Western Railroad Discussion > Crossover Speed Question

Good Evening:

What is the maximum speed allowed on BNSF and UP that trains can travel when crossing from one track to another? On CSXT, it is 45 mph where crossovers are installed to handle that speed. I think Amtrak allows 80 mph on certain areas of the Northeast Corridor. I am not sure about the NS.

Thank you in advance.

It all depends on the size of the turnout.

CSXT_8437 Wrote:
-------------------------------------------------------
> Good Evening:
>
> What is the maximum speed allowed on BNSF and UP
> that trains can travel when crossing from one
> track to another? On CSXT, it is 45 mph where
> crossovers are installed to handle that speed. I
> think Amtrak allows 80 mph on certain areas of the
> Northeast Corridor. I am not sure about the NS.
>
> Thank you in advance.


Highest I've seen is 60 MPH...

The speed through the curved portion of a turnout depends on the "size" of the turnout. Attached are two images.

The first image depicts a new Amtrak crossover utilizing two - number 32.7 turnouts. The 32.7 turnouts feature three (3) switch machines powering the switch rails and a fourth switch machine powering the moveable-point frog. This crossover was eventually installed at CP Post, Providence, Rhode Island.

The second image depicts a new turnout of unknown (huge!) size being fabricated at a turnout plant in China. This turnout will be used on one of China's high speed rail lines. When standing at the tips of the switch rails, the frog is barely visible in the distance.

Obviously, the greater the distance between the tips of the switch rails and the frog (as well as the angle of the frog), the greater the speed with which a train can negotiate the curved portion of the turnout.

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It depends on what the employee timetable and the signal
indication say for any particular crossover or turnout.

The Union Pacific and BNSF have several different turnout speeds:

No. 15 turnouts are good for 30 MPH.
No. 20 turnouts are good for 40 MPH.
No. 24 turnouts are good for 50 MPH
No. 30 turnouts are good for 60 MPH.

A general rule of thumb is the maximum speed for a turnout is twice or slightly higher than the turnout number.

Generally speaking, in new construction (like the double tracking work on the Sunset Route) has seen No. 24 turnouts used for crossovers. The Santa Fe and now BNSF have been using No. 24 turnouts on crossovers for decades now. While I have seen No. 30 turnouts installed in Nebraska, they don't seem to be timetabled and signals at 60 MPH. Only the crossovers at Gibbon at the Kearny Sub/Marysville Sub junction seem to have 60 MPH listed in the UP timetable. Its possible No. 30 turnouts have 40 or 50 MPH speed limits to reduce heavy wear on this turnouts since they are in heavy tonnage coal country.

I remember when SP and then UP added "high speed" cross-overs to the Cal-P line in Northern California. When riding through them on the Capitols, it still felt slow compared to the top speed of 79mph, but I'm sure it's much, much faster than what it would have been. Want to say those turnouts were good for 35-40mph, but I'm sure somebody will have better numbers.

Nathan

The number of the frog and the length of the points both are a factor.
The length of the point is the length of the movable part, from the tip ("point") to the heel block, where the rails are 6-1/2" apart. Note that now that turnouts are almost all completely welded, the physical length of the steel can be any length, but the heel is the definition point for the length of a point.
The number of the frog is the distance along the straight side that one travels in order to achieve a one foot lateral separation on the turnout side.
(Yard turnouts are No. 10 and down to No. 6, and while all trains can negotiate these, the speed is very limited. Where reasonable speed is needed the RR will spend more money for the bigger frogs as for ends of sidings, junctions, and crossovers.)
A very common western crossover has 39-foot points and No. 20 frogs and is good for 45 MPH on the crossover move.
The SP used to have some No. 20 turnouts with 30-foot points and their speed was 35 MPH.
The ATSF had many No. 24 crossovers that were rated at 50 MPH but they had 39-foot points and in my opinion they rode very rough at that speed.
Metrolink has some No. 24 crossovers and turnouts with No. 24 frogs an 56-foot points and I think they ride very well at their design speed of 60 MPH.
One of these is at CP Avery, in Laguna Niguel, and is used by almost all westbound (northbound) Metrolink and Surfliner trains.

The Surf Line has several 60 MPH crossovers, although this is not BNSF or UP territory.

You might ask this on the European board - years ago someone told me that the TGV lines had really fast turnout speeds...

Bill Deaver
Tehachapi, CA

In the old days, when virtually all turnouts were AREA (American Railway Engineering Assn.) standard designs, you could use rules of thumb like "speed through the diverging leg is twice the frog number". But even then, there were exceptions. AREA designs could use either straight or curved points. A #20 with straight points is good for only 35; with curved points, 45. An equilateral ("Y") #20 is good for 60 on either route (Southern used to use a lot of these).

All AREA turnouts use standard "rail bound manganese" (RBM) frogs. The heart of the frog is a manganese casting, sometimes explosively hardened. But even so, as cars keep getting heavier, the frogs take a terrible beating. So heavy haul railroads have been moving to "movable point frogs", which don't offer a gap for the wheels to pound. UP and BNSF use a lot of these on coal routes. They may or may not have asymmetric switchpoints (which increase diverging speed).

Amtrak, Metro-North, and LIRR have been big users of European designed turnouts with movable point frogs and asymmetric switchpoints. The MNR/LIRR standard seems to be a #27.5, good for 60 diverging. Amtrak has gone to a #32.7, good for 80. Some high speed railways abroad have turnouts good for 120 on the diverging side.

As a historical note, AREA designs for #24 and #30 turnouts have long existing, but few were ever installed by railroads. Erie had #30 turnouts at Howells Junction years ago (60 diverging). Some Western roads used #24 turnouts. Amtrak installed one AREA #30 at "Grove" interlocking south of BWI, and I think of it every Thursday as my train (196) crosses over at 60 preparatory to making a stop at BWI. It goes from Track 2 to Track 1, northbound. It's been in track since the late 1970s, but Amtrak never installed another. Instead, they went with a European design.

The criterion that determines the speed through crosovers is the turnout number.
The higher the no. of the frog the less the frog angle. Determined by the Cotangent of the frog angle rounded off the the nearest whole number.
A #7 frog has an angle of 8Deg 10'15" a length of 10 ft.
A #20 frog has an angle of 2deg 51'51" a length of 35 ft.
On the SP circa 1956-1988 #10 turnouts were restricted to 15 mph and smaller turnouts to 10 mph and #20 turnouts restricted to 45 mph unless they were equilateral.
The lead distance for a turnout is what determines the degree of lead curve(Length of curved closure rails from the switch points to the frog point.
Since the switch rails are fastened to the same switch ties at a the same elevations it is impracticable to super elevate the lead curve so the only practableway to get the speed up is to reduce the frog angle and lengthen the lead curve to reduce the degree of curve through the turnout. Length of lead curve of #7 turn out 63ft 2 and 5/8 in. Degree of curve 15 deg 18'. Length of lead curve of a #20 turnout 160ft 1/2 in. Degree of curve 1 deg 47'.
The only crossover on the SP during my tenure that was over 45 mph was installed at the end of double track and the juncture of the Phoenix Line at East Wellton in 1959. This crossover consisted of two #20 turnouts layed in an equilateral configuration that allowed a speed of 60 mph in four directions. These turnouts had 39 ft point rails that reduced the switch angle to 0 deg 47'. The taper on the switch point also served as the transition into the lead curve. Since both frog and switch points are straight the lead curve only extends from the end of the points to the toe of the frog.
The higher the frog number the longer the lead curve the longer the switch points the longer the lead curve radius
the less the degree of curve the greater the speed.