21.2 Texas Highway Freight Network (THFN)
On September 28, 2017, a memorandum was distributed by Bill Hale, P.E. (Chief Engineer) that provided general guidance for the TxDOT Freight Vertical Clearance Policy. The purpose of the policy is to make Texas the leader in providing movement of freight in the nation. This is a process that should be approached with a long-range vision and plan in place to provide a continuum of efficient freight movement within the State. Additional consideration and planning should also be given to existing bridges that act as freight bottlenecks due to low vertical clearances, even if there are no immediate plans for new construction or reconstruction of these bridges.
Consideration for exchanging overpasses for underpasses should be given as well
.This policy is applicable to projects that meet the following criteria:
- Required on all projects let on September 1, 2020, or later;
- Designated as being on the THFN as shown on the THFN map maintained by TPP; and
- New bridge construction or reconstruction including bridge widening. Bridge Maintenance Improvement Program (BMIP) and maintenance projects may not be considered bridge reconstruction, but this would need to be handled on a case-by-case basis in consultation with BRG. Re-decking a bridge will also be handled on a case-by-case basis in consultation with BRG.
The policy does not apply to THFN overpasses, frontage roads, direct connectors not on the THFN, and entrance and exit ramps that include bridge underpasses. Direct connectors that connect THFN networks must meet the THFN vertical clearance criteria.
The THFN vertical clearance requirements should be considered for bridge and incidental vertical obstruction to the Freight Network that support significant origin/destination locations.
Refer to the
for more information on the development of this network plan.
21.2.1 Vertical Clearance at Structures
Vertical clearance requirements for roadway structures can be found in
.
Minimum vertical clearances for bicycle and pedestrian crossover structures are
increased 1.0-ft from the minimum vertical clearance
requirement for vehicular structures due to the increased risk of personal injury upon impact by over-height loads and the relative weakness of such structures to resist lateral loads from vehicular impact.21.2.2 Signs, Overhead Sign Bridges (OSB’s), Signals
For the designated THFN, overhead signs shall provide a vertical clearance of not less than the requirement in
to the sign, light fixture, or sign bridge over the entire width of the pavement and shoulders. For traffic signals on the THFN, the bottom of the signal housing and any related attachments to a vehicular signal face located over any portion of a highway that can be used by motor vehicles shall be at least 19-ft above the pavement. Refer to the latest version of the
and applicable TxDOT standards for additional guidance.
21.2.3 Other Overhead Utilities
All overhead utilities over the designated THFN project must meet the requirements specified in TxDOT’s
, Chapter 3.
21.2.4 Bicycle and Pedestrian Accommodations
One other important consideration with freight mobility is the presence of bicyclists and pedestrians. These elements should be considered as integral parts of the THFN. See
and
for additional information on bicycle and pedestrian requirements. Additionally,
provides further information on bicycle and pedestrian considerations.