Sunday, August 3, 2008

Reunion Journey, Days 6-9 Dawson City to Watson Lake

The first leg of our journey took us from Dawson City to Whitehorse along the Klondike Highway. The weather since Fairbanks has been warm and sunny, a major improvement over the past month in Alaska. We were given an article from the Anchorage newspaper which noted that this is a La Nina year, which supposedly accounts for the markedly colder and wetter Alaskan weather this summer.
A Sunny Day Southbound on the Klondike Highway

So what’s a La Nina, you may ask? It is a periodic, transient 2 to 4 degree cooling of the southern Pacific waters off the coast of Peru. La Nina is the opposite end of the El Nino cycle, which is a periodic, transient warming of the same waters. The El Nino brings wet and stormy weather to southern California, while it’s La Nina counterpart brings nice weather to the southwest and @%^#$% weather to Alaska.

Meteorological explanations notwithstanding, the weather has finally turned nice, at least for a few days, and we are reveling in the dry, sunny skies as we travel south on the Klondike Highway.

The Klondike Highway is a paved road that is narrow and winding, particularly the northern half. Shortly after leaving Dawson Creek we had a serious construction detour onto a dirt road. Fortunately, the detour was only a few miles. We suspect that it followed an earlier generation of the current highway.

Back on the paved road, we passed huge and endless piles of brush cutting and burnings. They are cutting the trees back about 50 feet from the pavement. We are not sure why this is done. One major benefit is that it removes the cover for large animals, so they cannot lurk unseen at the edge of the pavement, ready to dart out when spooked by an approaching vehicle.
Brush Piles Waiting to be Burned

We stopped at Carmacks Hotel and RV Park for the night. We were treated to a pretty good meal at the Gold Panner Restaurant (3COWS). Kathy had pierogi; not as good as moms, but pretty good for the outback. Keith had a decent burger and fries.

Early the next morning we continued on to Whitehorse. The road improved as we drove south toward civilization. It became less winding, with fewer construction breaks. Shortly after setting out, one companion coaches experienced a serious flat tire on his tow vehicle. We saw them pull over and called on the CB, but receiving no response, we assumed they were off for a comfort break and drove on by. We felt chagrined, and apologize profoundly.
South of Carmacks the Road Improves

We stopped at Brae burn Lodge and purchased two of their world famous cinnamon rolls (2.5COWS) with a hefty price tag of $17.00. We met former caravaners, Bob and Marilyn, who were finishing their breakfast there.
Home of the $8.50 Cinnamon Roll

On the way into Whitehorse we passed Lake Labarge in the distance. Unfortunately it was too far away to take a good photograph. This body of water figures prominently in the Robert Service poetry about Dan McGrew, who is “cremated on the marge of Lake Labarge”.

We spent 2 days in Whitehorse at the Hi Country RV Park. It was a pleasant interlude and most of our group would have liked another day there. Whitehorse was an R & R stop for us. We shopped, did laundry and had a couple of good meals.

Keith was craving Asian cuisine so we lunched at the Asia Restaurant. The lunch buffet was small but tasty (2.5 COWS). As we were eating Keith remembered this was the same restaurant he had dined at with his sister on a previous trip in 1998.

We also dined with a group of 9 at the Klondike Salmon and BBQ Restaurant. I will give this restaurant 4COWS. It was a bit pricey but the food was excellent and the menu selections diverse. Kathy had Musk Ox Stroganoff. The meat was sweet and the sauce a rich sour cream and brandy concoction poured over garlic mashed potatoes. Keith had seafood fettuccini. A generous portion of seafood in a buttery sauce. The menu also offered bison, caribou and Canadian Alberta prime rib, as well as Alaska Crab and Char.

It was here in Whitehorse we said farewell to a former caravaner, Mary Ellen and er faithful companion Henri. While not one the original 5 coaches which left Fairbanks together, she joined us intermittently on our trek from Dawson City to Whitehorse. We were always glad to see her. Unfortunately, she got a flat tire on the way to Carmacks and was not able to purchase a replacement tire in Whitehorse for her Rialta. She was compelled to wait in Whitehorse for a replacement tire, which could take up to two weeks. We are wishing her the best of luck in remedying her plight.

In Whitehorse we did meet up with former Wagon master Carol, who is traveling with her mother and her niece Nicole. She will be traveling with our group to Prince George

After leaving Whitehorse, we retraced our northbound route through the Cassier Mountains along the Alaska Highway to Watson Lake. The southbound trip was a totally different drive, as the sun shone brightly and there was no fog , rain or mud.
Approaching the Cassier Mountains
on the Alcan South of Whitehorse

Along the Alcan south of Whitehorse, we passed a couple of visually striking bridges on our way to Watson Lake. Keith is fascinated with the structural aspects of bridges. There are a multitude of ways to span and carry loads across an obstacle such as a river. Keith likes to look at bridge structures, and try to figure out how the design engineer configured it to most efficiently fulfill it’s design intent.

The simplest bridge, emerging from antiquity, is a tree trunk laid over a creek. The log functions as a simple beam. It supports the load in bending, with compression (pushing) force in it’s upper fibers, tensilon (stretching) force in it’s lower fibers, and shear in the center of the log. These forces distribute the load from the middle of the log to the creek banks.

Recent improvements to the simple beam bridge include replacing wood with much stronger steel, and changing the form of the beam to place most of the structural material at the upper and lower surfaces, where the compression and tensile loads are greatest. These upper and lower flanges are joined by a relatively thin web, which ties the upper and lower load carrying members together. This form is sometimes known as an “I” beam, or a girder. The steel beam, or girder bridge is the simplest and most widely seen of all bridge forms.

A more sophisticated elaboration of the simple beam is the truss bridge, where the upper and lower load carrying members are more widely separated, and are joined together with a filigree of connecting struts that tie the primary upper and lower load bearing members together. The truss structure may be located either above or below the roadway; in either case, the truss functions structurally as a simple, but highly efficient beam. Being more structurally efficient, trusses can span substantially greater distances than a simple “I” beam, without collapsing under their own weight.

A beautiful example of a multiple-span truss bridge crosses Nisutlin Bay at MP 776 on the Alcan. The forces experienced by the primary upper and lower structural members are illustrated in the accompanying photograph. In this form of truss bridge, the roadbed is supported by the lower truss members, which are loaded in tension. The Nisutlin Bay bridge is the longest water span on the Alaska Highway at 1917 ft. The multiple trusses span this distance much more efficiently than would simple “I” beams, which would be shorter and require many more pilings in the riverbed.
Multiple Span Truss Bridge Crossing Nisutlin Bay
at MP 776 on the Alaska Highway
Scenic View of Teslin Lake
South of the Teslin River Bridge

Another very striking bridge crosses the Teslin River north of Nisutlin Bay at MP 808.6. This bridge is a hybrid of two bridge forms. The center span is a steel arch assembly. The arch form was used extensively by the Romans. It functions primarily in compression, so is amenable to construction from brittle materials which do not gracefully carry tensile loads, such as stone. When fabricated from steel, the arch bridge is strong enough to span greater distances than the beam or truss, and is used where it is undesirable to place a bridge pier in the main channel. The photo below illustrates the compressive forces in the primary arch structure, and shows how they are reacted at the base of the arch.

The bridge segments which join the arch to the riverbank are trusses, similar in principle to those in the Nistulin Bay bridge, except that they are located below rather than above the roadbed. These truss segments serve two functions. First, they carry the primary load in their respective sections of the bridge. Second, they react the horizontal thrust component of the force from the central arch, and transmit this force to the bridge abutments. In this respect, they function similarly to the flying buttresses found on many medieval cathedrals.
Combination Underdeck Truss and Steel Arch Bridge
Spans the Teslin River at MP 806.6 on the Alaska Highway

Interestingly, the I35 bridge, which collapsed last year in Minneapolis, was very similar to the Teslin River bridge. The central arch form was used to avoid a mid-steam pier, which would have interfered with navigation on the Mississippi. Where structural forms such as the arch are fabricated of multiple structural elements, rather than being a monolithic structure, it is essential that the elements be rigidly tied together to function as a unit. In the case of the I35 bridge, the gussets which tied together the elements of the arch were undersize, and eventually distorted, causing the bridge to collapse.
"And the Road Goes Ever On and On
Down From the Door Where it Began"

In Watson Lake we stayed overnight at the Baby Nugget Campground. After our arrival Kathy started preparations for a large pot of her world famous spaghetti sauce. She made enough that we were able to host supper for 10, with enough left over for a couple of meals. Keith gives Kathy’s sauce 4COWS, an she does not argue.
Spagetti Fest at Watson Lake
Hand Carved Door on Gift Shop
at Baby Nugget Campground in Watson Lake

Our next couple of days will be a drive southward along the Cassier Highway to the twin towns of Stewart BC and Hyder, AK, where bears may sometimes be seen fishing in Fish Creek. Stay tuned!

1 comment:

diannedoran said...

your mile posts are incorrect - Nisutlin Bay Bridge is Mile 804 Alaska Hwy and Johnston's Crossing is Mile 836