The Sheridan Boulevard Pedestrian Underpass is an important link in safely promoting a continuous pathway in Broomfield’s extensive bicycle and pedestrian trail system throughout the city. With the new developments to the north, Sheridan Boulevard is one of the busiest streets in Broomfield and is a major barrier for pedestrians to cross. This segment of the trail system is at the heart of its trail system along the southern portion of Broomfield. The Sheridan Underpass safely and efficiently increases accessibility in this area.

Muller provided final design of a 130-linear-foot, pre-cast concrete box underpass and trail from Highland Park at Dover Street to Country Vista Park on the east side of Sheridan Boulevard. The length of the underpass was designed for the planned future street widening of Sheridan Boulevard.

The underpass is sandwiched between a major drainageway to the south and a regional stormwater detention pond to the north. Consequently, the design required consideration for the control of seepage through the underpass joints, as well as flood control from the adjacent major drainageway. Because the underpass floor is below both of these drainage facilities on each side, a surface drainage system and underground perforated underdrain system with duplex sump pumping station was provided to discharge tributary stormwater runoff and groundwater from the underpass to the adjacent drainageway.

As with any project of this type in a major street in the heart of the city, there was coordination with utility companies and relocating their facilities over and under the underpass. For the Sheridan Boulevard Pedestrian Underpass project, the Muller team relocated fiber optics lines, dry utilities, a 42-inch storm sewer, and a 20-inch Denver Water line.

The underpass also parallels with a 42-inch sanitary sewer interceptor main, 42-inch stormwater sewer, and two 20-inch reuse lines. With all this congestion with the existing facilities in the area, the underpass is built with a sizable amount of reinforced concrete retaining walls on each side of Sheridan Boulevard to fit within a tight area. There was more than 1,500 lineal feet of walls that range in height from 4 feet to 15 feet high.

To relieve the large expanse of concrete, the two long tall walls on each side of the underpass are specially designed with artwork carved out in the form liners during construction. Broomfield chose an aquatic and wetland theme for the art walls that featured cattails, fish, toads, and ducks in a watery and wavey pattern.

The project team involved two landscape architecture firms. One firm designed the art walls, underpass hardscaping, planter wells, and landscaping within the underpass. The other firm designed the hardscaping at street level to correspond and provide continuity with the roadway improvements of Sheridan Boulevard north of the project.