It’s easy to get lazy and refer to everything on wheels transporting a ballistic missile a TEL or Transporter Erector Launcher. But we should be precise and follow correct usage.
In the case of the Hwasong-14 test the 8-axial TEL that was shown on the 2017 Day of the Sun parade was configured as a TE or Transporter Erector. From the armscontrolwonk article linked above a TE is
TE: Either a tractor-trailer combination or single vehicle that transports and erects missile, but leaves the missile on a firing table and departs prior to launch
You can see with the Hwasong-12 and the Hwasong-14 that North Korea has used a TE to transport and erect a missile on to a firing platform. This is a point emphasised by John Schilling regarding the Hwasong-14
Finally, while the Hwasong-14 appears to be carried by the same transporter used to parade the KN-14 through the streets of Pyongyang, it isn’t being used to launch the missile. Instead, the transporter simply erects the missile on a small, expendable launch stand, and drives away to a discrete distance. This will slow down launch operations to some degree, but greatly reduces the probability of an expensive and possibly irreplaceable missile transporter being destroyed in a failed test. North Korea may retain the ability to launch directly from the transporter in wartime operations. Even if they don’t, the missile is still at least somewhat mobile and so difficult to destroy in a preemptive strike
How mobile? Perhaps, not very we may answer.
It’s worth considering in this context China’s early experience with its liquid fuelled ICBMs, which were not initially deployed in silos. The DF-5 was China’s first ICBM able to strike the continental United States and it had a base and firing mode known as chu men fang pao or “shooting a fire cracker outside a front door.” According to the Federation of American Scientists, sourced from Lewis and Xue’s China Builds the Bomb, shooting a fire cracker outside a front door worked exactly as it sounds
As with the DF-4, initially the DF-5 was stored in a horizontal position in tunnels under high mountains, and are launched immediately outside the mouth of the tunnel. The missiles must be moved into the open and fueled prior to firing, an operational mode dubbed chu men fang pao (shooting a firecracker outside the front door), with the fueling operation apparently requiring about two hours
The North Korean military, a legacy of the US saturation bombing during the Korean War which literally flattened the country, we’ve forgotten but they haven’t, does like storing military hardware in mountains. I wouldn’t be surprised if North Korea’s liquid fuelled ICBMs will employ China’s early shooting a fire cracker outside the front door firing strategy. That is, what we have seen with the Hwasong-12 and Hwasong-14 firing sequence is exactly how North Korea will fire its ICBM’s during a conflict. The Hwasong-14, say, can be based in a mountain tunnel on its TE and then driven to a spot outside of the tunnel where it would be deployed on, and launched from, a mobile firing platform. It would be fuelled in situ as with the DF-5.
From a survivability, and therefore crisis stability, standpoint that isn’t ideal as fuelling can be time consuming. According to CNN, citing US sources, the United States picked up preparations for the Hwasong-14 test. According to the report, the US figured that it would be a test of the Hwasong-12 given that the Hwasong-14 uses the Hwasong-12 engine for the first stage and they saw preparations being made prior to the affixing of the new second stage and the RV. One must be careful regarding this report as US officials may be covering for the initial wrong assessment and the lack of a BMD intercept attempt, and the Hwasong-14 was undoubtedly fuelled at its launch point.
Shooting a firecracker outside the front door encourages a use them or lose them dynamic in a crisis, rendering a degree of fragility to deterrence in a North Korean-US military showdown which doesn’t augur well.