memorandum provides an update to the previous reports and documents produced for this project. This memo also identifies the new Preferred Alternative and describes the components and limits of the Proposed Action. This information as applicable is recommended for inclusion in an Environmental Assessment document for this project. 14

15 Material Data Sheet Lignosulfunate Product Name: Product Composition: Road Loc Greater than 60% lignosulfunate CAS No.: to 54% water CAS No.: Chemical Family: Chemical Formula Lignin Amorphous polymer Section I Company Identification Manufactured for: Desert Mountain Corporation Address: PO Box 1633 Emergency Telephone Number: Desert Mountain Corporation (800) Telephone Number for Information: Kirtland, NM Date Prepared: November 12, 2009 Signature of Preparer: TC 15

16 Section II - Hazard Ingredients/Identity Information Hazardous Components (Specific Chemical Identity; Common Name(s)) OSHA PEL ACGIH TLV Other Limits Recommended %(optional) None known N/A N/A N/A N/A Section III - Physical/Chemical Characteristics Boiling Point: 101 to 103 C Specific Gravity (H 2 O = 1): 1.2 to 1.4 Vapor Pressure (mm Hg.): Not known Freezing Point: Unknown Vapor Density (AIR = 1): Not known Evaporation Rate Unknown ph: 3 to 4 Solubility in Water: 100% soluble Appearance and Odor: Brown liquid with a slight odor 16

17 Material Data Sheet Magnesium Chloride SECTION I: MATERIAL IDENTIFICATION Product Name: Chemical Name: RoadSaver Dust Suppressant Magnesium Chloride Solution Manufacturers: U. S. Magnesium (801) North 2200 West Salt Lake City, UT Intrepid Potash Wendover, LLC (435) P.O. Box 580 Wendover, UT Distributed by: Desert Mountain Corp. (800) PO Box 1633 Kirtland NM Date Prepared: April 10, 2002 Updated: May 7,

18 SECTION II: HAZARDOUS INGREDIENTS / IDENTITY INFORMATION Hazardous Components: None SECTION III: PHYSICAL/CHEMICAL CHARACTERISTICS Boiling Point: 225ºF Specific Gravity: Vapor Pressure: N/A Melting Point: N/A Vapor Density: N/A Evaporation Rate: Not Determined Solubility in Water: 100% ph: as shipped Freeze Point: -10 F Appearance and Odor: Liquid, Clear to Slight Yellow, Very Low or No Odor 18