Section 1: Common Rail-Highway Design Issues
New At-Grade Crossings
Most railroad companies strongly oppose public projects that
introduce new at-grade crossings. New at-grade crossings add maintenance
and liability costs to a railroad company. However, in some cases,
new at-grade crossings are unavoidable and railroad companies are
willing to allow them if two to three other existing public at-grade
crossings are closed and anticipated traffic counts at the new crossing
do not exceed the combined traffic counts of the closed crossings.
The TxDOT
RRD Rail Letting Section
serves as
the office of primary negotiation with the railroad companies in
these scenarios.Frontage Roads
It is recommended that new frontage roads are designed as
either:
- Overpasses over a rail line.
- U-turns before a rail line.
Frontage roads crossing a rail line at grade are not desirable.
A U-turn before a rail line should consider a barrier to ensure
errant vehicles do not drive onto the railroad tracks.
Grade Separations
Overpasses are the preferred option versus underpasses
for grade separations. Overpasses are preferred due to:
- Minimum disruption to rail service during construction.
- Drainage.
- Simplify future track expansion.
- Simplify future highway widening.
- Clearance issues due tooversizedvehicles eliminated.
- Pedestrian design.
- Maintenance costs.
- Lowerthrowaway costs.
When designing overpasses, access to adjacent properties should
be considered early during project development.
Accessing Railroad Right of Way
The project designer should become familiar with the project
site and determine how project work within railroad right of way
will be constructed. Temporary at-grade crossings are discouraged
and may add both project cost and risk. Whenever possible, designers
should aim to design any temporary pavement, ramps
or
detours
that assist a contractor in construction
of
the project to eliminate the need for a temporary
at-grade crossing.If a temporary at-grade crossing is needed, it should be included
in the Exhibit A for the railroad company to review up front and
will be included in the C&M Agreement.
Oversize Vehicles
Oversize
VehiclesWhenever railroad protective devices are proposed, the crossing
should be evaluated for any
oversize vehicles that could
damage railroad signal equipment
. Possible solutions
include:- Avoiding use of cantilevers.
- Installation of median with flasher/gate to remove need for cantilever.
- Use of cantilever that does not cover all approach lanes.
- Use of non-standard cantilever23 foot 4 inches minimumof vertical clearance.
- Move masts further than design minimums from edge of roadway or shoulder.
- Use of cantilever further out than design minimum to cover lanes.
Advanced Flashers
At locations where the approach view of an at-grade crossing
may be obstructed, the use of ground-mounted or overhead amber flashing
beacons with the Grade Crossing Advanced Warning Sign (W10-1) may
be considered.
When used, the flashers should operate
without any actuation, i.e., always flashing. Train activated beacons
are no longer recommended. As an alternative, railroad provided
cantilevered flashing lights may be used in lieu of amber flashing lights.
Temporary Special Shoring
There may be cases with shoofly track alignments where temporary
special shoring is needed to shore a track section adjacent to an
open cut for:
- Roadway excavation.
- Construction of new substructure.
- Construction of new superstructure.
Traditionally, temporary special shoring on transportation
projects is designed by the contractor. The railroad company
requires
TxDOT obtain
a fully designed temporary special shoring system included
in
Exhibit A and approved by the railroad company prior to letting.The shoring
must
be designed in accordance
with AREMA and any guidelines provided by the railroad company.Design Guidelines
For development of Exhibit A plans,
project managers
and
designers are encouraged to familiarize themselves
with the railroad company’s design standards, as well as TxDOT annotated exceptions,
prior to design. While the railroad company does not formally accept
these annotated exceptions, they are published to give TxDOT’s recommended
practices to designers
where a difference of
opinion on certain guidelines exists. Many shortline railroad companies
do not have established design guidelines. Designers are
recommended
to follow the BNSF/UPRR joint guidelines.See the
RRD
website for railroad company
design standards and guidelines
. Additional design
references are found in Chapter 14.Standard Sheets A
A
Traffic Safety Division
(TRF) standard
sheets which apply to rail-highway projects include:- Railroad CrossingDetails (RCD signing, striping and device placement).
- Sign Mounting Details (SMD).
These sheets should supplement other design materials used
for at-grade crossing design and are inserted as part of the PS&E
on construction projects.
Refer to TRF website for more information
. Railroad or Highway Relocation
Relocating a rail line or highway may be considered as a design
option to:
- Improve operational problems caused byoccupiedcrossings.
- Improve environmental characteristics (ie., train horns, pollution, etc.).
- Improve safety by reduction of at-grade crossings.
- Use existing right of way for the rail line or highway for another public purpose.
Railroad relocation generally involves the complete rebuilding
of railroad facilities, including the acquisition of new right of
way. Designers should strive to avoid at-grade crossings on relocated rail
lines. Zoning the property adjacent to the railroad as light and
heavy industrial further isolates the railroad corridor from residential
and commercial activity. Businesses and industries desiring rail
service can
relocate
in this area.Planning for highway relocations should consider routes that
would eliminate rail-highway intersections by avoiding the need
for access over railroad tracks or by providing grade separations.
Humped Crossings
Vertical curves should be evaluated on all approaches over
an at-grade crossing. Significant grades can cause the following
problems:
- Low-clearance and long wheelbase vehicles can get stuck on thetrack at thecrossing.
- Crossing surface orfield panels can become loose or dislodged if a vehicle catches on the approach edge of the panel.
- Inadequate turning radius from the adjacent road, causing vehicles to leave the paved roadway, which could lead to the vehicle stalling on the crossing.
Adjusting the roadway profile to eliminate problems with humped
crossings can add significant cost to the project. The following
guidelines are
recommended
:- At an existing at-grade crossing, inspect the crossing for damaged,missing ordislodged field panelsas well as any other damageon the approach pavement adjacent to the panels to determine if vertical clearance is an issue. The maximum approach grade should not exceed 3 inches of the rail elevation at a point 30 feet away from the center of the nearest rail on both sides of the crossing.
- For new at-grade crossings, follow the above guidance.
- The crossing may be widened and/or additional pavement installed to keep the design vehicle on asphalt when turning onto the crossing.
As railroad companies replace ballast over time during routine
maintenance, the elevation of the rail will increase, adding to
the problem.
Solutions for humped crossings include:
- Installation of Low Ground Clearance Grade Crossing warning signs (W10-5 and W10-5P).
- Restricting use of crossing for low clearance and long wheelbase vehicles.
- Improving approach grades to the crossing,including any turning radii from an adjacent roadway.
Any changes to the crossing should be reported by the district
railroad coordinator to
RRD, including installation of
W10-5 signs so the TRIMS and Federal Railroad Administration crossing
databases may be updated
.Passive Crossings
All passive public crossings
must
have
a stop or yield sign installed with the crossbuck sign. Passive
crossings must have
:- Sufficient approach sight distance down the tracks to allow a driver to stop before the crossing when an approaching train is seen.
- Sufficient sight distance down the tracks to allow a tractor-trailer to clear the tracks from a stop at the crossing before a train arrives.
All new public crossings are recommended to include active
warning devices. Refer to Part 8 of the TMUTCD for
more
information
.