4.1.12 Grade Crossings (Roads)

Prototype Information

For the vast majority of the American public a grade crossing is the only interface between a person and a railroad. Most everyone is familiar with them, in some facet, and usually the grade crossing sits empty. There may be more trains in operation, but the main lines do not cross urban America like they did in ages past. 

In the prototype, grade crossing installations depend on the history. If a road exists prior to the railroad being built, the railroad has to both build and maintain the road crossing. But if a road is built after the railroad is in place, the city or county has to build it and also maintain it. The former case naturally results in great local frustration, because the railroad rarely cares as much about a smooth roadway as do the local citizenry, and it can be hard to get them to do maintenance.

Types of Grade crossings. Grade crossing in the 1950's were of four basic types, and those types were designed and constructed based on the the type of road and the traffic it carries. Railroad Common Standards may name them differently but those types are (from high traffic to low traffic): 

Type 1 crossings for state and federal highways with heavy traffic

Type 2 crossings for important streets in towns, main country roads and state highways which have heavy traffic.

Type 3 crossings for country roads and street crossings on which traffic is only moderately heavy.

Type 4.crossings for farm and unimportant public road crossings where traffic is light.

Here is a copy of the Union Pacific Common Standards page for Grade Crossings dated 1928, with notes indicating updated standards to 1937.

Three of the four types have different filling materials consistent with the era of the Common Standard: dirt, gravel, asphalt and concrete.

Later era saw engineering common standards for filling material includes timber, pre-stressed concret, rubber and metal panels.
 

 

 

The WWSL

The WWSL has a number of road grade crossings. The WWSL however reverses the road crossing type designations by traffic level identified above. Type 1 and Type 2 crossing are least expensive, more predominate, and use a variety of filling materials between the rails. Specific engineering is consistent with the Union Pacific Common Standard, when available, and other railroad Common Standards when appropriate..

Modeling Information

Engineering. Some basic rules for grade crossing engineering regardless of type are:

  • Road approaches should be level with the top of crossings for a distance of at least 20 feet outside the center line of track.. The road approach grade should conform to statutory requirements, but not more than one foot in sixteen feet.
  • When filling material (between the tracks) will not provide a hard smooth running surface, it should be topped with suitable material of adequate thickness to withstand the wear and maintain an even surface.
  • Rail joints should be arranged that they will fall outside of crossings wherever practical.

Road Construction Techniques. Road Construction techniques are not covered by the 4.1.12 series. See 5.9.1 Dirt Road, 5.9.2 Gravel Road, 5.9.3 Asphalt Road, and 5.9.4 Concrete Road for the appropriate road construction technique.  

Grade Crossing Construction Techniques. Here are the grade crossing construction techniques coverd in this series. 

Type 1 Unimproved grade crossings.  See 4.1.12.1 Type 1 Unimproved grade crossing for the appropriate construction techniques using dirt, gravel, road oiled ballast, or asphalt crossings.

Type 2 Rural Road Crossing (Light Traffic)
. See 4.1.12.1 Type 2 Rural Road Crossing for the appropriate construction techniques using timber planks along the rail using dirt, gravel, road oiled ballast, or asphalt crossings.

Type 3 Urban Road Crossing (Medium Traffic) See 4.1.12.1 Type 3 Urban Road Crossing for the appropriate construction techniques using wood plank, wood grate, or scrap rail.

Type 4 Major Highway crossing (Heavy Traffic). See 4.1.12.1 Type 4 Major Highway crossing for the appropriate road construction techniques using timber, concrete, rubber, or metal panels.   

Reference

Union Pacific Common Standard, Road Crossing 



No comments:

Post a Comment