Comments from the NM 14 Citizens Advisory Committee on Design Information assembled, mailed to the NM Transportation Department, Feb. 26, 2002 Assembled by Ross Lockridge, member of CAC HISTORY--EROSION CONTROL--TAPERS--GUARDRAIL INSTALLATION--10 FT CLEAR ZONES ~
Since our discussion (Jan. 31), the CAC has assembled in response to the issues additional information that we hope should aid the treatment needed to help minimize the overall width of the roadway.
"If the highway project is not on the National Highway System (NHS), the State does not need FHWA approval for a design exception. Under ISTEA, the State can request an exemption from FHWA oversight on non-NHS projects." From: Flexibility in Highway Design, FHWA, p 37.
"The size and mass of the highway as it passes through the landscape has a powerful effect on the traveler's aesthetic experience.... APPLIED STRICTLY BY THE BOOK, SUCH IMPROVEMENTS [wider clear zones, lanes, and medians] CAN CREATE A ROAD THAT OVERWHELMS THE LANDSCAPE" [emphasis added]
--From: "Lessons from the Road, Case#2", National Scenic Byway Program, NHWA, p. 4.
"[T]he treatment of that portion of the highway to the right of the actual traveled way, that is, the 'roadway edge,' provides the designer with a greater degree of flexibility" "From: Flexibility in Highway Design, FHWA, p.79
At the 2003 National Scenic Byways Conference in Albuquerque (May), we hope to speak well of the Turquoise Trail project.
At the final (EA) public hearing on the NM 14 project, the CAC voiced concern about aspects of the design plans set forth by NMSHTD.
The design issues with which citizens are concerned relate mainly to the treatment and dimensions of the roadside edge. If we accept the width of the pavement as fixed at 30 feet (& between Madrid and Cerrillos for the most part set at 32' to favor the projected 5.3% of trucks), then the treatment of the roadside edge, ie. guardrails, tapers, and clear zones, should be kept to minimum dimensions. Otherwise these elements compounded could create a wide paved, cleared and speed-inducing swath inconsistent in context with the scenic qualities of this intimate valley region of the National Scenic Byway.
Despite an Environmental Assessment (EA) comment deadline of Feb. 1st, 2002, because of the continuing concerns of the public, the NMSHTD agreed to continue meeting with the CAC on a "by-weekly basis" to consider further modifications in design. On Jan. 31st a productive meeting made a start on correcting these design problems. The CAC expects further CAC public meetings in an effort to come to agreement on final design.
HISTORY: The current design is considerably improved over the Holmes & Narver design of 1998. Rather than the large offsets that H&N was proposing, the road is on, or very close to the existing alignment. With the exceptions of the S curve & Rogersville Rd, the horizontal alignment is almost the same as existing. Also, all the massive retaining walls have been eliminated. But we feel there is need for ongoing progress, especially in view of the total width of the roadway (the urgency being from Madrid to Cerrillos), and suggest that perhaps this may need to be resolved by designing the roadway in a more specific location by location basis.
Perhaps the Devil isn't so much in the details, but in the combination of them: the resulting total size and mass, or width of the roadbed.
With the proposed 32 foot width of asphalt [12' lanes (striped 11') + 4' shoulders along most of the Madrid stretch], at places where there are not guardrails, Parsons Brinckerhoff (PB) and Department drawings show a 6' taper. There could be an undefined additional width of a ditch (assume 4 foot?). We might end up with a 52 foot roadbed (not counting clear zones).
Historically, considering that the CAC, the communities, rejected a 48 foot roadbed back in 1998, how can we be expected to accept the current typical? The H&N profile added 4 foot tapers and defined a ditch as 4 feet. PB defines a 6 foot taper and has not defined a ditch. This does not include the issue of a clear zone only recently under discussion. Again we support location by location designing.
It wasn't so long ago that the CAC and communities were favoring a 6 foot, half paved/half grass, shoulder. This we were denied and instead the compromise of a 4' paved shoulder was agreed to, without additional pavement on tapers.
We recommend some brief time in the field between Madrid & Cerrillos at various locations with tape measure and pin flags.
Although there is desire for resolution and expedience, in the interest of keeping the overall width of the roadway to a minimum, the design of the various elements should, during discussions, remain in the "process" stage.
EROSION CONTROL: Donal Simpson AIA, AICP, ASLA, the consultant hired for both the Department and the CAC, advises against asphalt solutions for erosion control treatment on both guardrails and tapers, preferring instead vegetative solutions as being more appropriate. The CAC concurs wholeheartedly and requests Sites SW be [further] retained.
Concerning vegetative alternatives along the roadside, the CAC has forwarded to Sites SW (& into the record) much supportive information on the subject, including this quote from FHWA:
"Currently, 38 states have programs to preserve and restore native vegetation. These states have discovered many benefits in roadside wildflowers, INCLUDING A MAJOR REDUCTION IN MAINTENANCE COSTS as a result of less mowing. Texas, for example, has documented a reduction of roadside maintenance costs of about 25 percent -- about $8 million per year. Other benefits include: increased wildlife habitat and biodiversity; IMPROVED EROSION CONTROL; enhanced aesthetics; increased planting success with hardy native plants; strengthened partnerships with natural resource agencies and volunteer groups; suppressed noxious weed invasions, which are costly; and a demonstrated commitment to the environment." [emphasis added]
--[An excerpt ON MOWING From] "Where Flowers Bloom, So Does Hope", by Bob Bryant and Bonnie L. Harper-Lore [both with the FHWA].
TAPERS: A 6 foot taper, part asphalt plus base course, has been proposed by the Department. Very late during Final Design, asphalt was proposed at the upper portion of the taper and the composition of the rest of the taper has become of concern to the CAC.
There are three issues: the width or variability in size of the taper, the use of visible asphalt in the taper and the use of "duffing"--a mix that includes some organic material in the taper. 1) Since there are planned pull-outs along the Byway, the CAC does not wish to encourage a continuous (perhaps speed-inducing) invariable 6' taper (attached to the 4' shoulder), especially if the road edge would have to be cut or filled to accommodate them. We have also suggested location by location understandings of the drainages, which would suggest consequent treatments of guardrails and tapers. This, to our knowledge, has not be done. 2) We were pleased that there has been discussion on reducing visible asphalt associated with the taper [to one foot], but again, we would like to see a plan for a "second lift" of duffing up to the 4' shoulder. [Note we have since learned that a second lift of duffing over the asphalt at the top edge of the taper would not work as plants need approximately 6" of soil and there would not be enough room. We can only ask that this asphalt be minimized or eliminated.] According to Leroy Brady, member of the External Review Committee for the FHWA's "Flexibility in Highway Design", this is the expertise of a Landscape Architect. When the issues of maintenance first manifested, March of 2001, the CAC requested such vegetative alternatives for erosion control be investigated by Sites SW. The requests continue. The CAC does not find it convincing or necessary for maintenance purposes, that exposed asphalt is needed with a taper. Clearly this would negatively impact the scenic qualities. 3) concerning the use of duffing, the issue of clogging was brought up early in our meeting (Jan. 31st) and District 5 PEs agreed that it was not significant enough to require removal (of these long-agreed to provisions) for duffing. At that meeting we also clearly outlined the priorities for duffing, that if there was not enough stockpiled topsoil to cover the entire work area, the duffing should come first, since graded soil areas will be reseeded.
GUARDRAIL INSTALLATION: Again the CAC would appreciate the Department reconsider and not use asphalt associated with the guardrails.
Consultant Donal Simpson points out that the road around San Pedro Creek Estates is an excellent example of why the Department's previously proposed type of guardrail installation would be inappropriate for a National Scenic Byway, and aesthetically in conflict with the goal of "no net loss of scenic value."
Mr. Simpson has found an alternative guardrail installation that addresses maintenance issues and one that could contribute also to a reduction in the size of the road bed:
Re: the Transportation Research Board article from the Transportation Research Record: Journal of the Transportation Research Board, No. 1743, 2001, entitled: "W-BEAM GUARDRAIL ADJACENT TO A SLOPE." Mr. Simpson writes: "this describes crash-testing of a guardrail in a situation where there is a 2:1 soil slope immediately behind the guardrail...no intervening taper."
"The research report recommends use of a 2134-mm-long [weathered cor-ten] steel post spaced on 952.5-mm centers as acceptable according to current crash-testing performance criteria. It DOES NOT recommend asphalt on top of the soil to stabilize the post, and did not test a condition with asphalt on top of the soil."
Mr. Simpson further notes, "the National Park Service has installed steel posts in the median of the George Washington Parkway in the Washington, D.C., area, painted dark bronze. They are reasonably attractive and would, I think, blend with the visual environment of NM 14, particularly if the guardrail and posts were painted the same color." Perhaps there are non-painted, weathered steel posts that would also work well with cor-ten rails.
Concerning the W-Beam Guardrail, Landscape Consultant and CAC member, Kim Sorvig notes: "What is probably most valuable is that, a) it addressed EXACTLY the concern about erosion (they call it reduced depth of embedment), b) it applies to areas where slope width has to be limited, and c) this standard of testing and design is going to be required for all fed-funded guardrails." He notes that given the reality that the FHWA has upped the ante on testing standards, even for retrofits, it seems that NMSHTD is going to have need for this design all over NM and thus they will have supplies and skills to maintain them. This design should not require any 'exceptions' to build.
The CAC is pleased that at the meeting of the 31st there was interest expressed about the use of steel posts. However, the CAC would support such installation with the understanding that asphalt could be replaced with vegetative solutions to erosion and that the need for extended space behind the guardrail would not be needed.
If the Department wants to standardize guardrail and treatment for the State, the CAC suggests that two standards be developed: one where visual qualities matter and one where they do not.
CLEAR ZONES--10 FT
Again, the Department's and CAC's consultant, Donal Simpson challenges the NMSHTD regarding the clear zone. Here Mr. Simpson argues for the flexibility called for in the context of the Turquoise Trail:
"The AASHTO Green Book states: "On a rural collector road WITH A DESIGN SPEED OF 40 MPH AND BELOW, A MINIMUM CLEAR ZONE OF 10 FT. FROM THE EDGE OF THE THROUGH-TRAFFIC LANE SHOULD BE PROVIDED [NOTE: FROM THE EDGE OF THE LANE, NOT FROM THE EDGE OF THE SHOULDER]. The Green Book refers the designer to The AASHTO Roadside Design Guide only for rural collector roads with a design speed of 50 mph and above. The AASHTO Roadside Design Guide supplements the Green Book, and is more complex. As the Alternative Design Plan states: "The AASHTO Roadside Design Guide provides a complex formula for calculating clear zone. For high speed rural collectors, these distances can range from approximately 13 ft. to 90 ft. FOR LOW-SPEED RURAL COLLECTORS (40 MPH OR LESS), AASHTO RECOMMENDS A MINIMUM CLEAR ZONE OF 10 FT. EACH CONDITION ALONG THE ROAD NEEDS TO BE CALCULATED INDIVIDUALLY." The Green Book, however also states: "For the intermediate range between high and low design speeds, it is desirable to provide the greatest clear zone associated with the high design speeds. IF, HOWEVER, THE CONDITIONS MORE NEARLY APPROACH THOSE ASSOCIATED WITH THE LOW DESIGN SPEEDS, IT WOULD BE PERMISSIBLE TO EMPLOY THE LESSER CLEAR ZONE WIDTH." [emphasis added]
"The design speed from Madrid to the S curve is 30 mph; the design speed from the S curve to just south of Goldmine Road is 35 mph....all within the 10 ft. from the edge of the travel lane horizontal clearance from obstructions zone. FROM GOLDMINE ROAD TO JUST NORTH OF COYOTE SPRINGS ARROYO IS 45 MPH....WHICH THE GREEN BOOK SAYS WOULD BE PERMISSIBLE TO EMPLOY THE LESSER CLEAR ZONE WIDTH. Again, these clear zones are from the edge of the through travel lane, not from the edge of the shoulder." (1)
CAC and NMSHTD find Agreement:
* The Department's concern about financial penalties for damage to existing features was clarified. There will be no penalties tied to specific types of existing features, but general liquidated damages and work-stoppage procedures will be invoked by the project manager. Site Southwest to play a supporting role in the environmental oversight process.
* RIPRAP: Both the CAC and the Department, per Miguel, would prefer erosion control blanket instead of riprap, wherever slopes are not too steep; the design team agreed to attempt this substitution. The team agreed to develop details for planting above and into any large gabions, and if possible to use these details also for the gabions on private land near Rogersville Road. Where riprap is used, its color will be matched to surround rock or soil type as best as reasonably possible.
The design speeds (as shown on the drawings).
1) For project TPM-BR-oo14(9)29, Madrid to Cerrillos, the design speeds are shown on sheet 2-2: 30 mph from station 13+50 to station 62+65; 35 mph from station 62+65 to station 115+40; 45 mph from station 115+40 to station 171+00.
For project TPM-BR-0014(10)32, the design speeds are also shown on sheet 2-2: 45 mph from station 171+00 to station 447+50; 55 mph from station 447+50 to station 507+00.
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