Wednesday, March 7, 2012

Vista Ridge Tunnels

The Vista Ridge Tunnels are highway tunnels under the West Hills that carry US 26 traffic to and from the city of Portland, Oregon. The tunnels are adjacent to the city and are some of the busiest in the Pacific Northwest. The twin tunnels were completed in 1970 and are a major link to the city's freeway system. The current system features a "freeway ring" that includes I-405 (Stadium freeway), I-5 (Minnesota freeway), the Marquam Bridge, the Fremont Bridge and the Sunset Highway. All of these projects were completed in phases in the 1960's and early 70's. Traffic through the tunnels travels east (into the city) and west (towards Beaverton). Each tunnel has three lanes of traffic. There was a ventilation system that was designed for the tunnels, but it was never used. The tunnel portals and ceilings are finished in ceramic tile. There are special rows of lights on the tunnel ceilings.

Planning of the tunnels was unveiled to the public on Feb 17, 1961. Construction began on November 15, 1963 with a pilot tunnel for the east bound tunnel. The pilot tunnel was 1000-feet long, 5-feet wide and 7-feet tall. It was done to explore the types of rock formation and geology that would be encountered during the massive twin tunnel excavation. The first work site for the eastbound portal was located on SW 19th and Mill Street near downtown. There was a tremendous amount of excavation and leveling of the roadways that was needed to build the freeway grades. Each tunnel was carved approximately 28-feet high and 62-feet wide. This would be the roughed out passage way. On a good day, miners would get 12-feet of progress. Eventually, the finished tunnel dimensions would be slimmed down to 16- feet high by 42-feet wide. The tunnels would get smaller because of reinforcing, concrete slabs, ceramic tiles, crawl space, ventilation, etc. The eastbound tunnel is slightly longer measuring 1001 feet compared to the westbound tunnel at 950 feet. Each tunnel has a 6% grade which is steep. You have to hit the accelerator pretty hard when climbing through the westbound tunnel and braking can be a bit unnerving when descending down into the eastbound tunnel. The State Highway Dept. completed the first tunnel in 1967 and used it to haul waste material from the excavation of the Stadium Freeway (I-405) to use as fill in the Canyon Rd construction. Canyon Rd was converted to a 6-lane freeway with shoulders and a barrier at the same time. This allowed a shorter trip for the dump trucks which could dump the extra material for fill for the highway being constructed at the same time. Blasting was done with a new product by Dupont called "Gellex".

Cost of the pilot tunnel was $79,400.
Cost of eastbound tunnel was $4.5 million.
Cost of westbound tunnel was $4.2 million
Cost of widening Canyon Rd was $3.3 million

There was no ribbon cutting or fanfare when the barricades were removed and the westbound tunnel was opened on Mar 3, 1970.

Not long after the twin tunnels opened, a high number of accidents and multi-car (chain reaction) pile ups began happening. At this point, the tunnels were criticized for design flaws and poor planning. The following reasons were cited as compelling factors in these accidents:

1. Steep descent into the eastbound tunnel (6% grade). Gravity accelerates cars entering the tunnel.
2. The lanes seem to narrow significantly as you begin to enter the tunnel.
3. Drivers enter the tunnel blindly, meaning you can't see traffic ahead. Cars enter the tunnel through a sharp corner.
4. Portland weather means rain/ice and slick roads create braking problems and fishtailing in the tunnels.

If you have ever driven down the hill towards the city and seen brake lights flash on, you can understand how gravity and momentum can test the brakes of your car as you enter the tunnel through a sharp curve.

There used to be a large electrified sign located at the mouth of the eastbound Vista Ridge tunnel on US26 that read "SLOW" in big red letters. This neon sign was taken from the I-5 interstate bridge in 1970.

Different types of asphalt and road surfaces have been tried to aid in traction and braking of vehicles through the tunnels. Special grooves have been cut in the pavement over the years to assist motorist in stopping and having better control of their vehicles.

Vista Ridge Twin Tunnel Time Line

1961 Highway Commission unveils tunnel plan and widening of Canyon Rd.
1963 Test bore to determine geology begins on eastbound tunnel
1964 Test bore tunnel completed May 15, 1964
1964 Highway Commission approves construction of first (eastbound) tunnel
1965 Drake and Winston Bros awarded tunnel job and begin work Nov 20, 1965
1967 Eastbound tunnel functional and used to haul debris from I-405 to Canyon Rd
1968 Drake begins construction on westbound tunnel March 10, 1968
1969 Eastbound tunnel opens for traffic on Feb 25, 1969
1970 Westbound tunnel completed, opened for traffic 9am Mar 3, 1970
1970 Ramp from I-405 opens to westbound tunnel Oct 7, 1970
1970 Speed limit dropped from 60mph to 50mph to 45mph from Sylvan to tunnels
1970 Neon "SLOW" sign installed for safety concerns
1971 Accidents and "chain reaction" pile-ups plague the new tunnel
1971 Large radio antenna installed for improved radio reception in tunnel for motorists

The eastbound tunnel through Vista Ridge is complete and carrying traffic in this 1969 aerial photo. The westbound tunnel would be completed the following year. This is the city-side view, looking west.