Colorado Highways:
The Denver-Boulder Turnpike

Colorado's highway system in the Denver area had big problem up through the 1940s: There was no direct route between Denver and Boulder. Up until that point the best way to get from Denver to Boulder was via US 287 north to Lafayette and then either South Boulder Rd. or Arapahoe Ave. (SH 7) west to Boulder. The original proponent of the Denver-Boulder turnpike is considered to be Prof. Roderick L. Downing of the School of Engineering at Colorado University. In fact, he would often take his students out to the route he proposed and have them do practice surveys.

Eventually, most Boulder civic organizations, the University, and prominent citizens signed on expressing their interest in the project. The Legislature finally passed a bill authorizing the Colorado Department of Highways (CDH) to build a road and to operate it as a toll road to recoup the cost of construction. The state got a Kansas consulting firm, Howard, Needles, Tammen, and Bergendoff to do a feasibility study. Unfortunately, the results said that the road would not pay for its cost and upkeep over a 30-year period.

Despite the report, support reached a fever pitch with everybody except the City of Longmont in favor. Bonds totaling $6.3M were sold, to be repaid over 30 years. CDH did not have enough engineers for all of its projects, so HNTB got to do the engineering and supervision. Grading and ballast contractors, the sections they did, the dates of construction, and at what cost are:


This is a scan from the 1955 CDH map, showing a picture of the Denver-Boulder Turnpike looking west toward the Cherryvale overpass. Original picture 1955 Colorado Department of Highways

Cleanup and shoulder paving didn't end until August 1952, but the roadway officially opened for traffic January 19, 1952. The DBT went from Federal Blvd. north of Denver to 28th St. in Boulder. It was built to freeway standards with fully controlled access. Each direction there were two 12-foot wide lanes, a 10-foot shoulder, plus a 20-foot depressed median. There were 12 major structures, including toll booths, built on the spot. This was the first project awarded by CDH that was of this magnitude.

The tollbooths were under the Wadsworth overpass at the Broomfield interchange. The toll to go from Federal Blvd. to Boulder was 25, and only 10 if you got off at Broomfield. Broomfield to Boulder was 15. Originally the DBT featured the Broomfield interchange as the only access to it other than the end points.

The DBT also had the disadvantage of originally not being tied in to the Denver highway system. Its end at Federal Blvd. and the north end of Denver's new Valley Highway were not directly connected by the SH 382 highway until 1956.

Despite that, traffic counts on the DBT far exceeded anybody's expectations. The HNTB consulting report was ultraconservative. It predicted 3170 vehicles per day for 1960-1980, but actual counts went through the roof to 13,774 vehicles per day in 1966. The toll revenue was so high that on September 14, 1967, ceremonies were held at 11am, the DBT became free and part of US 36, and the toll booths removed immediately thereafter. The tolls had managed to pay off the $6.3M in bonds, $2.36M in interest, resurfacing, and a realignment at Federal Blvd. in just a little over 15 years, 15 years ahead of schedule. It is believed that at that time the DBT was the only public toll road ever to become free.

When the DBT became free, the cornerstone from the Broomfield toll plaza was transplanted a little further west. It now resides at a small memorial to the DBT that exists at the Davidson Mesa scenic overlook, on westbound US 36 west of Louisville.

DBT-Broomfield map
According to Stephen Levine, one of the more interesting aspects to the original DBT was its interchange at Broomfield. Where the DBT met Wadsworth Blvd. was its only access point other than the ends. This also was the point all tolls were charged. The inventive layout of the interchange allowed only two tollbooths to toll all traffic on the turnpike. There was also some sort of utility or maintenance building in the median from what Stephen recalls.

Also according to Paul Haynes, later during the life of the DBT additional access ramps were built besides the ones at Broomfield. By the time the DBT became free in 1967, ramps had been built for eastbound on and westbound off at South Boulder Rd., eastbound on and westbound off at Superior, and westbound on and eastbound off at Sheridan. But only those ramps were built so it was still impossible to use the DBT without going through the tollbooths at Broomfield. After the DBT became free, those three interchanges had the rest of their ramps built.

According to Ken Johnson, a memorial and burial site for Shep, the tollroad's mascot dog, was for many years at the southeast corner of the Wadsworth interchange, but was moved to the Broomfield Museum due to reconstruction. Shep appears in one of the Denver Post photos below.

View some photos of the Broomfield toll plaza here, from the Denver Post. Thanks to Stephen Levine for the link.


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Page created 25 November 2006
Last updated 17 November 2013