Chapter 7: Exhibit A and PS&E DesignAnchor: #i1004729
Section 1: Common Rail-Highway Design IssuesAnchor: #i1004734
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 Traffic Operations Division-Rail Safety Section (TRF-RSS) serves as the office of primary negotiation with the railroad companies in these scenarios.Anchor: #i1004744
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.Anchor: #i1004774
Although grade separations across the railroad are preferred, overpasses are generally preferred over underpasses. Some of the reasons overpasses are preferred include:
- they provide minimum disruption to rail service during construction
- better drainage
- they simplify future track expansion
- they simplify future highway widening
- clearance issues due to overheight or overwidth vehicles are eliminated
- pedestrian design may be safer
- maintenance costs are lower
- there are higher throwaway costs associated with underpasses such as temporary shoofly track, etc.
When designing overpasses, access to adjacent properties should be considered early during project development.Anchor: #i1004829
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 or ramps that assist a contractor in building the project and 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.Anchor: #i1004844
Overheight and Overwidth Vehicles
Whenever railroad protective devices are proposed, the crossing should be evaluated for any overheight and overwidth vehicles which could potentially hit masts or cantilevers. Possible solutions may include:
- avoiding the use of cantilevers
- installation a median with flasher/gate to remove the need for a cantilever
- use of a cantilever that does not cover all approach lanes
- use of a non-standard cantilever with more than 17 feet of vertical clearance
- moving masts further than design minimums from the edge of roadway or shoulder.
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 may operate:
- without any actuation
- with actuation at the same time as the railroad warning devices
- with actuation with additional time from the railroad warning devices.
Alternatively, a railroad cantilever may be used for increased visibility on the approach.Anchor: #i1004909
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. However, because of the time risk in construction associated with the review of such temporary special shoring by the railroad company, TxDOT recommends that a fully designed temporary special shoring system be provided in the Exhibit A and approved by the railroad company prior to letting.
The shoring should be designed in accordance with AREMA and any guidelines provided by the railroad company.Anchor: #i1004944
For development of Exhibit A plans, 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 designers TxDOT recommended practices where a difference of opinion on certain guidelines exists. Many shortline railroad companies do not have established design guidelines; in these cases it is recommended to follow the BNSF/UPRR joint guidelines.
See the “Rail Safety” section of the Traffic Operations Division website for railroad company design standards. Additional design references are found in Chapter 14 of this manual.Anchor: #i1004959
TRF standard sheets which apply to rail-highway projects include:
- Railroad Crossing Signs and Signals (RCSS)
- Railroad Crossing Pavement Markings (RCPM)
- 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.Anchor: #i1004989
Railroad or Highway Relocation
Relocating a rail line or highway may be considered as a design option to:
- improve operational problems caused by blocked crossings
- 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 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 industry desiring rail service can locate 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.Anchor: #i1005029
Vertical curves should be evaluated on all approaches going over an at-grade crossing. Significant grades can cause the following problems:
- Low-clearance and long wheelbase vehicles can get stuck on the crossing.
- Field panels can become loose or dislodged if a vehicle catches on the approach edge of the panel.
Adjusting the roadway profile to eliminate problems with humped crossings can add significant cost to the project. It is recommended that the following guidelines are followed in evaluating an at-grade crossing:
- On an existing at-grade crossing, inspect the crossing for damaged and dislodged field panels and for scuff marks on the approach pavement adjacent to the panels to determine if vertical clearance is an issue. The suggested maximum approach grade should not exceed 5% at any point within 30 feet on either side of the centerline of the at-grade crossing (not an average).
- For new at-grade crossings, the field panels should be at the same elevation as the rails while approaches should be within three (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.
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 by low-clearance and long wheelbase vehicles via permit restriction to the Texas Department of Motor Vehicles (TxDMV); also report minimum number of inches of vehicle vertical clearance needed for safe clearance of crossing
- if a hydraulic low-clearance vehicle may use the crossing by lifting the trailer, report to the TxDMV the distance before the crossing in feet where the trailer must be lifted and beyond crossing in feet where trailer may be lowered.
- improving approach grades to the crossing.
Any changes to the crossing should be reported by the District Railroad Coordinator to TRF-RSS.Anchor: #i1005099
All passive public crossings should have a stop or yield sign installed with the crossbuck sign. Two common problems at passive crossings should be considered:
- There must be sufficient approach sight distance down the tracks to allow a driver to stop before the crossing when an approaching train is seen.
- There must be 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 (preferably gates). Refer to Part 8 of the TMUTCD for guidance on stop or yield signs.