DCR Access Road over Route 24 (Randolph Bridge Replacement)

Construction is underway on the DCR Access Road over Route 24 Bridge. The 4-span, steel girder structure, commonly referred to as the “Horse Bridge”, will be replaced with a 2-span, segmental “Channel Bridge”. The replacement bridge will have a length of 248', a width of 29'- 8", and a total depth (including barriers) of only 5'-4". The low profile of the bridge increases the vertical clearance over the heavily traveled Route 24 from 14'-3" to 16'-9" without altering the approach grade. Side piers of the original structure have been eliminated, thus increasing safety for the drivers on Route 24. The shallow depth of the DCR Bridge is achieved by using edge beams located above the deck surface that function as both main supporting members as well as bridge barriers. The edge beams are fully post¬-tensioned, using a mix of 19-strand and 12-strand tendons. Additional longitudinal tendons are provided in the deck slab, using flat 4-strand tendons. Transversely, the structure is fully post-tensioned using flat 4-strand tendons.

The channel cross-section is a precast-concrete superstructure system that uses post-tensioned segmental construction. This bridge type is used when a replacement structure requires an increase in the vertical under-clearance, as is the case for the DCR Access Road over Route 24 Bridge.  The channel cross-section does not use the typical bridge configuration of a deck supported underneath by a transverse or longitudinal support system. It features two edge beams that function as the main load-carrying elements with a deck supported between them, completely eliminating the need for a below-deck support system. This structure type provides numerous advantages including an increased vertical under-clearance, accelerated construction time, and a lower life-cycle cost.

Owners, Contractors and Engineers are continuously looking for ways to reduce or eliminate carbon footprints. Recycling components of old structures helps reduce construction costs and the impact on the environment. Once removed from the old bridge, the steel beams will be recycled and used as temporary supports in erecting the segments for the new bridge.

Construction of the new substructure, and precasting of the superstructure segments are scheduled to being this fall. Erection of the new superstructure segments will begin in the spring of 2010. The new bridge is scheduled to open in October, 2010.