Engineering report delivers new planning tool
An engineering report recently prepared for the Massachusetts Highway Department and the Executive Office of Transportation and Construction (EOTC) has identified numerous ways for achieving the vertical clearance needed on more than 100 bridges in the state that fall short of the 21-foot requirement for doublestacked container railcars.
The report is intended to form the basis of a bridge clearance improvement program, subject to funding from the state legislature and agreements among railroads, shippers and the EOTC as to which would open the Bay State to double stacks.
Supporters of the bridge, improvement program want construction to begin as soon as possible to keep the commonwealth’s transportation industry competitive nationally and in the global marketplace. The double-stack railcars would particularly benefit the port of Boston and be an integral part of an intermodal system of transportation envisioned by ISTEA.
A separate report prepared by Greiner’s Boston office involved roadway bridges over railroads along 400 miles of major rail corridors throughout the state.
This study identified 29 low overpasses along the Boston Maine RR between Williamstown and Ayer, 52 along the main line for Conrail between Richmond and Framingham, 34 others from Framingham to Boston and five to 10 along the Providence & Worcester RR, depending on which lines are included in the final plan.
Still more overpasses are along lines owned by the Massachusetts Bay Transit Authority. Some of the bridges are already slated for improvements as elements of other highway projects, and 19 others involve railroad bridges, pedestrian crossings or privately owned over, pass structures outside the commonwealth’s inventory. Funds to elevate those structures are excluded from the estimate for the highway overpasses.
The study team began by locating the bridges on a map to plan an orderly and sequential field investigation of each overpass. During subsequent site visits, existing conditions and alternative measures for achieving the needed elevation changes were compiled.
Measurements were taken of the existing vertical and horizental clearance windows between the high-rail mark and the low-steel point of the bridge superstructures. The vertical clearances were measured to the nearest quarter-inch and rounded down to half-inch increments.
Trackage extending 1,500 feet out from each side of the bridge was also walked to observe features that could affect tracks being lowered, such as below-grade culverts, underlying streams, roadways, grade crossings, utility runs, stormwater drainage structures and general embankment conditions.
Needed improvements were then divided into the following categories:
* bridge/roadway raising;
* superstructure replacement;
* track lowering; and
* complete bridge replacement.
The study also considered potential detours and sites for temporary crossings.
Approximate costs were established for the most appropriate method of attaining the elevation at each bridge using an Order of Magnitude Construction Cost Estimate. However, the figures were designed only for general program planning and must be refined into more detailed numbers for each project during the design phase.
